+++ #41
Subject: Leaking Acetylene Valve
From: Russell E. Erb

As I opened the valve on my acetylene tank, I heard the hiss of escaping
gas around the tank valve. Not a good thing. Not only a fire hazard, but
a waste of gas. Stuff smells funny too.

Eventually I figured out what the problem was. The packing nut (the one
around the valve) had worked loose. I got a wrench and tightened it up
some, re-compressing the packing around the valve. Opened the valve
again--problem solved!

Remember this in case it happens to you.

+++ #45
Subject: Re: Leaking Acetylene Valve
From: Bruce A. Frank

You ought to take a little soapy water and check that packing gland to
make sure there is no leak at all. Also, you probably already know, that
acetylene valve should not be opened more than about 1/4 turn so it may
be closed quickly in case of a leak or hose fire.

BTW, the oxygen valve should be opened all the way because it is what's
called a double seal valve that may leak around the valve shaft if not
turned far enough to seal at the top of its travel.

+++ #116
Subject: Welding Bearing Tubes
From: Russ Erb

HEATING CAD PLATING TO WELDING TEMPERATURES IS HIGHLY TOXIC! TOXIC!
THAT'S BAD!

(For that matter, heating zinc (galvanized) is toxic too...)

(For that matter, heating zinc (galvanized) is toxic too...)  So what to
do? First, sand off as much of the cad plating from the nut as you
can. Then take the nuts OUTSIDE and heat them with a torch until they
glow red. This will burn off the remaining cadmium. It wouldn't be a bad
idea to wear a respirator for this step, although I have no proof that
it would guard against this hazard.

+++ #118
Subject: Re: Welding Bearing Tubes
From: Bruce A. Frank

Cad plating is toxic enough when burned off with a torch(even in the
open air) that it is worth the effort to find a nut with the same thread
in a hardware store--zinc plated. Zinc plating, when burned off, is
mildly toxic with no effects that last more than a few hours. (actually
there has been some evidence that a heavy shot of zinc can increase
one's libido.)

Cadmium is cumulative and will kill you in very small doses. Even
relatively large doses of zinc is dissipated through the kidneys and
sweat glands and has no long term impact on ones health.

+++ #122
Subject: Re: Welding Bearing Tubes
From: Kevin Deutscher (bearhwk27-)

Just a CAUTION!!!!!

With respect to welding nuts.  Do not use a hardware store
nut.......plated or not.....they are inferior to the AN / MS NAS
hardware. Most hardware store nuts are class 2 threads and not a class
3. Material utilized in the commercial nut is not of sufficient
strength.  A commercial nut could be used only for the grease fitting
nuts.

Any plating should be removed prior to welding. Avoid breathing any of
it.  Most MIL - SPEC hardware is no longer plated with heavy
metals. Phosphate conversion coatings, irridite and zinc is used most
commonly in new production.

To remove plating, screw nut on a piece of bare threaded rod and use the
scotchbrite wheel to remove the plating, the nut rotating on the
threaded rod will wear most of the plating from the threads.

Nut attachment for the grease fittings is typically by brazing.

+++ #132
Subject: More Welding Notes, Flap Springs
From: Russ Erb

Yep, I've been welding again, and taking note of what works and what
doesn't. Time to do some more writing for my fellow builders on the ol'
Bearhawk list. I hope someone finds this useful.

The topics of the day are shrinkage and expansion, plus some others.
Welding is not a dimensionally stable process. That is, after welding
the parts are not necessarily the same size that they were before
welding. We have talked about peening when riveting, which may change
dimensions by 0.001" or less. Now we're talking about changes in size of
1/16" or 1/8" or more, which can make or break a part.

Why does this happen? It's a rather simple phenomenon, but one that
can't be prevented. Steel, like most things, expands as it is heated. If
a part is tightly fitted, it may push against the mating part. In the
case of a T-joint, one side of the tube is being heated more than the
other, so it expands more, bending the tube away from the joint. When
the steel is melted, the liquid cannot support any stress, so all of
that built up compressive stress is relieved as the metal collapses into
the puddle. In the case of the T joint, the tube straightens back out,
more or less. Then as the weld cools, the metal shrinks. Since the side
that was welded is cooling the most, it shrinks the most. Thus, on a
T-joint, the weld shrinks more than the opposite side of the tube, and
bends the tube toward the joint. This discussion assumes the metal is
not restrained in any way.

Let's look at some methods we can use to make this shrinkage a
non-problem, or at least control it better.

