+++ #33 Subject: Re: Nose Ribs From: Float-by Shooter > A question for anyone about the nose rib. Where the front of the rib > will contact the leading edge I am wondering if there will be a > problem with fretting since it will be contacting the skin without > being fastened. I have noticed on production aircraft this type of rib > is open in that area and the leading edge is probably pre formed. I > haven't got to that point yet but was wondering if anyone has any > information or view on this. You aren't the only person to wonder about that, but I don't recall ever seeing any of the engineer types say much about it here so I don't know how much of a concern it is. I wonder if the tips should be immobilized in some kind of sealer when the wing is skinned or if that is even possible. I'm sure making the edges smooth and burr free would probably have a big impact on it, but I too would like to hear from somebody who would know if this is a concern. +++ 278 Subject: Re: wing rib layout From: Steele, David A There was a layout on Dreams of Flight webpage http://www.geocities.com/CapeCanaveral/Hangar/4424/project.html > Greetings - Just recieved me plans. Somewhere I remember seeing a > layout someone had done to make the best use of space of Aluminum > sheets used to form the majority of the ribs. Any suggestions? > Thanks +++ #281 Subject: Re: wing rib layout From: Float-by Shooter On Thu, 30 Sep 1999, Todd Chisum wrote: > What are the blank sizes needed for the individual rib parts and the > quantity of each? I can't tell from the layout on the webpage below > how big the pieces are. I don't have my plans yet but I want to start > gathering aluminum. Are the ribs made from 0.025" 2024-T3 Clad? The blank size will be the finished size of the rib plus the width of the flange. There just isn't any getting around the need for the plans, they along with the newsletters should tell you what you need to know. Most of the ribs are made from the .025 material, and a few are .032. Knowing how much material I used on my ribs, if I were starting over I would probably order an 18 foot roll of the .025 from airparts, that ought to keep anybody busy for a good long while. Better to be worrying about how you are going to make your forming block, since you will need that first, along with any workbenches or whatever you will need. But until you get your plans, your hands are somewhat tied. +++ #314 Subject: Re: New-be Questions From: Timothy Neil What i did was to cut the ribs to length before bending or forming.Look at the plans and determine.If I were to do it over I would cut them all full length and trim when installing between spars.I found I had to trim a little anyhow on most of the ribs when assembling the wing. > All right all you master wing builders - I'm just getting started and > have a few "method" questions > 1 - Ribs vs spar - Looking over the drawings and noting the different > rib length requirement, (to compensate for the differing spar cap > strip thicknesses), I pose the question of whether to build the spar > and caps first, then the ribs. +++ #319 Subject: Re: wing ribs From: bearhwk27- Having completed the rib fabricating task I think that it is faster and results in a better rib to make them in sections and trim at final fit. 1. Shorter ribs handle easier in the shop. 2. Less material is wasted when making them in sections 3. If Murphy works second shift in your shop he might let you get away just remaking a few rib sections. 4. You will have to cut and final trim any way and it is actually not a big deal. 5. The shorter sections of ribs are easier to flute and straighten out than a full rib. 6. Whatever method is used to cut out ribs is easier when handling smaller blanks of material. I found that the rib fabrication process described by Bob in the newsletter was very accurate and enjoyable. +++ #320 Subject: New-be Questions From: Russ Erb > All right all you master wing builders - I'm just getting started and > have a few "method" questions... I've taken to supporting the idea that you should use the method that you feel most comfortable with. To help you in this decision, I'll tell you what I did. I built the ribs first, then the spars, but they were done independantly so they could have been done in either order. I cut my ribs by making a pattern block that I used to cut out the ribs using a router with a laminate bit (what they trim counter tops with). Where necessary, the pattern block was made to the length of the SHORTEST rib. On each end I added spacers made of the same material as the spar cap strips. I made a careful list of length (number of spacer blocks) for each rib, and developed a numbering system to identify each one uniquely. Note that these numbers have to stay with the rib until it is actually installed. Using the router jib results in very accurately cut ribs. Note that I have not assembled my wings yet, but the flaps (done with the same process) went together very well and fit much more precisely than I had hoped for. Note that my way requires a LOT of work and preparation up front, but it pays off in the end. Just like the FRAM commercial (paraphrased): You can do the work now, or you can do the work later. 2) - Shot bag - My brother worked for Cessna (back in the hay days of the late 1970's) and briefly described their prototype method. When hand building a prototype, they would form the ribs with a hammer and a shot bag to spread the hammering forces out. Is this a good idea or not neccesary?< I'm not familiar with the shot bag method described, but I know what I did. I whacked the ribs out with a 1 lb dead blow hammer (shot in fluid in the head to attenuate the bounce) with good results. I was so concerned about beating out the first rib I got it set up, then quit for the night. It was no sweat--in fact later I intentionally tried to screw one up and couldn't. That is if you follow two simple rules: First set the bend radius by whacking against the bend itself, and second bend it over evenly. Don't hammer one end all of the way down without starting the rest of the rib. A friend produces T-18 ribs for a kit manufacturer--he hammers them over, then beats the flanges with a lead bar (made by melting down tire balance weights--hazardous if not done right). Works very nicely--he then uses a shrinker in a few places and has a rib with no flutes--interesting, but not necessary for what we are doing. +++ #323 Subject: Re: Rib trim and attachment ,more thoughts (Teste From: bearhwk27- Hi Wing Rib Contemplators. A couple more tid bits. 1. To easily trim a rib I rough cut with snips. Belt sanded to final dim. I have a 2 in wide vertical belt, made a table extension from particle board to support the rib, flange up, have a rib guide,stop and a fence setup, so push into belt till stop then across rib edge. Done. Deburr. About 20 sec per rib. 2. Slow drum roll............ The ribs attach to the angles not the spars....! A rib trimmed to leave a slight gap between the rib and the spar may be a good thing. The rib material between the attach angle rivet holes and the end of the rib is there to allow for strength of the angle to rib rivet joint. The rib end material adjacent to the bend radius of the attach angle is just along for a free ride every time you fly. Watch this area for minimum rivet/edge requirements. By leaving a slight gap there is some adjustability and you eliminate a rib end from possibly working against a spar cap strip and fretting a stress riser. +++ #324 Subject: Re: New-be Questions From: t18co- The T18 ribs are being stretch formed from 6061-T4. The same technique will not work with 2024-T3, it will crack. It is possible to form them this way from 2024-T0 and have them heat treated, but then you have to correct the warpage and there are much easier and less expensive ways to go. Since I have formed many ribs using the stretch method in the past I originally thought I might get Bob's opinion on the substitution of 6061-T4 and form my Bearhawk ribs by this method. After building the form blocks and trying Bob's method I found it very easy and since I had almost enough 2024-T3 scrap I formed them just like he shows in the newsletter. The length issue has been well covered and of the methods mentioned should work fine. As Kevin mentioned the rib is riveted to the attachment flange and it is probably not desirable for the web of the rib should touch on the spar. +++ #331 Subject: New-be Questions From: CAROL L. FAGAN With the ribs being the first pieces I made, I was not totally convinced of my abiltiy to interpret the plans to the degree necessary to make them all the exact size, so I made them all oversize. I was glad I did, when it came time to install them on the spar, it was nice to have that extra material. I installed the tip end rib, the longest ones, first. If the spar end wasn't cut to the right angle, or if I didn't like how it fit after drilling, I could cut it down and use it over again over the 1/2 inch cap strips. Helped to save some parts. I am in the process of skinning the second wing now. When I riveted the first wing structure together, I riveted the angles to the ribs, then riveted them to the spars. Driving the 4 and 5 rivets with the ribs in the way was a hassle, and it was a lot of trouble to drill out any bad rivets. On the second wing I riveted the angles to the spars, after predrilling the whole structure. We had good access for riveting and for drilling this way and it went much better. It was a simple matter to then rivet the ribs to the angles. A much better way to go. +++ #467 Subject: wing ribs From: swordman- Hello everyone, My name is Brian Sword, Bearhawk builder#375. I`m just getting started and I have a question. Do you build the wing ribs in one piece and then cut them up, or do you build them in three pieces; Nose rib, center rib, etc...? I know this is old hat for some of you but I would appreciate the help. +++ #471 Subject: flanging tool... From: Steele, David A http://members.tripod.com/zodiacbuilder/ribforming.htm I found this on the web, at the site of a builder who's making a Zenair 601HD. Don't know if anyone has tried this, but I thought I'd pass it on. It shows a little tool this guy made to flange the holes on his Zodiac's ribs. I have NOT tried this, and can't vouch for whether it would be easier or anything, but thought you guys might be interested in at least taking a look at this gadget. +++ #472 Subject: Re: flanging tool... From: Float-by Shooter Avery makes a tool just like that using poly rollers of some kind. I tried it for the 1/4" flanges but I didn't care for it. If you are not careful, the bolts holding the rollers on could scratch the aluminum on the underside of the rib. You could probably switch to round-head machine screws to eliminate this problem. I imagine you could get different bearing widths to make whatever size flange you wanted. +++ #473 Subject: re- flanging tool From: amsp- i have seen those in the catalogs but have had no experiance with them.i know i repair alot of parts for the mil.in alot of them we have to make new lightning holes in.we have found the easiest way is to use dies for the lightning holes.if you have access to a small lathe they are easy to make out of a small chunk of alum or steel.then after you cut the hole you you file and sand to make smooth as possible.then just coat the area with a little oil and squeeze in a press or even a vise. if anyone needs help making them let know and i can give more advise on them. +++ #477 Subject: flanging tool... From: Russ Erb Message text written by INTERNET:bearhawk@egroups.com > http://members.tripod.com/zodiacbuilder/ribforming.htm > I found this on the web... I agree with Del. I have the Avery tool that is similar the one shown. You would think that you would just slip this over the edge and roll it around the hole until the flange was formed. However, it doesn't work that easy. The tool keeps twisting in your hand from friction. Apparently there is some technique involved that I haven't figured out yet. Del right that once you get to a certain angle the head of the bolt holding the roller starts to scrape on the material. I haven't found it to be much more useful than the slotted stick that Bob Barrows shows in the newsletter. +++ #478 Subject: wing ribs From: Russ Erb Message text written by INTERNET:bearhawk@egroups.com > I`m just getting started and I have a question. Do you build the wing > ribs in one piece and then cut them up Only the tip ribs (2) are formed as complete ribs. All other ribs are formed separately (nose, center, back, etc). You'll have to pay close attention to the length of the ribs as it changes depending on how many capstrips there are on the spar at that point. +++ #483 Subject: Rib Flanges From: t18co- Over the years I have tried a number of methods of flanging holes, including the slotted stick and the tool like Avery and others sell. All these methods work to some extent. Flanging dies are well worth the effort for the ease of use and the quality of flange. For doing the ribs on the Bearhawk dies made from hardwood will hold well enough. They could be made on a lathe, but I made them using a flycutter in a drill press. Grind the cutting tool to cut about a 45 degree angle. I used scrap birch cabinet grade plywood to make a male and female die and formed the parts in my hydraulic press. A vise will work, but on the center ribs and the tip ribs it is a bit unwieldy to do by yourself. A nice thing about the dies is they do not distort the part like most of the other methods. A tip on rib lengths. I made a template using the full size rib drawing that has all the tooling holes punched and spar locations marked. From this template I made my form blocks from 3/4" maple and templates for the nose rib, center rib, etc. These templates were cut to the length of the longest rib. I formed the longest ribs then cut my templates off for the next longest, etc. This method works for me and requires little or no additional trimming later in the project. The rib lengths are not called out on the drawings, but this is one of those things that will be easily determined as you study the drawings. +++ #560 Subject: Riveting From: bearhwk27- I am attempting to rivet the .032 angles to the rear spar at the vertical stiffener locations and am encountering a slight lifting or bowing of the angle leg in contact with the stiffener. This condition is present only on the shop head side of the rivet. Finished height and diameter are to spec. The area adjacent to the rivet is in good contact and the lifting starts about .060 from the rivet. Separation of the parts is maybe .005, the factory head side shows no gap. Any clues to what is happening? +++ #561 Subject: Riveting From: Russ Erb I had the same thing happen on the attach angles on the flap and aileron spars. I expect that you are "peening" the metal. Put a piece of aluminum on a piece of wood or a shot bag and whack it a few times with a ball peen hammer. You'll see the edges bend up. As the .032 sheet is compressed under the rivet head, it tries to deform outward, resulting in the bend in the piece. This is the way folks like Kent White put compound curves in aluminum. Additionally, if the shank of the rivet grows in diameter, you would see the same effect. While not practical on the stiffener angles, this is precisely why the edges of sheets overlapping other sheets (such as the gussets on the flaps/ailerons) should be bent down about 10 degrees. This will keep the edge from raising up when the rivets are driven along the edge. Avery and others sell a tool specifically for this purpose (edge rolling tool). I'm not concerned about it, since almost all of the loads are carried through the rivet junction anyway. The rivet joints appear fine otherwise. I hadn't thought of it earlier, but you might try hammering the rivet with less force. I don't know if it will make any difference. +++ #562 Subject: Re: riveting From: amsp- unfor it is sometimes common for the edge to lift a little when riveting.a couple of things that can be done to stop this is one like they were saying to roll the edge down a few degrees to cause a spring affect to pull the center down and keep the edge from lifting.another way is to set the rivet first then tap the part flat and then finish setting the rivet.if you also rivet in short hits you will get a better bucktail and wont compress the center to lift the edge. also when you lay out your rivet patern watch your edge distance.if it to far away from the edge it will cause it to lift.for edge distance i recommend the minimum for the type of rivet your setting. +++ #667 Subject: Re: rib/ CAD ??'s From: Float-by Shooter > Why doesn't someone in the group with CAD access, plot the airfoil and > run off a bunch of mylars which will be stable and easy to ship and > reproduce? Just about everyone would pony up the cost for a copy I tried the cad thing when I made my forming block. After several hours of fiddling with it I decided not to waste a second evening at it and traced the mylar onto my oak block using carbon paper and a nail with the tip rounded off somewhat. When the block was finished I checked it against the mylar and it was just about dead-on, which had nothing to do with how I drew the pattern onto the wood and a lot to do with slowly sanding down to the line with my bench-mounted belt sander. > effect the stall the most. Of more concern is making certain the > airfoil you've plotted for your ribs matches the spar > dimensions. It'll be a real bummer to fabricate your ribs and spars > and then find the ribs are narrower than the spars or vice versa. It is my understanding of the plans, that the spar webs are bent to match the ribs, regardless of the height given in the plans. I haven't attempted any spars yet, but my ribs turned out to be about 1/8" taller than what the plans show. I inquired about it on the old email list at the jbc.edu server (re: something is wrong) and everybody said not to worry about it, that is normal, and the air molecules will not know the difference. I think if somebody had access to a cnc router to cut out the forming blocks and ribs, then plotting the airfoil in CAD would definitely be worth the effort. I'm not sure what the coyright issues would be if a person were to share his cad renditions of Bob's drawings with the net. +++ #670 Subject: Re: rib/ CAD ??'s From: mskiba- About the rib blocks and CAD, the pattern on the full size #7 drawing is just a tracing of Bob's rib block. Doing that in CAD would not be like a plotted airfoil. everybody should concentrate on consistancy not getting it exactly to the thousanth of an inch. Also if you form your ribs using Bob's method the height will be the same or close as the plans, if you use another method like forming the flanges over the block with a larger rarius than 1/16 it will be a little higher. Whatever way you do it just get hem all the same. consistancy is the key. +++ #696 Subject: redundant question From: Jenni Thatch What radius did you put on your rib form block. I will be using the imput from this news group to run to sears and buy the proper radius for my block any info would be very much appreciated. I am hoping to get started on my first aircraft this weekend. Thank you in advance for your help!! +++ #767 Subject: Re: Wing rib lightening holes From: Float-by Shooter > I don't see any reference as to what diameter the lightening holes > should be in the wing ribs (The spar holes are listed). Is it an > educated guess as to whatever seems right but not too large as to > weaken the rib? I measured the holes as drawn on the plans and scaled them to the proper size for the ribs. Be sure to drill and flange only one hole at a time, Othewise getting your rib straight afterwards will be a nightmare, according to some of the list archives. Spose I ought to get that in the FAQ. +++ #771 Subject: Plans scaling From: Rod Smith Refering to the rib ligtning hole size question. Dimensions for a lot of the parts are not printed on the plans, you just have to measure the plans. The simplest way to do this is to purchase a triangular engineers scale. These come in 12 or 16 inch lengths. You want to get the type that have 6 scales from 1/10 inch to 1/60 inch. This makes measuring everything on the plans very simple. For the 1/10 scale drawings you use the 1/10 inch scale. The number you read x 10 is the length in inches. For the 1/4 scale drawings you use the 1/40 scale and the number you read is the number in inches. For the parts that are shown full size you can either use the 1/10 scale if you want dimensions in 1/10s of an inch or just use a regular ruler if you find it easier to deal with fractions. Somebody I was talking to before I had bought my plans said the plans look great but they are in metric and it is pain to convert them. Most of you probably already know this but it might help out those just getting their plans. +++ #773 Subject: Re: Plans scaling From: Rod Smith Bob has a good understanding of where tolerances need to be close and calls out exact dimensions in those locations. I would agree with Bob that you can measure a lightning hole from a 1/2 scale drawing "close enough". For the most part building this plane isn't rocket science. > Being an engineer, I expect the plans to be complete with most > every dimension needed to duplicate the aircraft explicitly > denoted on the plans. At best, I believe it is "tacky" to leave > these details off of the plans. Otherwise I call them a rendering. +++ #887 Subject: Hammering Fuel Tank Ribs From: Russ Erb Time for another installment from Erbman on observations on building processes. The subject today is hammering out the fuel tank ribs. These ribs (the ends and baffles) are made of .050 5052H-32 aluminum. This alloy of aluminum is easily formable and very weldable. The rib flanges are hammered over a forming block in similar fashion to the wing ribs. The forming block is different from the wing rib forming block, being slightly smaller in size. I found the flanges somewhat harder to hammer than I remember the wing ribs to have been (it's been a long time--that was early 1997). This was judged by how quick my arm got tired of whacking at ribs. You might think that obvious, since the ribs were thicker (.050 compared to .032 or .025). However, I think 5052H-32 is a softer alloy than 2024-T3. The springback in 5052 is significantly less than in 2024-T3. Whereas the 2024 ribs would have roughly 30 degrees of springback over a 90 degree form, the 5052 had very little springback, maybe 2 to 5 degrees. The 5052 had a little waviness to the flange, but nowhere near as much as the 2024 had. There was still some curvature to the ribs caused by the excess metal in the flanges. On the wing ribs we addressed this by fluting. However, in this case I'm looking to take the ribs to a friends shop who has a metal shrinker. This will straighten the ribs while leaving a flat flange for welding on. Since the end ribs are shown with flanges on the top, bottom, and both ends, it is important to make relief holes at the corners where the two flanges come together so that the metal doesn't tear or crack. See page 54 of the yellow Bingelis book if you don't understand what I am talking about. The bottom of the fuel tank rib is a straight line. A while back, someone suggested forming the spar web flanges by clamping the webs to a forming block and hammering the flanges over. The consensus was that this would not be a good idea, as the edge of the flange would stretch during the uneven hammering process, and would end up wavy. Based on the bottom flange of the tank rib, this is exactly what would have happened. Worse yet, the spar would have been curved and needed fluting just like the wing ribs. Better to fabricate or find some sort of brake for bending the spar flanges. When I made my forming block for the wing ribs, it was oak and had pieces of steel tubing (bushings) driven into all of the center holes so that the wood would not slowly work into a bigger and bigger hole with each drilling. For the fuel tank, since I was only making eight ribs, I made the forming block from plywood (had some laying around) and did not bush the holes for the two bolts. I drilled all eight of the ribs at the same time through these holes, and even this one drilling made the holes in the wood bigger. This would lead to inaccuracies if more parts had to be made from these blocks. I highly recommend bushing the jig holes in your forming blocks. +++ #1106 Subject: Re: 416th From: Float-by Shooter > I did forget to ask which side of the line do you cut the working rib > blank to? Inside or Outside? Do you mean the forming block? When I made mine I cut it slightly oversize and gradually sanded it down to the line. For cutting the aluminum rib blanks I just used my tin snips or air shears and cut about 1/8" oversize on the first pass, then cut as close to the line as possible on the outside. I found that if I really concentrated, my snips were actually capable of splitting the line (ultra fine point sharpie marker) down the middle. +++ #1109 Subject: Form block's & That Dam AFoil Line From: Tim Cramb The metal aluminum blank cutout, not absolutely critical. Your cut out line becomes the bent over flange for attaching to the stiffners/skins. Now for the wooden form block(s)........Here's the exact wording off my MM1 blueprints which is referring to the making of the wooden rib form block(s)........I think this puts it best> OUTER EDGE OF DRAWN LINE IS RIB O.D. FORM BLOCK TO BE .025" SMALLER ON ALL EDGES MAT'L .025 2024T3 Bill....Let's split some hairs here The above instructions mean, if you make the form block .025 thou smaller, you are allowing for the thickness of the material, so when you are finished your rib O.D. matches the outer line of the airfoil template. If you didn't allow for this, your ribs would be .025 thou bigger. Now Bob's thickness of the airfoil out-line the Pen drawn line thickness, I measured is pretty dam close to .025 thou. So if the designer intends for the outer line to be the rib O.D., you would remove material (sand) to the inside of the line.....If this is what he intends. On Bob's mylar/plastic template it doesn't say.....So this is what I did and to be honest if I'm off .025 thou (leaner) it'll just mean that I'll go .025 faster and will make my big mean .040 thou spar look like it's sporting a woody/got a chub-on ;-) Will the small details kill yeah???...Nope, but that ulcer you get from them might. +++ #1110 Subject: Re: Form block's & That Dam AFoil Line From: Float-by Shooter > On Bob's mylar/plastic template it doesn't say.....So this is what I > did and to be honest if I'm off .025 thou (leaner) it'll just mean > that I'll go .025 faster and will make my big mean .040 thou spar look > like it's sporting a woody/got a chub-on ;-) Hey Tim, remember when you were in school and the teacher would make you wear the pointy hat and sit in the corner of the room? 8^) Anyway, drawing #7 *is* the form block (it does say), so you shouldn't subtract anything from it. Bob did us another big favor by doing it this way instead of giving us a drawing of the rib or the wing cross section. +++ #1296 Subject: Re: No 7 drawing/tooling From: budd davisson Re: Drawing 7 A lot of major printing centers like Kinkos and Alphagraphics have Xerox machines that can easily run the full sized No. 7. They look like they work more like blue print machines than Xerox machines so the dimensional creep should be less, but I'm not sure. It could be worth investigating. Somebody in the group should have someone CNC out an 1/8" master out of aluminum that can be shipped around to everyone else for some sort of rental fee. As far as that goes, I may be wanting to rent some tooling from someone who has gone past the form block stage. Ditto hinge tooling. With this kind of communication going, it makes some sense for a number to go together to get hard tooling machined for certain applications and bicycle it from place to place, as it's needed. No need for every single one to re-invent the form block, etc. +++ #1299 Subject: Re: No 7 drawing/tooling From: The Martins Well, I was planning to go one step further and have form blocks and rib blanks waterjet cut. I keyed in a program to directly generate a dxf file of a 'pure' 4412 airfoil, and it matches pretty well except for the nose droop and the truncated trailing edge (my generated one comes to a point). I got that much done before Thanksgiving but we've had a bunch of production problems at work and I just never seem to get back to it. Getting it to match the mylar is going to be a process of plot, measure, guess, tweak, replot, and try again. When it all fits I'll import it into CAD and add the flanges and various holes. After a trial run or twelve, I hope to make rib blanks with jig and lightening holes precut. Only the unflanged nose region and the lengths and jig pin holes are critical, but the form block is obviously all critical. My brother in law will do the cutting at his business. When I get the outline right, a 1/8" master should be a piece of cake too, or even any number of form blocks. The problem is getting all this real world stuff out of the way first so I can pay the bills. +++ #1300 Subject: Re: No 7 drawing/tooling From: Bob Romanko > No need for every single one to re-invent the form block, etc. See here, Budd! The form block and a few jigs are all the wood we get to work with on this plane! Form blocks and tooling build character. I cannot imagine using someone else's tooling. Sheesh! I'm growing a maple tree now for my form block. My cubicle mate, who happens to have a forestry degree from VA Tech, inspected my form-block tree. He estimates that based on the projected climate of Central Virginia, I should have my form block completed around 2083. Rent a form block indeed. +++ #1301 Subject: Re: No 7 drawing/tooling From: Van D. Gray I like Bob's sense of humor. I also like Budd's request that tooling be made and builder's be able to rent it. Part of the spirit of homebuilding is helping others. Sure you can make every part; my problem is that I usualy have to make three. The first one I make is absolute junk. I refer to these parts as the cost of learning (and it is high in my case!). The Second part is recongizable, but no way would I rsik by behind on it. The Thrid time seems to the charm (at least for me). So any help with templates, form blocks, repeatable drawings, etc. would be a great aid. Just my opinion. +++ #1349 Subject: steel drill guide for forming block From: William L. Day (Bill) I must have missed this somewhere. What is used for the steel drilling guides in the forming block? Or, better yet,is there someone who is done with their block and is willing to lend/rent/whatever? +++ #1365 Subject: steel drill guide for forming block From: Russ Erb > I must have missed this somewhere. What is used for the steel > drilling guides in the forming block? Or, better yet,is there someone > who is done with their block and is willing to lend/rent/whatever? I used 5/16x.065 4130 tube for a 3/16" ID. Any steel tube with the right ID would work. Doesn't have to be 4130. +++ #1377 Subject: Re: steel drill guide for forming block From: J.T. Newbegin I didn't use inserts in my form block, I layed out the jig pin, spar web locations and ligthing hole locations. I drilled 3/16" holes and then put the blank under the form block and used a 3/16" bolt with a blunt point to mark all the locations. Be sure your drill press is set up square, mine wasn't and I had problems when I used a rib blank on the wrong side of the wood form block. I ended up with a lot of info on my form block as I progressed to the other wing parts. +++ #1403 Subject: Form block From: Alan Nauman Well, I sent off my order for a set of plans and I was thinking that one of the first items that I need to buy is the hardwood for the form block. I saw on Tom's "Dreams of Flight" page that he bought a 1x10 x6 foot plank of maple. I stopped at the closest Home Depot at lunch and all they had was red oak and poplar. They only had the red oak in 6, 8, and 12 inch widths. What size of plank do I need and is the red oak hard enough for this application? I will probably order a 4x12 sheet of .025 aluminum and a pair of fluting pliers from Wicks next month but I can get the wood and probably a few other small tools locally so I would like to pick thinge up when I get the chance and have the money. +++ #1404 Subject: Re: Form block From: T & E Yeomans Hello Alan. I used red oak for my form block.... it worked but by the time I got to the last rib it was starting to show signs of age. I used it because I had it . So if you are carefull it is ok. the other tighter grain woods will be better. +++ #1405 Subject: Re: Form block From: J.T. Newbegin I used ash but didn't get it wide enough so I added a strip at the highest area of drawing #7. After making all my parts it is still in good shape. My neighbor is building a sonnex and they use high density patical board and holds up very well. I used the same type mat'l for my pocket ribs ail. and flap nose ribs, it held up great. +++ #1406 Subject: rib form block From: Collin Campbell I also used high density (industrial grade) particle board for my form block. It held up very well, looked the same when I got through as when I started. This is the second project that I have done the same. There is really no need in my opion to spend a lot of money on high dollar hardwoods for just a form block. +++ #1407 Subject: Re: Form block From: Float-By Shooter Fancy hardwoods may not be necessary, but they sure make for a pretty forming block. I'm very near the end of the Bearhawk Supply Lines, and sometimes have trouble getting things. The local building supply is great if you want to build a shed, a house, or even EAA chapter 1000 worktables, but they drew a big blank when it came to suitable wood for my forming block (they probably would have had the particleboard mentioned, but I didn't even think about that). They didn't have anything big enough, or even straight enough so I ended up buying their 2 biggest pieces of Warped Oak, and ripped them into about 2" pieces on the tablesaw, which turned out to be not quite square. Drug them out to a friend's place and ran them all across his ancient jointer, then took them back to the shop and glued them up with elmers wood glue. The next day I took the whole mess back up to the lumberyard and had them run through the planer. I ended up with a plank about 1-3/4" thick, and enough leftover to make blocks for the ail and flap nose and ail pocket ribs, and all the bending blocks I could ever want. It worked out really well but I don't recommend it unless you can't find anything that will work. After going to all this trouble, I was out at the airport BS'ing with an old timer and told him about my project. Turns out he had a whole pile of ironbark planks out in his hangar and would have given me enough to make my block. I hear tell that ironbark is so dense and heavy, it can ruin steel cutting tools. Now that would have been a forming block (I'd probably still be working on it tho). +++ #1409 Subject: Re: Form block From: Bruce A. Frank I made a forming block out of a stair tread. I found that the local lumber yard carried stair treads of clear oak that measured 1.125" thick by 12" wide by 42" long. It wasn't cheap but it was available. I later made my forming block out of 1/2" steel and used the oak as the clamping board. +++ #1412 Subject: Form block From: Russ Erb I made my form block out of oak, but I couldn't tell you what color (brown?) Worked great; looks now just like it did before the first rib. Not exactly cheap, but good tooling builds good airplanes. I got cheap when it was time to make a form block for the fuel tank ribs. I used "standard" 3/4" plywood and it seemed to work out fine. My biggest recommendation is to put the metal bushings in where you'll be drilling holes after holes. +++ #1420 Subject: Rib Form Block Material From: bearhawke- To add some more information on the various types of manufactured materials that might be used for form blocks, there is in fact sheet goods that are called "high density (industrial grade) particle board" but this stuff is actually less dense and less hard than what is called "medium density fiberboard" commonly called MDF and available at most Home Depot sort of places now for around $20 for a 4x8x3/4 sheet. The difference is the particle board, common type or "high density" is made of wood chunks and resin and has a certain amount of void space in the material. MDF, by contrast, is made from something closer to sawdust and resin, compacts tighter and more homogeneous. One reference I have notes that 3/4 inch particle board starts with about 4-6 inch thick pile of wood chips and resin whereas MDF starts with a 23 inch pile of resin/fiber mix to compress to the same 3/4 inches. MDF machines very crisply and will hold the bend radius roundover detail very nicely. So where's the High density fiberboard you ask? I think that is commonly called "Masonite." Unfortunately only available in thicknesses to about 1/4 inch but can be even harder than MDF. The stuff you want for this sort of tooling application is called "service tempered" hardboard rather than the more common standard grade stuff. The service tempered grade should have two red striped painted on the edge of the stack, standard grade has a green stripe. On a single sheet these paint stripes may be hard to see on the edge of the material. Finally, you want to look for smooth both sides tempered instead of the smooth one side, waffle pattern on the other side stuff as the waffle pattern sided stuff doesn't glue up as well. A serious form block might be made from laminating a sheet of tempered hardboard to a sheet of MDF (using a PVA type glue rather than contact cement I would think). I also considered gluing on a sheet of Formica onto the surface of the MDF for a harder wear edge but decided that was overkill and made my form block from straight MDF. They apparently sell MDF as thick as 1 5/8 inches but I've only ever seen the 3/4 inch stuff that I used. Carbide tipped cutting tools will last longer and give a finer finish when working with MDF but its not essential. Last reason that you want to use MDF instead of real wood is dimensional stability. Red oak for example will expand and contract about 1% where MDF will do about 0.1%! I rest my case. +++ #1422 Subject: Re: Rib Form Block Material From: Bruce A. Frank I hadn't though about laminating tempered hardboard to make a forming block. That'a funny because I used tempered hardboard (glued it to the plywood)on my wing assembly table top exactly because of its hardness and dimensional stability. +++ #1427 Subject: Form Blocks by the pound From: robert gaddy I just finished making my rib form and back-up blocks. I have followed the recent discussions concerning the form block construction, and chose to use MDF as recommended by one builder. I used a technique that I haven't seen in any of the literature or discussions. I moved the work past a stationary router, rather then moving the router past stationary work. I first formed "master tooling" of drawing #7 out of 0.125 aluminum. This master pattern is screwed to the top of some MDF. The MDF blank was then trimmed to within about 1/4 inch with a small bandsaw. (Details of interest of only a few: I made drawing #7 in three pieces because I didn't have a piece of aluminum long enough. I don't recommend this technique. I think that it would be better to make one big rib pattern, make the form blocks for the tip ribs, then cut it into 3 pieces to form individual nose, mid and back ribs.) I mounted my ancient router to one of