+++ #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 time