Making shrinkage a non-problem means being able to trim a part to size
after the weld is done. This can't be done everywhere, but you should
attempt to do it where ever you can. For instance, Pat Fagan wrote a
while back on his techniques for welding the aileron bellcrank. A big
part of this was to weld the tubes onto the pivot point, then trim them
to length.  Weld in the 1/8 pieces, then the tube for the pushrod. Now
drill the holes at the right place. If you cut everything to precisely
the right size, then weld them, the shrinkage will pull all of the parts
slightly out of position.

If you can't allow the piece to freely move around and then trim to the
right size, you need to provide some resistance to deformation. As I
mentioned in a previous e-mail, when welding two tubes together, be sure
to put 3 to 4 tack welds around the tubes first. If you only have two
tacks, the tube can be pulled out of position as you weld around one
side. With 3 to 4 tacks, the tack on the opposite side from where you
are welding gives some resistance to pulling out of position. The EAA
welding video recommends welding around 1/4 of the tube, then doing the
opposite 1/4.  Then the remaining 1/4s are welded. This helps prevent
deformation.

The other way to provide resistance is to clamp the parts into some sort
of jig. For the aileron hinge mounts, the center part where all of the
tubes come together should be completely welded in the jig (BearTracks,
Summer 1995), so that the jig provides resistance against deforming as
the welds cool. This assumes you have already welded the parts around
the attachment bolts, which requires another technique.

Welding the parts around the attachment bolts can be difficult for two
reasons: The large amount of metal to be heated, and problems removing
the bolts. For both of these reasons, plan on only tacking the parts
together in the jig. Because you are heating the bolt and the jig, it
may take an inordinate amount of time to get a tack weld if you just try
to heat the part. Go ahead and play the flame over the jig and bolt to
warm them up and you should get better results. After the parts are
securely tacked, remove them from the jig and finish welding. Yes, you
may get a little bit of distortion on this step, but you should be able
to compensate when everything goes back into the jig.

The other big problem is with the bolts you use to hold this stuff in
the jig. They'll get almost as hot as the parts your welding. Therefore,
it is critical that you use stainless steel bolts, washers, and nuts for
this purpose. You don't want the cad plated bolts because cadmium at
welding temperatures is toxic!

Other problems with these bolts are stickage and breakage. As you weld a
piece, the scale that forms on the other side of the metal, usually
showing good penetration, forms on the insides of the little
tubes. Since the bolts already have a pretty close tolerance, chances
are high that this will cause the bolts to become stuck. I have also
found if the bolt gets hot enough, something happens, possibly as it
cools, that when you try to remove the nut, it will get stuck and using
big wrenches results in twisting the bolt off right under the nut.

So with these problems, what can you do to maximize your chances of
success? Well, I'll tell you what I did, which is not guaranteed to
always work.

First, make sure you have a sufficiently large amount of stainless steel
hardware on hand that you would not ever have to reuse a piece to weld
all of your pieces. That way, if it always breaks, you'll still be okay.

After tack welding a piece held in place with a bolt, immediately remove
the nut. I've had the best luck getting nuts off before they cool. As
soon as you get the nut off, remove the bolt. If the bolt gets stuck
half way out, try reheating the part to a red glow. Hopefully this will
expand the part enough to release the bolt. Work fast--as it cools down
the bolt will get stuck again if you don't get it out. It also seems to
help if the diameter of the bolt is slightly reduced with a belt sander
prior to assembly. After the part is fully welded and cooled, use a
reamer to ream the hole back out to the proper size.

One other lesson learned falls in the category of "Learn from other's
mistakes--you won't have time to make them all yourself."  Pat Fagan
wrote that while welding the flap and aileron hinge mounts, he found
that they would shrink. Therefore, I built my jig to make the part 1/8"
oversize toward the hinge line. Sure enough, the parts shrank about
1/16". When I was done, I trimmed off the excess and had a properly
sized part.

Some modifications I made to the jig for the flap and aileron hinge
mounts: I welded a stop piece to position the tube that receives the rod
end bearing in the right location. I also trimmed the tabs that hold the
bolt representing the hinge line because of interference with the hinge
mount tube.

I found the flap hinge mounts the most difficult to weld, and to a
lesser degree, the ends on the flap and aileron drives (compression
members). The plans are not clear as to how much of the joint between
the channel and tube needs to be welded. Silly me, as a glutton for
punishment, I welded the entire joint. This was quite difficult and not
real pretty (but should have sufficient strength) on the inside, as the
part was basically a corner reflector, bouncing the flame right back at
the torch and me. Besides getting hot hands, the torch would get hot and
go out with a big "pop". It seems as though these parts could be
redesigned to be more welding friendly, similar to the elevator horn,
which allows making the welds on the outside instead of the inside.