the standard size plastic plates (available from most woodworking stores) which is mounted flush with the surface of my work table. I used a flush cut router bit with a bearing on the top. After adjusting the bit height, I just ran blank around the router with the bearing running on the aluminum pattern. I saw this method on the PBS program "Router Workshop" where extensive tooling is used with a stationary router. (Some more details: I made two blocks of the full size rib, the leading edge rib section, the mid rib section, and the back rib section. One of the blocks will be used as the form block and the other as the backing block (after suitably trimmed). I "inlayed" the plastic router mounting plate into the surface of my 2ft X 5ft work table using the woodworker's technique using two different size bushings for the router base. The plastic plate is used as the guide to route out a template. This template is used (with a different bushing in the router) to cut the opening in the table to the debth of the thickness of the plastic plate.) My work table is very similar to the EAA tables mentioned here, except that I made the frame and legs of 1 1/2 inch thin wall square tube obtained locally as "wrought iron" fence material. Have welder - will travel. The top is attached to the steel tube frame with dry wall or deck screws, I perfer the square drive deck screws. Just drill a 1/16 hole through the plywood top into the steel frame and install the screws, making sure they are driven below the surface so they won't snag the work. I installed my router near one end of the table, should have mounted it in the middle so that I would have an in-feed and out-feed table.) I plan to make another master pattern of the flat layout of the rib blanks. I will make a "sandwich" of the rib aluminum material (enough pieces for at least one wing) between a sacrificial plywood lower "bread" and the master pattern. I may use a wooden "master pattern" for the actual cutting of the rib blanks, made from the aluminum master in the same way that the form blocks were made. I will not use this technique for the full size ribs since there are only 2 called out in the plans. I think that I will also use a router to cut the lightening holes, I really don't like fly cutters. +++ #1463 Subject: The Joys of Precision From: Russ Erb There are those who poo-poo the benefit of jigs and tooling, but here's a success story... I made jigs for drilling the holes in the rib attach angles on the rib side. (On the spar side, I drilled the spars first, then drilled the attach angles to match) This was not so much to make sure all of the holes were in the same place on each angle as it was a tribute to laziness--I didn't want to have to measure the position of each hole on each of thousands of angles. It was so much easier to slap the angle in, drill through the holes in the jig, then pull the angle out. First payoff: The thousands of angles were drilled much faster. Second payoff: I was installing the pocket ribs on my wing. By mistake, I drilled a right flanged rib where a left flanged rib should go. Rather than scrap the rib, I tried moving it to an angle of the same type where it would have the correct flange. The holes lined up perfectly! Save! It's been so long since I made those ribs, it would probably just take a few hours to find the jigs and tooling that I used to make them and remember how I did it. That would not have been fun. Shucks, pretty soon I'm going to have to actually rivet the ribs to the spars! (Not a trivial task. If not done in a carefully determined order, you can end up with rivets that can't be reached by a squeezer and have no room to position a rivet gun...bad news...) Right after that I'll have to start fitting skins... +++ #1506 Subject: Form block jig pin inserts From: Alan Nauman I recieved my plans on Thursday and I have been busy reading Bear-Tracks and looking over the plans. I bought a sheet of 3/4" MDF for the form block and I have the shape pretty close right now. My question pertains to the jig pin holes. I saw Tim Anderson's form block and he used metal tubing in all of the jig pin holes for durability. I looked but I have not been able to find any references to these reinforcements. What did you use Tim? Does anybody else have any suggestions? I also have a question on the size of the various ribs. I assume that the spar lines on drawing #7 are the edges of the various ribs. Is this correct or do I need to adjust for the thickness of the spars? +++ #1509 Subject: Re: Form block jig pin inserts From: bearhwk27- Welcome aboard. Drawing #7 represents the contour of the form block no adjustments should be required. After forming the ribs,the spars are bent to match the ribs and then a joggle is formed in the rib flange to nest inside the spar. I used commercially available drill bushings for all my tooling holes. +++ #1510 Subject: Re: Form block jig pin inserts From: Brian and Nancy In regard to your question about rib length. From main spar C/L (center line), on drawing #7, subtract 1/16" which makes jig zero. From this new "zero", make 3 at this length. Make 9 at zero minus 1/8". Make 10 at zero minus 1/4". This is for one wing only. This is to accommodate the thicker stations of the spar because if you'll notice on drawings #2 & #3, the cap strips are stacked for strength. At least, this is how I did my nose ribs. If anyone disagree's, please feel free to chime in. I hope this is of some help to you. +++ #1515 Subject: Ceremonial Removal of the Tags From: Russ Erb Well, Erbman has been out in the shop the last two days riveting ribs to spars. And, as is his custom, he has observations to pass on... So all of the ribs are riveted to the spars for the left wing. This isn't as impressive as it might sound, as without the skins the structure would easily deform if removed from the jig. One big difference is the freeing up of several hundred clecos! The subject line of this message comes from the "dog tags" that have been with the ribs since mid-1998 to identify each rib. The tags were pieces of scrap aluminum (mostly lightening hole centers) with a hole drilled in them and a piece of safety wire tying them to the rib. The identification number for the rib was stamped on the tag. I used this method because it was the only method I could come up with that would survive the process of alodining and priming. You don't want to stamp the ribs directly because of the resulting stress risers. Anyway, now that the ribs were riveted in place, there was no longer any requirement to be able to identify them individually, hence the removal. +++ #1516 Subject: Form block jig pin inserts From: Russ Erb I think I started this whole idea of drill bushings in form blocks. At least I didn't see anyone else mention it before I did those many years ago. Anyway, I didn't use anything cosmic, just pieces of 5/16"x.065" 4130 tube. Just about anything will work if it has a 3/16" ID. You might consider using a drill bushing with an ID of 1/4" for the centers of the lightening holes, that is if your fly cutter has a 1/4" pilot drill. I'd do that if I was doing it again, since lining up a 1/4" drill in a 3/16" hole was a pain. Use a drill press to make the holes for the bushings, especially if you want to use both sides of the form block. They need to be perpindicular! +++ #1518 Subject: Re: Ceremonial Removal of the Tags From: Russ Erb > > I had originally thought that I would be able to squeeze most of the > > rivets attaching the ribs to the spar angles. It turns out that the > > rivets are too close to interfering structure to get the pneumatic > > squeezer in. I ended up driving almost all of the rivets with the > > rivet gun. > > Russ, do you think a hand squeezer would have a fighting chance of > getting in there? I doubt it, and not just because of the length. The problem is in the diameter of the squeezer sets. The set hits the side of the angle and gets pushed off center. If you prefer, the distance from the center of the rivet to the side of the angle is less than the radius of the set. +++ #1521 Subject: Re: Ceremonial Removal of the Tags From: Rod Smith Russ I'm wondering how useful overall that the squeezer has been for you on this project. Is it a must have, nice to have, or just makes some jobs easier. To me it seems that it would be great for times that you dont have help on parts where you can use a squeezer. On the other hand if there are not that many locations where you can use it, I could just save the money for another tool. +++ #1522 Subject: Re: Form block jig pin inserts From: Rod Smith Alan I know you have already received answers to this but I will tell you what I did. All you are trying to do with the metal tubing is keep the jig holes from wallowing out. I just used 1/4 by .035 tubing for the jig pin holes. I used a reamer to get a 3/16 inside hole but I'm sure a drill bit would have worked just fine. As Russ suggested you will probably want 1/4 inch holes for centering the flycutter for the lightning holes. I used 5/16 x .035 tubing for those. If you dont have Russ's CD get it. It will really help you get set up for rib forming. +++ #1523 Subject: Re: Ceremonial Removal of the Tags From: Russ Erb > Runs I'm wondering how useful overall that the squeezer has been for > you on this project. Don't be mistaken, the squeezer is a very useful tool, just not in this one particular instance. Off the top of my head, I've used it to squeeze almost all of the rivets on the rib stiffner angles, the cap strips on the rear spar, over half the rivets in the flaps and ailerons. Good for nutplates near edges (i.e. access covers). It is also preferred for dimpling. I expect to use it all over the rib flanges, and used it a lot on the flap and aileron skins. Many years ago, a guy who had just finished an RV-4 was asked if he used a pneumatic squeezer on his project. His answer was "No, but I wouldn't do another without one." Yea, they're not cheap, but I think I'll get my money's worth out of it by the time I finish the project. +++ #1524 Subject: Lightening hole flange size From: Rod Smith I'm getting ready to make a set of dies for making the lightening hole flanges like Russ did. I just realized that the flange width is not called out on drawing #6 for the nose and main ribs like it is on the back ribs, and flap and aileron ribs (1/4"). I've looked for it in the newsletters and on the CD but cant seem to find anything. I seem to remember 3/8" but I dont know where I came up with that. This was probably discussed on the list in the past. +++ #1525 Subject: Re: Lightening hole flange size From: Paul Foster The flange size is on the same page in the 1995 summary newsletter as fluting pliers are described. The depth of the mouth for the suggested hardwood flange tool is 3/8" as I recall. I am at work so don't have newsletters handy. Will check tonight and if any different will pass on information. +++ #1526 Subject: Lightening hole flange size From: Russ Erb > I'm getting ready to make a set of dies for making the lightening hole > flanges like Russ did. Well, if you're getting ready to do what I did, let me tell you what you should do different. As I recall, I used a 3/8" flange everywhere ahead of the rear spar, and 1/4" behind it. That was a long time ago. (If it was so long ago, why aren't I done yet?) I made the plugs for pressing the flanges with a 30 degree angle, which is what the plans call for the flanges to be bent to. As much as I didn't want to believe it, springback exists even when stretching these flanges, so my resulting flange angle was something less than 30 degrees. The female part of the die was cut with a 45 degree chamfer bit in a router, so that would be the upper limit of the plug angle. If you want a 30 degree flange, the plug angle will need to be bigger than 30 degrees. I can't tell you what the right number would be but you could experiment. I'm guessing something not too much more, like around 35 degrees. I made the female part of the die like a big wing rib with all of the holes in one piece. While this would seem to be a good idea, and the block fits inside the flanged rib, there is a weakness (literally). The thin section of wood between the holes is not very strong and will easily crack (voice of experience) under clamping pressure if not supported. I ended up putting an extra block with a hole just larger than the lightening hole behind it in the vise for support. To avoid this problem, make each female die separately. This might also be a good use for plywood, since the grain of the plies would run both ways. When I pressed the flanges in the lightening holes, they didn't press real evenly. Along the top and bottom of the hole, the flange of the rib stiffened the material, and the lightening hole flange pressed in nicely. However, at the front and rear of the hole the metal was not as constrained and thus did not deform as much under the die. As a result, the ribs were bowed in the vertical direction (perpindicular to the direction of bowing from bending the rib flange). I was able to remove this bowing by bending the flanges at the front and rear of the lightening hole a bit more with pliers. All that fancy tooling and I still had to do part of the job with hand tools. +++ #1738 From: Alan Nauman Subject: [Bearhawk] Wing ribs/spars I asked a question a while back about the length of the wing ribs with respect to the form block. One of the responses mentioned making several of the ribs shorter to compensate for the multi-layered spar. I know that several of you have finished the wings and I was wondering how this all fits together. Do I need to make different length ribs or are they trimmed to fit prior to assembly or are they all the same? It also appeared to me on the wing drawing that two of the nose ribs had flanges that were in the opposite direction of the rest. Is this correct? One more question. Did you make small form blocks for the aileron/flap nose ribs? +++ #1739 From: PFflyerz Subject: [Bearhawk] Re: Wing ribs/spars When building my ribs, I elected to make them all one length and trim them later, as I wasn't so sure about my abilities to get things just right from the git-go. It was no trouble to do them that way, but now that I understand the process, I would build a second set to the proper size. One advantage to having them over size is, if you start to fit the nose ribs from the outboard in, and don't get the alignment right on the first try, there is enough material there that you can trim off the end, where the bad rivet holes are and use the rib again in the central section. Believe me, I know. Yes, you do make small form blocks for the misc. ribs. It's not shown on the plans, but you need to cut some reliefs in the top of the flap nose ribs, similar to the ones on the aileron pocket ribs. As for learning from my mistakes and the many errors of my ways, a letter in Beartracks long ago asked if it was OK to build the flaps and ailerons first. Bob's response was yes, as long as you followed the plans EXACTLY. Well, try as I might, exactly seems to be a pretty tall order for me. Had I built my control surfaces first, they wouldn't have fit my wings, though I couldn't tell you if the problem was in the plans or the execution, most likely the latter. Once my wing was built, I installed the hinge supports on the wing, clamped the brackets to the control surface spars, then spent a LOT of time sliding them around until I was sure where I wanted to drill the holes. Food for thought for those of us precission challenged. Pat Fagan #232 Pearblossom CA +++ #2441 From: Bob Romanko Subject: Anal-retentive form block issue I remember a thread earlier where it was mentioned that everyone's ribs seemed to be a bit on the large side. This was found when building the spar. I remember 1/8" as being the average excessive measurement. Being the anal-retentive type, I made my form block a bit small. What I did was simply cut out my mylar (drawing #7) with a pair of scissors, keeping to the inside of the line. I then tacked the mylar onto a real nice piece of ash (ASH, I said ASH you weirdo. Sheesh!) I went around the template with a fine pencil, marked the center points, and that was that. I cut out close to the line using a reciprocating portable jigsaw. No CNC machines, no lasers, no aluminum templates, no computers. I then sanded to the very, very thin line. I put in 1/2" solid steel inserts at the jig pin locations, and drilled accordingly. As a result, I have a "short" form block. If you tack drawing #7 back on, the black outline is just a fine hairline, and I'm just to that line, within 1/48" of an inch all around. One spot, on top of the block about a foot in is short about a 1/32", but I'm not worrying about it. It's tough getting accurate with wood when you're the anal-retentive type. I see no reason for 1/32" of an inch to make much difference on a form block anyhow. The spars are built to fit. I talked to Bob Barrows the other day about the 1/8" "tall" ribs. He pretty much said that it's most likely a dimension that needs changed on the plans NOT any issue with drawing #7. Ouch! That was AFTER I made my short form block, of course. Bob's not concerned about the dimension as much as he's concerned about how good your ribs fit the block AFTER they're formed. Consistency is the key. To sum it up, the 1/8" tall ribs are not a big deal, and you folks who have assembled your wings already know that. I'll let the group know how mine turn out. I think I've made up for the 1/8", but then again, I'm just being anal retentive...as usual. +++ #2444 From: Russ Erb Subject: [Bearhawk] Anal-retentive form block issue > I talked to Bob Barrows the other day about the 1/8" "tall" > ribs. He pretty much said that it's most likely a dimension that > needs changed on the plans NOT any issue with drawing #7. My theory on the ribs (gee, that was the first half of 1997...) from what I've managed to piece together like any good intelligence agent (not that I claim to be either) is this. And this is my theory, the theory which is mine. The brontosaurus is...oops, wrong show. Several people have said that Drawing #7 is produced by Bob "The Man" Barrows tracing around the Mother Form Block (namely, his original one) directly onto your sheet of mylar. If so, the drawing is going to be bigger than the original by two marker widths. If you build your block to the outside of that line, your block will be slightly larger. Thus your ribs will be slightly larger. But as Bill Murray said in "Meatballs," "It just doesn't matter. It just doesn't matter. It just doesn't matter. It just doesn't matter. It just doesn't matter..." +++ #2542 From: John Morrison Subject: Rib blanks Reading through the archives I see the two most popular methods for cutting out the rib blanks are tin snips and a router. Has anyone tried cutting the aluminum sheet into appropriate rectangles (presumably with a power-snipper), and then stacking them (perhaps as many as 12-20 deep) with a wood mold on top and then running them through a very slow and fine-toothed bandsaw? The bottom blank would be scratched, but is sacrificial and would be re-used for all subsequent stacks. ====================== mold -------------------------- -------------------------- -------------------------- aluminum blanks ******************************************************* bandsaw base +++ #2543 From: Bill Cox Subject: Re: [Bearhawk] Rib blanks John, I cut out the aileron and flap nose ribs and the aileron pocket ribs using a similar method. I used normal wood speed and a 10 tpi blade, then finished all edges on my bandsander. Works great and saved a lot of time. +++ #2544 From: Bob Romanko Subject: RE: [Bearhawk] Rib blanks You guys are both missing out on what is probably the best therapy there is: snipping out your ribs as God (and Bob Barrows) intended. I'm pretty quick at it and can snip one out in no time at all if I want to. Cutting out a rib quickly, however, is like eating a lobster tail in five minutes; it just shouldn't be done. Ribs are meant to be cut slowly, with every pull of the snip savored like a fine wine. The occasional cut finger is something that you can have with you for several days as a reminder of the wonderful experience you had parting the aluminum by hand. Bandsaw indeed! If you have two good snips, a comfortable seat, a nasty cup of day-old coffee, and the sun rising through the window of your shop, you're BEGINNING to experience Bearhawk building. Seriously. I can split a Sharpie ultra-fine line with no problem at all with my snips. A swipe of the Scotch-brite on the edges, a touch of filing of the nose in the block, and I'm good to go. No sanding required other than that. It's fast, simple, and requires no electricity. Why bother to complicate things? To save time? Heck, why bother taking on a Bearhawk if you're in a hurry? I just planted my 4130 last month, and don't expect a yield for at least a year. By then I'll be needing the steel for my wings. If I hurry the ribs and spars my schedule will be all out of whack, so I'm relaxing and having a blast with the aluminum, in spite of the @#$% spontaneous scratching I wrote of earlier. My suggestion is to take your time. Enjoy. That's why we're building this plane after all, isn't it? +++ #2565 From: Bob Romanko Subject: Rivet Spacing - Nose Rib Bottom Flange Something's been bothering me for quite a while, but thank God for term limits...enough about Clinton...now for my question: Regarding nose ribs, I've noticed in Mike's Rib Building book that he has nine rivet locations on the bottom flange of the nose rib. I see NO WAY to put nine rivets in that flange if you maintain the 1.5" rivet spacing. It's too short for that, at least on my blanks it is (are, was, @#$% grammar). Just for a reality check I measured the flange against the plans. I'm dead on. The only way I could be short is if I cut my relief hole in the wrong spot. To find the location of the hole (no dimension shown on the plans), I just measured from the centerline of the jig pin hole to the centerline of the relief hole and multiplied by 2. My ribs LOOK like the pictures proportionally, so I doubt if I'm off any. To sum up my question, I went with nine rivets and just tightened my spacing to accommodate. Structurally it makes more sense to go with the volume, and damn the visual. I doubt if most eyes would catch the shorter spacing, but now that I've told all of YOU pukes everyone of you will point at my plane at the fly-ins and say, "There's Romanko's Bearhawk. Look at the rivet spacing on the bottom of his leading edge. They're too close! He's such a slacker!" Nah...you folks wouldn't do THAT, would you?!? Just to set me at ease, if anyone of you folks did manage to pull of 1.5" spacing and nine rivets on the bottom flange of a nose rib, would you please measure your rib for me? Put the rib on a flat surface on its bottom flange, and tell me what distance do you have from the tip of the nose to the vertical centerline of the relief hole? If you all had to tighten up your spacing as well, just call me anal retentive once more and well stop this thread before it starts. If we all had to make it tight, however it's good for future builders to know. +++ #2573 From: Bob Romanko Subject: RE: [Bearhawk] Rivet Spacing - Nose Rib Bottom Flange Folks, I just got off of the phone with Bob Barrows. Here's the scoop. He has nine rivets in his, starting about 1/2" from the spar centerline, per the drawing. The spacing rivet spacing is, indeed, 1.5". The trick is to make sure your flange goes as far forward as necessary. Having said that, you need to figure out yourself where the flange needs to end at the nose. Bob said the drawing in his hand matched the rib in his other hand with nine rivet locations, so I have to assume that Russ and I made the same "error" in our measurements as to where we figured out the relief holes are located. Personally, I'm at the point of my project where I can make the correction. In other news, Bob Barrows asked me for Russ' phone number, but I didn't have it. Russ, you may want to give Bob a call. He's concerned about you... ....not!...frankly, Bob said that 8 vs. 9 really doesn't matter. He continued that considering the way most folks build, if he made the design where the omission of one rivet on a flange made a difference our planes would be falling apart. If anything, he said it's over-engineered with the number he has in there. His whole design is that way, so rest assured we're all happy, safe campers. Bob Barrows...gotta love that guy. +++ #2612 Bob Romanko Subject: @#$% Lightening Holes Has anyone perfected the "Barrows Method" of flanging the @#$% lightening holes? Mike's book as well as "BearTracks" makes this look real simple. "Barrows" Method: 1. Wax it up. 2. Using the flange tool, lift the hole 30 degrees by smoothly going around it about 2-3 times. 3. Flip the rib over and push it down with the back of your flanging tool to lock in the 30 degrees and tame any bends. 4. Sit back, admire your work, and realize that you're God's Gift to the Bearhawk community and builders world over. "Romanko" method: 1. Wax it up. (Even I couldn't screw up this step) 2. Fail at smoothly taking the flanging tool around the @#$% hole. Instead, use the flanging tool like a soda pop opener and go around the @#$% hole lifting it up in increments equal to the width of the flanging tool. 3. Admire all waves you just put in the @#$% hole. 4. Wax it again, and go around the @#$% hole with the flanging tool, realizing the waves will never come out. 5. Flip the rib over and push the waves with the back of the flanging tool until you realize you really are having a hard time judging 30 degrees with your eye at 0400 in the morning. Induce more waves. 6. Sit back in amazement as you realize what was once a straight rib has turned into an oil can. Go outside. Look up. If you see stars, leave for the airport and get in some quick flying before work. I know that some of you have built elaborate dies for forming your holes, but I really hate the thought of spending time doing that. Frankly, I'd prefer to keep everything "Barrows Simple". I keep looking at Bob Barrows as my example. If he built THREE sets of wings using this method, it's good enough for me. I think it's just an issue of practice, but I really thought I'd have it down by now. Until I do, I will continue to refer to them as the @#$% lightening holes. +++ #2613 From: Subject: Re: [Bearhawk] @#$% Lightening Holes I did it the way Bob shows it in the news letter, If I were starting over, I would make a set of dies. They could be made of MDf board, it is easy to use and is uniform in density. I say use dies because my arm gave out after a few holes, but I just did something else for a while. +++ #2617 Float-By Shooter Subject: Re: [Bearhawk] @#$% Lightening Holes From: Bob Romanko romanko@v... > Has anyone perfected the "Barrows Method" of flanging the > @#$% lightening holes? The Romanko method sounds suspiciously like the Rawlins method. I did eventually get all of the .025 holes flanged, and also refer to them by your terminology. I skipped the flanges on the .032 ribs since Bob Barrows has said it is OK to do this and it saved a lot of frustration, although the .032 ribs will be slightly less stiff as a result of this omission. If I had all the ribs to do over again, I would beg/borrow/steal a lathe and make a set of flanging dies to use in my press. At my current rate of progress I could easily get access to a lathe before my wings are assembled anyhow, so the .032 lightening holes may end up getting flanged after all. +++ #2619 From: Subject: Re: [Bearhawk] @#$% Darkening Holes All seriousness set aside. I made a set of flanging dies out of wood. ( Very earthly and holistic method of construction). Cut the female hole out with a router, the plug that dropped out was used as a male die for the next size down. The angle on the nose of the male die had to be 42 degrees to allow for spring back. Now here is the best part. I sanded the male plug on a sander and did not even use a lathe. Clamped the stuff in a sandwich ( Whole wheat of course). Plug pulled in by a 1/2 in bolt. No modern hydraulics for me, just a helical inclined plane with grease. One afternoon to make all the tooling. 12 hours to flange all the ribs. It's OK to use a better tool to make better parts, faster, leaving you more time to tend to the crops. I have an aunt who is an Amish Nun, at the end of a hard day she sits in a chair and has a beer. ( Go figure ! ) +++ #2631 From: Subject: Re: @#$% Lightening Holes > Has anyone perfected the "Barrows Method" of flanging the > @#$% lightening holes? Aircraft Tool Supply has a hole flanging tool that looks like it might work. I bought one but haven't used it yet. Their URL is www.aircraft-tool.com +++ #2659 From: Bob Romanko Subject: RE: [Bearhawk] Re: @#$% Lightening Holes I went on the website and saw the tool. For only $13 this thing CAN'T work (grin)! Has anyone out there used this thing, and if so, howsabout a PIREP? +++ #2661 Schutt, Barry C Subject: RE: [Bearhawk] Re: @#$% Lightening Holes OK, OK you guys are making this hard, Sooooo I guess I'll just have to jump in. Let me explain how I did it and it is easy and makes flanging a quick snap. So put your "picture this" hats on because I cant draw on this fool computer. OK here goes------ buy some 3/4 oak boards and also some 1/2 in oak boards enough to do this job---you'll see in a minute. (1) have your local lumber supply plane one board down to about .18 to .20 thick (2) from this board cut out circle pieces the hole dia plus 1/2 inch one for each different dia hole drill a 3/8 hole in the center and put a 3.8 bole thru it clamped with washers and tighten the nut down tight-put the bolt in your drill press on medium speed and using a wood file and sand paper taper the edge over 1/4 inch---now you have a thin wood washer with a tapered edge the smaller dia is the same size as the hole you want to flange. (3)Next cut a 1/2 inch dia piece the same size dia as the hole and drill a 3/8 hole in its center (4)next m! ake a 3/4 thick round part about 3/4 to an inch bigger in dia than the hole to be flanged and drill a 3/8 hole in its center ----now glue these three pieces together to make the male tool align them using a 3/8 bolt thru the center holes (5) for the female tool just make 3/4 thick piece to fit the inside of your rib and cut a hole in it the same size as the hole you want to flange before cutting this hole though using a compus mark a circle 1/4 in bigger in radius and using your rounded wood file taper this hole to about 30 degrees or slightly more 1/4 inch around the entire hole , make this piece to clear the rib flanges as well as the adjacent flanged holes----------this entire process sounds long but it only took about maybe 1/2 hour per tool total---------I made one for each size hole from the nose ribs on back to the smallest in the ailerons----and using my 12 ton hydraulic press-----cheep from tool town or harbor freight----- was able to press my entire rib set in mayb! e three hours total Note, I used the drill press method to turn all the pieces round, a wood lathe would be better---I used oak but any fairly hard wood would do I think Barry(036) +++ #2667 Russ Erb Subject: [Bearhawk] Rib Lengths > From digging through different spots (Web, CD, etc.) I'm trying to > gather how to trim the ends of the ribs. I made all my nose ribs > to the CL of the front spar, and will trim them when I build up > the wing. I took the opposite approach. I cut out all of my ribs using routing template (as you saw on the CD) to the precise length required for each station. This, of course, meant that each rib was unique and labeled for each location. It worked for me, but your method is valid too. +++ #2670 From: Subject: Re: [Bearhawk] Re: Ribs - layout A question here on scaling the lightening holes, and the flange cut outs for the nose ribs. 1:The 3/32" relief holes for the end of the flange on the nose rib scale from the plans to be placed 12" from the main spar. Drawing a line from the (fore) end of the center line to the center of each relief hole does not scale the same on the full size drawing as on the plans drawing. While I know this is not critical, I seem to remember some talk about getting X number of rivets on the nose rib. Any reason not to set the holes 12 1/4" from the main spar? This would give forward almost 1/4" more flange. On the other hand, I don't suppose it would hurt a bit to space the forward rivets less than 1 1/2". 2: On scaling the lightening holes. The holes are really this big? e.g.: 1st hole behind the main spar is 5 1/4" This is the actual hole & doesn't include the flange? Incidentally, I copied my full size rib plan at Kinkos and found upon arriving home that it was 3/8" too long when laid upon the acetate rib plan. It threw all the spar locations off, and blew $10.00 for 2 copies. I ended up using carbon paper & ships curves to transfer it. Worked very well. (dead blow hammer arrived today from MSC & I'm ready to work off frustrations). +++ #2671 From: Russ Erb Subject: Re: [Bearhawk] Re: Ribs - layout 1. Relief hole location is not super critical. However, the farther forward you carry the flange the more fluting it will require to straighten the rib. 2. I interpreted the circle size shown on the drawing (scaled appropriately) as the hole size to cut. The flanges will leave just enough room between them for the vertical stiffening angles to attach. +++ #2672 Doug Knight Subject: Re: [Bearhawk] Re: Ribs - layout Having just measured my spare Kinkos copy, mine measured .125 long. So what, it only fits air or what you put around it. Your error represents only .068" per foot. Mine represents .023" per foot. Now you're going to make me go back to the shop to check my sawn and sanded rib form. I have looked carefully at that extra .125" and all it represents to me is a line on one side of the rib form. Shifting the template to the Nose and slightly trimming the tail is all that's required for me. I can adjust stations and lightening hole centers. No need to get anal here. Another day mine would set in Oak. Still waiting for drill bushings as I am rather fond of these type of setups indexing and drilling. Measuring and layout is sometime subjective. I have done so much layout over the years I keep forgetting all the tricks, as each project becomes a war to finish before the designer and engineer change their minds and change something. I had a conversation with an engineer years ago and his comment was,"Build it the way I designed it, but leave out all of my mistakes." At some point you will have to throw the plans away. Another saying is, "shoot the engeneer and get on with the project. At some point Bob's plans ends and you will have to carry on without his drawings. Some builders frezze at this juncture. I want to ask you a very important Question. When you cut out your wing form board, how square is your cut going to be front to top, top to back, back to bottom, and bottom to front again. If the the form is not square you will fly with one wing high. This would be more important than worrying about .375" long. Trick #1 Using paste copies on boards. Make sure the copier device is calibrated to the proper scale, if not, calibrate it. Paper grows and shrinks with moisture. After receiving your copy, dry it out in an oven at 300 and remove just before use. Remember paper will burn I tried to get a mylar copy, but knew that it had to be CAD generated and to copy the wing form, meant it would have to rastered then to vector. There could be much more error than you experienced. Then again not all copy paper is created either. I couldn't see cutting Bob's perfectly good #7. Just think, with that .375" you could have some extra space for some O ring seals, "go at throttle up." I guess I'm buying the beers tonight. +++ #2677 From: Paul Foster Subject: Re: [Bearhawk] Re: Ribs - layout I asked Bob and he suggested gluing #7 to form block which I did. Cut out, formed radius, and drilled holes for all that were marked on the drawing. Drawing is still attached to form block. At some point it may end up in tatters. Will need to mark in spar locations etc on form block. I figured if I needed another #7 could get from Bob for a nominal fee. We will have an informal gathering of Bearhawk builders at the Rocky Mountain Regional Fly In on Saturday June 24 at 2:00 PM. I will be camping in the grass/weeds just west of the western edge of the ramp which will be our rendevous site. Looking forward to seeing builders and interested parties. +++ #2678 Bob Romanko Subject: Ribs: What REALLY Matters... I was thinking while pounding nose ribs this morning: What REALLY matters with nose ribs? By "matters I mean, what is REALLY critical? It's easier for me to think in terms of what DOESN'T matter. Here's a short list I came up with: 1. Width of the flange. As long as you can get a rivet in it and have enough there to support the skin it doesn't matter. 2. Shape. As long as they're all consistent with each other, the shape doesn't matter. If you have a spot on your form block that's 1/16" thinner than Bob Barrows' it doesn't matter. The plane will fly. 3. Number of rivets. 8 vs. 9 rivets on the bottom flange? Doesn't matter. The leading edge will not fall off the airplane without warning. 4. Grain direction doesn't matter, even if you grow your own aluminum. 5. Length of the rib. Doesn't matter, as they're all trimmed upon assembly. Actually talked to Bob about this every thing yesterday. He said he cuts the rib at the spar centerline, and always trims his ribs to fit after the spars are in place. 6. Oilcanning. Face it, you're flanging 2 @#$% lightening holes, adding a stiffener, and then an attach angle. I'd say here's another doesn't matter. If you have an oilcan after all that THEN I'd start to worry. 7. Using hand snips to cut out your ribs. Bob Barrows built 3 sets of Bearhawk wings using hand snips. It's quiet and if you have two good pair can be done in minimal time. I can cut out a nose rib in just over two minutes. When I'm done I only need to hit it quick with a rose scotch-brite and I have a finished blank ready to flange. 7. And last, my favorite, CUTTING DRAWING #7! This is becoming my official "Pet Peeve". Why for the life of me are folks hell bent on making COPIES of drawing #7?!? Bob MEANT for us to cut the silly thing, glue it to a piece of hardwood, and cut out a form block. I took my drawing #7 and (weak of heart should sit down for this) cut out the form and attached it to my lumber. Sacrilege! You burned the Shroud of Turin! Smashed the Holy Grail! Destroyed the Temple! Hardly. It's not sacred, folks, it's just a harmless piece of mylar. My form block's good enough, and my plane will fly just fine, in spite of the fact the most advanced technology touching my block was my Bosch jigsaw (yes Budd D...I DO have 'lectricity here in VA), a 4" portable sander, and a router for my 1/8" radius. No CNC aluminum templates, no blueprint paper, no French curves (or curves of other obscure national origin), no Kinko's, no paper stretching, etc. Just cut out the silly thing, glue it on, hog it out, then slap a sander to it and take it 1/2 way through the line. Make sure your edge is square, put a 1/8" bit in your router, drill your holes, and call it a form block. If you spend more time than two hours making a form block you may want to consider buying a kit because you're way to anal retentive to take on a Bearhawk. (grin) Now on to what DOES matter: 1. Your ribs had better all be consistent, especially in height. This ONLY matters if you're concerned about not having a rippled skin. If cosmetics aren't a big issue a few waves here and there won't affect much. 2. Jig pin hole location. This is important because it is used to align the rib geometry to the spar. 3. DEEP scratches. I say deep, because minor scratches are not a big deal, as a nose rib isn't under much stress. 4. Bend radius. Use an 1/8" radius, and pound it properly to set the radius on the block. 5. Final bending. Make sure as you bend/flute that the radius on the part stays straight and set. 6. Lands flat and even. Make sure the land where you're putting your rivet is flat and perpendicular to the rib. 7. If you do the above, your nose ribs will be fine. Let's not get too carried away with paralysis of analysis. The plane takes long enough to build without getting all engineering/scientific whacko with this stuff. Build the plane, build the plane, b u i l d t h e p l a n e +++ #2679 From: Subject: Re: [Bearhawk] Ribs: What REALLY Matters... << it's just a harmless piece of mylar. >> I was more concerned with the plastic melting or fuzzing from the sanding if I glued it on the wood. Didn't consider cutting the line first. In any case, I can draw as good or better line using carbon paper as I can cut with scissors. More to the point, they won't let me have any sharp tools here, and will only give me plastic blunt nosed safety scissors. +++ #2682 From: Bob Romanko Subject: RE: [Bearhawk] Ribs: What REALLY Matters... Regarding Drawing #7 and making your formblock... There is one BIG advantage to cutting out the pattern: Remember not long ago how everyone was talking about "Fat" ribs? Well, it makes sense if you cut to the middle of the line you'll have fat ribs. Why? Because Bob makes drawing #7 by hand tracing around "Mother Formblock"! So if you REALLY want to be anal-retentive, do as Bob recommends and cut out the form, but cut EXACTLY on the inside of the line on drawing #7. Then, after you glue (or tack) it onto your formblock, cut JUST to the mylar. You will be D.N.O. (dead nuts on) to "Mother Formblock". That's what I did anyhow, and one of these days I'm going to take my formblock on the 125 mile trip to Bob's and introduce him to his mother. Should be a touching reunion, don't you think? Bob will understand I'm sure. Maybe we should post images of our formblocks to a website and fire up the imaging software and make a group family portrait of our formblocks? Mine's made out of ash, so I imagine it's the black sheep of the family. The sun's starting to fry my brain here... +++ #2685 From: Float-By Shooter Subject: Re: [Bearhawk] Ribs: What REALLY Matters... > 7. Using hand snips to cut out your ribs. Bob Barrows > built 3 sets of Bearhawk wings using hand snips. It's > quiet and if you have two good pair can be done in > minimal time. Plus, hand snips don't throw little bitty particles of aluminum EVERYWHERE, like a router will. > 7. And last, my favorite, CUTTING DRAWING #7! This is > becoming my official "Pet Peeve". Why for the life of > me are folks hell bent on making COPIES of drawing > #7?!? Bob MEANT for us to cut the silly thing, glue I did the carbon paper thing, so in case I screwed up making the form block, I wouldn't have to send away to Virginia for a new #7. I guess it doesn't matter if you are already THERE... +++ #2587 From: Russ Erb Subject: [Bearhawk] Ribs: What REALLY Matters... > 4. Bend radius. Use an 1/8" radius, and pound it properly to set > the radius on the block. (I'm sure Planter Bob did it right, but for our newbies...) I've said it before, but it's about time to repeat it--remember that a 1/8" radius is a 1/4" diameter! That means your bend should match the curvature of a 1/4" drill bit. If you somehow glossed over this higher math, you probably found that it's very DIFFICULT to bend 0.032 2024-T3 to a 1/16" radius anyway, whether it cracks or not! The metal will almost protect you from such buffoonery unless you fight it real hard! +++ #2689 From: Bob Romanko Subject: RE: [Bearhawk] Ribs: What REALLY Matters... Del, You do have a good point about my living here close to Bob. I've visited Bob's shop multiple times, and having him so close did help out quite a bit in terms of project selection. I first chose the Bearhawk because of its specs, but after driving down to Fincastel to meet Bob and see the plane, I was sold on Bob Barrows himself. Bob's good company to be with, and I have the utmost respect for him. Bob Barrows is a gift to aviation, and when there are about 50 Bearhawks flying around he's still going to exhibit the same humility and honesty he does today. I joke a lot here, but one thing I have to pass on to the folks is this: Bob's shop is SIMPLE, just like his techniques. I'd bet there isn't a single tool there he doesn't need, and plenty of tools there he's made himself (i.e. Fluting Pliers). It's so easy with the Net, etc. to get carried away with the technology and tooling to ignore what it really takes to build this plane: basic tools, good 'ol fashion effort and consistency. To the post-builders on the group, I'm preaching to the choir, but to the new folks I'd have to say be careful not to get too caught up in the trap of spending so much time setting up your shop you never build your plane. You really only need MINIMAL tools and space to get started with the ribs, so don't be too intimidated with the techniques some folks have used to start production. Some people have so many tools they just HAVE to find a way to use them all. Something about cost justification to their wives, I imagine (grin)! +++ #2692 From: mailstuff Subject: Re: [Bearhawk] Ribs: What REALLY Matters... One more way of making the template and form blocks... I took an exacto knife and cut out the Mylar template...somewhere around the middle of the line, and then stuck it to a thin rigid sheet with thin double-sided tape. I then cut the thin rigid sheet to the exact shape I wanted (I goofed a little on the under side of the rib, so no looking at the bottoms of my flaps and ailerons for conformity) I was able to drill pilot holes for all of the lightening holes. I drilled through the lightening holes with a drill guide into my form block. Next, I bolted my template to my form block and drew around the template onto my form block. I have a rigid template of my wing that I can reuse at any time. Many of the holes that pertain to only a rib or two I drilled with a number 30 with a drill guide. I can bolt my blanks into the forms and drill 2 #30 holes to mark the spar centerline for trimming ribs per each station as I need them. The ribs that have the odd-shaped holes, I can drill a #30 hole to pick up the center of them as well. For those that haven't made their form blocks yet, I recommend maple. I know I am swatting at the hornets nest, but we pound out tons of DC-9 parts on maple form blocks and they hold up really well. The day I went to Lowe's to buy my maple they were out of what I needed, so I settled for a piece of great looking poplar. I was straight, tight grained, and one solid piece. Oak tends to break off around the edges. I saw Tom Yeoman's form blocks after he finished, and they were not good for many more ribs (Oak). Remember to put that bend radius around the edge of the block. If the bend radius is correct, you won't have to worry about grain direction. I used a 2x10 for my backing block. It was free from the local construction site (Burn pile honest!) Seems to work just fine. +++ 32695 From: Subject: Re: [Bearhawk] Ribs: Rib Manufacturing What Counts?Radius? Maybe I am building a different airplane or the heat has damaged my brain but......... 1/8 th in. radius is 1/2 half of a 1/4 in. diameter.... bear with me ..... form block, my Bear-Tracks 1995 condensed version says that form block RADIUS is 1/16 th of an inch. Not 1/8 th in radius. oops! I am now past ribs and spars and into flaps and ailerons but Bob R has me scratching my head and worried. Got the right number of rivets on the nose rib. Whew ! Bob mentioned that cutting out ribs was easy with tin snips and with a little practice he could split a sharpie line down the middle! Question? Was that sharpie split length wise or cross wise? +++ #2696 From: Subject: Re: [Bearhawk] Ribs: What REALLY Matters... About form blocks, First if you bend the ribs the way Bob does in the newsletter and construction booklet you need a 1/16 radius ( it ends up a 1/8 radius after it is formed I tried it both ways. also you have to follow Bob's technique if you do it that way) Second if you go the 1/8 radius route you need to subtract the thickness of the material you are using or you are going to have fat ribs or worse different sized ribs (same form block different thickness material ) The process Bob uses enables you to use one form block to form different thickness material and end up with the same final size or height. Try it on a scrap piece of material and measure the final radius and size. Just be sure to follow Bob's instructions. I bought two slabs of maple, would like to prevent someone else from doing the same. +++ #2704 From: Donald Schindler Subject: Re: [Bearhawk] Ribs: What REALLY Matters... OK OK I'll confess!! Yes I too copied drawing number 7. But then I ask, why did I commit this crime? I think it must be some primordial fear of violating the plans, or that I would screw up the original, or that maybe I would need it again some day after that ground loop or whatever, or that the originals will all be collectors items someday equal to the price of the airplane, or that it seems like such a personal piece from BOB, or that it rolls up so nice and that there's something cool about Mylar, or that when your friends ask you about the wing you roll it out and their always impressed. I dont know, but drawing number 7 just has that certain something. Don(In love with #7). +++ #2713 From: Subject: Re: [Bearhawk] Making Nose Ribs Well, thanks to Russ I'm pounding aluminum! I built a router jig as described in Russ's very informative CD. I used 1/4" Plexiglas for the template, scribing it from the maple form block. I then rubbed a little ink in the scratch for better visibility, rough cut & sanded to the line. Using it as a pattern, I routed a couple more for a wider base for the laminate bearing to ride on. The only change I made from Russ's jig, was to under cut or bevel the top plate of the jig. This deflects almost all of the aluminum chips down into the box. Combined with some duct tape on the open side of the router, and around the sides of the box, very little escapes. Really neat! It takes only a couple of minutes to load (I've only tried 6 at once so far) the rough cut aluminum, and well less than a minute to trim them. Using the air shears to rough them out, the whole process looks like it will average only a minute or two per nose rib. Granted, it took a couple of hours to make the jig, but every rib is identical and flawless. I purchased a 3/4 hp royobi from Home Depot for about $75.00. Really nice tool! It even has a light inside it. I hammered a half dozen out on the form block, but don't have the fluting pliers yet. I had a friend at a cabinet shop a route a 3/32 radius on the form block & it works just fine. With the new laminate cutter, the edges of the ribs are smooth. This may change as more are cut, but by then my Scotchbrite wheel will have arrived from MSC. I am cutting the longest ribs first, then will progressively shave off 1/8" from the template for the shorter ribs. I also cut the pattern 1/32 from the spar. I posted a picture of the jig at: http://hometown.aol.com/vberthels/BH.html +++ #2717 Rob Gaddy Subject: Another way to skin a cat I've been good success cutting rib blanks, and form and backer blocks using a router, in a similiar way that Russ used. However, instead of holding the work fixes and moveing the router, I mounted my router right in my work bench top and have been moveing the work past the cutter. I first made a pattern for cutting the rib form blocks out of 1/8 inch scrap aluminum I had laying arount the shop. I just screwed the pattern on a roughly shaped piece of MDF. I used a straight cut router bit, with a bearing on the top. The bearing followed the pattern perfectly. A simple 1/8 inch round-over router bit took care of the bend radius in about 10 seconds. I can now make form blocks by the pound. I used one of the form blocks as a backer block. To do this, I needed to reduce the "height" of the block 1/4 inch for clearnace when hammering over the flanges. I used a rabbit bit with a bearing on the top. I adjusted the height so that the bearing rode on one edge of the form block, and cut 1/4 inch off the other edge. Next the straight cut bit was re-installed in the router, the block turned over so that the bearing rode on the newly cut surface. Two passes, and exactly 1/4 inch clearance for the backer block Next I made a pattern for blank aluminum out of 1/4 inch plywood. I made a "sandwitch" with the pattern on top, followed by 6 pieces of .032 aluminum and on botton a sacrificial 1/4 inch plywood. The whole mess went through the router, the bearing rideing on the pattern, and 1 pass, perfect blanks. I thought I would have sharp slivers of aluminum so positioned by vacuum near the cutter, but the aluminum is more like metalic snow, soft and fluffy. +++ #2724 From: Bob Romanko Subject: Center Rib Flanges and Form Block I read in "BearTracks" that Bob Barrows "stepped" his form block to form the front lip of the center ribs where it fits under the flange of the front spar. If that's the case, having my nose ribs finished, I'm thinking that now it makes sense to make my two tip ribs prior to dressing my form block for my center ribs. Is that how you other folks did it? I'm not crazy about having a step in my block and working over it for my tip ribs later. I'm also not crazy about what some of you did, and go ahead and build multiple blocks. If I liked to work with wood, I wouldn't be building a Bearhawk! If you understand what the heck I'm talking about, please let me know what you did. Any pro's or con's either way? +++ #2725 From: Montee, Dan L. Subject: RE: [Bearhawk] Center Rib Flanges and Form Block I'm pretty well along on nose ribs as well and I had the same question as Bob the Planter. I read in one of the "BearTracks" that Bob was building one of his wing sets without the joggle but I could not find a follow up on the result. Mike, can you comment? +++ #2726 From: Mike Meador Subject: Re: [Bearhawk] Center Rib Flanges and Form Block Proto II wings were built without the joggle and Proto I was built with the joggle.. You can't tell the difference so you shouldn't worry about it.. +++ #2731 From: Subject: Re: [Bearhawk] Form Blocks and Joggles a Caution ! Re Bob's Question. I made my form block one piece. Formed all the ribs. Made a simple block to put in all the joggles. Joggles to joggle or not to joggle! If you do not joggle there is one Item to be aware of. The first rivet in the rib flange aft of the spar flange should be installed at near maximum spacing. The idea is not to rivet the skin too close to the spar flange and cause a "Hard Spot" that will lead to cracking later. The skin should have no stress in the transition over the spar to the rib. +++ #2734 Bob Romanko Subject: Fat Ribs and My Numbers Fat Ribs Part Deux: My goal was to avoid "fat" ribs. Most folks here have ribs a bit taller than the '7.59" REF' Bob calls out in the main spar drawing. I made my form block somewhat "short". This was done by cutting out drawing #7 to the INSIDE of Bob's traced line on the mylar. I just taped my mylar on my hunk of ash, traced around it with a fine pencil, and sanded until the line JUST disappears. I then bent my ribs over a 2x4 to the 90 degree, smacking the flange edge at a 45 degree angle to preserve the radius. From there it was just a matter of fluting and adjusting. My results are very interesting. Here are some observations: 1. My ribs after being flanged "shrunk" and are not flush with the edge of my form block. The entire rib is about 1/32" shorter than the form block edge, all the way around to form. That gives me a total rib "shortness" of 1/16" from my block. This came from creating the final 90 degree bend prior to fluting. I don't see how one can preserve this radius using the construction method we are using. Some is going to suck in. It's a physics thing God doesn't want us to understand. If you were able to perfectly preserve and not enlarge this radius, you're a bigger man than I. Maybe that's why Bob recommends the radius on the form block to be 1/16" rather than the 1/8" many of us used. I should have listened to Bob. A 1/16" radius would minimize the shrinking when I put in the final 90 degrees of bend. 2. In spite of the shrinkage, my ribs measure an average of 7.61 at the spar, .020" FATTER than Bob Barrows' reference dimension of 7.59" on the drawing! Before measuring, I was convinced my ribs would be very short. For me, using such a primitive construction method and getting within twenty thousands of an inch of the plan is nothing short of miraculous (grin)! I'm chalking this one up to luck. My conclusions are that you'd have to work your form block to LESS than drawing #7 to get 7.59". Of course, .020" is pretty darn close. It's all an exercise of how anal-retentive you wish to be and, unfortunately, I'm a bit over the edge. I'm wondering what other folks' "Fat Ribs" are measuring at the spar. Anyone even close to 7.59"? If you are, did you make your form block even shorter, or are you pounding your 90 degree angle on the flange tighter than I am? Good for the next group of rib-pounders to know. Well, I'm probably done discussing nose ribs. After 46 of them, you could say my cup is filled. Now it's on to center ribs. I've changed my build schedule from five days a week to seven days a week. I'm waking up on the weekends at 0300 without an alarm clock. Once awake, I may was well work as I do during the week. I'm getting in 3.5 hour days, so now it will be around 24.5 hours a week. I think during the course of a year I'll skip 14 days, so that works out to 1,225 hours a year. If I could finish in three years I'd be amazed. My momentum is building pretty quickly, much faster than I expected. I think I'll be bending spars the second week of July. If I retained my riveting skills from when I passed my FAA exam for my A&P ticket, I actually have a shot at getting it done. I'm comfortable with gas, so I'm hoping the wing steel will go quickly as well. I'm not running a race, but I think the focus I'm putting on the project is really starting to pay off. I'll have my center ribs done early next week. I'm putting off the @#$% lightening holes on all my ribs and doing them all at once when they're all finished. I've decided to go with a set of dies I'll spin up on my lathe. Thanks to everyone who forwarded advice on die construction methods. I figure that will save a lot of time, just as you all suggested. My biggest problem is my crop isn't keeping up with my pace. @#$% the Virginia summer. Too much heat, not nearly enough good, long rain. I hate to say it, but I had to call Wicks for more .032 sheets. I hang my head in shame...... I'm going to miss pounding nose ribs. They were totally enjoyable. Now it's on to bigger and better things. Anyone else suffer nose rib withdrawl (grin)? I know I'll be spending more "quality" time with them once the wings get assembled. Overall, I find this project to be HIGHLY addicting. If you're "on the fence" about whether or not you want to build a Bearhawk, go for it. This is the most fun I've had in a long time, and I feel about ten years younger. Great, great therapy. +++ #2743 From: Russ Erb Subject: Re: [Bearhawk] Ribs: What REALLY Matters... > For those that haven't made their form blocks yet, I recommend > maple. I'm sure maple works well. I had a different experience with oak. I think mine was "Red Oak" but I can't verify that. After forming all of my ribs, I cannot detect any wear on my form block. Poplar was available when I was looking for form block material, but my research showed that it was softer than oak, even though it qualified as a "hardwood". I find it interesting that we've finally arrived at what I've always expected--the second (or is it third) generation discussions of rib forming. Some of us were having very similar discussions back in late 1996/early 1997. Back then, many of us wondered if we were embarking on building an obscure airplane with no hope for help except a letter or phone call direct to Bob Barrows. Thanks to the power of e-mail, we seem to have created a large support group for ourselves virtually out of nothing. This is far more efficient than trying to get together for a meeting or relying on just a monthly newsletter. I see it as a sign that our group is growing, and I predict another discussion of wing rib forming in another two years or so, though I doubt it will be as lively or entertaining as "Planter Bob's." +++ #2744 Russ Erb Subject: Re: [Bearhawk] Ribs: Rib Manufacturing What Counts?Radius? > Maybe I am building a different airplane or the heat has damaged > my brain but......... 1/8 th in. radius is 1/2 half of a 1/4 > in. diameter.... bear with me ..... form block, my Bear-Tracks > 1995 condensed version says that form block RADIUS is 1/16 th of > an inch. Not 1/8 th in radius. oops! Here's my attempt at sorting out the 1/8" vs 1/16" radius issue. I started out by looking at the normal bend radius tables. From AC43-13 (available on the Bearhawk CD--blatant plug), for 0.032 2024-T3 sheet, the recommended radii are 2t-4t (2 to 4 times the thickness) which would be .064 to .124, or 1/16" to 1/8". The smaller the bend radius, the greater the risk of cracking and the greater the difficulty of bending. I planned to hammer my ribs as far as possible on the form block, so I decided to go with the 1/8" radius. I still had to free form the remainder of the bend off of the forming block. The radius still looks close to 1/8". This has not caused any problems that I can tell. Bob's method described in Bear-Tracks speaks of bending only the first 60 degrees on the form block, then free forming the rest. Because of the difficulties of bending to that tight of a radius and the free-forming off the block, I suspect that the resulting radius is still close to 1/8" anyway. This may be the reason why Planter Bob's ribs ended up taller than he thought they would. So my take on the form block radius is: 1) It is important to have a radius on the edges of the form block. 2) Any radius between 1/16" and 1/8" (the curvature of a 1/8" to 1/4" drill bit) is acceptable and will lead to similar results. Planter Bob reports that his nose ribs were 7.61" tall, compared to the 7.59" on the plans. Digging back in my records to 23 May 97 (Boy I feel old in this group!) my nose ribs called for a main spar height of 7.69", a full tenth of an inch taller. This is why you should form your ribs BEFORE bending up your spar webs. As for the joggles in the ribs, I had to put them in because I formed my spar webs before the joggle/no joggle question was answered, and I was so successful in forming them to the size that I wanted that the ribs would not fit without the joggles. I used a piece of steel left over from making a bucking bar and ground it so that I could hammer joggles into the ribs without cutting into the forming block. You can see this tool on the first page of "wing assembly" on the Bearhawk CD (another blatant plug!). +++ #2746 From: Subject: Re: [Bearhawk] Fat Ribs and My Numbers My ribs came out fatter than normal (Bobs), I took some up to him and he said they were good even though the radius was larger than normal(Bobs) Mine came out to 1/8 radius. As far as the rib to spar match, mine were about what you have. The only thing Bob said was to keep the spar caps in the correct place, center line to center line. Also it keeps dimensions for the 4130 parts, bolt holes, to agree with the plans when you build the jig for the parts. I drilled pilot holes for the 31.59 length parts, in my spar caps, I would not do that again, I would wait untill I had the 31.59 pieces made and pilot drilled. This rambled on a little, maybe it helped. +++ #2928 From: Alan Nauman Subject: Nose rib oops I have been working on my nose ribs and apparently in my excitement to get started I miscalculated the size of the holes that are at the front to prevent cracks in the bend for the flange. I have 26 of them made with 1/8" holes in place of the 3/16" that are called for in the plans. I am not real excited about the idea of scrapping the work I have done to date so do any of you have any suggestions? I am not sure if the radius there was done because the rest of the holes in the rib are 3/16" or if there is a specific engineering reason. The bend radius I am using is 1/8" so even the 3/16" would not completely cover that. Please let me know if anyone has any suggestions. If not, I will give Bob a call to find out from the source after Oshkosh. +++ #2929 From: mailstuff Subject: Re: [Bearhawk] Nose rib oops Most of the time, a 1/4 inch hole is used to prevent cracking. This has a large enough radius to lower the stress concentrations and prevent cracks from emanating from the holes. Since this material is so thin, a 3/16 hole is used. I would get a rat tail file (cheapest fix) and dress out the radius to the correct size. Cracks emanating at this location will be hard to spot at annual time, and even more difficult to fix. Don't remake them, just dress up the radius into a smooth curve that is about 3/16 of an inch DIAMETER. +++ #2930 From: Subject: Re: [Bearhawk] Nose rib oops > I have 26 of them made with 1/8" holes in place of the 3/16" that are > called for in the plans. I am not real excited about the idea of > scrapping the work Have you already hammered the flanges? If not, drill them larger. If so, check them for cracks, and work them larger with a small file. IMHO: Don't scrap them! The forward part of the nose rib is non structural so as long as the relief hole is large enough to prevent fatigue cracks you shouldn't have a problem. 3/16" is easier to cut to with snips, but 1/8" should be OK also. I made mine slightly larger to prevent the kink that can arise at that point when folding the flange over. As I cut mine en-mass with a router, I ran the router bit in just far enough to clear the radius when bent. The wing won't care! Victor NO, WAIT! You should scrap them. Send them to me for inspection! :) Victor +++#2931 From: Bob Romanko Subject: RE: [Bearhawk] Nose rib oops You're in good shape, just inspect them for cracks and open 'em up to the right radius with a rat tail file. You can also use a mini-rotary tool to do the same job. I find mine invaluable. It mixes a good drink with the proper attachments. Very refreshing tool, indeed. +++ #2932 From: Alan Nauman Subject: RE: [Bearhawk] Nose rib oops Thanks to everyone for the help. I had guessed I would be ok if I enlarged the holes. I do not have any cracks so far. I was think of either using my dremel with a chainsaw sharpening stone or the chainsaw sharpening file. I believe I have both of them in a 3/18 diameter. I just got the latest news letter and it reminded me of the earlier email about flanging the lightening holes. I have not tried that yet. I have only cut out six of the lightening holes and I am about afraid of what may come from my first attempts at that. What kind of wax for the flanging? Is it paraffin wax, candle wax, or??? +++ #2933 From: Bob Romanko Subject: RE: [Bearhawk] Nose rib oops I used carnauba car wax. Basically anything to get the flanging tool to slide around the @#$% lightening hole. Believe me, the wax you use will be the LEAST of your worries! AAGGHHH!!! By the way, I plan on taking Bob Barrows and Mike Meador up on their offer for a private, one-on-one workshop! (grin) +++ #2934 From: Bob Romanko Subject: @#$% Lightening Holes and BearTracks Well, wasn't I surprised when my eGroup post regarding the @#$% lightening holes was on page three of the BearTracks I had in my mail yesterday! Like my momma always said, "Watch what you say, 'cause you never know when it may come back atcha." I'm glad I did, 'cause I had NO IDEA that Bob and Mike were going to print that post! My wife read it and didn't see the humor. Women. Regardless, I AM going to take those two up on their offer for the private one-on-one workshop for the "Barrows Method" for flanging the @#$% lightening holes. I'll have to wait for them to get back from Oshkosh (er...Air Venture..sheesh). I will, of course, provide a full report of the workshop here on eGroups. I'm looking forward to the day I can stop calling them @#$% lightening holes. Since I haven't heard from anyone with dies up to this point, I'm going with the "Barrows Method". It's the way I'd prefer to go anyhow. +++ #2935 From: Float-By Shooter Date: Tue Jul 25, 2000 4:40pm Subject: RE: [Bearhawk] Nose rib oops > I just got the latest news letter and it reminded me of the earlier > email about flanging the lightening holes. I have not tried that yet. > I have only cut out six of the lightening holes and I am about afraid > of what may come from my first attempts at that. If they are anything like my first attempts, you will definitely want to try a few holes on a piece of scrap before you try it on your ribs. It doesn't take too long to get the technique down and then it is just a matter of slowly grinding (figuratively) them out. My suggestion would be to make your first attempts on the control surface ribs which only need a 1/4" flange, they were easier than the 3/8" flanges and didn't seem to distort the ribs as much. Plus you will get to put off flanging the lightening holes until you get those ribs made now. 8^) > What kind of wax for the flanging? Is it paraffin wax, candle wax, > or??? I used paraffin because it is what I had around; didn't know where to find beeswax and didn't think to try car wax. It did make a difference, but I'm still not sure it was the right stuff to use. There has to be something better. I was really glad to be past that stage. +++ #2938 From: Tim Anderson Subject: Re: [Bearhawk] Nose rib oops Alan - are you talking about the hole at the front edge of the nose rib flange? It doesn't make a hoot of difference. I have some tiny files and have filed mine to the shape I wanted. They simply are there to stop the flange from starting to break. Are are things that are important, and then things that are not. That item is not critical. +++ #2942 From: Subject: Re: [Bearhawk] @#$% Lightening Holes---DIES After the Air Adventure thing cools down hit up Russ the Erb man. I have sent him photos and drawings on the flanging dies that I made. He may be able to post the info in an electronic format for others to use. ( Now it's time to be kind and lighten up on the Russ bashing just a little.) Rob Gaddy......... have you tried the flanging dies yet? How are you doing? +++ #2948 rom: Subject: Re: [Bearhawk] @#$% Lightening Holes---DIES I can report that your die design works just fine. The die was easy to make with my bench mounter router, and a disk sander. I constructed and have used the design to flange the holes in the nose ribs. I'm working on the mid-cord ribs now. I did have to use a "BOB-STICK" on the flanges after forming to straighten out a little bow in the rib caused by the flanges, the bow was in the opposite direction you get when you bend over your edge flanges (where the skin in riveted on). I used a little silicon spray as a lub. I just had to increase the angle of the hole flanges slightly on their leading and trailing edge sides. By the way, I have made an extra set of tip ribs, to be (possibly) used on the fuselage to facilitate the wing-to-fuselage transition. I haven't put lightening holes in these extra ribs yet, thinking that either no holes will be used, on different holes will be needed to clear the wing attachment fittings, etc. This will also be the location of the fuel level gages, fresh air vents, and possibly some switches for nav lights, strobes, etc. Additionally, I was wondereing if a small change in the odd shapped hole in the 0.032 mid-cord ribs may be in order. Perhaps to incorporate a guide or fairland to ensure that the aileron cable does not rub on the flap linkage. Any comments group? +++ #2949 From: Alan Nauman Subject: Re: [Bearhawk] @#$% Lightening Holes---DIES Ok... I think I missed something... Has the design for the die been posted somewhere? I would like to make them if it will save time overall. Please post details! +++ #2950 From: Bob Romanko Subject: RE: [Bearhawk] @#$% Lightening Holes---DIES Regarding detailed @#$% lightening hole forming... The "Kevin Method" is eGroup message #2619. Here's the URL: http://www.egroups.com/message/bearhawk/2619?&start=2607 A great post by Barry Schutt is: http://www.egroups.com/message/bearhawk/2661?&start=2617 If I don't have success in my "Barrows Method" workshop down in Fincastle I'll go with Barry's method. I have a 6' wood lathe, so I imagine you folks think I'm nuts wanting to go with the "Barrow Method". I guess I'm a sucker for simplicity. +++ #2957 From: Subject: Re: [Bearhawk] Nose rib oops I used plain old Crisco shortning to lub. the rib for fly cutting the holes. After cutting the stuff washes off with dish soap. +++ #3032 Subject: RE: [Bearhawk] @#$% Lightening Holes---DIES From: Montee, Dan L. I use J-Wax 140 stick wax. It is designed for general machine shop use, drilling, tapping, general die lubrication. I use it to lube the jig pins as well. I don't know where you'll find it today but I'd guess MSC would have it if anyone does or try your local machine shop supply house. Still making ribs, Dan Montee +++ #3034 Subject: Re: [Bearhawk] Serious @#$% Lightening Hole Question From: Tim Anderson Bob - Go with the "Bob-stick"--you will have the job done quicker then you think. I didn't use any wax, but my oak stick seemed to slip around, espieclly after the notch got a bit worn. It really isn't that bad. If you started on the nose ribs, and got the hang of it, I bet you would continue. Cutting the holes was much more a gruesome task then flanging them. Now the angles, those are a pain!!!!! +++ #3035 Subject: Re: [Bearhawk] Serious @#$% Lightening Hole Question From: Seriously, I used a Malco hole cutter to cut the holes in my ribs. I wasn't happy with the results. The holes were not round and the surface of the aluminum was scarred. I transitioned to a fly cutter and am happy with the results. I was orginally against the use of the fly cutter from a safety point of view, but with a drill press, adequate clampling and a couple of simple jigs it should be OK (safety issues that is). The fly cutter makes round holes with no marring of the ribs. I just have to keep the cutting edge sharp. I'm planning to use a fly cutter for the spar holes. A simple clamping jig will ensure safety and accuracy of the holes. The Malco works great on the odd shapped hole in the mid span rib. I made simple tooling from MDF using Kevin D's method. One tool for each size hole, even the odd shaped ones. They are relatively easy to make. I used a threaded rod through the tooling (same as Kevin) to squeeze the flange into place, but if you have a press it would be much faster. I'm satisfied with the flanges that the wooden tooling made. I'm starting to manufacture the little 1/2 x 1/2 angles. I also started on the back ribs, got confused on the hole spaceing. I hope that my back ribs can become aileron or flap ribs. +++ #3036 Subject: RE: [Bearhawk] Serious @#$% Lightening Hole Question From: Bob Romanko I'm using a good fly cutter, and am happy with my results as well. Cutting/drilling isn't the problem. It's the @#$% flanges. I think I'm just trying too hard. This is the first time I've had any problems with any metalworking technique. I'm thinking that tomorrow morning instead of coffee I'll switch to PBR and see if that helps. Worst case, I fall in my shop, clap twice on the way down to the concrete, and autodial 911. For the spacing of the @#$% holes on the back ribs, I just measured parallel from the rear spar for horizontal spacing, multiplying x2 of course. I then just centered them on the rib, and didn't bother with any vertical measurements. I'm not building a watch, I'm building a plane. My dad ALWAYS used to say, "Robert, you're not building a watch!", anytime we worked on a project together. It was anti-anal talk. I think that really has helped me with the Bearhawk. It's so important to keep in perspective what's critical and what isn't, otherwise you can drive yourself mad with this project. I'm happy to report all my ribs are withing 1/32" of each other. Amazing. Now, don't ask me about how precise my flanges are to 9/16"! In all honesty, they're closer to 5/8". The extra weight will blow my gross out of the water. (grin) As far as cutting/drilling the @#$% holes, did you do all yours at once? I've heard quite a few folks here mention doing the @#$% holes individually. Cut, flange, deburr, next...etc... Any reason for that? I imagine it has to do with the rib wanting to transform itself into some mutant spiral during the process if you do them all at once. It would then probably become a spiritual experience to figure out which @#$% hole you have to mess with to make it right again. Oh Lord, I just thought of something. This may sound stupid, but could my problems be because of my Bob-Stick? I made mine out of the same material I made my form block, ash. Could it be too hard? I would think the harder the wood, the easier it would slide. Less porous and all. Nahhh...that's couldn't be it....could it? My big problems are flanging to 30 degrees (I'm a bit short) and keeping the rib from mutating into the above mentioned spiral. +++ #3037 Subject: RE: [Bearhawk] Serious @#$% Lightening Hole Question From: Float-By Shooter On Fri, 4 Aug 2000, Bob Romanko wrote: > As far as cutting/drilling the @#$% holes, did you do all yours at > once? I've heard quite a few folks here mention doing the @#$% > holes individually. Cut, flange, deburr, next...etc... Any reason > for that? I imagine it has to do with the rib wanting to transform > itself into some mutant spiral during the process if you do them > all at once. Exactly, if you cut and flange each hole, then straigthen the rib before moving on to the next one, you know which hole to fiddle with in order to straighten the rib. And did you know that Bob has said flanging the holes for the .032 ribs is not mandatory? > Oh Lord, I just thought of something. This may sound stupid, but > could my problems be because of my Bob-Stick? I made mine out of > the same material I made my form block, ash. Could it be too hard? The only problem I had with my bob-stick, which I made from left over formblock oak, was that it wanted to split down the middle. I drilled a hole top to bottom right behind the slot and put a small stainless bolt (8-32?) through it to prevent the splitting. After you've waxed up your rib, don't try to form the whole flange in one pass, or even 2. Go around it gradually and the flange will be formed much more evenly. > I would think the harder the wood, the easier it would slide. Less > porous and all. Nahhh...that's couldn't be it....could it? My big > problems are flanging to 30 degrees (I'm a bit short) and keeping > the rib from mutating into the above mentioned spiral. I think if you wanted to spend more time making tools than ribs, you could make a really nice bob-stick handle out of thick aluminum, with flanging inserts made out of that thick plastic like they make cutting boards out of. Then you shouldn't have any need for lubricating the rib. +++ #3038 Subject: Re: [Bearhawk] Serious @#$% Lightening Hole Question From: Float-By Shooter On Fri, 4 Aug 2000, Bob Romanko wrote: > Be honest. If you guys ahead of me used the "Bob-Stick" (great > term), would you do it again? At the time, I told myself no, I'd buy a lathe and make a nice set of dies and use my hydraulic press. Looking back, the bob stick worked just fine and the memories of frustration are fading, so I might do it again. > Is it REALLY that satanic of a job once you have are enlightened > (pun intended) on the technique? Yes, but it does work, and you will be finished with it soon. Even if they take you a couple months to finish, what's that to a scratch builder? Especially to "Planter Bob"? As for becoming one with the bob-stick, it only feels like that after a few hours. +++ #3039 Subject: RE: [Bearhawk] Serious @#$% Lightening Hole Question From: I made my "Bob-stick" out of plastic, the white stuff used for saw fences, etc. It seems to work, but I didn't like how the flanges turned out. If I were to do it again this is what I would do: **WARNING, Long, Boreing Area Ahead ** 1- out of 3/4 thick MDF, make a form block type block that fits inside the rib, between the flanges, clearing the flutes. I duplicated my orginal form block with a router, then deminished the height (as in rib height) by 3/8 inch, using my router. Made sure that there is material that sticks out beyound the aluminum. This extra material will be needed for clamping and for flangeing the lightening hole later. 