For the last several years I had been concerned trying to figure out how
to flatten the ends of the tubes onto flat pieces, such as on the
aileron bellcrank. Eventually I figured out that it was not necessary to
make them as pretty as drawn on the plans (which I suspect were just
easier to draw).  Pat Fagan clued me in on the way to do it--cut the end
to shape, then heat it to red hot, then simply squeeze it down with a
pair of pliers. (Then weld, of course.) Far simpler than I had imagined.

I've also made up the springs for the flap drive. As mentioned in the
newsletter, I picked up 4 screen door springs at the local Home Base.
These are 1/2" in diameter. Thinking the "20#" on the plans meant 20
pounds/inch spring constant, I first tried to figure out just how many
coils on the spring that would be. Eventually I realized that it was
going to be ridiculous at about an inch of coils. Therefore, I tried
another tack. The plans seem to show 10 inches worth of coil, so I went
with that.  The newsletter glibly says to straighten out some coils to
make the hooks.  This isn't as easy as it sounds. Here's what I finally
found would work: Stick a 1/8" wide screwdriver between the coils at the
desired point, and push it down inside the long part of the
spring. Stick another screwdriver down the short end portion and use it
to bend the spring about 90 degrees to the rest of the spring. This
makes the initial opening. Separate the coils enough to get a small
vise-grip on the coil where you want to start straightening. Put this
vise grip in a vise. With a steel tube or screwdriver stuck through the
coils to be straightened, grab the tube with both hands and pull,
unrolling the spring.

On my flap drives, there was a distance of about 14.75" between the
spring mounts in the "flaps up" position. I bent the hooks on the
springs to be a resting length of 13.75" to leave some tension on in the
flaps up position.  The limiting case is having enough spring tension to
keep the flaps up on the ground. In the air, air loads will keep the
flaps up. If my flaps won't stay up on the ground, I'll shorten the
resting length of the springs some and re-install.

Many of the procedures I've described will make more sense on the CD
with pictures to illustrate what I'm trying to say.

That's my "how to" or at least "how I did" installment for now.

+++ #431
Subject: Re: TIG Machine
From: Archie Dunbar

> What manufacture, price and source for your TIG machine?
> Why did you select this specific model?

Lincoln squarewave 175. Recommended by the guy at the welding supply as
better than the miller econotig.

I'm very happy with it. good results and very easy to use.

I think it was around $2000 with all the accessories and argon tank. Del
has the same machine.

+++ #433
Subject: stay of electrocution
From: Float-by Shooter

I've just about got all of the stuff I need to do the job, but today we
got our 20' freight van a day early and so my welder and tools are
buried behind pallets of freight in the warehouse. So even though I can
access all the electricals there isn't a lot of point in hooking up an
outlet I won't be able to use possibly for several days. If I am
extremely fortunate, maybe the electrician will be back from his
vacation by then.  Thanks for all the advice, I think I have a much
better chance of success than I would have otherwise. BTW my dad is
certain it is only single phase.

As for the gentleman who was asking for specifics on Archie's welder, I
have the same unit and it was chosen based on several knowledgable
people having told me it is the best small TIG unit for the money. It is
the Lincoln Electric Square Wave TIG 175 and they are in the
neighborhood of $1500 depending on where you get it. I opted for TIG
over oxy-acetylene, primarily because I want to learn the TIG process (I
can already gas weld), and for somebody my age (25) buying tools, it
doesn't make any sense at all to make do with less than I really want,
if I can afford otherwise. If I was only going to use it to build 1
airplane I would gas weld it instead, and be perfectly happy to do so. I
plan on getting my money's worth out of it over my lifetime. No doubt I
will have to modify my philosophy of tool purhasing somewhat after the
wedding next year.

But last night I found something that might really interest you. You can
download the complete owner's manual in Adobe .pdf format off Lincon's
website. It wasn't very well linked so I had to do some poking around to
find it, but it is there. If you can't find it, and if you can view
email attachments let me know and I will send it to you that way. I
think it was (only) about 500K. http://www.lincolnelectric.com/

+++ #435
Subject: Re: TIG Machine
From: Rodney Smith

I'll jump in to the discussion about Tig welders. I think that one thing
that would make Tig welding easy for anyone is if you already have
oxy-acetylene experience. Both methods use a torch and a filler rod. The
hand motions involved are nearly identical. I have looked at the Lincoln
squarewave 175 and it has very simple controls compared to larger
industrial units. It also has a high frequency starting current so you
dont have to scracth start the arc like some cheaper units. That
probably helps a lot with the learning curve. I'm not saying that you
couldn't just start out learning to weld with a Tig machine. It would
just take a little longer. It probably would be quicker to learn than
gas welding if you have no welding experience. There is something wrong
with our old Tig machine at work. It works fine at high amperages, but
wont maintain a low amperage arc that I need. Of course I cant get
anyone interested in fixing it since the welders dont work on anything
much less than 1/4" thick here. Therefore I brought up my Henrob gas
torch and have been using that. Its a delight to use and does a real
good job but I had been hoping to Tig weld some of the more critical
parts.