2- clamp the rib on the form block 3- flycut the lightening holes in the aluminum, using the guilde holes on the rib to center. You did transder the hole centers to each rib didn't you? Don't drill though the MDF backing block. When transitioning from left side to right side ribs, use the same backing block but make sure that the lightening hole centers are co-located "one on each side each the same ???". 4- after all holes in all ribs are cut, drill through the form block with same fly cutter diameter as the hole in the rib. Now you have an MDF block with holes identical to the lightening hole diameter in the aluminum rib. 5- enlarge the holes in the MDF backer block 3/8 or 1/4 inch using your router in the same way that your reduced the height of the form block. Now you have holes in the form block that are the outside diameter of the flange that you want to end up with. 6- duplicate this form block so that you have two 7- make a "plug" of 3/4 thick MDF the same size as the hole in the backer block, as in step 5. This plug should be snug but not tight. 8- use 5 minute epoxy to attach another 3/4 inch MDF disk of about 1/2 larger diameter, to the "plug" that you just made. Call this larger diameter disk the "upper" and the "plug" the lower. 9- use you router to cut this larger plug "the upper" to the same diameter as the lower, except keep about 3/8 inch uncut. This sounds a little complicated by hang in there. It you were to take a cross section of this glued up assembly, it would look like a fat "T". The top of the T is the larger plug, and the straight up and down portion of the T is the same diameter as the outside diameter of the flange that you want to form, but longer than 3/4 inch. 10- now on the very botton of the T, add a 45 degree chamfer. This chamfer is cut so that the distance from the underside of the T to the start of the chamfer is 3/4 inch. Hang on, it should become clear any minute now. 11 - make a sandwitch of your two form blocks as the bread, and the rib as the meat. You should center the form blocks, so that the aluminum showing in the hole of the form block is centered. I used 1 inch drywall screws to hold the two form blocks togeather in the area that is clear of the aluminum in step 1. 12- If you have a press, now insert your plug and push down until it seats on the underside of the T. The chamfer will push the flange around the hole. If no press, use a threaded rod to tighten. I know this seems like a lot, but it really goes fast. I make tooling for each hole size, but you could make a block that includes all 5 holes in the mid-span rib for example. I hope this helps, if you want to talk about this in more detail, just say so and I will forward my phone number. +++ #3044 Subject: Re: [Bearhawk] Serious @#$% Lightening Hole Question From: I used the BOB-STICK method, I always wished I had taken the time to make dies. I strained my elbow and it botherd me for a month. All my ribs came out with a twist that is hard to fix, the more I tried to fix them the worse they got. They will straighten some when you rivet the stiffeners in, which by the way is the easiest part. As far as the lub. I used a candle stick for the flange bending, then I used generic Crisco for the fly cutter and on my drill bits. +++ #3063 Subject: Re: [Bearhawk] Serious @#$% Lightening Hole Question From: Float-By Shooter > I'm glad you said that, I have never used a fly cutter before. I > did'nt know you had to lube them. I have a Malco Hole cutter > also. I was not sure which I should use, I was thinking the Malco > was only good on wood. Someone posted a bad experiance with > it. Any thoughts or hints would be appreciated. I used the Malco hole cutter for making the goofy shaped lightening holes in the back of the .032 ribs. It is simply the right tool for that particular job. For all of the regular circular holes, the flycutter does a better job (leaves a cleaner hole, IMO). I didn't lube either the flycutter or the malco and they both seemed to work just fine. +++ #3074 Subject: How many little 1/2 X 1/2 aluminum angles? From: Rob Gaddy I've started a list of the little 1/2 X 1/2 aluminum angles. Does anyone have a complete list? I would be happy to crosscheck my list with someone else's. I've come to a couple of conclusions after looking at the plans. 1) the full size end ribs gets the same stiffeners as the other ribs, plus an additional two (each) to attach them to the front and rear spar. 2) the 0.032 ribs also get the stiffeners between holes although the lightening holes are not flanged. They are of course attached to the spars with angles. Is this right? +++ #3097 Subject: Re: [Bearhawk] How many little 1/2 X 1/2 aluminum angles? From: Rob: That little angle thing seems correct except that I can't count as high as the number needed. Remember that the angles contacting any spar at any location are .032 material. Be sure not to make them under .500 because some locations get a -4 rivet. Too short a leg will compromise hole to edge distance. Shear them and brake them as individuals, if you brake them long and then slice them down to length the legs legnths may vary due to brake error. +++ #3124 Subject: Tip Rib Tip From: Bob Romanko I made one of two tip ribs this morning. The tip rib is the only full rib on the Bearhawk, and compared to the other ribs, this thing is LLLLOOOONNNNGGGG! Having said that, fluting tip ribs straight can be a pretty spiritual experience, especially if you've only had one cup of coffee. After going NUTS for about a half hour chasing curves, I figured out an easy way to eyeball this thing. When I was finished, I had a tip rib that was as straight as a Kansas Interstate. First, get yourself four blocks of equal thickness. I used four pieces of 2"x6" lumber that were shaped relatively square I had laying around the shop. Take your rib after you've fluted it as straight as you can eyeball, then lay it on a flat, straight surface, with the flanges up. Raise the rib on three of the four blocks. Put two blocks under the flange you're checking, one about 1/3 in from each end. Put a third block on the opposite side of the rib (the back as you're facing it) in between the two front blocks. The key is you only rest the rib on one corner of each block. The blocks are at a 45 degree angle to the edge of the rib, and only under the flange about 1/2" or so. So, if you visualize this, nearly all of the block is NOT under the rib. The reason you do all this is to eliminate any oil can in the center from the rib throwing you off as you adjust the flutes. If you were to just sit the rib on the surface directly, you can go bonkers trying to figure out whether there's a can in the middle, or if your flutes really need adjusted. Now that your rib is perched on the three blocks, take the fourth block and use it as a go-no-go gage and slide it between the flat surface and the bottom of the flange on the side with two blocks. If there's a gap, you need to flute more nearby, if it doesn't go under you probably need to open up a flute somewhere. You should repeat this process from side to side a few times, because I've found when you flute one side it has an impact on the other side, especially where the rib is thinner toward the back. When you're all finished, you'll have an anal-retentive tip rib you can be proud of. One you can tell your grandchildren about when you're a crotchety 'ol cuss. The local paper may write a feature article about you. You may finally be elected deacon at your church. Your wife will gain a new respect for you. Your dog will now come to you when you call her. You'll never be audited by the IRS again. Your life will be good. +++ #3125 Subject: Re: [Bearhawk] Tip Rib Tip From: Not having made any tip ribs yet, I guess this is the time to ask..... Is there any reason not to make them in three pieces and rivet them together with a doubler? +++ #3126 Subject: RE: [Bearhawk] Tip Rib Tip From: Bob Romanko Yes. It would be more work, add a bit of weight, and look ugly when you take off your wing tip. Nothing like people gawking at your tip rib when it's hanging out all naked 'n such! > -----Original Message----- > From: Vberthels@a... [mailto:Vberthels@a...] > > Not having made any tip ribs yet, I guess this is the time to > ask..... Is there any reason not to make them in three pieces and > rivet them together with a doubler? +++ #3133 Subject: [Bearhawk] Tip Rib Tip From: Russ Erb To flute my ribs, I just looked down the edge and squeeze the fluting pliers until the edge was straight. If I overshot, I squeezed the flute a little with the seaming pliers. Seemed to work okay. Of course, I'll probably be accused of blasphemy since this method does not involve expensive tooling or computer-aided or computer-controlled anything. After all, isn't the reason we build airplanes is to have a reason to buy lots of cool tools? As for that tip rib being LOOOOOOOONG, take it to show to your buddies at the EAA Chapter. They'll think you're building a C-5 or a Jumbo Jet! When my friend first offered to help me make the wingtips, he was thinking of his Pulsar, where the wingtips have a chord of about 18". +++ #3134 Subject: Re: [Bearhawk] Tip Rib Tip From: Russ Erb Victor said: > Not having made any tip ribs yet, I guess this is the time to > ask..... Is there any reason not to make them in three pieces and > rivet them together with a doubler? My response would be that I can't think of any good reason to support doing it that way, especially if you made your forming block in one piece. Of course, you would be joining them together right where you should be attaching it to the spar, which would make that area unnecessarily complicated. +++ #3140 Subject: Re: [Bearhawk] Tip Rib Tip From: I made my tip ribs first and after making all the other ribs the tip ribs looked terrible. I went ahead and put the angles on and they look pretty good now. They were a lot of work and they take the longest, every rib after is a lot quicker. Jim #284 - +++ #3150 Subject: Lightening Holes (sans "@#$%")! From: Bob Romanko That "MR. LIGHTENING HOLE FLANGER" to you, pal! Yes, I no longer will call the lightening holes "@#$% lightening holes". I'm a flanging fool, and want to share some of my thoughts on the flanging of these little buggers with the rest of y'all who are where I am in the process. Before I go on, I want to thank everyone who sent me emails and suggestions on die construction. I came VERY close to making a set of dies, but as I always said, what's good for Bob Barrows is good for me. I know NO ONE who has built a Bearhawk (okay...TWO Bearhawks) as fast as Bob Barrows. If Bob felt we needed to make dies, I believe God would have put it in his heart to tells us. Agreed? Having said that, I made the decision to stick with the "Bob Stick" (named after Bob Barrows, not me) method of flanging. These past few days I discovered a few "Bob Stick" tricks, and here they are in no particular order: 1. The better you prepare the hole, the smoother things will flow. Use a file and a scotchbrite wheel and polish the edge up real nice 'n such. 2. Wax is good. Use regular 'ol canning wax your wife has laying around. Do both sides of the hole. It's cleaner than anything else, and easier to remove. You can also chew it if you run out of beef jerky (my early morning snack of choice). 3. Build an ACCURATE flanging tool no more than 3/4" wide, per Winter Edition '95 newsletter. 4. Roy Nash's "T-Tool" (push tool) in the Jan/96 newsletter is MANDATORY. You just have to have something you can put some pressure on the flange with to set the 30 degrees after you've lifted the hole with the flanging tool. Make both of these tools out of something HARD. The harder the better. I used ash, my wood of choice. I like ash, because as the tool wears it smells like an old ball bat. On top of that, I have better luck with it not splitting than I do with oak. 5. Don't sweat a warp. 97% of the time you'll take a warp out with the push tool if you ralph on the flange enough. A warp is usually removed with a push on the front and back of the hole. The other 3% of a warp will be removed by the stiffeners and/or attach angles. 6. Don't spend your time building the female board that Roy suggests. Although I'm sure it works great, you really don't to spend time with any elaborate setup to support the rib as you do this process. I used a piece of 2x10 pine I had laying around that's about three foot long. I ripped a piece of 3/4" pine 1/2" wide, cut it into short pieces to go around the rib under the flange and between the lightening holes. I took a handful of 4d finishing nails and attached them to the 2x10 where they needed to go. That's it. Total time to build the board: about ten minutes. 7. Although Bob Barrows told me he cuts all of his holes at once, I still went ahead and cut mine sequentially. I like having that extra material on at least one side of the hole while I flange. So, how long does it take to flange a hole? From the time I pick up a rib until I put it down takes all of two minutes. I know that's probably long for you folks who made dies, but I find the time it takes acceptable. All in all, I enjoy the process. It's fun playing "Tin Man" for a bit. I'm no Kent White, but flanging holes is a relaxing, gratifying task, and one that I'm not at all unhappy with. Again, the secret to completing the plane is to work on it every day, and enjoy the building process. I'm having a ball, and so far I'm up to 25 days in a row working on the parts. The gap in the schedule was to attend a funeral in PA. I hope these tips helped fellow new-builders. As far as you 'ol timers go, sorry to bore you with what you've already gone through! Y'all have a great week, +++ #3154 Subject: Lightening Holes From: dmccarroll1 I've noticed many e-mails and ideas on ways to cut the lightening holes in the ribs. Has anyone thought of using Greenley Punches? I have several that I have used for different jobs such as openings for SCAT hose, instruments, etc. They are easy to use and leave very clean edges. +++ #3155 Subject: Re: [Bearhawk] Lightening Holes From: Float-By Shooter On Tue, 15 Aug 2000, dmccarroll1 wrote: > I've noticed many e-mails and ideas on ways to cut the lightening > holes in the ribs. Has anyone thought of using Greenley Punches? Can you get them in all the sizes needed for the rib lightening holes, and how much would such a set cost? As I remember, the fly-cutters I bought weren't very expensive and between the large and small ones they cut every hole I needed, except the goofy ones in the .032 ribs. +++ #3156 Subject: RE: [Bearhawk] Lightening Holes From: Bob Romanko I doubt if you could punch one much faster than I cut one. With a fly cutter around 370 rpm I can clamp and cut a hole in less than 30 seconds. You're right about how clean the hole ends up, but you still end up having to polish the hole with a scotchbrite wheel in a press. If you have the right sizes I'd say go for it if that's the method you'd prefer. +++ #3157 Subject: RE: [Bearhawk] Lightening Holes From: Bob Romanko For the goofy holes, cut one hole with your fly cutter, the other one(s) out with a 1/8" bit spaced close together, punch out the piece along the perforation, and dress with a cutter in a high-speed rotary tool. Or you can cough up the bucks for a Malco hole saw to cut twelve holes (grin). +++ #3159 Subject: Re: [Bearhawk] Lightening Holes From: Donald Schindler Greenlee punches work real well, and for anyone who might be interested Lowbuck Tools makes a hand operated press designed to use Greenlee punches. Don 068 +++ #3167 Subject: Re: [Bearhawk] Lightening Holes From: Donald Schindler From: budd davisson budd@g... >What's a Greenlee punch and where do you get them? Hi Budd, Greenlee punch's are what Electricians have used for years to punch out various size holes in electrical box's so they can run conduit etc. They come in various sizes and resemble two hockey pucks that have a machined male and female face. The pucks oppose each other on either side of the metal and there is a hole drilled through each puck that a bolt goes through. When the nut is tightened on the other side it draws the pucks together and a circular hole is cut. The big electrical shops sell them individually or in sets. They work real well but do cost some bucks.....PS I am going to get your novel. I gave up on novels years ago cause Im to impatient and bored to get through them. I think that I might enjoy yours, if I dont then I know there is no hope for me and I am sentenced to a life of just magazines. Soldier on........ +++ #3176 Subject: Cutting the goofy (lightening) holes From: Benton Holzwarth > > I've noticed many e-mails and ideas on ways to cut the lightening > > holes in the ribs. Has anyone thought of using Greenley Punches? > For the goofy holes, cut one hole with your fly cutter, > the other one(s) out with a 1/8" bit spaced close together, > punch out the piece along the perforation, and dress with a > cutter in a high-speed rotary tool. Or you can cough up the > bucks for a Malco hole saw to cut twelve holes (grin). Anyone used a 'nibbler' for the odd shaped cutouts? It's a 'V' shaped hand tool, with a pivot at the bottom to operate a small chipper at the end of one of the legs. Inserted from the backside (underside) through about a 3/8" hole, it takes out a chip of metal about 1/4" wide by about 3/32" deep per stroke (hand-pump of the 'V' action.) pro's: - quiet - good control - reasonably cheap ( < $20 ?) - less dressing req'd, compared to 1/8" 'perforations' - low set up time, reasonably fast - chips are easy to clean up - zero distortion of the metal as it works con's - gives you one of those impressive handshake grips - takes a 1/4" kerf +++ #3198 Subject: How to REALLY Cut Odd Lightening Holes! From: Bob Romanko Okay...you folks are SICK of hearing about lightening holes. However, ANYONE who has reached or gone through this step knows just how long they take to cut/file/polish flange/etc..... These things just flat out take time, regardless of the method you use. This morning I came across a VERY nice way to easily cut out the "oval" holes in the back of the center ribs. This is a fool proof method that WORKS and gives awesome results, and some of you folks before me may have used this method. Planter Bob Method of Whacked-Out Lightening Hole Cutting: (instructions for LEFT ribs. Reverse rib orientation for your RIGHT ribs!) 1. Sharpen your fly cutter. 2. Make sure you have a piece of plywood bolted on to your drill press bed. 3. Set up your press for about 375 rpm. 4. Cut out a 3 1/2" circle from a scrap piece of aluminum. 5. You should already have the two center line holes 3/16" for the two circles that make up the rear oval holes in your center ribs. With the front of the rib facing to your left, put the hole of your template (from step 4 above) over the left center hole. 6. Take a sharpie marker and draw the circle around the template. 7. Clamp the rib on your press, front of the rib facing to your left, and use your fly cutter to cut out the first circle, the one on the right that you didn't mark. 8. Now, position the rib so that the circle you drew is exactly under the track of the fly cutter. Keep the rib front to your left. Carefully align the rib so that the fly cutter, when lowered by hand (your drill press should be turned OFF!), follows along the line. 9. Clamp the rib in this position. When clamping, use a 3/4"x3/4" piece of wood about 6" long along the bottom (facing you) where the cutter will start cutting. Put a clamp on both ends of it. This needs to be FIRM. 10. Take a sharpie, and mark the plywood around the outline of the rib in this position. Also mark the inside of the hole you drilled in step 7. These marks will help you to quickly align all the rest of the ribs. 11. Insurance. To make sure you ALWAYS remember to mark your rib BEFORE cutting out the first circle (causing you to lose your centerline) write "MARKED?" on your plywood somewhere where you can always see it. 12. Here's the secret. You're going to cut a ramp, by hand, where the fly cutter first hits the moon-shaped piece you're about to cut out. To do this, lower the fly cutter so that it's about 1/2" or so in from where it first hits, lower it into the material gently, and turn it by hand counterclockwise while increasing force on the press feed. You're cutting backwards, removing less material from where you first hit, and more material in the area where the hole will begin. 13. The ramp in step 12 prevents the fly cutter from catching the material you're cutting, and allows you to now turn on your drill press and SLOWLY feed the cutter around the rest of the material. What you will produce is a crescent piece that makes a perfect ear ring for your wife. Be sure to file and deburr the piece before giving it to her. If things get too hairy and you think you may damage the rib, only cut until you've scored the rib, then take it out, flip it over, and remove the material with a pair of needle nose pliers, ala opening a can of smoked oysters (the SECOND most preferred shop snack, after jerky). 14. Now that you have your second hole cut out, remove the rib and file down the two tips with a small flat file. Go around the whole thing with a half-round bastard (that's a file, not your brother-in-law), deburr, polish, etc.... 15. Viola. You are now on your way to rapidly cutting out some real nice holes. I sure hope this helps someone. I can't wait to move on to something else. I'm getting tire of writing about lightening holes, and you folks are getting tired of hearing about them. Still, this went so well this morning, I just had to let someone know! +++ #3254 Subject: [Bearhawk] end ribs From: Russ Erb Tim Anderson #398 wrote: > I'm getting ready to drill the angles and cleco my wing tip end > ribs in place. Bob's plans don't specify which side, not that it > makes any difference. I am contemplating putting angles on both > sides of the spars along with a small re-enforcement plate on the > rib. Anyone have good or bad thoughts on end rib mounting? Per Mike's picture book (and the way I did mine). the stiffener angles (except those at the spar locations) go on the tip rib on the same side the flanges are. That is, the side away from the fuselage and wing spar. This makes it consistent with all of the other ribs. At the spar location, the angles are on the side of the rib where the spar is (well, Duh!). One angle is used at each spar on the rear side of the spar. I would say that adding another angle and reinforcing plate would just add complexity and weight with no needed increase in strength. +++ #3316 Subject: Wing Iron Question and #433 update From: Doug Knight On Dwg. #11 the bell crank has (2)bearings listed as part (MRC R-4FF), what's the source as their are not listed in any of my aircraft catalogs? Has any body tried to use an oilite bronze bushings for for the flap torque tube at the flap arm mount and at the support assembly at the the wing root? Requires a larger receiver tube to accommodate the bearing and some machining will be will be required, there is room there and a slight weight penalty. #433 is progressing quite well, I lost July doing a major overhaul on my BMW. I promised myself no new transportation till after my bird is flying. All my ribs are rough flanged and I'm in the process of fluting and straightening. Made a custom 7/8" wide set a seaming pliers like the Avery kind, easier with the 1 1/2" rivet spacing. Aluminum Notes for those who want to get started, ribs required 28' of .025 and 4' of .032. That included a losing 9 nose ribs and redoing them. I first ordered 36' of .025" and 12' of .032". When you get well in the the pile-O-parts will have a good handle on what other aluminum to order. +++ #3319 Subject: RE: [Bearhawk] Wing Iron Question and #433 update From: Bob Romanko Doug, a quick suggestion. Don't get too balled up in making your ribs PERFECT in this point. Also, don't pay much attention now to minor scratches. The time to buff and polish is before you prime, not during fabrication. Also, don't sweat your ribs being perfectly straight when you first flute. You're going to put new, more interesting twists in them when you do your lightening holes, especially if your a REAL builder, and use the Bob Stick. (grin) +++ #3328 Subject: Armchair Bearhawk Building Was:Wing Iron Question and #433 update From: Doug Knight > To: metalfab@p... > > Doug, was that 28 ft of 4 ft wide sheets of .025, and 4 ft. of 4 > ft. wide .032 for all the ribs? Did you carefully lay out the > individual ribs to get the most out of your sheets? Come to think > of it, the four .032 end ribs are over 62 inches long. You > couldn't have gotten them out of a 4 foot sheet. I must of > misunderstood something. Thanks. First off I think it is very rude to blindly ask a question and not even give a name. Out here on the Left Coast we refer them as AOLammers. If you take offence, so be it. I don't know if you're in the game, did you buy a ticket and get a program? Take your seat please. LIKE I SAID ""Aluminum Notes for those who want to get started, ribs required 28' of .025 and 4' of .032. That included a losing 9 nose ribs and redoing them. I first ordered 36' of .025" and 12' of .032"."" In 'plane' English I could have used less, parts were nested best fit with an adequate temeplate no more than 1/2" oversize as required, I filled a 55 gal drum with the trimings. What a shame, but that's part of the job. The 4x8 .032 left over is now destine for my front spars. Now if you had a set of plans you would see that there 46 nose ribs in .025. 14 mid ribs in .025, ((6)) mid ribs in.032. (((2))) full size end ribs in .025. 4 tail ribs in .025. 18 flap ribs and 16 aileron ribs of .025. I want to know what Plane you are talking about, can't be the same as mine as stated. Only 2 ribs are full size and those are on the outboard end of the wings. Just tell me how you intend to fit the other two. When in doubt read the plans! Now pony up to Bob Barrows widow and get your own plans. Doug #433 (fangs showing and I've fired lame workers for less offences) I feel better already, I vented, now where is my fluting pliers? +++ #3375 Subject: Nose Rib Tip and Aluminum Cleaning From: Bob Romanko Here are a few recommendations for someone just starting out with lightening holes using the "Bob(Barrows, not Planter)-Stick" method of hole flanging, as well as a tip on cleaning ribs: Flange your center rib holes BEFORE the nose ribs. Drill a hole with your fly cutter in all the ribs, deburr, scotchbrite, wax, and flange that hole BEFORE drilling the next hole. Why? Well, I found it's better to have the extra material there when you're just learning this technique. Another tip is to wax the hole right after you get it off the scotchbrite pad you have spinning as fast as possible in your drill press. Mine goes 3250 rpm. That way the wax melts from the heat, and puts a real nice layer on the rib. For the rear lightening hole in the center ribs, drill three holes as I described in an earlier post, and the best way to cut out the rest of it is with a nibbler. These things are great, and I think it would be pretty tough doing any sheet metal work without one. Buy a REAL nibbler, made in good 'ol US of A. Don't buy one of those commie pinko nibblers. There only five bucks cheaper, and are worthless. You can't nibble jello with those things. Once you have all the lightening holes finished, you'll want to clean up the wax. I use isopropyl. Here's a shot of the method I use to clean up aluminum: http://www.people.virginia.edu/~rr3d/cleanrib.jpg Once your holes are cleaned up, be careful how you stack up the ribs for storage until you can get to the stiffeners. You may want to have a neighbor help you store them, just in case you got too carried away with wax cleaning. You want to get the wax off when you're done because it sure has a way of finding every little flake of aluminum you have laying around. On the nose ribs (which you should attack AFTER you've become real good with the center ribs), you can drill and deburr both holes at once. Flange the smaller hole first before moving on to the bigger hole. When you flange the bigger hole, you are going to inflict a WICKED bend in the rib. It'll be as warped as a liberal newspaper reporter. Don't worry about that, because the Push Stick will take out any bend you put in it with the Bob-Stick. I quickly cut out a female block that a nose rib just fits over, with both holes cut in about 1/2" bigger than the rib. This thing works great as a support for the rib. For the center ribs it's not necessary, but it makes the nose ribs go much faster. Speaking of speed, this morning I finished up my nose ribs, taking a polished nose rib from nothing to waxed and flanged in 4.5 minutes. Acceptable for me. Center rib holes go faster because there isn't as much deformation of the material, and you don't have that smaller hole to contend with. If I were to do it over, I probably would have made a smaller Bob Stick for the small holes in the nose ribs. For center ribs, a width of about 3/4" works well for the business end. The end in my hand is 7/8". I'll be making a new, thinner Bob-Stick for the smaller holes. I'm thinking along the lines of 1/2" or so wide. I'll let you know how that works out for a dimension. Hope this all helps someone. Ya'll have a wonderful weekend! +++ #3469 Subject: Re: Serious @#$% Lightening Hole Question From: - In bearhawk@egroups.com, newbegin@i... wrote: > I used the BOB-STICK method, I always wished I had taken the time > to make dies. --I'm new in the group and maybe late with this advise, but I used the avery flanging tool with no problems.To make the 3/8" flanges I put a washer between the bearing and the rod. That made the 3/8" flanges very well with no ripples. To make 1/4" flanges on flap and aileron ribs just remove the washers Jack +++ #3541 From: Benton Holzwarth Subject: YA Rib Formblock Idea Yet another formblock idea -- I've been contemplating making up a formblock and had a thought that I haven't seen mentioned before. I thought to start with a piece of 3/4" plywood, and surface both sides with Oak flooring. Compared to using a solid Oak plank, I think the costs would be comparable, the effort maybe a little higher, but the result a tad better. The floorboards have a relief milled into the backside, that I don't think will interfer with the forming edge at all, and I'll adjust the airfoil to minimize the acute intersection across the f-board edges. Nor do I think the tongue-n-groove will be a problem. And let me say MDF is a total non-starter, since I intend to hang it on the wall of my office (maybe with a clock set in the center!) when I'm finished with the ribs. As I see it: Flooring - requires laminating - can glue and tack (w/ tack strips to ease removal) - vs.clamps (I don't have that many clamps) - presumably flat enough to skip planing - will hold size/shape better over time, temp/humidity shifts - costs about $20-25 to do both sides (unfortunately just half of a $45 bundle of boards) Single Plank - will require planing (joining?) to true up faces, and - if it curls in six months - can't be refaced again even with plenty of thickness margin due to extra HW -- fixed drill guides, locating pins, etc. - will 'breathe' with temp/humidity changes - costs $4.60 / brd-ft for 9" Oak plank ~1 3/4" thick. - about $27 - $28 for the rib block. Now if I were to do it in Parquet, you might believe I'd gone too far, but I'm thinking this plan has some merit. +++ #3542 From: Float-By Shooter Subject: Re: [Bearhawk] YA Rib Formblock Idea > - will require planing (joining?) to true up faces, and > - if it curls in six months Mine didn't, but it was laminated of several thick strips of oak. > - can't be refaced again even with plenty of thickness margin > due to extra HW -- fixed drill guides, locating pins, etc. Yeah, that's the one advantage to not having installed drill bushings-- I can have my block run through a planer again should it become necessary (all my ribs are formed, and it wasn't). Some have expressed concern in the past about the radius on an oak block not holding up under repeated hammer blows, but it wasn't a problem with my rubber mallets. +++ #3580 From: Rob Gaddy Subject: Table mounter Router works again For what it's worth. I've posted a couple of times in the past praising the use of a table mounted router to make multiple aluminum parts. I used it to shape the rib blanks, and recently to make the 338 1/2 inch X 1/2 inch aluminum angles. Just last night, I used the router to make the 1/8 inch thick spar end plates. Worked like a charm I layed out and cut one example of each end plate, but didn't shape it completely, leaving a small amount of material to be removed to get to the lay-out line. I then rough cut the other three fittings. I used the carefully cut fitting as a pattern and used the router to cut the other three (one at a time). I made a sandwich, the fitting to use as a pattern on top, above a little bit of 1/4 Masonite ( to ensure that the bearing on the top of the router cutter would follow the pattern), above the rough cut blank fitting, above a final bit of 1/4 inch Masonite. All was held together with the "wing nut" type of clecos through 3/32 inch holes. The bottom piece of Masonite is there so that the cleco end sticking out of the bottom of the rough-cut fitting would have a place to "hide" and not interfere with the router operation. I used the existing holes as the location of the clecos. Where there was not more than one or two holes, I used a location where a radius would be needed later. This location was used for the cleco, then drilled to a larger size for the desired radius. All four fittings were then clecoed together, and sanded and filled to the final size together. All fittings of the same size. The process was so easy, I was even tempted to make 5 of each fitting, saving one as the pattern (just in case or to make other fittings for possible sale). +++ #3581 From: budd davisson Subject: Re: [Bearhawk] Table mounter Router works again Re: routers, etc. I recently returned from Aviat who, until they purchased a CNC router, did all of their aluminum blank shaping on a router. Rather than using a bearing-guided router, however, they used a pin-router which uses a stationary pin in the table located directly under the router as a guide. They use a down-cutting spiral router bit and cut one blank at a time that's sandwiched between 1/2" plywood and an .090 pattern. NOTE THIS! They cut the lightening holes in the rib blanks with the router while they are cutting the blank. just thought someone might care. +++ #3618 From: Kent White Subject: Re: [Bearhawk] Table mounter Router works again Routers are the traditional aircraft production method of blanking sheet parts. At least since WW2. Our vintage film of the Airacobra production in the Bell factory shows much of the methods of the day. Fascinating stuff. I can supply the special spiral router bits for those interested. +++ #3621 rom: Russ Erb Subject: [Bearhawk] Lotsa Questions While finishing up Ver 2 of the Bearhawk CD, I came across a recent message that had not been responded to. I'll answer the questions that I can. > Well, I've studied the plans and the newsgroup postings and I am > getting closer to starting the work. > > Would some of you answer some questions for me? Most are about the > wing. I don't have the wing photo pak yet (I have the fuse pak) and > I can't seem to figure these things out. > > 1. Are the rib attach angles mounted to the spar with the same > rivets as the capstrip or with their own rivets? The attach angles are held on by the capstrip rivets (at either end) and the same rivets that hold the vertical stiffeners in place. The center rivet on the vertical stiffeners is countersunk on both ends (NACA riveting) and is used to hold the stiffener in place while the other rivets are installed. The center rivet does not go through the attach angle. The other four rivets through the vertical stiffeners also go through the attach angle. The -5 rivets in the capstrip also go through the attach angle. Get the wing photo pack and it will be more apparent. > 4. How are the ribs and attach angles located (installed) over the > middle bolt head for the wing strut attach fittings? ( Web splice > area) The rib and attach angle are between the bolt heads. There is a cutout in the attach angle and rib for the steel strut strap. See the wing picture book and the CD (Ver 2 will be out shortly) for details. +++ #3623 From: Steve Eldredge Subject: RE: [Bearhawk] Table mounter Router works again What is the special about a spiral router bit? I've done some work with the edge lamination bit.... Is it that you don't have to drill a hole first if you want to start someplace other than an edge? +++ #3624 From: Kent White Subject: RE: [Bearhawk] Table mounter Router works again Router bit designs vary according to material and speed of cut. Wood-type bits, while acceptable for aluminum, are not always courteous and obedient. Designed more like a milling machine's end mill, the spiral bits cut very predictably, without the sudden leap, grab, or chonking action that make the chisel-type cutters so vastly more entertaining. +++ #3658 From: Paul Foster Subject: Re: [Bearhawk] Mahogany As I recall the recommendation from earlier conversations was to use either maple or walnut or something equally as hard. I made my form block from maple. Have not pounded enough ribs to notice any problems. > A local cabinet shop has suggested mahogany for my rib form block as > being hard enough to hold a radius while pounding ribs. Any thoughts > from the group??? +++ #3659 From: Tim Anderson Subject: Re: [Bearhawk] Mahogany I used oak, cut into strips, then re-glued. The only "wear" all be it slight, was around the spots where rib piece ended. ie, right near the spar. All that hammering on the edge of the rib put a slight beating on the wood. +++ #3661 From: Subject: Re: [Bearhawk] Mahogany I used MDF, $20 for a 4 X 8 X 3/4 inch sheet. Showed no problem after my ribs (almost all) were formed. for what it's worth +++ #3826 From: DANFORD, GARY Subject: RE: [Bearhawk] Progress and Question > From: Steve Eldredge > > Is there a flange on the ribs where it meets the spar? or are they > just connected with a L bracket. > > If there is no flange, do you cut out you blank for the whole rib > then section it at the spar lines? There is no flange on the ribs. I made the two