+++ #436
Subject: Re: TIG Machine
From: Bruce A. Frank

There is no substitute for the skill developed by welding with
oxy/acetylene. I have been welding for almost 25 years now and have also
taught welding at a technical college. When I went to school we had to
practise with oxy/acet for 4 months(4 to 5 hours a day) before we were
allowed to touch the TIG torch. Oxy/acet welding teaches not only how to
manipulate the torch and filler but lets you see how the molten puddle
is created, moves across a seam and the impact of cleanliness and fitup
on the weld process. If you are learning to weld for the first time and
plan to do it while building your project, buy the best oxy/acetylene
outfit you can afford. Buy the TIG for the next project.

+++ #451
Subject: Re: TIG Machine
From: Archie Dunbar

> What training and or background made it so easy ?

My previous experience is a little gas welding.  By easy to use I mean
that the preflow & post flow settings are automatic. A purest might not
like this. Another hint. I tried chemical sharpners for my tungsten and
have settled on a dedicated grinder instead. It is faster and I have
more control of the point.

+++ #452
Subject: Re: TIG Machine
From: Float-by Shooter

> automatic.  A purest might not like this.  Another hint.  I tried
> chemical sharpners for my tungsten and have settled on a dedicated
> grinder instead. It is faster and I have more control of the point.

I was thinking of using my 1X42" belt sander to sharpen my tungstens, is
there any reason I would not want to do this?  (like the abrasives used
in the belt possibly contaminating them)

It seems a lot easier (and cheaper) to dedicate a belt to this purpose
than a grinder, since I can change belts in a matter of seconds.

+++ #454
Subject: Re: TIG Machine
From: Bruce A. Frank

Where I work we use nothing but the belt sander to sharpen
tungsten. Another usefull tool is a keyless cordless drill. Slip the
tungsten into the chuck and spin it against the belt. Gives the most
uniform points.

+++ #456
Subject: Re: TIG Machine
From: Float-by Shooter

I'd probably never have thought of using my drill.  And after using
them, I don't even understand why all drills don't come with keyless
chucks.

Thanks for the quick answer and for being a member of the Bearhawk
group.  Your presence has been an immense help to quite a few of us, I
am sure.

+++ #458

Subject: Re: Gas Weldiing
From: Bruce A. Frank

At one time or another I have tried just about every brand of
oxy/acetylene torch that is produced and I still own about half a
dozen. Out of all of them I will have to say that I find the Smith
Airweight the hands down best.  The Smith torch over the decades has
carried a couple of names: Aircrafter and Air Lite are two I have
seen. The design is a small torch with the gas valves forward of the
handle. Let me say that before I began using an old Smith that my father
left me I welded many a mile of tube with a Victor brand torch. There
are a couple of reasons for the Smith. First I find the valves on the
torch body to be the smoothest, not sticky in their rotation, allowing
very fine adjustment. I also find the torch tips to produce one of the
nicest flame configurations, giving a steady and clear profile of the
flame parts allowing me to easily adjust to a neutral flame. I also find
the valves hold their adjustment much better than my Victor.(Victor also
makes a forward valve torch that resembles the Smith, but I've have no
experience with it)

The only other suggestion is to avoid the promotional regulator kits
that the welding supply sometimes have on sale, though I have bought and
have used one of those myself. They are not really bad but there is much
better.  The ideal is a two stage regulator because they maintain
exactly the same gas pressure as the cylinder empties. A single stage
regulator, though today they are better than they used to be, allows the
line pressure to vary a good bit as the tank pressure drops requiring
relatively frequent readjustment of both the torch and/or the
regulators. Let me add that two stage regulators are becoming
scarce. Many welding suppliers don't carry them because they are more
expensive and not many people demand them because there are few weldors
who need precise regulation. The more expensive, higher quality, single
stage are almost as good as the two stage. It has gotten so that some
manufacturers don't even say whether their product is one or two
stage. Don't get hung up on this point, even the cheapest regulators can
do the job.

Expect to spend about $300-$350 combined price for the better quality
torch(Smith), hose and regulators. You can get by with a Victor
promotional outfit for about $160 to $225. By the time you add the
striker, goggles, gloves, filler rod and other misc. stuff the price may
reach an additional $100 dollars.

Hope this is helpful. If you have any specific questions just ask.

+++ #459
Subject: Re: Gas Weldiing
From: Russ Erb

As with many things, I'm sure that there are many welding torches out
there that are adequate for our purposes, and it is worthwhile to ask
for other's opinions so that you can benefit from their
experience. Bruce had some good things to say, and I'm sure he
recommends a good torch. Even so, let me throw in my comments.

At Sun'n Fun 99, I watched a complete demonstration of the Henrob 2000
torch. This is the torch that has the pistol grip. I had already decided
to buy one, and did from the vendor there (McGill Distribution,
888-342-6461). He includes an instructional video with the torch. I have
been very happy with it, and as far as I can tell it does everything
that the ads claim it will.

Some people have said that they don't like the Henrob because it is
heavier than other torches. I haven't found this to be a problem.

By the way, if you don't have welding tanks yet, he recommended to me
the "B" size acetylene cylinder and a 58 cu ft oxygen cylinder. These
cylinders stand about 2 feet high. I found these to be a manageable size
and would last me for about a month before needing exchanged. Note that
if you get the B size cylinder, you will need an adapter to attach your
regulator (for some reason it doesn't use the same connector).

+++ #469
Subject: Re: Gas Weldiing
From: Tim Anderson

I'm new to the gas welding world, (tried it for the first time this
weekend).  A friend told me about the Smith Air lite, but he thought it
wasn't made any more.

I bought a Smith, cavalier, supposidly for aircraft.  Probably not the
ideal torch, but It seems small enough.  I tried it on 1/8 inch steel (I
had to build bar gages for my garage windows, to protect all my tools),
what fun.  The thin material must be a real challange.

+++ #480
Subject: Tig
From: br-

Remember that the dust from the tungsten is radio active.  I have been
using 16th inch tungsten and just breaking it with wire clippers. A
welder told me if you have to sharpen it your using to big of a
tungsten. Its nice to use a smaller gas cup in the tight spots too. Also
most of the belts you get for you sander are aluminum oxide and
contaminate the weld.

+++ #487
Subject: Re: Tig
From: Float-by Shooter

> Remember that the dust from the tungsten is radio active.

The 2% thoriated tungsten normally used for welding steel is slightly
radioactive.  I am using a 1/16" 2% "ceriated" tungsten which allegedly
is not radioactive.  As a plus, they are supposed to start better at
lower amperages.  The downside is they don't do as well at higher levels
of output, but I don't plan on spending much time there.

> I have been using 16th inch tungsten and just breaking it with wire
> clippers. A welder told me if you have to sharpen it your using to big
> of a tungsten. Its nice to use a smaller gas cup in the tight spots
> too. Also most of the belts you get for you sander are aluminum oxide
> and contaminate the weld.

And how would I tell a contaminated weld?  The welds I have been getting
so far are about what I would expect from gas welding, not the
super-uniform bead that a pro would produce.  I expect it to improve
with practice.

+++ #490
Subject: Re: TIG
From: Rodney Smith

I have wondered also about the slight radioactivity due to the 2%
thorium present in tig electrodes for welding steel. For aluminum
welding you use pure tungsten electrodes. I have used a respirator with
a dust/fume cartridge when grinding Tig electrodes but you still end up
with the dust laying around your shop. There is an alternative electrode
available for steel that doesn't contain thorium, I believe it uses one
of the other rare earth elements. Anyways check with your local welding
supply shop about it.

+++ #505
Subject: Re: TIG
From: Bruce A. Frank

Your filler rod is supposed to be mild steel (RG-45,E70S-2,E70S-6 and
similar fillers). There is no problem filling a "burn through" or "melt
out". Actually, the additional heat input at that spot lessens the
likelyhood of cracking. If you melt out an area that is larger than
about 1/4" it becomes difficult to close it just because of the thin
edges with which you are having to work. At that point I will sometimes
cut a little disk of material to patch the hole and weld around it.

If you weld 4130 with 4130 rod as the filler you have a very high chance
of a cracked weld. It takes much more care for an inexperienced welder
to weld defect free with 4130 alloy rod. On top of that, if the part is
not a piece that will be heat treated then you are waisting money and
effort. A weld, using mild steel filler rod, on 4130 tube will exceed
the strength of the base metal (the tube). Weld a little setup of a fish
mouthed "T" joint, a good fillet all away around. Let it cool, clamp it
in the vise and take your 3lb ball-peen hammer and try to beat it
apart. if you get it apart there will be several places where the base
metal tore.