end ribs first since they are full size. Then I cut off the front of the form block and made the nose ribs. I then cut off the form block and cut the long tail ribs then cut the form block to make the flap ribs etc etc. The problem is that the spar is thicker in some areas than in others because of the spar doublers. Thus each rib in the center section is a different length (so it appears, I haven't started assembling the wing yet. You'll have to get Russ to expand on the wing assemble process. (for both of us) When I formed the ribs, I formed them over the form block and had marks on the form block where the flutes went, transferred the marks to the rib flange with a magic marker (red for .025) and green for .032) then removed and fluted them. I then put them on the form block inverted (flange out) reinstalled the backing block and hammered the flange to 90 degrees. A short paragraph for a long project, hope it helped. +++ #3828 From: Subject: Re: [Bearhawk] Progress and Question It can be built either way, but Bob's intent was to have the rib mounted by an angle bracket riveted to the spar and rib. I believe someone has incorporated a flange while building the rib and Bob OKed it. No need to worry about cutting out full ribs,then sectioning them into three pieces, easier to lay out if you just cut out nose ribs, mid ribs, etc. Besides, you need twice as many nose ribs as mid ribs. I didn't worry about making my ribs to the proper length for the various spar cap dimensions. I just cut them all out the same size. It is easy to trim them to proper length when doing the final installation. This give you the added benefit that if you screw up drilling your attach angles holes on a full size rib, such as at the wing tip where there is no cap strip, you can salvage it by trimming it down to use mid wing where the cap strips are thickest. +++ #3829 From: Bob Romanko Subject: RE: [Bearhawk] Progress and Question Don't use attach angles? It's beyond me, having made all of my ribs, how anyone could make EACH rib accurately enough (using the form block method) to form an angle at the EXACT length to match up with varying spar thickness. Kent White could do it, Russ Erb could do it, Bill Johnson could do it, and Bob Barrows could, of course. Average Joe builder (yours truly) will be lucky to pull it off even with forgiving attach angles. +++ #3831 From: Bob Romanko Subject: RE: [Bearhawk] Progress and Question > From: Steve Eldredge > > Am I correct in assuming that you have to drive the rivet that > attaches the rib to the spar all the way through to the front or > rear rib at once? Yup..you got it! Nose rib attach angle, cap strip(s), web, cap strip(s), center rib attach angle...nothing but Net. +++ #3847 From: Russ Erb Subject: RE: [Bearhawk] Progress and Question Just to note: I found it much easier to rivet the angles to the spars first, then rivet on the ribs later. This is backward from what the newsletter said but much easier. +++ #4117 From: Benton Holzwarth Subject: Formblocks, spell-checkers, and etc. Had a couple thoughts to share, that I thought I'd bundle into a single post: I can't put off cutting into my first sheet of Al much longer. I've been trying to get all the other little bits in place to make nose ribs before attacking it, and am getting close. After a week hiding inside while the unheated garage dropped down to the low 40's, it finally warmed back up a bit outside, and the garage climbed to a balmy 46-48 deg (Fahrenheit, Tim). A couple good hours were invested in the #421 this weekend. Re: drill-bushings in the form-block -- as I thought about it, and given the earlier discussions about the disadvantage of having 'em in the form-block itself as a problem when re-planing the form-block, I put mine in the hold-down block that clamps down onto the form-block. My thought/procedure is to, load a nose-rib blank into the form-block hold-down, with it's edge aligned with the spar CL marked on the block, and held with the jig-pin; drill 1/4" through one bushing, through the metal; drop a pin into the hole; and drill the other lightening-hole center; and drop a pin through it. Then commence with hammering the flange down. I was unsatisfied with my attempts to center-drill solid mild steel rod out with a 3/16" or 1/4" hole to make bushings, so finally ordered a couple feet of 4130 tube from AS&S for the bushings, as someone suggested a long time ago. 3/8" x 0.065 is just a tad smaller than 1/4" ID. I was, this evening, working on the back-up block, to be used when pressing/straightening the lightening-hole flanges down to position. Finishing cutting the lightening-holes in it (yeesh -- I really dislike fly-cutters!), and making a couple bob-sticks and push-tools about wraps up what I can do w/o getting a piece of Aluminum involved. Re: fluting pliers -- made a pair, per Bob's description in Beartracks. (Adjacent to the Bob-sticks hint.) Expect they'll work fine, and with only $2.50 ventured, I won't be devastated if they don't live up to my hopes. Re: lightening hole flanging dies -- I'd planned originally to go the flanging die route. When I realized that every hole is a different diameter, save two in the center-rib, I kinda' decided maybe it'd be worthwhile to try the Bob-stick route first. But did have a thought to toss out: If one had a spherical tool to use for the male side of the form, one size might fit all (or at least most). In particular, I thought an old bowling ball might be about the right size to press a flange into several of the ribs. +++ #4238 From: Benton Holzwarth Subject: re: @#$% Lightening Holes Hey, Planter-Bob, when you gonna have that rib-flanging video ready? I've generated the nose-rib "first articles" from my tooling, and have with (really) nominal effort got 'em flat to within about a 1/4". What's reasonable? Back when you were shouting profanity how far off yours were, how far off were they, and how far off were they were they once you "learned to stop worrying and love the Bob-stick?" #1 came out like a real pretzel, but I'd flanged the lightening hole to about 45-deg. When I stopped at 30-deg, they were much less torked. Also, #1 and #2, from opposide sides of the formblock, were about 3/32" different in height at the main-spar end. I believe I can attribute this to evolving technique, since #3 (again from the first side of the formblock) came out much more similar to #2. In wading through the archives, I chanced upon Del's suggestion to cut and flange one lightening hole at a time. I'd cut both in the nose ribs, then flanged. I've put together the beginnings of my Bearhawk construction chronicle at if anyone is interested in having a look. Before jumping into 'mass production techniques', I'm trying to catch up with a local tech-counselor who flies a Supercub and is building an RV. Seems like a good combo to second-guess what I'm working at. (But I'm interested in all the second-guessing y'all can do over the net, as well.) +++ #4454 From: Bob Romanko Subject: RE: [Bearhawk] Oboyoboyoboy! Absolutely wonderful, and many congrats! Ever so closer to that MAGICAL 500th set of plans!!! Yes, I remember meeting you at Winchester. That was the morning I had the engine failure in a 150. Thank God for altitude. That's the only reason I can explain being 3000' AGL vs. the normal 1000' I usually fly over the top of that range (grin)! Another 2000' less and ya'll might be talkin' about me in the past tense. Yes, harvest all you can, for tomorrow we build. I'd be more than happy to host a visit at my shop. Just let me know when you'd like to drop on by. Feel free to send personal email at any time you care to. I'm here to help. To answer your questions. Cut inside the line, cut and double sticktape the mylar to your form block. Drawing 7 is not a sacred scroll. Maple is good, but everyone knows I prefer ash. Cut out the block diagonal to the grain as much as possible and route an 1/8" radius on the form block vs. the 1/16" in the plans. Sorry if the formatting in this post is whacked. I'm using my html Outlook client instead of native. +++ #4478 From: chris hoppe Subject: RE: [Bearhawk] stiffener fabrication I've got a real basic question: How are builders fabricating the rib stiffeners? Are you cutting and bending them or is there a source for angle of the appropriate dimensions? If you're going the cutting and bending route, is it worthwhile to invest in one of the 3-in-1 sheet metal machines available from Grizzly or Harbor Freight? +++ #4484 From: Bob Romanko Subject: RE: [Bearhawk] stiffener fabrication Welcome, and a good question. I cut all mine out by hand, then used an 8' brake I have laying around (thanks again, Shelly). Now, would I do it again that way? Heck no! See, when you hand cut alloy this thin only an inch wide you're going to put a twist in the piece. This twist is darn near impossible to get out. Now, you've got a twisted piece of aluminum in your hand, and you want to bend it 90 degrees. Guess what? That's right, it's IMPOSSIBLE! You get to go to the head of the class. Why? If you put a twisted piece of thin stock into a brake, I don't care HOW good the brake is, you're going to come out with one end being more than 90 degrees, and the other end less than 90 degrees. You may do like I did, and fool with your brake for about three hours until you realize the computer adage also applies when describing this process: garbage in, garbage out. There is a lot of physics going on here. Things that only Erbman could probably explain. Solution? Yup...use a shear to cut your stiffener and attach angles. It would totally eliminate the twist, and you'll have a nice even bend in your angle. What am I going to do? I don't know yet. I have finished all of my stiffeners and attach angles. With the stiffeners, I've chosen not to worry too much about it. With the attach angles I'm hoping that once I rivet them in place they'll sort themselves out. One of the little voices in my head says to do them over on a shear, and I'll probably listen to it. My dad always used to say, "How hard does God have to hit you on the side of your head with a 2 by 4 to get your attention?". I figure I'm hearing the voice for a reason. Now, about those 3-in-1 machines. My gut feel says they're not worth it, but that's only may gut (although quite large) talking. I've only seen one, never used it. I like the idea better of finding a place to go to do the work. In my case, I happened to befriend a guy here at Materials Sciences at UVA, and I have access to a complete machine shop. (Side Bar: I'm going to be selling my 8' D&K brake on eBay here shortly). In the grand scheme of things, you only need a shear and brake for a few things on the Bearhawk. You can, in one night, produce all of your attach angles and stiffeners in a machine shop. With my 8' brake, I was able to line up a HERD of angles, and bend 'em all up at once. If you have two guys working, one can cut, the other can dress (bench belt sander, 220 grit, then Scotchbrite wheel in a drill press, 3,000+ rpm), the first guy can then bend, then the second guy can drill (use a jig on the press). Sounds like a lot of work, but it COULD be done if you were focused and kept it down to less than three beers each until you're finished with the task at hand. +++ #4502 From: Del Rawlins Subject: RE: [Bearhawk] stiffener fabrication If you can beg or borrow access to a real squaring shear, do so! I went over to a friend's hangar and used his shear to cut them out. It was much faster and more accurate than anything else I could have done. To bend them I bought one of those cheap $30 18" brakes out of the Northern tool (like harbor freight) catalog, and beefed it up following Russ Erb's directions (for the most part). There are pictures of it someplace on my website and I believe on the CD if you have that. +++ #4506 From: Russ Erb Subject: RE: [Bearhawk] stiffener fabrication > How are builders fabricating the rib stiffeners? I cut my blanks on a friend's shear and bent them with a modified 18" aluminum brake sold by several sources, including Harbor Freight. You can see it on your Bearhawk CD. The brake is mostly useless as it comes from the store. Be sure to look in the tools section of the CD to see how to modify it to make it work adequately. I only recommend this because the price is reasonable. +++ #4671 From: "Float-By Shooter" Subject: Re: [Bearhawk] Building Status report > Last spring I began work on the Bearhawk. I finished the > forming blocks and made a lot of patterns. Then cut out all > the 268 rib blanks with tin snips. There are only 168 ribs, it just seems like more. 8^P +++ #4949 From: steve atkins Subject: Laser Cut Wing Ribs I have order the plans from Bob Barrows and ready to start punching out wing ribs. I just wanted to get some advice on the matter of laser cutting the ribs. I have access to a laser cutter that I can cut several ribs at a time from a single sheet of metal. do any of you fellow builders have any opinions on this? The laser requires the ribs to be in a .dwg drawing from AutoCad, I can draw these on CAD but has anyone already done this? +++ #4954 From: Budd Davisson Subject: Re: [Bearhawk] Laser cut ribs In the amount of time it takes you to program a laser to blank out ribs, you could have whacked out a bunch of them with a router. Besides, laser cut aluminum is hardened enough that you need to sand back the edge a little. Yet another operation. Technology often complicates what shouldn't be complicated (Hey! I just made that up!). +++ #5023 From: Brian Cox, bcox@a... Subject: Rib Form Block I purchased a sheet of MDF at the local Home Depot. They ripped a 9" wide by 8' long section for me, which I intend to make into the master rib Forming Block. To transfer the airfoil shape to the MDF, I used carbon paper (try explaining what carbon paper is to the young kid at Office Max!), then laid the mylar drawing over it. Instead of a rounded nail, as one builder suggested, I sanded down an old toothbrush handle to a rounded point. It worked very well and didn't cause any harm to the mylar. I will borrow a friend's bandsaw and cut it out, then finish with the belt sander as shown on Russ' CD (what a GREAT resource). Also per the CD, I intend to install fluted drill bushings for the jig holes and centers of the lightening holes. Any recommendations on bushing sizes? One way would be to use 3/16 in the jig holes and 1/4 in the lightening hole centers. However, I'd like to know if others may recommend using smaller bushings to create pilot holes. In any event, I do want them large enough so I can hold the form block and backing block together with fasteners. Any advice? +++ #5024 From: Russ Erb Subject: [Bearhawk] Rib Form Block I had used 3/16" ID bushings everywhere (5/16x.063 tubing). If I were doing it again, I would use 1/4" ID bushings on the lightening hole centers to match the pilot bit on the fly cutter. Keep the jig holes at 3/16" +++ #5025 From: newbegin@i... Subject: Re: [Bearhawk] Rib Form Block I just drilled small holes in my form block for the lightening hole center location and used a small nail and put a nice dent in the rib blank. When you fly cut the hole it will center on the dent. I put the dent in when I bent the flange, so the flange is up when you cut the holes. I also used the cheapest "Crisco" shortning for lub. when fly cutting, it washes off with dish soap and does not get all over everything else. Jim #284 +++ #5026 From: Budd Davisson Subject: Re: lightening holes Has anyone tried cutting the lightening holes with the router in the same operation when cutting the blanks? That's the way Aviat and Maule do it and that's what we're tooled for. The guide block you use for the blanking operation just has lightening holes cut in it and you plunge the router in and hog it out. The only question I have is whether this effects the flange forming operation at all. +++ #5027 From: Bob Romanko Subject: RE: [Bearhawk] Re: lightening holes I doubt if anyone has, as it's usually necessary to have other 3/16" holes on the blank other than the jig pin hole (i.e. Nose Ribs) in order to secure the piece for beating. I would think that with the .025 ribs having the lightening holes cut prior to flanging might cause the metal to stretch between the holes as one beats the flange over. If you're pressing your ribs I imagine this would be much less likely to happen since you'd have the material clamped as you stamp. Test, test, test... +++ #5028 From: Budd Davisson Subject: Re: [Bearhawk] Re: lightening holes This was my thought too, and I just wondered whether anyone had actually tried it. We're gonna answer this question in a month or so. +++ #5029 From: "Daniel Fox" Subject: Re: [Bearhawk] Re: lightening holes > From: Budd Davisson > > Has anyone tried cutting the lightening holes with the router > in the same operation when cutting the blanks? I was thinking about trying this very approach. The drawback is that a person would have to have 3" dia "guide pins" on the flange forming blanks, but that might not be any worse than 3/16" ones. I have never personally plunged a router into sheet AL and so cannot speak about the potential lunacy of such an action. Budd, I assume your process is some version of pin routing and not freehand? A related topic: pressing flanges in lightening holes. Bill Johnson used a shop press/gear press to make them. Russ Erb used a bench vise. I was thinking about putting a bolt through the middle of the 2 mating parts of the die and pulling them together. This is the approach used on the Pazmany illustrations recently posted to the files section. Does anyone have any experience/opinion about that approach? Will I need anti-oilcanning backing blocks as Russ Erb used? Did Bill Johnson find a need for backing blocks, or did he just press the flanges into otherwise unconstrained ribs? Also, information/opinion on the referenced book "Light Plane Construction"? Thanks in advance - +++ #5030 From: Brian Cox Subject: RE: [Bearhawk] Re: lightening holes As I prepare to make my rib tools, I've been reviewing Russ' CD. Look at Kevin Deutschers routing block. I believe that this allows him to do the lightening holes with a router as you describe. +++ #5031 From: Brian Cox Subject: RE: [Bearhawk] Re: lightening holes Look at Russ' CD. There is a section on making wing ribs, page 8. It shows Kevin Deutscher's flanging method with a bolt drawn die. +++ #5032 From: Budd Davisson Subject: Re: [Bearhawk] Re: lightening holes We are pin routing, as does Aviat, but I've done similar operations free hand using a guide bushing on the router. Something fairly heavy, like the 3 1/2 horse Porter Cable plunge routers willhave enough inertia that they'll go throug the sheet before they start skittering across it. An alternerative is to simply drill a 3/u8" hole in the aluminum to accept a piloted router bit. This has the advantage of having smaller holes in the guide block, as you don't have to allow for the guide offset. A thought: we've left a lot unsaid here, for instance this assumes a lightinging size hole in the form block and at least that big of a hole in the clamping block, plus the guide offset, if you go that route. Also there should be bolts going through the sandwich into the bench top of someting else to holdit stationary. As far as forming versus hole cutting goes, you could flange the ribs first, then make a set of MDF routing guides to cut the holes. +++ #5037 From: Steve Eldredge Subject: RE: [Bearhawk] Re: lightening holes This is what was experimenting with last week before I crashed my bike and put my hand out of commision and into a cast Friday. 1. Route out the outside dimesion and lightening holes 2. bend over the edges 3. flange lightening holes I was using a collar router bit so I could plunge through the center of the lightening holes. I did add jig pins outside of the lightening hole locations to secure for routing and bending. Didn't think of problems that might crop up trying to beat the edges over after cutting lighting holes. It will be a month before I get to try. My hammer hand is now encased in fiberglass. +++ #5038 From: Brian Cox Subject: RE: [Bearhawk] Re: lightening holes Got my plans a week ago and am making the form block. Here is my plan of attack: 1. Route outside dimension 2. Flange the edges 3. Cut lightening holes with fly cutter 4. Flange lightening holes with hardwood die On the lightening hole flanges, I tentatively plan to use a hydraulic press, which is available at Harbor Freight for ~$100. Even so, I may not want to invest the money and shop space for the press. I was thinking about a less elegant method, however. On the farm, we used to pound in metal fenceposts with a steel tube that was closed on one end. Slip it over the post and slide up and down to pound the post in the ground. Perhaps a crude slide hammer like this could be placed on the die plug to pound in the flanges. The backside would be supported by a tool with circular openings and a beveled edge, similar to the ones used by other builders in a vise or press. Lay the backing plate on a flat surface, place the rib on top, drop the flanging die in and pound the flange with the slide hammer. I don't know if this would tend to work harden the material or not, but we do pound the edge flanges. +++ #5039 From: "Daniel Fox" Subject: Re: [Bearhawk] Re: lightening holes Budd Davisson wrote: > Plunge routing always assumes a bare router bit. Right. I was trying to make a joke around that; they can't all be winners. Forgive my density here, but if you plunge through a flat surface into a circular pocket with a bare router bit, what is keeping you from routing your merry way through the blank, the template, and anything else in the way? My experience is limited to woodworking, but I've only seen piloted bits with the bearing at the top or bottom, not the middle. Unless, your "pattern" was designed for the outer edge of the router base to ride against, a la door hinge templates. +++ #5040 From: "Daniel Fox" Subject: RE: [Bearhawk] Re: lightening holes Thanks for your reply. I'm seeing this better, but I'm not out of the woods yet. You wrote 4 steps: > 1. Cut or route rib blanks I'm with you. > 2. Flange the edges Still with you. > 3. Place the flanged blanks over an MDF routing tool that has > the lightening hole guides, then route the holes. This is where I have the heartburn. Whether the edges are fluted or still wavy, I can't see putting the rib blank down over a form tool and maintaining registration. If you're finished flanging the edges and they are all a nice 90 deg to the surface of the blank, you could place the blank _into_ a female form tool and get away with it. But placing it face down over a male form is dicey at best for accuracy better than a 16th. Or, I'm missing something, which is still the likeliest scenario. >4. Flange the new lightening holes Bobstick or press die, I'm with you here. Thanks to all for tolerating me while I flange a dead horse. +++ #5041 From: Brian Cox Subject: RE: [Bearhawk] Re: lightening holes I think we're in violent agreement. Also, I seem to be a few steps behind you, so I'm not an expert. I'm just passing along my interpretation of the great work done by pioneer Bearhawkers. My two cents worth: 1. For those using a fly cutter to cut the lightening holes, the 1/4" pilot holes are made when the rib is still flat. Then the backing doesn't have to be the means of registration. The center drill bit of the fly cutter fits in the pilot hole. I may have misrepresented my proposed technique, but I'm planning on cutting the lightening holes with a flycutter. 2. One method of using a router for the lightening holes is to do it prior to bending the edge flanges. I saw pictures of one builder doing this. 3. One builder suggested adding another 3/16" jig pin to align the rib when using the router method. If a pin is not used, I agree that it will probably be tough to use the flanged edges against the form block to maintain alignment. I went back through the references on the CD and just read through them. The more I think about it, then go back to the archives, the better I understand. Or at least I think I understand. +++ #5044 From: Budd Davisson Subject: Re: [Bearhawk] Re: lightening holes Daniel Fox wrote: > Forgive my density here, but if you plunge through a flat > surface into a circular pocket with a bare router bit, what is > keeping you from routing your merry way through the blank, You get a guide collar for the router, which is a round piece of tubing mounted on a base that screws to the base of the router. The bit sticks out of the middle of the tube. Then, the bit always cuts a given amount away from the edge of the collar regardless of which direction you move it. The collar/router base rides on a pattern that sits ON TOP of the material to be cut. The pattern underneath it just supplies support. The radius of the pattern hole has to be bigger than the hole to be cut by the distance from the edge of the router bit to the outside of the collar. The pattern and the blank have to be indexed together via pins, screws etc.This means the rib blanks have to be predrilled with those index holes. It might be simpler to put holes the size of the lightning holes in the form block, and drill a 3/8 hole to let a piloted bit through the rib blank. Then the router guides on the bottom pattern. You still need a pattern of some sort on top to supply a bearing surface for the router to ride on so it doesn't scratch the rib and to index it to the bottom pattern. Exactly where did I lose control of this conversation? +++ #5047 From: Russ Erb Subject: RE: [Bearhawk] Re: lightening holes I've done this with fence posts. If you try this, I think you would need a steel female die. Wood would split rather quickly under that kind of pounding. You may also find that the springback of 2024-T3 will drive you nuts. Hammer on it and it may just spring out of the way, then spring right back. +++ #5048 From: "Tex and Pat Goerger" Subject: Re: [Bearhawk] Re: lightening holes We use this system where I work doing the tooling and building jigs for P-51 components. Have no problem with the material stretching as it is put in a hydropress with all the lightening holes cut and flange them with the outside flanges also being made. It works with .025 through .063 in 2024-0 +++ #5049 From: Mike Guthrie #235 "Mike & Wendy" Subject: Re: [Bearhawk] Re: lightening holes Well I can tell you from experience that pounding flange dies works. I made my dies from UHMW [similar to nylon] Without a large backing plate the dies would spring back so I simpley used a BFH and hammerd around the edge of the dye with good results. The reason I used UHMW was It is soft enough not scratch the materieal and would not split like wood. +++ #5050 From: "Kent White" Subject: Re: [Bearhawk] Re: lightening holes Tex Goerger: > "We use this system where I work doing the tooling and > building jigs for P-51 components. Have no problem with the > material stretching as it is put in a hydropress with all the > lightening holes cut and flange them with the outside flanges > also being made. It works with .025 through .063 in 2024-0." Agreed, and I am with you on the "0" condition material as well as the T3. The edge flanging operation does not require nor does it apply any tension (stretching force) across the web, or face of the rib, so the anticipated distortion of the openings is moot. So therefore, the holes may be cut during the rib-blanking process. Hole flanging: You need force to flange the holes. Whether it be gradual as in a press, vise, bolt-drawn squisher, C-clamp, or Bob-stick, you will need pressure. If you use sudden, all-at-once force as in a ball-pein whammer, one-shot rivet gun, fence-post slammer, slidehammer, or whatever it still adds up to either 16 one-ounce taps or one one-pound blow. You choose the method, the tool, and simply adjust your technique to satisfy. Cutting the holes: I think I have found a light one-handed router for doing free-hand openings. But it needs a particular router bit in order to do it. The manufacturer of said router is Not Interested in Aluminum At All. The bits are pretty accurate in following a line, and they plunge right in. I will post photos soon and will try to find out where the danged bits come from, if anyone is feeling experi-mental. I did a nice round hole in 2024 T3 .025 material recently with no distortion at all. Nice discussion, guys. +++ #5051 From: "Float-By Shooter" Subject: Re: [Bearhawk] Re: lightening holes > The edge flanging operation does not require nor does it apply > any tension (stretching force) across the web, or face of the > rib, so the anticipated distortion of the openings is moot. > So therefore, the holes may be cut during the rib-blanking > process. If you form your edge flanges as Bob recommends in Bear-Tracks you might have a problem. The flanges are formed most of the way clamped between the form and backing block, but due to springback they are free-formed the rest of the way to 90 degrees on the benchtop with the hammer. With the lightening hole material already removed there might not be enough strength there to resist bowing the rib up in the middle. Just my speculation, however. +++ #5054 From: "Kent White" Subject: Re: [Bearhawk] Re: lightening holes OK, so you may have a reaction 90deg. to the flanging action, but not stretching. Why can't a block/dolly/bucking bar be laid flat on the partly -flanged rib and leaned on whilst banging the flange fully over? This would trap the thin section at the edge of the hole and support it. An angled/beveled/wedged edge on the block might help avoid contact with the flange, or even help stop it at the 90. I would like to have some of the "wasters" that you BH builders toss as you get the testing done. Would make for a good informative article. "Rising tide lifts all boats." +++ #5055 From: "Tim Anderson" Subject: Re: [Bearhawk] Re: lightening holes I have been using a Rotozip tool lately to auger out my larger fuel tank holes and it works well....But it can get away from you real quick. For those that don't know what a rotozip tool is, it's basically a smaller, hand-held router with small streight bits. I didn't use this on my lightening holes, I used a hole cutter on my drill press and then bob-sticked. But, the rotozip has it's uses. Should be able to see one at Home depot if your interested. $60-$70 range as I recall. +++ #5059 From: Tony Dean Subject: Re: [Bearhawk] Re: lightening holes The guide collar is usually part of a hinge routing kit. We just replaced the old doors in our house with nice new six pannel blanks. The hinge routing kit is a rectangular guide and the guide collar bolts to the bottom of the router. The guide collar follows the guide and you get perfect hinge slots every time. For the lightening holes you need a circular guide and simply follow the edge. Since I don't have a plunging router I'll simply hage to put a hole in the scrap part of the cutaway and then follow the guide. The local Home Depot or other building supply stores cary these. +++ #5060 From: chris hoppe Subject: Re: [Bearhawk] Re: lightening holes Your acronyms have me stumped; What's "UHMW" and where do you get it? What's a "BFH" ... another name for a dead-blow hammer? +++ #5061 From: Tim Subject: lightening holes....Spring back Ref: Kent's comments.....Below is a small pic reference spring back and how to compensate for it, in your form block...I guess Bob didn't bother for simplicity, but as you can see, 'it ain't no big task' ....The plus is that the forming is done while supported by both blocks...Clickon link- instant pic +++ #5062 From: Brian Cox Subject: RE: [Bearhawk] More Lightening Hole Stuff There are a lot of current discussions on lightening holes. On my way in to work, I was wondering why everyone raved about the Malco hole cutter for the oval holes, but most were cutting the round lightening holes with a flycutter or router. This is especially true after spending the money for the Malco. Your pictures are timely and answered my questions. The Malco works, just as long as you adjust technique to be compatible (paraphrasing the Tinman's post on forming or pounding flanges). The tradeoff seems to be moving the clamps as the hole progresses. Nice work and good pix. +++ #5063 From: Doug Knight Subject: Re: [Bearhawk] More Lightening Hole Stuff I might add here that I modified the Malco. Piviot pin size is 3/16", my bushing size was 1/4". Easy fix with lathe to make a 1/4" pivot pin. The standard 3/16" piviot also had a hook type barb that I did not like. Minumum hole size for the Malco was about 2" IIRC. I used a fly cutter on a few smaller and hole saws for a few more. Malco was the hands down winner in tools to use.Just remember the golder clamping rule. Also remember I make a living with tools in my hands. Look in page #13 for flange pics +++ #5065 From: Brian Cox Subject: RE: [Bearhawk] Re: lightening holes I did a Google search on UHMW and found a lot of info. It is a type of polyethylene, referred to as Ultra-High Molecular Weight thermoplastic. Check out www.snapidle.com/uhmwdata.htm. Looks to be a good anti-abrasive coating, and has solid lubricating properties like teflon. I'm going to check into sources and cost, as this looks to be a pretty neat flanging plug material. I know solid teflon is very expensive, so this may have similar properties at lower cost. As far as BFH, I can tell you from some of my summer jobs during college that "B" means Big and "H" means Hammer. Don't want to start another philosophical outpouring if I say what the F means, and it would not be in character to say it anyhow. +++ #5070 From: Daryl Van Zee Subject: Re: lightening holes We have used UHMW Polyethylene at our company. It is highly abrasion resistant, but soft. It will cold flow and is not very stable dimensionally. It is usually quite expensive, particularly in thicker sections. +++ #5074 From: Benton Holzwarth Subject: Flanging dies (was Re: lightening holes) Daryl Van Zee said: > We have used UHMW Polyethylene at our company. It is highly > abrasion resistant, but soft. It will cold flow and is not > very stable dimensionally. It is usually quite expensive, > particularly in thicker Bing - a light just went on... We have in our kitchen a cutting block of nylon (I presume) about 12 x 18 x 1/2". Couldn't have spent more than a few bucks on it. If I bought the cook a new one (this one is getting *terribly* nicked and cut, yeah, that's the ticket) I'll bet she'd let me have the old one... I've got the bobstick about down, I think, but might have to go back and reconsider a bolt-drawn die... +++ #5076 From: Rob "$.02 worth" Gaddy zipppydoggg@y... Subject: Flanging dies (was Re: lightening holes) > I think, but might have to go back and reconsider a bolt-drawn > die... I did the draw-down type of flange tool, after Kevin D. showed me how they work. I ended up using a 3/4 threaded rod and went through a couple of nuts. I did use, however, an air driven ratchet to save my arm. I bought the little MECO torch, from the Tinman, and it is great! (no financial interest, only a recommendation to the group). I ended up using a fly cutter for my holes, I didn't think the Malco hole cutter was the way to go, after I bought one and used it on several holes. Is this a "drive-by yapping? +++ #5082 From: Russ Erb Subject: [Bearhawk] lightening holes....Spring back There is a specific reason for not doing this--If the form block edges are kept at 90 degrees, then both sides can be used to form all of the ribs. If you follow the method shown, you will need two IDENTICAL form blocks, one set up for left flanges and one set up for right flanges. I made the choice to free-form the last few degrees of the flange rather than try to make two identical, mirror image form blocks. Shucks, making the first one was plenty of work. All of this talk about rib forming is making me feel old--I finished mine back in mid-1997. It didn't used to bother me as much, but now it's getting far enough in the past that I can't remember how I did some of the operations. +++ #5083 From: Del Rawlins Subject: RE: [Bearhawk] More Lightening Hole Stuff On Thu, 8 Feb 2001, Brian Cox wrote: > in to work, I was wondering why everyone raved about the Malco hole > cutter for the oval holes, but most were cutting the round lightening > holes with a flycutter or router. This is especially true after spending > the money for the Malco. Your pictures are timely and answered my That would have been me raving about how well the Malco tool worked some time ago. The key piece of missing information that you were wondering about, is that I didn't spend the money for the Malco, I borrowed it from a friend. I did all the other lightening holes with a flycutter and it worked just fine. Some people have managed to do the oval holes with the flycutter but it is pretty nerve-wracking. I did one that way successfully and decided to find a better way (the malco) because I was afraid it would get away from me and ruin a rib if I persisted in doing the rest that way. THe oval holes were the last holes I cut in the ribs that needed them; if I had been thinking far enough ahead I would have done them first and probably used the flycutter since a lot less work would have been at stake. +++ #5090 From: "Montee, Dan L." Subject: Malco I'll add my experience with the malco and flycutter operations to the discussion. On the malco; it is definitely not a precession tool. The diameter set up is difficult to control and if you use the tool as recommended the brad point/necked-in guide will let the hole wonder +/- .030 or better. OK for furnace work but not what I was looking for on my ribs! I finally built a jig from an old piece of shelf material about 6" wide, 3' long. I transferred my jig/pilot holes for both the oval sizes to the jig. I set the required diameter on the malco and routed the board. I used my jig pins to locate the rib on the jig. The brad point fits nicely into the 3/16" hole in the jig and is guided by the jig, not the part. Clamp the daylights out of the part on to the jig. The cut was started by plunging in near the intersection of the diameters, the throw away stuff. Cut about 270 degrees, switch holes, use the previous cut to insert the malco, ( in the right direction of course) and you have a somewhat precision figure 8 core and hole that is identical on all the like ribs. And, since my techniques are closer to Planter Bob's than Erbman's, I finished up with a hand nibbler, files, and scotch brite. I prefer the fly cutter for the larger holes since it is more precise and easier to set up. I can slow my drill press down to about 100 rpm and that's what I use to flycut. Use a jig, clamp the daylights out of the part, lube the tool and the part (I used a machining wax), keep one hand on the kill switch, and you shouldn't have a problem. +++ #5094 From: "Tim Anderson" Subject: RE: [Bearhawk] Re: lightening holes As to the time investment and builder preference..I quickly looked over my builders notbook as to time spent on cutting lightening holes (flycutter) and Bob-sticking the hole flanges for all the ribs, both wings, nose,main, flaps,ailerons. About 80 hours. That total may include some rib edge flanging...Not sure..Could be done quicker but my drillpress slows to only 600 RPM, is not prefectly level on the table, and I have ten thumbs at times...making flycutting a very interesting experience. I didn't have a wood lathe, so making all those forms and dies was quickly a non-player...But, I bet half that total would have been eaten up making all the wooded jigs and dies. Flanging dies do have there place though in my pea brain opinion. To each is own... +++ #5302 From: Jim Ash Subject: Too flute or not two flute, that is the question While the plans call for fluting the flanges on the ribs to even out the pressures they apply and thus allow the rib to be straightened, is there a reason for using this method, vs. shrinking the flange flat by slapping it down on the form blocks or just using a shrinker? It looks to me like straightening a rib by adjusting flutes would end up similar to trueing a bicycle wheel. +++ #5305 From: Russ and Penny Erb Subject: RE: [Bearhawk] Too flute or not two flute, that is the question Fluting is quick and easy. Works good, lasts long time. Slapping works for 6061 over form blocks--2024-T3 has too much springback. Using a shrinker would work, but would probably take longer, and you'd have to figure out how to get that wavy flange into the thin slot in the shrinker. Then you'd have to dress out all of the grip marks from the shrinker. Get yourself some good seaming pliers too to flatten the flutes when you get a little too aggressive. To fix the same mistake on a shrinker, you'd have to change out the jaws to the stretcher. +++ #5457 From: Donald Schindler (Don 068) Subject: Routing Ribs For those of you just starting out, I decided to give the router a shot at the ribs, and it's a nice way to go. If you have a Porter Cable router, they have Templet guides(which is just a bushing with threads that screws in the bottom) that maintain a clearance between the form boards as you rout. I have a Makita router but Makita makes a Templet guide adaptor that screws on and then will accept the Porter Cable templet. This is my setup: Makita templet Guide Adaptor #321492-3, Porter Cable Templet Guide #42048, templet guide locknut #42237, and two Vermont American straight router bits # 22004 and 22007 both High speed steel one 1/8 and the other 3/16th, which will give you your 1/2 and 9/16 inch flange respectively. With this setup it is more fun then work, cuts in a fraction of the time and does a neater job. +++ #5685 From: Jim Ash Subject: flutin Russ - A month ago you had responded to my inquiry about the need for fluting. Did you try slapping without fluting? If I can get a straight rib without having to do the fluting, is there any other benefit to having the flutes? Jim Ash +++ #5686 From: Russ and Penny Erb Subject: RE: flutin Slapping works better with 6061. 