Take Finch with a grain of salt. I like his books. He says many things
that go against the accepted standard, but, from my experience, I find
to be true. But, there are mistakes and in some areas he is
wrong. (don't ask me where, its been a year and a half since I read
"Welding for Performance" or what ever the name is)

+++ #507
Subject: Re: TIG
From: Archie Dunbar

Thanks for the quick reply. I also got to spend a little time picking
the brain of the head welder at Wag-Aero. I had to go up & get some more
tube. He just confirmed what you said. By the way. I had another break
through today. Everyone else is probably way ahead of me on this but I
have noticed that; if the fit up is perfect, the metal clean, tungtsen
sharpened & clean and if I have support for both hands, I can make a
perfect weld. Well the support part of the equation eluded me until
today. It occurred to me to take one of my yellow & black vice grip one
handed "quick clamps" and clamp onto the truss where I needed the rest
for my arm. It works very well.

+++ #510
Subject: Re: TIG
From: Bruce A. Frank

THe "vise grip" rest is something I have recommended several times. I
don't always find in easy to set up so I can rest my forearm. But if
you'll use a pair of the curved jaw Vise Grips®, the all metal ones
so they can take the heat, and clamp them on a tube close to the weld
you'll find that even being able to extend your pinky finger out to rest
on that clamp will improve the weld dramatically.

I have a dedicated pair of Vise Grips® on which I have smoothed the
teeth somewhat so they leave no real bite marks on the tube. The tubes
can take a significant amount of clamping pressure but adjust the pliers
just tight enough to hold and not to the level of distorsion of the
tube.

+++ #609
Subject: Re: Interested builder
From: budd davisson

> Just curious, Budd, what is your definition of a rediculous fit?

Conventioinal wisdom says the right gap is about the thickness of a
hacksaw blade, which is about .032 but the reality is it can be a little
looser than that and still get the parent material to flow together
before the rod is actually added. What you don't want to be doing is
running consistently much bigger than a 1/16" in clusters and fittings
should be tighter than that. Don't try to get a push-fit in which all
the tubing edges touch or the expansion during welding will push your
fuselage all over the place. Some gap is desirable. I'm certain someone
out there with more expertise than I have can amplify on this.

+++ #623
Subject: Video Review
From: Rodney Smith

In the past month I have purchased two welding videos. Performance
Welding is a 90 minute video by Richard Finch who also wrote the book by
that title. If you have read the book, you dont need the video as it
seems to be scripted from the book. I did pick up a few tips from it. He
covers the techniques and advantages of Tig, Mig, and gas welding of
4130 tubing. He also explains how to gear a bandsaw down to low speed
for cutting steel, and shows a press set up for bending fittings. I was
disappointed that filters weren't used on the camera so that you could
see the actual welding process. This video is available at
http://www.buildersbooks.com for $17.  The other video is actually a two
video set called 4130 Chromemoly Aircraft Construction by Kent White. It
is 4 1/4 hours long and expensive at $85. I had read a highly positive
review of it in Custom Planes so gave it a try, I was not disappointed
at all. The amount of information presented is just unbelievable. I have
watched the whole thing three times now and picked up more tidbits
everytime. Everything is so pertinent to building the Bearhawk. Three
EAA techs cover in detail every aspect of constructing steel aircraft
parts from small pieces up through the fuselage. They first talk about
reading plans and appropriate precision for various parts.  Several
techniques for cutting and fitting tubing are demonstrated.  Appropriate
jigging for various parts is discussed. They are strong proponents of
gas welding aircraft parts but also discuss areas where it is better to
Tig weld if possible. They demonstrate quite a bit of welding with a
couple types of gas torches. They have an in depth discussion on what
filler rod to use that finally makes sense to me. I was intrigued with a
Mieco (sp?) torch they were using as it was so small and light. They
also used 6 feet of very light hose attached to the heavier hose which
stays on the floor for a very light set up. Several methods of tube
bending are demonstrated. My one disappointment was that again no
filters were used with the actual welding. Those who have seen the
Henrob torch demonstration tape know what I mean. I could go on and on
about this tape and still not do it justice. Despite the expense I would
rate it as a must have for a first time steel tube fuselage builder like
a lot of us are. It will probably save you much more than the cost of
the tape. Maybe those of you lucky enough to live near an EAA Chapter
could talk them into buying it for their library. The tape is available
at http:/www.tinmantech.com.

+++ #798
Subject: welding alum
From: stephan pelgar

i saw what is being discussed about the fuel tanks.i agree with budd
about the welding aluminum.if you already welding the fuselage with a
tig machine then your already half way there on being good at welding
alum.first thing is though make sure your machine can run in ac.there is
a couple if simple things you have to do for good alum welds.first is
like any material you have to have it extreamly clean.second is you want
pure tungsten.it balls up easier and holds a better ball on tip which is
very important.third is you want to have argon on the back side of the
weld.this will give you a nice bead on the back side of the weld to
instead of having slag on the back which can cause a crack.to weld large
item with out alot of distortion it is better to make alot of small
welds a couple of inches in length.with a few days of practice and alot
of little 2x5 inch plates.

if anyone wants anymore information welding alum please feel free to ask
and i will let you know what i can about it.

+++ #799
Subject: Re: welding alum
From: budd davisson

FYI, about welding aluminum and otherwise, 

Most of us are probably welding with gas. I give seminars at Oshkosh ,
and have for probably ten years, on welding and there are pros and cons
to using gas versus tig on 4130, primarily in terms of pre-heating and
stress relieving afterwards. FYI, I wrote a 12 part series on welding
and I'm thinking about putting it into a book, if there is enough
interest.

Also, I hope no one is using Mig as it is really easy to make a brittle
weld (Rockwell numbers into the high 40's and low 50's) unless you have
a huge amount of experience in welding 4130 with it AND stress relieve
it immediately aftewards. Ideally, you should also preheat with a torch.
It's fast and it's clean, but it's hard to control and needs a lot of
operator talent.

I've never been able to get the hang of oxy-acetlyne aluminum welding
and finally gave up because I tired tired of having the work piece
suddenly melt and ruin a good pair of boots.

Gas welding aluminum with hydrogen is much, much easier but it's a real
bear trying to find hydrogen, the right glasses, flux, etc.

Which brings us back to the original comment: Isn't it easier, and
probably safer for those of us who can't reliably weld aluminum, to go
with composites? The probability of an aluminum tank welded by an
amateur cracking is fairly high. Glass is pretty hard to keep light, but
it's also pretty hard to screw up.

Let's talk about this one. 

+++ #800
Subject: Re: welding alum
From: Float-by Shooter

> Also, I hope no one is using Mig as it is really easy to make a
> brittle weld (Rockwell numbers into the high 40's and low 50's) unless
> you have a huge amount of experience in welding 4130 with it AND
> stress relieve it immediately aftewards. Ideally, you should also
> preheat with a torch.  It's fast and it's clean, but it's hard to
> control and needs a lot of operator talent.

There has been some really good discussion on rec.aviation.homebuilt
about why one shouldn't use MIG for thinwall 4130.  Anybody thinking
about it would be well served to do a search on deja.com and also I have
saved a few of the posts and put them in the FAQ.

> Which brings us back to the original comment: Isn't it easier, and
> probably safer for those of us who can't reliably weld aluminum, to go
> with composites? The probability of an aluminum tank welded by an
> amateur cracking is fairly high. Glass is pretty hard to keep light,
> but it's also pretty hard to screw up.

I was interested in making my tanks out of composite at first also.
Notwithstanding the fact that they will be heavier, I figured they would
be easier to make.  I started looking at some of the canard/composite
web sites and read about people who had problems with fuel additives
reacting with the resin in their tanks and that effectively scared me
away from making my tanks from composite.  Of course, now that I have
the TIG I would be stupid to try any material but aluminum.  Even if I
can't get my skill to the required level, I have a friend who is a
professional welder and would probably weld them up for me if it came to
that.  I plan to do lots of practicing before I even think about cutting
out material for them.  My honda 3 wheeler will probably end up with an
aluminum tank as part of the learning process.  8^)

+++ #803
Subject: Re: alum welding
From: stephan pelgar

i wasnt trying to say that my way is the only way and that i doubting
who people are in here.all i say is i saw there was a few people who got
small personal tig machine.and alot of people think oh aluminum is so
hard to weld.its not that hard at all with just a little practice.at
least with tig.once you learn how to control the puddle and what to
see.you can make the puddle do anything you want.if anyone is interested
in a good book about tig welding i heard that the american welding
society has a few good ones.i have a copy of a article from one of the
months american welder magazine about gas welding and a tips for welding
alum with tig.i will see if i can get permission from them to copy it on
here if anyone is interested.

fyi i didnt try to discredit anyone or anything like that i just trying
to pass down some tips and things i learned when i began welding and was
in my welding certification classes for the military

+++ #813
Subject: Alum Tank Welding
From: Rod Smith

The February [2000] Custom Planes magazine has an article by Kent White
on gas welding aluminum. He says it is easier to gas weld a tank without
cracks than to Tig weld it, assuming a skilled welder. Thats not the
first time I have heard that. Using the correct flux is very important.
When the time comes I will buy some extra material and give it my best
shot.

+++ #815
Subject: Re: Alum Tank Welding
From: Bill Cox

> The February Custom Planes magazine has an article by Kent White on
> gas welding aluminum...

I learned to gas weld aluminum from Kent at Sun n Fun 5 or 6 years ago.
I also bought his video which is excellent. When I came home that year I
practiced for a while and got to the point I was doing a very
respectable job. I haven't done much for the past few years and I can
see some serious practice will be in order.