2024 has too much springback. Fluting isn't hard and works well. No one will ever see your ribs after the wing is complete. Quit stressing and just do it (no apologies to Nike). Russ Erb +++ #5687 From: "Float-By Shooter" Subject: RE: flutin > Slapping works better with 6061. 2024 has too much > springback. Fluting isn't hard and works well. No one will > ever see your ribs after the wing is complete. Quit stressing > and just do it (no apologies to Nike). And you probably already thought of this, but be sure to mark the rivet locations on your rib prior to fluting so you don't wind up with a flute where a rivet should be. You could always adjust the rivet spacing to compensate for a misplaced flute but then you'd lose the visual effect of pretty rivets all in a row. Mark the rivet spacing on your form block to simplify transferring it to the ribs. +++ #5701 From: Benton Holzwarth Subject: RE: flutin Float-By Shooter (Del Rawlins) said: > > You could always adjust the rivet > spacing to compensate for a misplaced flute but then you'd lose the > visual effect of pretty rivets all in a row. Mark the rivet spacing on > your form block to simplify transferring it to the ribs. I made up a pasteboard template to mark cutting lines for my rib blanks. The template also included a 'tick' at the locations for the rivets. It's just visible in the 'click for larger image' template picture here, third up from the bottom -- http://www.siletzbay.com/Bearhawk/bhConstWing.html The template is outlined with a fine-point Sharpie, and I always remark bolder the tick for the rivet position before going too much further. Benton 15apr01 +++ #5704 From: Russ and Penny Erb Subject: RE: RE: flutin I just marked the locations for the rivets on the hold-down block on the form block. Mark the positions either before or after hammering the flanges down. Russ Erb +++ #5768 From: Doug Knight Subject: Re: Rib layout quickie Jim Ash wrote: > > Somewhere I saw a sketch of the layout of a bunch of ribs on a > sheet of aluminum to optimize material use. Is this on Russ' > CD somewhere? Jim, I remember seeing it too. In reality it was bogas. I used something near 30' of .025 and less than 4' of .032 and got "ALL" my ribs, (nose, center, tail, full sized and flap and ailerons.) make cardboard templates and "start nesting." Remember the grain. doug #433 +++ #5769 From: Bob Romanko Subject: RE: Rib layout quickie Well, the grain is not an issue with the bend radius we're using. I think we've beat the grain horse to death on several occasions. Still a good "practice", but for our purposes with 2024-T3 and a radius close to 1/8" we're in pretty good shape stress-wise-speaking-wise....... In the grand scheme of this airplane if you waste a few square feet of 2024 I don't think you'll break the bank with the loss. Of course, it all adds up in the end. Planter Bob +++ #5770 From: Brian Cox Subject: RE: Rib layout quickie I finished my rib forming jig, and decided to use 3/4" MDF. I also used MDF to make routing templates for each rib type, and have these complete, including chipboard frames as shown on Russ' CD. Thanks for the feedback on the layout. I suspected that it had some errors, as the 6" X 6" blanks for nose ribs may have been calculated on the half scale drawing by accident. As far as grain orientation is concerned, I will align all the nose, mid, and back ribs as recommended, perpendicular to the grain. For the two tip ribs, I plan on orienting them at as much of an angle as possible with respect to the grain. I'll start with the template running parallel, then rotate it until it fits within the 48" width. After I cut these out, the grain will be neither parallel or perpendicular, but at some angle that I guess would be between 30 and 60 degrees. In any event, it will be better than going straight parallel. The left over pieces of the sheet will be triangular or trapezoidal, and I can nest in the templates for various nose, mid and back ribs. It may result in a little more scrap. Brian Cox, #478 +++ #5771 From: Doug Knight Date: Tue Apr 24, 2001 8:25 am Subject: Re: Rib layout quickie Brian, Don't strain yourself on fitting the full size rib at a diagonal. It is the only set of ribs that you can't cut with the grain orientation. As it is, you will be triming off a whole lot of scrap that ends in the recycle bin. I pretty much filled up a 55 gal drum with trim strips. Make the most and nest tightly. http://www.geocities.com/doug_knight_94501/Bearhawk/pic3.html Doug #433 +++ #5772 From: Russ and Penny Erb Subject: RE: [Bearhawk] Rib layout quickie I looked at Doug's picture in the link below. Since I trimmed my ribs to final shape in the router jig, I just needed rough cut blanks. Doug's site says that he used two power shears that he wasn't happy with. I've used power shears quite successfully, but it did take a while to learn the finesse of using them. When everything was lined up right, they cut great. When it wasn't, they didn't. The point I wanted to make was that Doug used a very nice plywood template to mark out the ribs. Something to consider: In the NASA "faster, better, cheaper" line of thinking, or at least "faster, cheaper" I used a corrugated cardboard template to lay out my blanks. Very cheap, and worked plenty good for as long as I needed it, which wasn't that long. Russ Erb +++ #5774 From: zipppydoggg@y... Subject: Re: Rib layout quickie Jim Ash wrote: > > Somewhere I saw a sketch of the layout of a bunch of ribs on a > sheet of aluminum to optimize material use. Is this on Russ' > CD somewhere? I found no need to be that concerned with the scrap. It turns out that the little 1/2 X 1/2 inch angles consumes a lot of aluminum (more than I thought it would anyway). I used most of my larger scraps making the angles. Rob "$.02 worth" Gaddy +++ #6736 Date: Tue, 3 Jul 2001 08:30:46 -0600 From: Brian Cox bcox@ Subject: RE: Erbman's possibly useful trivia... Good Morning, Here's my 2 cents worth on using MDF. I bought a 4X8 sheet (very heavy) and used it to make my form block, and to make routing jigs for the ribs. I used carbon paper and the mylar drawing to transfer the image onto the MDF. Instead of a rounded metal scribe, I used an old toothbrush (yeah, I replaced it with a new one) and sanded the end into a rounded tip. This worked fine as a scribe, and didn't seem to harm the mylar drawing. I don't have a bandsaw. To cut out the rough shape, I used a handheld circular saw. The first cuts left plenty of clearance to the line, then I shaved closer with the saw, still keeping clearance between the rough edge and the line. To finish the tool, I used an inexpensive tabletop sander. It's the Delta unit that has a 4" wide belt sander and a 6" diameter circular sander. The belt sander was good for removing material, but I couldn't keep a right angle between the edge and flat surface of the MDF because I was holding it free hand. To do the finish work, I held the MDF flat against the small platform and gently faired the edge against the circular disk. After a little practice, it worked pretty well, and this kept the edge at a good right angle. I went through about 3 disks (150 grit) to do all of my MDF tools. I first made the wing rib forming tool, then followed by making routing jigs for each type of rib. I made the following routing tools: 1. Nose rib 2. Mid rib with oval hole in the MDF tool for 14 ribs 0.025" 3. Mid rib with oval hole in the MDF tool for 6 ribs 0.032" NOTE: I'm going to route the oval holes, and use a flycutter on the round lightenening holes 4. Back rib for wing (Yeah, I know there are only 4 ribs, but it was getting easier to make the MDF tools) 5. Nose rib for Aileron 6. Nose rib for Flap 7. Tip rib for Aileron and Flap (different from wing tip rib because the flange is only 1/2") The rest of the routing fixtures are made from 3/4" chipboard, just as shown on Page 2 of the Wing Rib Construction Photos from the CD. I recall reading in the CD that you liked the belt portion of the sander better than the disk portion. My own experience, as related above, was that I could rough the part in with the belt portion and do the finish work on the edge with the disk. Just an observation. Overall, I think the MDF is easy to work with. Using the sander as my tool, I had a real dust problem, and in the interest of family harmony, had to wait for good days to do this work out in the driveway. Otherwise, EVERYTHING in the garage would get a coating of dust. I'm saving up to buy the aluminum and start routing ribs, probably after Oshkosh. I'll bring a few of my MDF routing jigs to Oshkosh to show to any interested Bearhawkers. Brian Cox, #478 +++ #6741 Date: Tue, 3 Jul 2001 07:03:47 -0400 From: "W. Shalm" FORM BLOCKS > >I'm making my form blocks out of maple gym flooring. Form Blocks. On my Zenith CH-300 the form blocks were made from 3/4 inch plywood that were faced with 1/8 inch Aluminum plate. (When does sheet become plate?) Anyway, the faced aluminum was then filed, by hand, to produce a 1/8 inch radius. There was a 10 degree overcut on the wood backer for the springback of the rib blank sheet. There was a lower block, as above, and an upper block that was maybe 1/2 inch smaller in all directions than the lower block. The upper block served to hold the sheet flat and to confine the bending of the blank to the radius area. The upper and lower block were pilot drilled at 1/4 inch and the rib blank had matching pliot holes. These pilot holes would soon become the location of the center of a lighting hole. You could bolt this "sandwich" together and with the flange of the blank sticking out, proceed to form it over the radiused aluminum. Since most ribs were the same, you could also cut "scallops" in the wood backer block for the formation of the flute to take up the excess metal so as to make a flat rib. My ribs were of 0.032 stock, and took some work to make. I made all of the ribs for the Zenith this way. And the rib forming blocks are still in great shape. Oh, yes. Save them. You may run into a telephone pole some day. Or a runway light. No, but a friend of mine did. Tim Hickey +++ #7229 Date: Tue, 14 Aug 2001 23:29:18 -0500 From: Tim Hickey Are your light'n holes flanged on the CH-300? Yes. Done with a male/female die in a big vise. Worked very well. Tim Hickey +++ #7238 Date: Wed, 15 Aug 2001 08:17:21 -0600 From: Brian Cox bcox@ Subject: RE: OT: Rib Form > OK, talking about rib forms, ... > > If they are made in one piece and subsequently cut to three > pieces, is this done in a band saw ? Cutting thru the flange > gets a little touchy with snips. My form block is one piece. I installed drill bushings at the locations for the two tooling pins (3/16) and centers of the lightening holes (1/4). I'm making separate ribs, as I believe all others have done. 46 nose ribs (.025"), 20 mid ribs (14-0.015" and 6-0.032"), 4 back ribs (.025"), 2 tip ribs (0.025"). When using the large form block for the nose, mid, back ribs, I plan to use the bushings to hold them in place. It's OK to make separate form blocks, and they would be less cumbersome to handle. I don't think anyone will be making full sized ribs then cutting them. There are different numbers of nose, mid and tip ribs. Oh, also there are some short filler ribs behind the false spar by the fuel tanks. Brian Cox, #478 +++ #7241 Date: Wed, 15 Aug 2001 08:48:48 -0700 From: "Greco, Bob" Form block question...... and yesterday I routed the edges to > .250" radius. ...... How much shoul I worry about the (very > little) daylight about the (very little) daylight under the > square. The required radius IS .125" (1/8"), and you could even use .063" (1/16") if you were cleaver. Trick #1 cut several pieces of wood at all the same dimentions, give each block it's own radius and beat up some parts. You will see the difference as you complete each part and it will become evident on what you will want to use. HINT!! Don't be affaid to screw up some parts as you surley will, it is just part of the process. Take a C-note and buy some aluminun and beat some fake parts, this might be the best $100 spent on a proper start. The daylight? You should be your own judge on what you can get away with. Do the above and you'll know. It's not rocket science. Doug #433 +++ #7345 Date: Wed, 22 Aug 2001 18:01:49 -0700 From: Russ and Penny Erb erbman@ Subject: RE: perfektion? I agree the proper radius is 1/8" (.125), in keeping with 4T for 2024-T3. Bob Barrows says the form block should have a 1/16" radius. (He even said my form block had too much radius on it--Mark Goldberg showed it to him after he bought it for possible use at AviPro--and you thought Planter Bob was a trouble maker...) In the end, because of the way we form ribs, it just doesn't matter (Bill Murray, "Meatballs" 1979). Also, the fact that your block is not exactly square won't matter either. Because of springback, the flange only forms 45 to 60 degrees when hammered over the block. When you free form the flange the rest of the way, the unrestrained aluminum will naturally form to a reasonable radius. Just make sure that if you use both sides of the block to form ribs of alternate flanges (as I did) that the two sides are essentially the same. Russ Erb +++ #7388 Date: Fri, 24 Aug 2001 20:44:03 -0400 From: sonny cilley woodpret@ Subject: Re: Digest Number 523 Hi Jimmy M, as to you using the oak, it will be alot more stable than the cherry. but I think that I would bring it inside and let it settle in for awhile before cutting the form. in Vt. no matter what wood we use , if it is air dried it only comes down to about 12 % moisture and if I were to lay a floor in someones house they say let it aclimate for a couple of weeks before using it when you do use the oak, and cut out the form,seal it with something just to try to keep it fairly stable it'll be fine. most important is that you have fun building this plane. anyone else got any thoughts. sonny #234 +++ #7563 Date: Wed, 05 Sep 2001 08:33:43 -0400 From: "Chris Vuxton" christopher.vuxton@ Subject: Drilling Rivet holes before or after Flanging I have gone through 1085 pages of email traffic and found several references to rivet holes but my question is...has anyone tried drilling all rivet holes in their ribs adn then flanged the ribs? I was thinking about cutting reliefs in my form block to set the locations of the reliefs. Chris #515 +++ #7609 Date: Thu, 6 Sep 2001 17:11:26 -0700 From: Russ and Penny Erb erbman@ Subject: RE: Drilling Rivet holes before or after Flanging > ...has anyone tried drilling all rivet holes in their ribs adn > then flanged the ribs? I assume you're talking about the rivet holes for the rivets that will hold the skin on. I think you'd be very disappointed with what you suggest, because there is a high probability the rivet holes won't end up where you want them. In general, the accepted method is to drill the skin and the rib at the same time--that way you know they'll line up. Russ Erb >>> 2mar02 #7686-9153 +++ #7950 From: "Jim" Subject: Nose rib My name is Jim Van Fossen. I've had plans #411 for several years now and never found time to start building but have been lurking here. I retired this summer and have finally worked through most of the honey-do list and am just now starting. I have looked through Benton's archive of all the posts and through all the newsletters and can't find the answer to this question and hope someone else can help me. In Mike's construction manual he says that when you have the nose rib blank clamped to the form block you can file the unfalnged part of the rib to the form block contour. My question is this - shouldn't the unflanged part stick out 0.025" from the form block? If it doesn't you will have a 0.025" step in the profile between the unflanged and flanged part. I know, the skin will bridge this step and I'm sure the plane will fly just as well either way; I guess I one of those anal retired engineers. Thanks for your help, jim +++ #7951 From: Russ and Penny Erb Subject: RE: Nose rib Yes, you are worrying about insignificant things. You wouldn't want to do what you suggest anyway because that would make for a non-smooth transition from the flange and set up a stress concentration. Let the skin bridge the gap. The Bob has said that the joggle on the ribs is not required either. Russ Erb +++ #8057 From: supermexgarza@a... Subject: form blocks About to start cutting some southern red oak (don't ask about the southern part, it must have an accent, or curse a lot) i want to trace the drawing of the rib on to the wood #1 do we cut the wood so it will be exactly like the drawing or cut inside the line to make room for the flange of the rib, there for leaving the wing rib the same size as the drawing after it is bent (formed) #2 do we seal the wood with some type of wood sealant to prevent moisture changes (i might be splitting hairs on that one) but it is quite humid around here Javier Garza #497 +++ #8058 From: "Dan Montee" Subject: Re: form blocks Before you get the inevitable rehash of all the opinions that have been expressed on this topic in the past, let me give you the laymans summary version. #1 It doesn't matter. #2 Sealing is good thing. Dan Montee # 415 +++ #8059 From: Russ and Penny Erb Subject: RE: form blocks Dan--very good! Even shorter than my short version would have been! Erbman +++ #8073 From: newbegin@i... Subject: Re: form blocks Sonex uses form blocks for the ribs the way you describe and they come out straight. Sonex used MDF and marked the rib outline then drilled (1/4) holes centered on the line, then cut out the form block. My neighbor built two Sonex's with one set of form blocks and they are still in good shape. Use a 3/16 rod shaped on the end to form the crimp. If I ever make alum. ribs again,I will use this method. Jim #284 +++ #8150 From: Russ and Penny Erb Subject: RE: "Gotcha List" ( Kevin's Wing List ) > 2. A really clever builder would understand that the flutes in > the flanges of the ribs should be located so that the flute > lines up with stiffener. Well, then demote me to just "clever builder". I didn't pay attention to this, and ended up with stiffeners in one position on pretty much each rib rather distorted between the dimple squeezer and driving the rivets. I highly recommend you that you follow Kevin's advice here. Something else I remembered that I don't think has ever been mentioned. If you place a rivet in the center of the main spar flange and then lay out your rivet spacing from there, it is very likely that the next rivet forward of the main spar flange will be positioned right over the capstrips on the front of the main spar. Quite tough to buck rivets there, and the holes you drilled into the edge of the capstrips don't do wonders for its strength. Be sure to watch out for this. Also pay attention to the same problem at the first rivet hole forward of the rear spar. Russ Erb >>> 4sep02 #9154-11297 +++ #9204 From: Del Rawlins Subject: Re: Detail check - l-holes in 0.032" > Working on the six inboard center ribs of 0.032" mat'l -- noticed > the detail on plans sheet 6 that suggests only the lightening holes in > the 0.025" center ribs need to be flanged. Is that right? > > I looked for confirmation in Mike's wing photo-pack, but couldn't > be certain. You'll probably have to go to the list archives from jbc.edu on the Bearhawk Reference CD for confirmation, but you are correct in that The Bob is on record that the lightening holes in the .032 ribs do not need to be flanged. It may be beneficial if they are, however. +++ #9246 From: Del Rawlins Subject: Re: Bob-stick, Usage of > Some of us are not building Bearhacks, but merely come here for sheet > metal working tips. I've read the various posts about flanging > lightening holes with a notched hardwood stick, but some pictures of > the process would help. > > Could somebody post a few in the Photos section of the Yahoo Groups > website? Or, are there any on the Russ' CD? Russ' CD contains the Bear Tracks newsletters, which have a pretty good description of the bob sticks and their use. The bob stick is basically as you describe, a short (6-8" long) hardwood stick, about 3/8" wide and 3/4-1" deep, and with a hacksaw kerf slot in one end, with the depth equal to how wide of a flange you wish to produce. The flanging process is pretty self explanatory, you use the stick to bend the flange down gently, working your way around the lightening hole. It will generally take 2-3 complete circuits of the hole to achieve the recommended 30 degree flange. That is the easy part. Once the flange has been bent, your part will have taken on a concave shape, due to incomplete stretching of the flange metal. That is dealt with by using the imaginatively named "push stick" to fully stretch the metal around the hole so the rib can return to its normal flat shape. Several different push stick designs have been used, ranging in complexity from the basic design (my push stick falls into this category) which is little more than a bob stick without the slot in the end, to more complex T-handled units for builders with sensitive hands. To use the push stick, the rib is placed flange down on the worktable and the flange stretched carefully by pushing down on it with the push stick. Again, work your way around slowly and carefully; it will probably take several passes to get it just right. It is also helpful when using the push stick, to place a couple short blocks the same overall thickness as the rib (including the edge flange) underneath the rib around the lightening hole, to prevent stretching too far with the push stick. The whole process is outlined pretty well in the newsletter but the technique does have a bit of a learning curve to it. Some guys seem to have more trouble with it than others, but with remedial training even the Planter was able to master the bob stick; fortunately it isn't rocket science. Oh also it is recommended to wax the working end of both the bob stick and the push stick, so they will move more smoothly over the metal. I know you were really looking for pictures of the process but I don't think it is something that is explained well by still photos. Maybe somebody with a video camera would be willing to record the process and post an .mpg in the files area, but I wouldn't hold my breath. +++ #9456 From: Don Rennie Subject: Forming blocks Well today I finished my forming blocks. I know, I said I was going to do this a couple of weeks ago, but who knew life would go on happening when I'm trying to build a plane. I used a gig saw to cut them out. Then used a belt sander to finish. It worked very well. For the drill hole bushings I used slotted keys this also worked well. The lightning holes I cut with an adjustable round hole cutter and made the angle with a rouder. I'm going to try to tap the hole bevals with a rubber hammer. I made my forming blocks with 3/4 MDF because I had it I'll let you know how it works. I got the metal for the wing ribs and spars at Ideal metal in calgary. 5...4x12 sheets of .025 and 2....4x12 sheets of .032 for $1454.13 canadian. I'm ready to make ribs I'll let you how I make out. +++ #9548 From: Bob Romanko Subject: RE: Making Ribs Bearhawk#540 For the large tip ribs you should use several blocks of equal thickness on a large, flat surface. Placing the blocks under the ends of the rib, use another as a go/no-go guage to see where you need to flute further or flatten the flange. That's how I did mine, and they're straight with no twists at all. At least none I could measure on a flat surface. For what it's worth... +++ #9628 From: "t18cox" Subject: Re: flange on lighting holes I think there are plenty of advocates for both methods here. If you take the time to make the flanging dies the actual flanging goes very quick with little or no distortion. For one set of ribs the dies can be made from hardwood plywood and will holdup OK. Look at page 80 in Tony Bingelis book Sportplane builder for a good sketch of the dies. The Bob stick will work fine also. If you read and follow the instructions in an early newsletter you should be making nice flanges with a little practice. Good luck! +++ #9638 From: Del Rawlins Subject: Re: Centre Ribs > At the front of the center ribs, the plan shows the first 1 1/4" of > the rib recessed to allow the spar edge to fit in and become even with > the rest of the rib. How does one do this ? Per The Bob, you don't have to do that even though the plans show it. Just make your spar webs to the appropriate size to fit over the ribs without the joggle and the skin will still fit up okay. Not that there is anything wrong with making the joggle if you want the top of the spar flanges to be flush with the ribs. You can form the joggle by making a male and female block that you will sandwich the rib flange between and beat the top block with a hammer. Just don't use an air rivet hammer in place of the top block (its been done). +++ #9639 From: Russ and Penny Erb Subject: RE: Centre Ribs I think you are referring to the "joggle". I sanded/ground a piece of steel which I used to hammer this in. You can see it on the Bearhawk Reference CD in the "Wing Assembly" HOWEVER, if you haven't bent your spar webs yet, you can bend them slightly larger so that you can insert the ribs without joggles. According to Mike Meador, Proto I was built with joggles, Proto II was built without joggles, and there's no noticeable difference. An official Bob-approved change. +++ #9751 From: Don Rennie Subject: Re: Bearhawk muster 2002 #423 I don't think you have to scrap your nose ribs. The bend is so tight on the nose ribs its hard to flute them at regular intervals,you have to flute where necessary to get the rib straight. The other ribs can be fluted at the 1 1/2" intervals. If you want to change your flutes, you should be able to put them back on the forming block tap them smooth ,and then re flute them. If a part is no good through it out. But I don't think that's the case here. Those with more knowledge can correct me if I'm wrong. +++ #9807 From: Drew Schumann Subject: Criticality of wing rib jig Just finished cutting my wing rib jig out of oak. (all the local lumberyard had available) Noticed that my saw left little lumps and irregularities where there were knots and where I made really tight turns at the leading edge. How critical is the shape of the jig? Can I just sand the irregularities out and give it a sweet shape and call it good, or do I need to chuck out the whole thing and try again? Drew (If you can't tell, I'm in the nervous nellie phase of building. My head tells me that the 1/32" or so I'll change the rib profile can't make that big a difference, but my gut says, "AAAH! You fool! You just ruined it all!") BTW, that is ONE BIG MOTHER of a wing rib. Gulp! What the heck am I getting into? +++ #9810 From: "Bruce A. Frank" Subject: Re: Criticality of wing rib jig There is "absolute this is what it has to be" and there is "build to fit". This is a build to fit situation. Smooth the dimensions with a sanding block and build the plane. Does anyone remember a few years ago there was a story in one of the homebuilding mags about a machinist who decided to build a foam and fiberglass plane, I think it a Long EZ. He didn't like the tolerances of the prints so he re-drew the plans to + or - 1/64th (or something ridicules like that) then built the plane to that spec. He agonized over imperfections smaller than the weave of the cloth. Once flying the plane he concluded that he couldn't pilot the plane to the precision he felt necessary so he decided to scrap it....luckily he had become friends with someone he though up to the standards necessary to fly such a meticulously (obsessively)built aircraft and sold it to that friend. This was not a story of a project, but the case history of a psychosis. My point is for people not to get hung up on details that are insignificant to the proper function of the aircraft....such as a detail discussed here before as to whether to scrap parts formed to the outside or inside dimension of the drawing or whether the rib dimension allowed for the thickness of the wing skin. In my eyes, parts I fabricated when I first started my project are grossly imprecise compared to what I can accomplish now. Hardly a day goes by that I don't consider scraping those parts and making them again. Don't succumb, you will NEVER finish. As your skills evolve so does your dissatisfaction with early work on the project. Don't let yourself get into that mind set. You will NEVER finish. +++ #9811 From: Russ and Penny Erb Subject: RE: Criticality of wing rib jig > There is "absolute this is what it has to be" and there is "build to > fit". > This is a build to fit situation. Smooth the dimensions with a sanding > block and build the plane. Yep. There are some airfoils (laminar flow, GAW-*) that are very picky about surface imperfections. Typically those can only be realized in composites (stiff) with a lot of work. The 4412 that we are using is not that picky. It has a turbulent boundary layer and is relatively insensitive to imperfections. Sounds like sanding it smooth will get you plenty close. A few years ago we had big discussions about whether or not to cut drawing #7, how to transfer the shape to the wood block, and whether we should trim to the inside, outside, or middle of the line. Once we realized that The Bob draws each #7 by hand around the (literally) "Mother of all Form Blocks", we realized that this discussion had all of the makings of a Shakespeare play, specifically "Much Ado About Nothing". If your ribs are smooth and reasonably close to the right size and shape, your airplane will fly just fine. > Does anyone remember a few years ago there was a story in one of the > homebuilding mags about a machinist who decided to build a foam and > fiberglass plane, I think it a Long EZ. He didn't like the tolerances > of the prints so he re-drew the plans to + or - 1/64th (or something > ridicules like that) then built the plane to that spec. He agonized > over imperfections smaller than the weave of the cloth. Yep, and that one came up the last time we discussed that. It was in Sport Aviation sometime between 1990 and 1993, and I remember at the time thinking the guy was loopy. The article was written as celebrating someone who was at the pinnacle of the homebuilding art, but came across as someone who never learned the difference between when precision was required and when it was not. I remember reading once that +/-1/64 inch was acceptable for metalworking, while +/-1/16 was good enough for woodworking, because the material wouldn't support that precise of dimensions. I don't care to discuss if you think those are the right values, my point is different material require different levels of precision. Anyone used to putting together aluminum parts may be appalled at how "sloppy" steel tube can be fitted for welding and still come out just fine. Wonder how many builders that ultimately ended up discouraging because they thought they weren't "good enough". Remember, most of the folks hammering together Cessnas, Mooneys, Gulfstreams, etc are not college trained engineers or even fully qualified machinists. > (If you can't tell, I'm in the nervous nellie phase of building. My > head tells me that the 1/32" or so I'll change the rib profile can't > make that big a difference, but my gut says, "AAAH! You fool! You > just ruined it all!") Not to worry. We've all been there. You'll develop the feel for what is required, both through experience and reading. We'll be here to help. Someday you'll be the one answering this same e-mail from another new builder. +++ #9814 From: Don Rennie Subject: Re: Criticality of wing rib jig I put carbon paper under my wing rib drawing, then marked the rib , spar locations and hole centers , it worked Very well . 3/4 MDF also has worked well for the form block. I have most ribs done and there is no deterioration at all , even when I did the .032 stuff. +++ #9849 From: "Chris Vuxton" Subject: Wing Rib Cut sheet files in Files section I think I may have this down pat. I've uploaded a zip file (125K) to the files section that has pdf's, dxf's, and dc's (for those using DesignCAD) of the cut sheets I've been working on. So, pdf's to look, the others to play. PLEASE MEASURE YOUR RIBS BEFORE YOU CUT OR DEPEND ON THESE SHEETS. I tried to allow a reasonable amount of space around the ribs (w/ flanges) and in the case of back and nose ribs have two together in each space. Make sure you check and see that I haven't left some out. You'll notice that in each case, except for the full sized ribs, I've included space for a few extras of each rib. I'm counting on buggering up a few. +++ #10171 From: Drew Schumann Subject: 3/32" relief holes in nosepieces I am having an odd problem. When I work rapidly on my nosepieces, during the fluting process, my work turns out okay. When I take my time with the flutes, I'm getting cracking around the lower relief hole only. During the forming process, you can see the stress building up around the top hole, but so far, no cracks. What I've done to correct the problem, is to put my first flute a little farther back. Also, I'm fixing the cracked pieces by cutting off a little of the flange and redrilling a new relief hole. Anyone have any good ideas? I just don't like the look of all that concentrated stress around the (surprise) relief hole. Drew PS - My fluting tool I made according to the newsletter, however, I used epoxy putty instead of brazing a rod in the drilled hole. It formed perfectly, with electrical tape on one side of the hole to prevent bonding both jaws, and to provide clearance for the work. It leaves no marks whatsoever and doesn't need filing to smooth out. It took a couple days to reach full hardness, however, I ruined it twice before getting some patience and just letting it cure before use. +++ #10172 From: Russ and Penny Erb Subject: RE: 3/32" relief holes in nosepieces I'm not real sure what you're saying. By "relief hole" I assume you mean the one at the front end of the flange. My first flutes were at least an inch or more back from there, leaving room for a rivet hole between the forward end of the flange and the first flute. +++ #10173 From: Drew Schumann Subject: RE: 3/32" relief holes in nosepieces Those be the ones. Problem I got, is that when I go an inch or more back, the nosepiece is still quite warped. When I get closer, it sometimes cracks around the hole. I was initially really worried about my rivet pattern here, but then I looked at the wing of a Cessna 150 and quit worrying. Won't that leading rivet cause even more stress at that point? +++ #10175 From: Russ and Penny Erb Subject: RE: 3/32" relief holes in nosepieces All I can say is that I haven't had a problem with it, nor have I heard anything like this before. However, now that I think about it, I cut out my ribs with a router using a 1/2" diameter laminate bit. Therefore, the relief on the front end of the flange (which is a 90 deg corner on the pattern) has a radius of 1/4", significantly larger than the 3/64" radius you get with a 3/32 bit. If you have ribs you haven't cut yet, use a bigger relief radius. For those you have, file out a bigger radius. Any that have cracked, file out the cracks. There's not a lot of stress in this area (other than from forming), but cracks are generally bad and need to be dealt with. +++ #10186 From: "Dan Montee" Subject: Re: 3/32" relief holes in nosepieces/airworthy repairs I think Russ has identified the source of your problem, Drew. The plans call for a 3/32" Radius, not a 3/32" hole. +++ #10188 From: Russ and Penny Erb Subject: RE: 3/32" relief holes in nosepieces/airworthy repairs > On a related note, I keep hearing about folks "ruining" pieces of > aluminum. Myself, I use that opportunity to practice my airworthy > repairs, and "fix" whatever problems I create. This question calls for the universal answer: "It Depends." Can it really be repaired or not? For instance, scratches on aluminum. Since I'm not going to polish the aluminum, I just get out the Scotchbrite pad and rub down the scratch until I can't catch a fingernail on it. Not really a big issue since the whole surface gets Scotchbrite-d before alodining anyway. On the other hand, if you find you've cut it twice and it's still too short, you probably should make another. Oddly enough, in many cases with steel you can weld a piece back on and solve this problem. It's also a balance of how much time and how much expense it will take to re-make the part. For instance, after drilling an entire wing skin, I found two holes were in the wrong place (missed the rib). Instead of spending another $100 on materials and many hours to re-drill it (at much greater difficulty since it would have to match the existing holes in the ribs), I just put some non-functional rivets in those holes and drilled more where they should have been. I challenge you to look at my wing now and tell me which two holes have non-functioning rivets. It's not perfect, but definitely airworthy. One test I use: When your EAA buds come to visit and look at your project, would you be able in good conscience convince them that the course you took was acceptable? If you're not sure, time to remake the part. +++ #10264 From: "Alan Nauman" Subject: Router jigs Things have been quiet so I will pop in with a question or two. Does anyone have an idea how many jigs need to be made if I am going to use a router to cut the ribs? Should I make the forms to the longest length and then trim them down to fit the location they will go? Is there a good way to cut the lightening holes with a router? I hate the fly cutter and I don't want to drop another $50-75 on a ?Matco? hole cutter. I have been trying to figure out a good way to set up a form that could be used after the ribs had been formed. I read that Budd's crew uses the router to cut the lightening holes at the same time that the blanks are cut, but I would have a real hard time lining everything up if I cut them before I shaped them. +++ #10352 From: Russ and Penny Erb Subject: RE: My Route to Alaska (Was: FAT RIBS) > Regarding flanging: has anyone tried the hole flanging tool that Avery > sells? Couple of wheels on a stick for $12. Just curious how this > might stack up against the Bob Stick. I have one, and have come to the conclusion that it takes as much skill and finesse as the Bob Stick to learn to use properly. I haven't really developed that skill yet. +++ #10357 From: "Pat Fagan" Subject: Re: My Route to Alaska (Was: FAT RIBS) > Regarding flanging: has anyone tried the hole flanging tool that Avery > sells? Couple of wheels on a stick for $12. Save your money, I bought one and still haven't figured out how to make it do anything. Better yet, don't save your money and buy mine. Stick with the Bob stick. +++ #10358 From: Del Rawlins Subject: Re: My Route to Alaska (Was: FAT RIBS) > Regarding flanging: has anyone tried the hole flanging tool that Avery > sells? Couple of wheels on a stick for $12. The Avery flanging tool just plain sucks, and is a rip-off at any price. It can kind of be made to work if you need a 1/4" flange, but most of the flanges for the wing ribs need to be 3/8" wide. The biggest problem has to do with the way it is designed. Holding the flanging wheels on are a couple of sharp edged nuts. They are thin nuts in order to provide clearance for flanging, but even so, if you work the tool past a certain angle (like, say, enough to actually form the flange) the nut will scribe an arc on the workpiece. If enough force is used (again, enough to actually form the flange) the resulting scratch will be deep enough that the standard scuffing with a scotchbrite pad won't get it out. I threw mine in the can. (I may not be able to work on my project but I can still write a decent tirade) +++ #10645 From: Russ and Penny Erb Subject: RE: Repairing the wing rib form > I'm just about done finishing the forming of the nose ribs, when my > wing rib form decided to start letting go along the radiussed edge > right next to the maximum camber line. > > I repaired the form by building up the edge with polyester resin > thickened with microballoons and then recutting the edge to the > correct radius. Three more nose ribs later, it appeared to be holding > up, after allowing it to cure overnight. I'm impressed with your "thinking outside the box" to come up with a repair for your form block. An excellent use of available technology. As I was reading this, my first thought was that you were going to drag out another piece of wood and make another, which might have been fun trying to get exactly the same shape as the first. It's good every now and then to ask "Is there some other way possible to do this?". +++ #10722 From: Drew Schumann Subject: Fluting pliers (was: Repairing the wing rib form) So would it be okay to explain how to make a quick and easy fluting tool that is non scratching? Follow the instructions that come in one of the early newsletters, except, once you've drilled the 1/4" hole down the jaw faces, put black electrical tape tightly on one side, and clamp down hard on some epoxy steel type epoxy putty. Leave it that way, at least overnight. The epoxy will cure and the electrical tape would add the clearance you need. Then, take some additional putty and swipe it along the female side of the jaws until it just fills in the serrations in that side of the jaw. If you do a neat job, it should dry smooth and need "zero" finishing. Use good steel putty or it will deform under pressure and not flute enough. 'nough said. +++ #10802 From: "Schutt, Barry C" Subject: RE: Wavy flanges > I'm just about finished with the noseribs and I'm in the process of > straigtening out the 9/16" flanges formed by the forming block (on the > outside of the ribs, not the lightening holes). While doing this, I'm > wondering if anyone else has wavy flanges and if so, is it normal or > an abnormal condition. the flanges must be fluted after forming---look at the plans for rivet spacing and put flutes inbetween rivet locations----buy or make a pair of flutting pliers----see a catelog like aircraft spruce for a picture or I think that Bob shows how to make one in his early news letters---flute the flanges just deep enough to make the web section straight and taking out the wave in the flanges +++ #10805 From: Drew Schumann Subject: RE: Wavy flanges >> Okay. I know that. What I'm concerned about is the "after fluting" >> mild variety of waviness. > then you should use two flutes between rivet locations Two flutes! Sometimes I'm so stupid I scare myself. It was so obvious, I didn't think of it. Thank you very much, Mr. Schutt. And the waviness mostly happens at the curviest part of the top of the nose rib. I'll go back and correct the ones that need it. >>> 20may03 #11298-18250 +++ #11310 From: "miknaitis" Subject: waxing lightening holes I am in the midst of hammering and flanging all the ribs - using both the flanging die method and the bob stick depending on the hole. Out of curiosity, I tried flanging a hole with out wax and found virtually no difference. Pardon my ignorance, but why is the wax used? Just to make the stick slide better around the hole, or is it more complicated than that? Thanks, Rimas +++ #11540 From: Drew Schumann Subject: Perfect flanges Is there something wrong with me if I'm able to do 30 degree flanges in one pass? I've also noticed that I don't need to use the push stick anywhere near as much. Am I developing some kind of skill, or am I making a judgement error? Drew +++ #11558 From: Bob Romanko Subject: RE: Perfect flanges Drew, I'd look really close at your ribs. If you're flanging the holes in one pass and not using the push stick much, something distorted somewhere. Now, some ribs (nose in particular) twist more than others when flanging, especially the rear hole of the nose rib. As far as what is happening to you, you're developing a skill and possibly making a judgement error as well. I think it's impossible to flange a lightening hole and not have to use a push tool. I flanged all my holes, and never once had it happen that I didn't need to push it a bit. For what it's worth... Planter Bob +++ #11561 From: Drew Schumann Subject: RE: Perfect flanges Thanks, Bob, I'll do some measurements Monday at school. I tend to worry about these things, and it has been bothering me a bit. I still have to use the push stick, I just find that I have to use it much less than at the beginning. I can see where the aft part of the nose rib distorts quite easily. Drew +++ #12016 From: "bearhawk260" Subject: Lightening hole bevel I came across this web site that show a different method (at least to me) for forming the flange on the lightening hole. Take a look at http://members.tripod.com/zodiacbuilder/ribforming.htm ht +++ #12146 From: "Dan Shilling" Subject: Nose rib question "Desert Hawk" TakenI bought this project from a guy a while ago and he had built most of the wing parts. However, it looks as if he built all the nose ribs one direction instead of half left and half right. Thankfully, everything else seems to check out pretty nicely. How critical do you think this is. Do I need to build the other half the correct direction, or is this not a structually critical point? I'm pretty sure I know what you are going to say, so go ahead and get it over with. I have a "Bob" stick securely clamped between my teeth. Dan Shilling +++ #12147 From: Bob Romanko Subject: RE: Nose rib question I'd find someone who did the same thing, but with the flanges all going in the opposite direction, and just arrange a swap for 50% of your ribs! Problem Solved! Seriously, take that Bob Stick in hand and have at it! Building half the nose ribs is a three short-day job at most. Just make sure your heights match. You got the form block to that project, didn't you? If you keep the ribs as they are your rivet line will be staggered, but I don't have the wing assembly burned into my brain as well as folks who have already assembled them to answer whether or not there are any interference issues. Dan, I'm planning on spending this weekend in Anchorage. Mrs.. Planter has a hankering to damage the bank account, so we're coming up with the Excursion and loadin' the puppy up. If you want me to drop by with my Bob Stick, a Push Tool and a block of wax. We'll bend some ribs and talk Bearhawk. Fire off an email to me. Planter Bob +++ #12163 From: "Bruce A. Frank" Subject: RE: Nose rib question On most metal wing kits I have had a chance to see, if there is a flange they are always designated left and right. From a structural point of view it certainly makes no difference. Maybe at the last outboard rib a flange turned one way or the other would provide attachment points for a wing tip. Other than that I see little reason other than aesthetics. With a nose rib, there is no reason to fabricate more or discard any already fabricated ones because the flange is "right" or "left". Bruce A. Frank +++ #12167 From: "newbegin" Subject: Re: Nose rib question You are missing the point of left and right nose ribs, ease of riveting on the skin is the why there are left and right ribs, nose, center and any other. Jim #284 +++ #12168 From: Bob Romanko Subject: RE: Nose rib question Huh? Maybe I'm missing something on the assembly, but it seems to me that if you turn the attach angle 180 degrees from where it's supposed to be your rivet holes could would still line up. Remember how this thread started...from the question of whether Dan had to make all his ribs over again? I understand the need for all the different ribs, but we're talking about the direction of a flange on a rib that isn't even very structural. Planter Bob +++ #12169 From: Del Rawlins Subject: RE: Nose rib question Before you guys get too worked up about it, I spoke with Dan the other day and the ribs are all per-plans. The way they were stacked created an optical illusion making them appear to all be bent the same way. -- Del Rawlins +++ #12170 From: Budd Davisson Subject: Re: Nose rib question After all the intense conversation I find that pretty funny. bd +++ #12176 From: Del Rawlins Subject: Re: Nose rib question > You are missing the point of left and right nose ribs, ease of > riveting on the skin is the why there are left and right ribs, nose, > center and any other. I fail to see how the flange direction will make much difference in riveting the skins except at the wing root and tip. I haven't assembled any wings yet, but I was under the impression that the whole skin had to be installed at once, due to the overlapping seams. One way or the other you are going to have to reach your hand in there with a bucking bar. +++ #12179 From: "Bruce A. Frank" Subject: RE: Nose rib question Oh well! As this topic is winding down now let me pass along a little trick that worked for a friend of mine. He built a 2+2 Sportsman and while it is a fabric covered wing the leading edge is an enclosed "D" cell containing the noses of full ribs and false ribs. Standard Piper type ribs are difficult to rivet because of the small flange associated with the narrow and "T" shaped section of the rib caps. He obtained some specialized silicone caulk type glue . Not RTV which emits acetic acid as it cures, but one of a myriad of silicone seals available that is compatible with aluminum (check out McMaster-Carr). He ran a bead of caulk down each rib as he closed the aluminum over it giving a totally bump free leading edge with none of the problems of dimpling and flush riveting. Bruce A. Frank +++ #12663 From: Jim Ash Subject: Form block thickness I just went looking for form block material tonight. I want to make mine from Maple, but the thickest stuff I saw was 3/4". I did see poplar in 3/2", but I don't know enough about poplar to spring for the lumber. I like the built-up idea that Del uses in his FAQ, but I don't (yet) have access to a thickness planer. Can I get by with the 3/4" or is this pushing it? Jim Ash +++ #12664 From: "piperthorp" Subject: Re: Form block thickness I used 3/4" maple. It held up fine. Bob's method is not hard on form blocks. T-18 ribs are strech formed where there is a lot of hammering necessary and my 3/4" maple forms held up fine to at least 6 sets of ribs. Bill Cox #303 +++ #12670 From: Russ and Penny Erb Subject: RE: Form block thickness Built all of my ribs on 3/4" oak. Works good, last long time. 3/4" is plenty thick. Russ Erb +++ #12672 From: Del Rawlins Subject: Re: Form block thickness According to the newsletter, a 3/4" thick formblock is fine. Mine ended up just shy of 1.75" thick but that is just the way it worked out and you don't need to go to that extreme. The lumberyard in Cordova is pretty much limited to house building supplies; the only sizeable hardwood they had was a couple of thick, warped pieces of oak that were not nearly as wide as I needed. I wound up ripping them on a tablesaw, then running them across a jointer and gluing them up with lots of clamps. I was then able to take them back to the lumberyard and have them run the resultant block through their thickness planer. It resulted in a nice block, but with a lot more effort and expense than I would have liked (remember, this is the same lumberyard that charges 9 bucks for an 8 foot 2x4). Later on some people on this list discovered that medium density fiberboard works just fine for form blocks, and I would probably use that if I had to do it over again. The one nice thing about my monster thick formbock, is that if I do somehow manage to screw it up, I have lots of extra thickness to have it run through a planer again if needed. -- Del Rawlins +++ #12676 From: "Russ Kaye" Subject: RE: Form block thickness I'm just curious, is there any reason not to make the form block from steel? Russ K +++ #12677 From: Tony Dean Subject: Re: Form block thickness The MDF fiberboard worked fine on my MII ribs. The MII wing is tapered and that means only one rib per side of a form block. Yet, I have heard that it works well for B'Hawk ribs too. td +++ #12678 From: "Dan Montee" Subject: Form Block Material I used select 6/4 maple for all my form blocks. I cut them all from a single 7 1/2 ft board. The board cost $25.46 including tax. That included planing to 5/4. With the problems some of you have finding material it may be worth the UPS to have them ship it. (I'm guessing they will ship)Here is the address and phone #. Kettle Moraine Hardwoods, Inc 195 S. 27th St Caledonia, WI 53108 262-835-9212 Dan Montee # 415 +++ #12679 From: bearhwk272@a... Subject: Re: Steel form block Well: It would weigh a bunch, hurt when you drop it on your foot, could not be altered easily, your friends would ask you why did you make it from steel, it is hard to transport to flyins to show off your progress, you have to coat it or it will rust and not look pretty, it would take a bunch more time to fabricate, might ring like a bell when hit. Just a few thoughts. Might check with PB about growth rings and yield. Kevin +++ #12680 From: "Bruce A. Frank" Subject: Re: Steel form block The rib forming block I made is made from steel. I bought the steel, laid it out and cut it with an oxy/acet torch close to dimensions. Cleaned it up with a belt sander, then took it to a machine shop with the airfoil curve precisely marked. The machinist eyeball milled it by using the x,y controls of the milling machine's table. This got me to a useable form, but I then used a belt sander to eliminate all ripples along the edge and to create a radius. For me, making it from steel was the logical thing to do....this form was made before I was aware of the Bearhawk's method. (my project is not a Bearhawk...just a close approximation) My total expenditure including the machine shop work was about $90...not counting my couple of hours on the job. My choice of steel, besides the fact that it is with what I like to work, was also dictated by the fact that I needed to make airfoil shaped fuel tank ends and baffles out of .065 5052 aluminum. Yes, the form block *IS* heavy. Bruce A. Frank +++ #12681 From: "Don Rennie" Subject: Re: Form block thickness I used 3/4 MDF with hesitation , but it worked great.I did keep them dry... +++ #12692 From: "Bruce A. Frank" Subject: Re: Steel form block ? It just has a smooth finely sanded finish (260 grit done with a palm type random/orbital action sander), no paint. With all the corners radiused there is nothing to cause scratches. Bruce A. Frank +++ #12693 From: "Bruce A. Frank" Subject: Re: Steel form block ? I forgot, the steel is 1/2 inch thick. Bruce A. Frank +++ #12715 From: "bearhawk260" Subject: Re: Form block thickness Just completed my form block blank. Made from 1.5" thick Hard Rock Maple glued from 9 strips. Darn thing is heavy...Should be able to cut and route this weekend. I went a little overboard as I will have nearly 8 hours in prep. Not very effective use of time, but then again, I enjoy the time. If you do glue, try to glue strips on the face not edge. Wood tends to move across the grain. If you glue on the face (3/4 thick by 1" wide, the face is 1" if the grain runs the length fo the board) movement should be in the form of thickness variations, which is not a problem. One question for the group, did anyone place a finish on their form block, such as polyeurothane(sp?) to help with moisture control? I ask because I will be forming ribs for a few years, at least at this point and would like to protect this 40lb work of art.. ht #584 +++ #12716 From: Russ and Penny Erb Subject: RE: [Bearhawk] Re: Form block thickness I didn't put any finish on mine, but I live in the desert. My recommendation would be to keep it in the house if you're worried about humidity variations. If you want to finish it to hang it on the wall, do it after you've beaten out all the ribs. It's a tool, after all. If you want it to look pretty you'd have to refinish it after whacking out ribs anyway. I do recommend metal tube bushings in the jig holes that you use to bolt the thing together. Russ Erb +++ #12718 From: "Montee, Dan L." Subject: Sealing form blocks I used maple and poly sealed the block(s). Nary a scratch after forming all the ribs. One suggestion I have is before you seal the block mark your spar centers on the block. I marked the centers and the 1/8" and 1/4" cap strip representations as well. I marked the rivet spacing on the backup block. I went by the Erbman's recommendation and steel bushed the holes for the jib pins. Dan Montee # 415 +++ #12719 From: "bearhawk260" Subject: Re: Sealing form blocks yep, plan to place all that information on the block before poly is applied. I will install bushings for the jig pins. As for the backup block, I think a nice 5/8" plywood, that does not take 8 hrs to construct... thanks ht #584 +++ #12720 From: "kb8rnu" Subject: Ribs cut to length before or after? I'm getting ready to make nose ribs (got the lumber for the form today and the aluminum is coming from Airparts). Has a consensus been reached on whether or not it is easier to cut the ribs to length before forming or make them all the same and trim them during installation? Also, since the rib seems to be attached to the angle bracket, which is then riveted to the spar, would a small gap be critical between the rib edge and the spar? Would having the rib end touch even be desirable? Thanks! Jason (#585) +++ #12723 From: wgraff@j... Subject: Re: [Bearhawk] Ribs cut to length before or after? I numbered and cut all my ribs the correct length according to the location on the wing. Allso I left about a 1/16 or 1/32 on the length to file or sand to fit. It takes a little extra studying of the drawings to locate the position of the cap strips. Note that there is fillers under most of the rib attachment angles. Wil +++ #12724 From: Del Rawlins Subject: Re: [Bearhawk] Ribs cut to length before or after? >Has a consensus been reached on whether or not it is easier to cut >the ribs to length before forming or make them all the same and trim >them during installation? It's been done both ways. I trimmed mine to length before forming, but that means that I have to keep them numbered through the priming process prior to assembly (there is good info on Russ' CD on doing this). Even so, I expect that I will have to trim at least a few of them again to make everything fit up just right. >Also, since the rib seems to be attached to the angle bracket, which >is then riveted to the spar, would a small gap be critical between >the rib edge and the spar? Would having the rib end touch even be >desirable? I will let somebody with more experience answer whether a slight gap might be desirable to prevent the ends of the ribs from fretting against the spars. To my way of thinking it should be a rigid assembly once riveted together and won't be moving around, but I've been known to be wrong before. In other news, we are now moved into the new house here in Anchorage and the house is set up well enough that I feel like tackling the gara... er shop over Thanksgiving weekend. The first project is to build a loft in the back end where I can keep miscellaneous clutter off the floor and hang the heater (which is currently sitting on the floor) from so I can hook it up. Then I get to set up the new drill press which has been in a box for over a year, and arrange the rest of my tools and stuff. Should be fun, and I'm looking forward to resuming work on #316 finally. -- Del Rawlins +++ #12727 From: Russ and Penny Erb Subject: RE: [Bearhawk] Ribs cut to length before or after? And the consensus is...that there is no consensus. Bearhawkers have done it any combination of these two ways. I've heard of guys who cut them all long and trimmed on assembly. Seemed to me that would be tough to do precisely, but maybe I'm just too picky. I chose to identify the exact length required for each rib and route each of them to the exact size. Of course, this required giving each rib a unique identifier and keeping up with it through the whole process. In the end, I lined up all of the nose ribs with a line through the jig hole, but each one just sat on the spar with no adjustment required (I was shocked and amazed!) A small gap between the rib and the spar is not a problem as long as it is not so big that you lose the required edge distance around the rivets. There won't be any relative motion between the rib and the spar, so touching is not an issue. Russ Erb +++ #12733 From: Budd Davisson Subject: Re: [Bearhawk] Ribs cut to length before or after? FYI-our ribs are all just a little long and we have a form block with the right lenghts marked on it that we use to mark the right length for the different ribs and we try to have them just barely not touching. bd +++ #12826 From: "kb8rnu" Subject: Lightening holes flanging question I'm gearing up to start making ribs for my first parts. I got the drill press and fly cutter setup and did a few practice cuts with the fly cutter, since I had heard horror stories. Works nicely at 200 rpm as long as the sheet is clamped. I decided to try to flange the hole to see how the process works. I gave up in disgust with the tool I bought from Aircraft Tool and made a Bob stick, which works well. (It appears sometimes "the right tool for the job" really is a stick with a notch in the end. :) ) Bob states that after flanging the rib will be slightly warped - my test sheet looks like a potato chip. Is this likely because the edges of the sheet are not bent 90 degrees as the rib's edges will be? I know that will add a fair amount of rigidity. I had hoped to work out the flanging process on scrap sheet rather than using a rib I had pounded out, but if that's a silly idea I'll make a couple and see how it goes. I'm taking 2-3 passes to get to 30 degrees. Should I not mess with this, and just try it on a formed rib after I make one? Thanks! Jason Bowling +++ #12830 From: Russ and Penny Erb Subject: RE: Lightening holes flanging question The flange will keep the ribs straight in the fore-aft direction. The distortion will be in the up-down direction, but is easily fixed by adding a little more bend at the right place. Russ Erb +++ #12842 From: "kb8rnu" Subject: Re: Lightening holes flanging question I see... so you're removing the up-down distortion by actually increasing the angle of the flange a bit in the needed areas to bring it straight? Thanks for all the help. Jason +++ #12843 From: Russ and Penny Erb Subject: RE: Re: Lightening holes flanging question That's pretty much it. Planter Bob is the master of the Bob-stick--he's even featured prominently on the Bearhawk CD! Russ Erb +++ #12850 From: Bob Romanko Subject: RE: Re: Lightening holes flanging question A hammer's a great source of white ash. I didn't wire mine at all, as you can see on the CD, and it held up through all of my ribs just fine. Even my "Bob-Stick-Lite" held up. It's all in the quality of your wood and the direction of the grain. If your Bob-Stick splits you're either pushing too hard or not using proper lubrication. Waxing is important too. I just took a slab of regular 'ol paraffin and used that. No need to get real fancy with it, just use it. Over time, your Bob-Stick will have a good coat of wax in the slot as well as on the handle just from you using the thing and transferring the wax to the handle. A well-used Bob-Stick has a real nice sheen to it, and is suitable for mounting over the mantel. I highly recommend you make your Push-Stick in the shape of a "T". Some folks have just used the back of their Bob-Stick as a Push-Stick, but it sure is nice to have the comfort of the "T" handle when pushing the flange home to 30 degrees while taking out those nasty bends that will appear. Planter Bob +++ #12851 From: "bearhawk260" Subject: Backing plat for Form Block Reading the archives and BearTracks, I have not found the proper edge distance for the backing plate used to hold the alum to the form block when bending the flanges. The closer the better since this will hold the alum from bending up but the hammer needs its space to work. 1/2" smaller for the backing plate vs. form block? hugh +++ #12852 From: Bob Romanko Subject: RE: Backing plat for Form Block Mine's a bit more than 1/2". I'd say anywhere between 1/2" and 3/4" will work. Not rocket science. Once you get started you'll see that the aluminum doesn't really bend off of the form block IF you have the proper radius on your block and IF you hammer with the proper swing and take your time with it. You don't really swing the hammer. It's more like a gentle series of love taps being careful not to bend the flange too drastically in any one place. Work your way up and down the rib trying to bend the flange evenly as you go. I've seen ribs where someone has smacked the flange all the way over, then move on to the next spot. Ugly ribs are not happy ribs. Planter Bob +++ #12976 From: Del Rawlins Subject: Re:Another one flies > One especially noteworthy comment that he made was that he plans to > rebuild his wings using more precisely formed ribs. After skinning, > he believes inconsistent rib height is apparent (wavy skin syndrome > perhaps). Aside from cosmetic reasons, he also wants to beef up the > wing due to his use of amphibious floats. > > This comment certainly got my attention, as I am building ribs at this > time (a'la Bob stick). I plan to review my Erb CDROM to determine > whether others have reported this issue. The issue that has been reported so far is variance between the rib height between different builders, and height not matching the plans (which clearly state to make sure the spars fit the finished ribs), but this is the first I've heard of variance in the height of ribs produced by the same builder off the same forming block. It is also a little surprising considering Mr. Stout's described skill level. -- Del Rawlins +++ #12978 From: Russ and Penny Erb Subject: RE: Re:Another one flies I find this odd too if he is as good as you say. I haven't seen any waves in my wings or in Pat's wings. In fact, I was rather surprised at how very consistent my ribs were in spite of the manual forming technique. Add to that .025 and .032 skin is rather stiff anyway. I wonder if he was talking about slight depressions around the rivets from driving them? Let us know what you see. Russ Erb +++ #12979 From: Budd Davisson Subject: Re: Re:Another one flies I think you're more likely to get waves from not getting all the ribs set the same height on the spar than from differences in the ribs. If one rib is even a full 3/32 fatter than the rib next to it, but it is centered on the spar, I still don't believe you'll get waves (as in canning). If the rib doesn't match the rear spar height however, you'll get dips and stuff. bd +++ #12988 From: bearhwk272@a... Subject: Wavy Wing Skins*&^%$# I have them! I am the proud owner of at least one wing with wavy and or oilcanitus. ( I will try to have the second wing vaccinated.) I am trying to deal with it the best I can and will post my observations after the holidays. I figure that it will take a couple of days to fix after the holidays. Might as well fix it now, too cold to prime. Kevin +++ #13171 From: "kb8rnu " Subject: Form block jig hole question I am in the process of finishing up my form block so I can start making some ribs. I've installed 3/16" drill guide bushings for the two jig holes, as recommended. After installing the guides, it appears my forward jig hole is shifted forward relative to the drawing 1/32"-1/16". It is aligned properly top to bottom. I understand the need for each rib to be as close to exactly the same as possible (hence the bushings), but will a slightly shifted jig hole cause alignment problems later? As long as all the ribs have the same location, I would think it would be ok, but figured I should check.... If this is terribly bad, I can cut out the offending area and replace it, just wondering if I need to. Any thoughts would be appreciated. Jason +++ #13174 From: "kb8rnu " Subject: Re: Form block jig hole question After some thought and reading I've decided just to fix it... it should not take long to cut out the section and install a fresh slug of wood to redrill... safer just to spend an hour and make sure it's right. I ran across a Planter Bob comment to the effect of "What can you possibly screw up on ribs?!" and jig holes were about the only thing he considered crucial. If it's good enough for Planter Bob, it's good enough for me. :) Jason +++ #13177 From: Bob Romanko Subject: RE: Re: Form block jig hole question Hmmm..........about the only way you can screw up a jig hole is to make it too big. If yours is tight you're going to be okay. All your ribs will be made with the same block, so you're in good shape. If you make a second, smaller block for the controls surface ribs as I did, the front jig hole at the nose big doesn't matter. Later you'll pass a straight line through the holes to align them on the spar, but even that won't be an issue. Jason, if you're within a sixteenth on that hole I don't see any reason why you're in trouble. Hammer away I say! Planter "We're Not Building a Watch" Bob +++ #13333 From: "kb8rnu " Subject: Rib making question Just got done forming and fluting my first nose rib. Had a question involving drilling the jig hole. I made a template for the rib blank out of 1/4" ply and traced around it with a fine tip sharpie and cut with shears. My form block has drill bushings installed in the jig hole. My question is this: how do you consistently align the rib blank on the form block to cut the jig hole? Lining it up wih the leading edge does not seem real precise. Obviously if it is not lined up the same way for each rib, the hole will move. Any advice would be appreciated. Jason +++ #13334 From: Russ and Penny Erb Subject: RE: Rib making question That's part of why I cut the rib blanks with a router. The first step was to drill the alignment holes (jig holes and centers of lightening holes). Then the ribs were routed to shape. I would say you could put bushed holes in your template for drilling before marking/cutting. You'll probably need something more substantial than 1/4" ply for that. Russ Erb +++ #13335 From: "kb8rnu " Subject: Re: Rib making question Makes sense. I was thinking of cutting another template and laminating it, then installing a drill bushing. I can't come up with another way to do it consistently.. 1/2" ply should do it, I'd think. Now that I know I'll make the templates for the other rib sections out of something beefier. Thanks. Jason +++ #13336 From: del@r... Subject: Re: Rib making question > My form block has drill bushings installed in the jig hole. My > question is this: how do you consistently align the rib blank on the > form block to cut the jig hole? Lining it up wih the leading edge > does not seem real precise. I used the forming block for my rib marking template using a marking tool as shown in one of the first Bear-Tracks newsletters. I would lay my sheet of aluminum down on the bench, lay the form block on top, clamp it down and trace the rib blank outline using the sharpie and marking tool. Then while it was still clamped, I marked the jig holes with a 3/16 transfer punch, but since you have drill bushings in your block you would just drill them at that time. I don't know how you could do it more accurately than that. I also have the spar locations drawn on the edges of the forming block so that information was transferred to the blank at the same time. Del Rawlins +++ #13348 From: Benton Holzwarth Subject: re: Rib Making Question My procedure was a little different from any so far mentioned, I think. I made a pasteboard template by tracing around my formblock onto a section of cereal box. It also has marks for the 3/16" jig pin, the relief holes at the forward limit of the flange on the nose ribs and the rivet lines. The jig pins (one at nose and tail end) are press-fit into the hold-down block (3/4" ply), protruding from both sides about 1/2", so it can be used with either side of the form block, and mates to un-bushed holes in the form block. With the template, a sharpie-line is marked on the Al, the jig and relief holes are marked and center-punched then drilled, and then the rib is snipped out. The jig pin hole and spar position markings on the form block help get the Al blank loaded into the form block straight, and clamps are applied. Then the bushed locator holes for the lightening holes are drilled. I made up some 'dogs' out of 1/4" rod to drop into a couple of the lightening holes, and then with the clamps in place, the flange is worked over. Benton +++ #13351 From: "Vuxton, Christopher" Subject: RE: Rib making question adding drill bushings I used brake line for bushings. #1 couldn't find regular drill bushings when I wanted/needed them, like RIGHT NOW! and #2, a 5 foot length was $5.00. Used a dremel to cut and score the lengths of line and used my assembly tool of choice (JB Weld) to glue the little bugger in place. Just take your 3/16" bolt to the parts store and see what brand fits best. Chris +++ #13356 From: "Bruce A. Frank" Subject: RE: Rib making question adding drill bushings For future reference, McMaster-Carr carries hardened drill bushings and in most cases, in my experience, shipment arrives next day. Bruce A. Frank +++ #13369 From: Russ and Penny Erb Subject: RE: Rib making question adding drill bushings I used an appropriate size of 4130 tubing. Pretty much any steel tube that won't wear from the side of the drill will work. Russ Erb +++ #13468 From: "kb8rnu " Subject: Nose rib rivet spacing question, again... I have researched this on the newsgroup archive and the CD but have not convinced myself one way or the other. I am trying to sort out an apparent inconsistency on drawing number 6 (revised 10/02) regarding the location of the first rivet on the nose rib. On my drawing, the first rivet is shown at 1/4" from the edge of the rib, and 7/16" from the centerline of the spar. (top rivet) I first made a few ribs with the spacing calculated from 1/2" from the edge of the rib blank, which ends at the spar centerline marked on the full size mylar formblock drawing. The ribs looked just like the ones on the CD, so I was fat dumb and happy. However, it occurred to me that my blank went to the centerline, so my flutes were in the wrong place. I made another template marked with the first rivet at 7/8" from the spar centerline, if I interpret the drawing exactly as shown. This results in rivets ending extremely close to the front edge of the flange. The length of my flange was as shown on the drawing. It appears I have two options: 1) Decide the first rivet is actually 1/2" from the centerline of the spar. This results in 9 very nicely spaced rivets, centered on the flange, and ribs that look like Del's and Russ's pictures. However, since I'll be hacking off 1/4" off the spar side egde on some of those ribs, it will result in the first rivet on the spars at the thickest part of the spar being only 1/4" from the edge. 2) Decide the front of the flange should be extended. Start the first rivet at 7/8" forward of the center line. Can anyone shed some light on this? I apologize for what is likely a very basic question, but I want to make sure I do this right to avoid problems later. Thanks! Jason +++ #13470 From: Russ and Penny Erb Subject: RE: Nose rib rivet spacing question, again... Not exactly an answer to the question, but a caution to watch out for--the nominal spacing for skin rivets is 1.5 inches. However, note that it will vary around the spar to get sufficient edge distance on the rib flanges. I figured this out because 1.5 inches forward of the center of the spar flange goes into the forward capstrips. You can imagine how I figured that out.... Russ Erb +++ #13471 From: "kb8rnu " Subject: Re: Nose rib rivet spacing question, again... If that's the case, would anything stop me from using 1.5" spacing except between the first two rivets? While it would deviate slightly from the drawing, moving the first rivet forward a 1/4" would give plenty of material at the thickest part of the spar, but also leave plenty of room at the front edge of the flange. There would still be 9 rivets. Thanks for the help. Jason +++ #13472 From: "kb8rnu " Subject: Re: Nose rib rivet spacing question, again... On second thought, examining the ribs more closely it looks like all I need to do is extend the front edge of the top flange forward by a 1/4" and all is good. That gives me plenty of material on the ends, uniform spacing, and the same number of rivets. It occurred to me that shifting my lines of rivets 1/4" in either direction was highly unlikely to matter structurally. I think I just need to calm down a bit. :) I will certainly heed your warning about the middle ribs where the spar flange becomes a factor. Thanks! Jason +++ #13478 From: "kb8rnu " Subject: Re: Nose rib rivet spacing question, again... > No! not the dreaded 8 rivet vs 9 rivet nose rib issue again! See > message # 2566 or there abouts.... I read those, but there is not an answer, aside from Planter Bob mentioning Bob Barrows saying you can extend the front edge of the flange if you need to. No clear answer as to where the first rivet is. I'm going with starting it 7/8" from the centerline, as shown on the plans, and extending the edge of the flange a little. Jason +++ #13605 From: bcgh@a... Subject: RE: Suggested tools? > You don't need a router for the rib blanks. Use snips. It's just as > fast, cleaner, quieter, and MUCH more relaxing! For the price of a > router you can buy a left/right/straight pair of good snips, a good > fly cutter for your holes AND a dead blow hammer. I agree with him on snipping out the rib blanks. It's everything he said, and a darn sight less messy. I'm still getting the AL chaff out of places I didn't know I had places. Here's my thoughts -- Yes, snips and a fly-cutter to make rib blanks. You will need a drill press if you ever expect to have any of your holes drilled *straight* through the material. (Like getting jig pins in the same place on both sides of the formblock.) I have one of the $100 Taiwan Delta benchtop drill presses. I can't recommend it. Both for quality and size. It has plenty of oomph, but just *barely* enough throat to reach the center of the lightening holes in the largest rib. The minute I have a need that this unit can't handle, I'm out the door to go buy another. Start with a larger one if you're shopping. It doesn't have to be a genuine (domestic) Delta, I've heard Jet is a decent brand. Having said yes, snip out the ribs, I'll go back and say, the router *is* just the "bee's knees" for doing long straight cuts. I wanted to avoid all the sharp slivers (hacked edges) and bending required to get the metal out of the way, so tried the router to cut my flap and aileron spar pieces. These points seemed key: I tried a 1/4" laminate bit, thinking I'd save a little metal in a narrower kerf. Wound up going back for a 3/8", it really does make a difference. (Higher cutter velocity?) Budd and others said to wax or oil along the cut line. It seemed to be working well enough without so I just did it that way. On the last cut I did, I happened to notice a candle on a shelf (the pumpkin had finally decayed enough to reveal it 8*) ), so thought what the heck, and smudged a bit along my line. Result -- there *is* a difference between 'well enough' and 'better'. I'll use wax on all future cuts. Not essential, but it reduced the clean up from a quick swipe with a file and then scotch-brite pad, to just the swipe with the scotch-brite pad. Very tidy cuts. Notice that, because of the rotation of the router cutter, as you work from side to side, it'll try to climb towards or away from you. Since I'm working with the straight edge behind the cutter, I cut from left to right. Helps hold the cutter against the straight edge. For my cutter straight edge, I made another field mod (337 papers not yet completed) to my Chapter 1000 work benches. First I made the benches 8' long (sorry Russ), less waste, and makes a good 8' long surface for rolling out Al upon. (And with two end to end, I don't even need to clear the entire length to lay out a full sheet of Al.) Then, I shopped up an 8' length of extruded Al angle, about 1-1/4" by 1/8". Routed out a nice straight line in the table edge (using the new extrusion, well supported along it's length) to inset the Al, and screwed it down to the bench top/edge. Now to cut, say an 8' long flap spar piece, I just measure in the needed distance, add the 3/8" for cutter kerf, and clamp the metal down to the bench, and rip it out with the router. I will say that it's worth while to plan to make as many cuts at once with the router as you can, since the cleanup is such a nuisance. Benton 9jan03 +++ #13842 From: "drandall99031 " Subject: Wing Rib AutoCAD14 Drawing and DXF Drawing For all of the waterjet and CAD/CAM Bearhawk builders out there, I have just added a wing rib AutoCAD14 Drawing and DXF Drawing to the Files section of the group. For the rest of us builders, the drawings can be used to generate full size templates to cut from, or to help in the layout process. Let me know if you find problems, I can make changes easly and repost to the group. Thanks David Randall +++ #13866 From: Scott Bailey Subject: Routing Lightening Holes How will routing the lightening holes prior to forming affect the ribs? Has anyone done any scientific analysis or asked "The Bob" if this is an acceptable process? Scott Bailey +++ #13869 From: Tony Dean Subject: Re: Routing Lightening Holes I made my lightening holes prior to making the ribs. These were hand made with snips & files. I found that there is a tendency of the rib to flex around the lightening hole when flanging. You have to be careful that the pieces you clamp it between are completely covering the lightening hole when finishing the part. For example, the bland is slightly smaller than the form block. I switch positions with the block and bland to finish the flange or take the spring back out of the flange. In cases where I was not absolutely careful I got a bit of flex at the lightening hole. Now this seems to be improving with flanging the lightening holes. For this I am using the time honered Bob Stick. I think it is going to all work out. Since I am the rare Mustang II guy hanging out here, I would like to point out that a tapered wing really lends itself to a Bob Stick approach. The idea of making aroung 25-35 different lightening hole flanging dies is much scarier than just making the Bob Stick and starting the flanging process. Regards Tony Dean +++ #14034 From: Tony Dean Subject: Re: [Bearhawk] Routing Lightening Holes > My question, maybe, should go more like this: > > If I cut the lightening holes before pounding out the ribs, will >this cause stress (due to the decrease in material) that might >(will?) ultimately be catastrophic? Has anyone done any scientific >analysis or asked "The Bob" if this is an acceptable process? > > My suspicion is "no", but I need more analysis than opinion. Near as I can tell this is standard procedure. I found that doing a good job of positioning the bland to completely cover the lightening hole for final forming produces a clean bend on the edge flange. Step one place the rib blank between the form block and bland. Step two gently whack it into shape. Lots of small whacks which will produce a flange that bends most way to the angle wanted (may leave you whacko as well :-) Step three swich the smaller bland with the form block and clamp the partially formed rib into the reversed forming parts. This gives you room to work the springback out of the bend. Here is where the evenness of the rib bend is assured by careful placement of the bland to cover the lightening holes completely. Step four flute the ribs to get the rib flat. Step five bob-stick the lightening holes. Step six, amazement! Stand back and wonder how that happened. td +++ #14040 From: Tony Dean Subject: Re: Routing Lightening Holes > If I cut the lightening holes before pounding out the ribs, will > this cause stress (due to the decrease in material) that might > (will?) ultimately be catastrophic? One more data point, This is also the sequence that the MustangAero manual suggests for building ribs. While many Mustangs are kits, there are also many plans built MII & MI aircraft that used this sequence and some have been flying 20 years. td +++ #14111 From: "Shawn Burns " Subject: Re: Cutting .125 capstrips Eric, I just got a replacement for my Roto-Zip tool (the Rebel model with 2 speeds) after the first one up and died. I found that it does not cut .025" 2024 T3 well at all- loads up the bit as Budd mentioned. It did do a good job with the 1/8" roundover bit to form the radius on my "mother board" forming block. However, with a 45 degree chamfer bit to make my "bolt action" flanging die, it locked up. Roto-Zip did send me a replacement pronto- kudos to them for customer service! Before it's demise, I did learn that it is the perfect tool for cuttting MDF. It runs right through it and makes complex shapes much easier than a jigsaw. I need to post some photos of my MDF tooling for rib forming, the stuff is great! I made the male and female dies of MDF for the lightening holes. The male die also gets additional support VIA large fender washers to spread the load over the surface. I also put springs on the bolts to aid in ejecting the male forming block from the rib, with an O-ring to retain the spring and prevent the bolt from falling out. I tightened the 3/16 bolt until it's snug, which did take a few times to develop a the right feel. I then take my Bob-Stick and a rubber mallet and give it a few whacks around the perimeter of the male die to ensure that it is completely seated in the female die. The results were perfect ( well, I could not not find any flaws by naked eye or with my go/no-go guage) flanges in my center ribs. Each rib with it's 5 holes took approximately 4 minutes to clamp the rib in the fixture, form and remove the finished rib. The nose ribs, which I Bob- Sticked, took 5 minutes per hole, at a minimum, plus it took a lot of work to make then lay flat again. I ended up putting them all in my "bolt action" flanger and all 46 were straightend and true in about 2 hours time. Now this was all on .025" parts- I will be starting 0.032" ribs this spring in my next "building frenzy". I will report my success/failure with the thicker stuff when I get to that stage. Hope this is useful to someone. If I were to start over, I think I would make all my forming blocks of MDF. I think I paid $24.00 for a 3/4" sheet and will have enough to make all the forming blocks I need for the wing parts. Shawn Burns, Building a BH in MO while in CA BH #535 +++ #14114 From: "Shawn Burns " Subject: Re: Cutting .125 capstrips I just realized that I did not give credit to Kevin on the "bolt action" hole flanging tool. I took his idea and made some modifications. My female die has a chamfer cut to match and oppose the male die. I built a similar face plate to prevent the flat portion of the rib form moving/distorting while forming the flange. I did break a couple of plywood male dies and an oak die, but when I tried the MDF, it held up well. I do not yet own a hydralic press, but will my next trip to the Grizzly Showroom ( a dangerously close 50 miles from my home). Then I will set up roller stands on either side and press the flanges in my dies. this should allow more uniform pressure over the surface of the dies with less chance of breaking them. I will then just roll to the next hole and so forth. I think it will speed the process even more and improve quality. Shawn Burns, BH#535 +++ #14124 From: "Kent White" Subject: RE: Re: Cutting .125 capstrips If the router bit loads up, then spray the cutting path with light machine oil prior to making the cut. Or wipe the path with beeswax. The lubricant will greatly free the ccutter, and the machine will work much better. Another thing is that the spiral up, single edge, 1/4" bits are best on aluminum, imho. Kent +++ #14130 From: "Penner, Larry" Subject: RE: Routing Lightening Holes When I did my lighjtening hole flanges I cut all of the holes with a circle cutter and cleaned up the edges with a 6" file after bending and crimping the edge flanges. Then as long as the blank is clamped down flat and securely so it doesn't slide around, you shouldn't distort the blank when you bend the LH flanges. Use plenty of wax around the holes and sweep around the hole with a slightly narrowed Bob stick. It gives a nice smooth flange after about 3 passes and is easier than the prying method that's been described. Larry P. +++ #14183 From: Tony Dean Subject: Re: Attention rib pounders > I do have some suggestions regarding rib forming hammers. I am > using a Sears Craftsman rubber mallet. It has plenty of mass and > will press the rib to comform to the formblock with minimal > stress/disortion of the sheet thickness at the bend. I believe that > this translates to stronger parts. I started off with a plastic face hammer (two sizes) and then one day I was looking at the slight dings left by the plastic hammers and desided to try my rubber mallot. I switched to the rubber mallot as it does a more even job of distributing the hammer blow and thus reduces the possibility of leaving dings in the flange. Now keep in mind that after fluting the ribs those little dings nearly all came out but the newer ones are still better. td +++ #14224 From: Russ and Penny Erb Subject: RE: Routing Lightening Holes > I think you'll be creating more hassle for yourself than you need > to. Way back in the shrouded past of this list, there have been > some people who tried to do all their lightening holes at once, and > they found the ribs difficult to straighten afterwards. What was > recommended at the time, was to cut one, flange it, then cut the > next. Del--I think you must be referring to the experiences of the Bob-Stick crowd. I'm not sure because I don't remember and I'm too lazy right now to sort through the archives. What I do remember is that I cut out all of lightening holes (after flanging the outer edges), then I flanged the lightening holes. No problems. The difference was I was a member of that radical splinter group who used flanging dies, much to Planter Bob's disgust...at least he would have been disgusted, except that I had finished my ribs YEARS before he joined the group preaching the gospel of the Bob-stick. Russ Erb +++ #14266 From: "Shawn Burns " Subject: Re: Cutting .125 capstrips Russ, I was in error. It was a 1/4" bolt. I did try 3/16" bolts but quickly realized they were too light. I did have to get grade 5 bolts because of breaking the standard bolts off after 4 or 5 holes. But the grade 5 bolts held up pretty well. I I did it again, I would probably use a 3/8" or even 1/2" inch bolt to pull the dies together. I am going to build new dies for the flap, aileron, and back rib holes, and will probably use a 1/4" bolt as I am planning to press the remainder of my lightening hole in a hydrallic press and the bolt will function as a guidepin and not be exerting the forming pressure. I will keep the o-ring/spring set up to eject the male die from the lightening hole and female die. +++ #14473 From: "rodsmith52 " Subject: Question about Wing Changes Just read the latest Bear-Tracks with the suggested wing plan changes. Item #1 is change rear lightening holes on .032 center ribs (dashed outline) from oval to round. Diameter is not given. Dimensions on my plans are 4 inches fore-aft and 2 7/8" up-down. My guess is to go with the smaller dimension. Has anyone verified this with Bob. If this is changed on plans 583 and up can someone post the dimension. Rod Smith +++ #14842 From: Budd Davisson Subject: Re: Form Block > So now the next step is to make a form block. What methods have you > used to transfer the wing shape from Dwg 7 to the form block? How > well do you feel that your method worked? Would you do it the same > way again? Here's a transfer method I don't think I've seen anyone mention here. It comes from the dress making industry and we used it a lot back in the days when we were building "real" model airplanes, not kits. Get something called a "pounce" wheel from a dress making shop. The exact same thing is sold by Tandy leather shops. It's a little wheel on a handle that is meant to poke small holes through paper as you roll it along a line (Or make deep punches into leather on a regular spacing for stitching). You roll it along the outline and punch a series of holes. Then you tape the mylar down and you can do as the dress industry does and dust chalk powder through the holes (works best on a dark background) or hit each hole with a marker. It leaves a series of dots on the surface that you connect with a french curve or a piece of aluminum on edge and sprung into shape. Just a though. bd +++ #14845 From: "Kent White" Subject: RE: Form Block Dang! I thought it was a pounce bag and a dritz wheel. Our antique oak dining table has those little tracks all over it. My feminine persons love working on a nicely restored surface. Kent +++ #14883 From: "Kent White" Subject: RE: Aluminum to start ...Sorry Chris, I just cannot resist one more shop method after thinking about that "flaming" reference: In the past, when transferring an outline from a pattern to a block of wood, I have occasionally been in a little bit of a hurry and with having all of the aluminum tools handy I learned to combine my tools for a faster transfer: I would adhese the pattern (mylar, paper, thin aluminum) to the wood, set the torch with the big flame and a lot of acet feather, and then smoke the whole thing to transfer the outline. I have to go rather quickly with the paper patterns, because they may only last briefly, but the shadow is ... um ... crisp. Kent +++ #14981 From: Bob Romanko Subject: RE: Nose rib forming question > On some of my ribs, after flanging the rear hole via BobStick, there > is a small flex in the rear section behind the lightening hole, > accompanied by a gentle arc or a slight wave in the rear edge if > viewed from the rear. No sweat, Jason. Just the physics of the thing You'll be fine. Attach angles and stiffeners cover a multitude of sins...or in this case, Bob-Sticking..... Planter Bob +++ #15214 From: Del Rawlins Subject: Re: Question about wing ribs >I've got a question about the flanges on the wing ribs...and my >bearhawk CD seems to be MIA. > >The prints seem to show that the outside flanges of the ribs on the >center and back ribs stop short where the ribs tuck under the spar >flanges, giving a sort of built in jog to have the spars more or less >flush with the rib. Correct? > >Now the aileron and flap ribs, are they the same? its a bit hard to >tell if the flanges stop short of the spar flanges. The flanges on all the ribs should extend underneath the spar web flanges. Whether or not to put a joggle in your rib flanges is optional, according to The Bob. I will probably waffle between doing it or not, up until the time when I actually bend my spar webs. Actually, I'll probably plan on not joggling them, and then if I have to anyway, "I meant to do that." -- Del Rawlins +++ #15220 From: Russ and Penny Erb Subject: RE: Question about wing ribs No, no, no, no, no! It is very important that the rib flange continue in under the spar flange--there is an important rivet (-4, all the others are -3) that goes through that junction. As originally designed, the rib flanges were joggled to fit under the spar flange. This is how I built mine. Find your CD and you can see how I put in the joggles. The Bob has said that it is okay to make your spar slightly larger so that the ribs fit in without joggles. However, if you put the first rivet behind the spar flange too close to the spar flange, you'll get a lump in your skins. Is this bad? It depends on how picky you are. Don't short flange your ribs! Russ "Still happy to answer rib questions after all of these years" Erb +++ #15913 From: John Thompson Subject: rib length list I've been studying the plans to determine the length of ribs. Here's what I came up with (for each wing): Nose Ribs all .025 (shorten from rear) 3 full length (no capstrips) 9 1/8" short (1 capstrip) 11 1/4" short (2 capstrips) Center Rib (not counting capstrip at front of rear spar) 1 full length (no capstrip) .025 4 1/4" short (2 capstrips) .025 2 1/8" short (1 capstrip) .025 1 1/4" short (2 capstrips) .032 1 1/8" short (1 capstrip) .032 1 3/8" short (1 capstrip and front and rear spar plates) False rib all .032 2 each full length Back Rib 1 1/8" short (1 capstrip) 1 1/4" short (1 capstrip and spar plate) Nose flap rib all .025 13 each full size Aileron nose rib all .025 8 each full size Aileron pocket rib all .025 8 each full size Flap rib all .025 9 each full size Aileron ribs all .025 8 each full size Any differing counts? John +++ #16092 From: "Mark Conover " Subject: .032 Center Rib Lightening Hole Modification One of the optional design modifications that resulted from last October's wing testing by Avipro was a change of the oval lightening hole in the .032 center ribs. The latest Beartracks (4Q2002) mentions the hole, as of plans #584, will be round. I asked Bob what is the center of the hole. His reponse was that the center is the forward of the two indicated centers for hole type E. Now, if only I'd asked about the radius. Mark Conover, #502 +++ #16314 From: "Mark Conover" Subject: Modified 0.32 Center Ribs Another Bearhawker with a recent plans number has provided a photo of his drawing #6. Now, those of us with plans numbers less than 584 can finally see the redesigned 0.32 lightening hole. Large Image: http://www.conotech.com/bearhawk/public/mod-center-rib-032-BIG.jpg Small Image: http://www.conotech.com/bearhawk/public/mod-center-rib-032-SMALL.jpg Mark Conover +++ #16324 From: "Mark Conover" Subject: Rib Mod -- Aileron Cable Clearance Hole Question The modified .032 center rib drawing has a callout that states: "Cut Clearance Hole Ribs (.032) For Ail. Cable". The associated arrow points to a location above and to the right of the circular lightening hole. While no radius is indicated, I assume it will be approximately the same as on the original design. True? Original Design: http://www.conotech.com/bearhawk/public/orig-center-rib-032-SMALL.jpg New Design: http://www.conotech.com/bearhawk/public/mod-center-rib-032-SMALL.jpg Mark Conover, #502 +++ #16332 From: Russ and Penny Erb Subject: RE: Rib Mod -- Aileron Cable Clearance Hole Question I noticed that too. I would suspect the hole would need to be big enough to pass the control cable through. With a standard thimble on the end, that would be at least a 3/4" diameter. Of course, if you really like making work for yourself, it doesn't have to be round, but getting the correct location could be tricky. Russ Erb +++ #16609 From: "Bill Burton" Subject: Beginner Question - Sorry Plans have not arrived yet. Got the CD yesterday, however. (The CD is going to be a great help. An Excellent Job was done on it!!) So I'm starting ..... A couple of days ago I put in an order with Dad to rip out some 2 x 6 birch for my forms, at the family sawmill. By the looks of the CD (and other sources) 6 inches is not going to cut it? Or will it? (Can't find a reference to thickness anywhere. Probably under my nose) Can't wait to get the plans, Bill Burton +++ #16613 From: Benton Holzwarth Subject: Re: Beginner Question - Sorry > Bill, As I recall the dimension at the main spar is something > like 7.59" +/- depending which side of the line on your form > block drawing you cut on. And the thickest point of the wing is about 9" to the rear of the main spar, at just a titch over 8" thick, on mine. Benton +++ #16625 From: "kb8rnu" Subject: Aileron rib forming note... A note to the guys who have just started forming ribs: I found it much easier to get consistent results on the trailing edge of the aileron ribs if I left a little extra metal (about 1/4" in addition to the allowance for the 1/2" flange) and then trim it to size after forming. I would assume flap ribs would work similarly. Have any of you more experienced folks seen this? My apologies if it's old hat to everybody. Jason +++ #16630 From: "doug" Subject: Re: Aileron rib forming note... Forming the flanges was not a problem. Usa a good hammer. Neat trick and sounds like extra work. Another note on the ailerons: The lighting holes are drawn wrong and I talked to the "BOB" after it was too late. The lighting holes need to be smaller than are drawn or scaled. Building to the plans means real tight "BOB sticking" for the flanges. He suggested on making new ones, yea right like I din't have anthing better to do. Smaller holes are OK or use the bigger holes and suffer the tight flanging. Doug +++ #16767 From: Jason Bowling Subject: Flanging tips for new folks In response to a couple recent comments regarding flanging the lightening holes on the aileron and flap ribs, I figured I would pass on a couple of notes on lightening hole flanging I found while tinkering with it. - First, read Planter Bob's essay on hole flanging on Russ Erb's CD. You do have one, right? -Very small hammer handles (got mine at Walmart) are tough and cheap. They make good BobSticks after a few minutes on the bandsaw. - A small addendum: it cannot be stressed enough the importance of supporting the rib during the flanging process. I had best results with a peice of wood that the rib just fit over, with holes about 1/2" larger than the lightening holes drilled in it. Example: http://wright.cs.uakron.edu/bearhawk/photos/station.jpg - The pictures you see of used BobSticks all have a slightly odd shape to the notch on the flanging end - it widens out at the rear. Do NOT try to duplicate that on the bandsaw when you make the Stick - it happens naturally with use. It is one of the more mystical aspects of the Stick, as it adjusts to your technique. Start with a very narrow cut, the thickness of the bandsaw blade. If you cut it wider, as the stick is used, the notch will widen to the point it will slop - Wax everything. The first couple holes you do will be very hard - do not despair. As a wax coat builds up and the notch widens and shapes with use, it will get very easy. - The small holes in the aileron and flap ribs require a BobStick Lite, since the flange width is different and a standard one will not fit. The design I arrived at was this: http://wright.cs.uakron.edu/bearhawk/photos/bslite.jpg +++ #17219 From: Budd Davisson Subject: Re: Ribs > One more question for Budd. How are the ribs themselves build in > production? They are hydro-pressed by the same people who make Van's. bd +++ #17886 From: Scott Bailey Subject: Formblock radius: how much is too much? How much radius is too much? I have more than the called out 1/8 inch radius on my blocks. I think I have 1/4 inch to 1/2 inch radius (probably closer to the 1/4 inch). My block is, maybe, 1.5 inches thick, so I can plane and re-radius; however, re-planing the aileron nose, pocket, and flap nose blocks is a tricky operation. The only negative outcome I can think of is some extra weight for the slightly larger bend. Should I re-plane? Why? Why not? Thanks, SB +++ #17887 From: Scott Bailey Subject: Re: Formblock radius: how much is too much? Let me ammend this. Probably closer to the 1/2 inch radius. I will check when I get home. sb +++ #17889 From: Russ and Penny Erb Subject: RE: Formblock radius: how much is too much? First of all, let's make sure you're using the words radius and diameter correctly (this has been a problem before). For a 1/8" radius, your edge should look like part of a 1/4" DIAMETER drill bit (or 1/4" rod). If it does (and you've just made the same mistake that many of us have), then STOP, go merrily on your way and beat ribs. If it really is 1/4 inch RADIUS or more, fire up the planer and start over. The problem with too much radius is that you won't have enough flat area left to rivet to. The Bob has designed many of these wing parts to have enough room for the rivets when built to spec, without a lot of extra left over (extra=excess weight) Russ Erb +++ #17892 From: "Bruce A. Frank" Subject: Re: Formblock radius: how much is too much? Let me see if I understand your statement. With a 1/2" radius you could take a rib formed on that block, place a 1" diameter ball bearing into the corner of the flange and the web of the rib and the ball bearing would make a contact fit through the full arc of the bend? A 1/4" radius would allow a 1/2" diameter ball bearing to fit full contact and a 1/8" radius would allow a 1/4" ball to fit the corner. You may actually have created a 1/2" radius on your block, but it is easy to get confused when thinking about it and to transpose in our minds the difference between diameter and radius. I have done it and made many a part with the incorrect bend or milled radius because of this brain hiccup. How did you radius the edges of the forming block? On an early block I made I used my router. If you did the same thing, a bit that would cut a 1/2" radiused edge would be a monster...very expensive and large enough to make one think about holding (ability to hang on to it) control of the router. Let us know what you find when you look at the block. Bruce A. Frank +++ #17952 From: Russ and Penny Erb Subject: RE: Formblock radius: how much is too much? > Has anyone used the MDF to make the ribs? How is it holding up? I > know this has been covered, but just wondering from those using it. I haven't used MDF for that, but I did use "regular" exterior 3/4" plywood to make the form block for the fuel tank ribs and the flange at the front of the doors. Looked none the worse for wear when I was done. Russ Erb +++ #17956 From: "Shawn Burns" Subject: Re: Formblock radius: how much is too much? Arnold, I have used MDF for forming blocks and even for flanging dies with it holding up very well for forming blocks. I have cracked a couple of male parts of the flanging dies, but that I attribute to excessive torque applied to the bolt. I learned to tighten to snug and then work around the edge with an old bobstick and mallet to seat the rib firmly in the female die. It is good stuff, I just bought a second sheet to set up bucks for the wing tips, a drill press table to use to locate the centers for the dreaded circle cutter on the center ribs, and any other forms or fixtures that come up. I have found that if you keep this stuff out of the rain it is super stable in size and shape. If my red oak form blocks senses a small change in temp or humidity, it gets literally "bent out of shape"! Shawn Burns +++ #17957 From: Tony Dean Subject: Re: Formblock radius: how much is too much? I made my wing ribs with MDF. My project is a Mustang II.This means that I made 12 ribs from the center section form block and I only make two ribs per formblock for the remaining ribs (taperd wing). So far the stuff seems to hold up well. It is very tough and taks a whacking well. td +++ #17960 From: Jim Lathrop Subject: Re: Formblock radius: how much is too much? I am using MDF for my forming block, I have already knocked out all 46 nose ribs and there is no sign of wear on the block. After I finish the wing tip ribs today or tomorrow, that should be the maximum of whacking on any one part of the form block. To make my form block, I roughly cut out two rib patterns on 3/4" MDF and then glued them together for a little added thickness. I then sanded them down to the inside of the drawing #7 line. The MDF is easy to work and the whole process only took 3 or 4 hours (not counting the curing time of the glue). I'm very satisified with the results. Jim Lathrop +++ #18133 From: Scott Bailey Subject: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? I went ahead and re-planed my form block, radiused it (with a laminate trimmer and 1/8" round-over bit! Nice.), and gave it a quick sanding (power tool!) with 180 paper. (Temptation just took me away, I didn't have a chance.) After all this, I double checked my angles and all looked well. The block is 15/16ths of an inch thick. My next step is to locate, drill, and bush the jig pin holes. But a single flaw remains: in my initial build of this block, I over sanded by about 1/8th along the bottom, just aft of the front spar location. This over sanding runs about an inch in length and is in the form of an arc. At first, I was thinking this was an acceptable defect, it will all come out in the wash, but then I got to thinking (I know, stop thinking and just build the thing, but I have plenty of time to ponder my build process while I'm at work.) that it would be hard to put the correct radius in the aluminum rib. Kevin D. has graciously offered to let me visit his project while he critiques my form block; is this the block I want to have critiqued? Side note: my plan to start beating metal on June 1 is not a go. I will build at least 2, maybe 4, of Russ' "EAA 100" workbenches before attempting to make the rib cut templates. Reorganization of my tool closet is probably necessary, also. Scott Bailey +++ #18139 From: Russ and Penny Erb Subject: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? > But a single flaw remains: in my initial build of this block, I over > sanded by about 1/8th along the bottom, just aft of the front spar > location. This over sanding runs about an inch in length and is in > the form of an arc. As I interpret your description, that's big enough to be a problem. My recommendation--cut out that section, glue in another piece, then shape it properly. The 1/8" discontinuity will mess up the airflow--I don't see you being able to get the aluminum to ignore it as you're whacking away. Take the time to do the form block over so you can do the ribs right (and not do them over). Trust me, this won't be the last time you have to convince yourself to do something over so that it will be right. See my latest story in another e-mail. Russ Erb +++ #18140 From: Benton Holzwarth Subject: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? > My recommendation--cut out that section, glue in another piece, then > shape it properly. The 1/8" discontinuity will mess up the > airflow--I don't see you being able to get the aluminum to ignore it > as you're whacking away. I suspect Russ is right, but would suggest at least trying it out before the rework. Try clamping a scrap of metal (ooh, you probably don't have scraps piling up yet) over the problem area, and see if it tries to form into the dip, or just bridges over it as you pound the edge over to about 60-deg. If it does show the dip, I think Russ' fix is easiest, take a nice square notch out of the plank and glue in another piece, then sand (by hand this time?) to match. Benton +++ #18142 From: Scott Bailey Subject: Re: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? The selection of a power sander was correct as my process was to cut the block with a jig saw, then "sand to the line". Unfortunately, the wood, the tools, and my skills set weren't compatible. I have done very little wood-craft in my life and actually think that the block came out very nicely for my first use of a disc/belt sander and jig saw! Scrap of metal, not a one, not even aluminum soda cans. I won't be buying any aluminum until I have the following items, in order, completed: 1. Workbenches. 2. Form blocks. 3. Backing blocks. 4. Rib cutting templates. So I guess I'll see, building benches, if my wood-craft improves. I think maybe I'll give the form block one more go, with fresh lumber. Scott Bailey +++ #18145 From: Tony Dean Subject: Re: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? I have found that some wood fillers take a good beating but do not know how well it would hold up where that many ribs are being made from one form block. I was able to fix a defect in one form block where two ribs were made from it that way. My defect was not in as critical a location as yours is either. Just an idea and it may or may not work for your application. td +++ #18147 From: "Bruce A. Frank" Subject: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? I have fixed my original forming blocks when such mistakes were made by using automotive body putty. Never had it chip, dent or pop out while beating .050" aluminum over it...softer material but heavier blows required because of the thickness. Bruce A. Frank +++ #18148 From: "Bruce A. Frank" Subject: RE: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? Besides the sanding mistakes (more than one) I had my router guide template move during the process creating a gouge about half the diameter of the router bit (1/2") extending about two inches along the edge of the form. The body putty saved the day since I was using part of an oak stair tread and there was not enough left to do it again. (nor the desire to cut and fit a section and wait for the glue to dry...impatient, me? No way! I just want to "get on with it") Bruce A. Frank +++ #18150 From: "kb8rnu" Subject: Re: The Form Block Saga Continues -OR- Another Form Block Question: How Good is Good Enough? I like Russ's idea of cutting out a square chunk and replacing it, then recutting that section. I had to do something similar when I drilled one of the jig holes 1/16" of an inch off. I drilled out a 1" hole centered on my bad hole, epoxied in a slug of oak dowel, and sanded smooth. Works just fine. Personally, I'd take the time to make the form as perfect as you can. It won't be the last time you trash a part - I hosed a bunch of aileron ribs before figuring out how to get the trailing edge to form correctly. A day lost in the grand scheme is not that big a deal, really, and it's worth it to know it's correct. The airfoil isn't something I'd want to experiment with, and a 1/8" deviation in a small area is significant. Of course, I'm only a few months ahead of you, so don't assume I know what I'm talking about. :) Jason +++ #18168 From: "gmgdls" Subject: Re: Form Block, template kit and rag wings > Just remember that this really isn't rocket science....> There has > been discussion about accuracy of the size of the finished rib as to > whether the rib produced on the forms created followed the inside of > the drawing line, outside of the drawing line or matched the drawing > line. Sheet metal fabricated componets produced on form blocks, or joggles from joggle dies or break formed components for large commercial aircraft companies per the manufactures mylars (yes 95% of the fabricated components are digitized, fabricated and inspected to 1:1 scale mylars) are nominal to the line with a +/- 1/32" tolerance applied (1/32" inside the line or 1/32" outside the line.) This is very aircraft standard tolerancing. I have seen and inspected numerous components with a +/- 1/16" tol. also. By the same token some tolerancing is radically tight +/- 1/64" This tolerance is applied to several areas or features of a part at the same time, i.e. the web of a rib,(+/- 1/32"), the bend radius in the corners of the flange bends (R +/- 1/32") and the flanges themselves (+/- 1/32") Lets see here using that logic on a 2 flange rib (2) Radius, and (2) flanges and the center web sounds like it could add up to allowable variation. The key here is uniformity, uniformity, uniformity Just passing thoughts Michael Corrigan +++ #18177 From: "John Thompson" Subject: Form block saga Well, when I made my form block, I used spray adhesive (sp) to put drawing #7 directly on the plank. Cut real close to the line, and sanded the rest down on my little delta 1" belt/5" disk sander. I sanded down to the line, and sometimes past the line, but only just. I made sure that it was smoothly merged to the parts sanded to the line over long distances. You won't be aware of these very shallow dips. To the person who reworked their block because of one of the holes being 1/16th off, don't worry about it. thats .0625 of an inch and won't be a big deal when you cut out that big ol' lightening hole. John +++ #18178 From: "kb8rnu" Subject: Re: Form block saga > To the person who reworked their block because of one of the holes > being 1/16th off... Sorry if I said it was a lightening hole - I mispoke. It was a jig hole, used for aligning the wing assembly, so I decided it was worth fixing. Jason +++ #18194 From: John Thompson Subject: Form block jig hole Thinking about this, would it matter if the jig hole was off a bit anyway? I mean if your jig holes are all in the same location on the ribs, it should be ok, unless these holes are used in reference to something else not to do with the wing? Don't know enough about that aspect to be sure. John +++ #18232 From: "kb8rnu" Subject: Re: Form block jig hole My best guess is it would PROBABLY be ok, but I figured I'd feel awful silly if I made a warped wing because I had been too lazy to spend 30 minutes to fix it. I suspect as long as they are all consistent it would probably work. Jason +++ #18233 From: "Bruce A. Frank" Subject: Re: Re: Form block jig hole > I suspect as long as they are all consistent it would probably work. Apparently you missed my treatise on "build -to-fit" and how consistency is the goal. Bruce A. Frank +++ $Id: 2.1.1-Wing-Rib,v 1.17 2003/05/21 14:53:52 bentonh Exp $