The keys are very low torch pressure, clean metal, the proper flux and a
lens that will let you see through the orange haze that is a result of
the flux. The welds are very nice without the slag that is often seen on
the back side of a TIG weld on aluminum. Both Kent White and Ron Corvel
have some good instructions if you want to try it. One other thing Kent
put me onto that really helped, he uses .035 wire. When you use even a
1/16 rod welding on sheet it is hard to keep the rod warm enough to not
chill the weld puddle and not fall off in balls from being to hot. The
wire cures a lot of that.

+++ #816
Subject: Tank welding
From: Bill Cox

Here is kent White's web site.
http://www.tinmantech.com/html/aluminum_gas_welding_system.html

+++ #819
Subject: Re: Alum Tank Welding
From: Thomas E Trissell

> I bought a Henrob 2000 torch and aluminum flux at Sun N' Fun 99.  I
> have the aluminum welding rods of the type recommended.  What I'm
> still confused about is that I got a blue piece of plastic labeled
> "Lens for welding aluminum" with it.  I'm trying to find out if I'm
> supposed to use this blue lens by itself or in combination with the
> green lens already in my welding goggles.

I use a cobalt blue lens in My welding goggles when doing aluminum with
the oxy/act rig. I use the aluminum rods with the flux inside bought at
the local welding supply house. I dont remember the name on the aircraft
torch that I have, but I normally use the standard Victor handle for the
aluminum work.

The blue lens will kill the glare of the flame and let you see when the
metal goes molten.

+++ #825
Subject: Re: Alum Tank Welding
From: Russ Erb

And now, showing the tops in efficiency, answering my own question...

I finally got a hold of the guy who sold me the Henrob 2000 and he said
to use the blue lens behind a green shade 3, which also came with my
torch.  "Normal" goggles for oxy-acetylene welding are #5.

+++ #827
Subject: Re: Alum Tank Welding
From: Bill Cox

> And now, showing the tops in efficiency, answering my own question...

Russ, Glad you got an answer. I've been using a cobalt lens with some
type of coating that I bought from Spruce some years ago. Kent White has
his own proprietary lens that works very well, but is expensive.

+++ #834
Subject: Re: Alum Tank Welding
From: Thomas E Trissell

I will have to find My shop note book. I moved from the sheetmetal shop
to the electrical shop at the airlines about 5 years ago so it might
take a few days to find it. At work, one of the others could weld coke
cans with the tig welder, I had problems on the .032 and thinner stuff,
so it is just a matter of practice with what You have.

+++ #1745
From: Tim Anderson  <fuzzet@h...> 
Subject: [Bearhawk] Brazing 

OK, so I'm going to throw out a topic for discussion regarding welding.
Now, I'm a very new-be welder (AKA someone dangerous with a torch). In
one of my welding books they discuss the merits of brazing (lower temps
and slightly more idiot-proof). The book states that the tensel strength
of a braze is at/or as high as a good weld, excluding butt joints which
are a brazing no-no. (I have no way of knowing the truth of this
statement)

Now I'm no idiot (well maybe sometimes) and I am not suggesting such
put-me-in-aircraft-welders-jail hairacy like brazing an entire aircraft
fuselage, but there would seem to be applications that it is
appropriate.  Or maybe it's a case of "aircraft have always been welded
and that's the way we have always done aircraft welding"

Any thoughts from you expert welders?

+++ #1747
From: Budd Davisson  <budd@g...> 
Subject: [Bearhawk] Re: Brazing 

I'm certain some of the pros out there will jump on this one too, but
I'm sitting at the computer (per usual), so I thought I'd jump in too.

First, with certain caveats, I think I can say that your welding book's
statement about a brazed joint being as good as a welded joint is, if
not pure BS, in our environment it's at least close enough to pure BS to
pass as such in most polite circles.

Brazing, even the new versions utilizing Eutectiloy and other high
strength brazing materials are nothign more than high tech
soldering. They just "glue" the pieces together and don't actually join
them. The biggest unknown is the fatigue resistance in high
flex/vibration environments. If one of the new alloys were to be
designed into a design from the beginning, it could probably be used,
but probably never will.

For secondary structure (mounting tabs, etc) there are places brazing
would work fine, but it becomes a real judgement call trying to figure
out which applications are kosher for brazing and which ones
aren't. Probably the way to decide is "If if breaks off, will I really
care?" Since we care about just about every part, it's just easier to
remove the doubt and weld it. Also, brazing requires a fair amount of
surface contact where it can "wet out' so it'll have a large enough foot
print to work so pieces sort of have to wrap around each other for the
joint to work well.

Where brazing works best is sticking together lots of thin sheet for
framing, etc, but again, it requires lots of lap joints for
strength. Personally, I enjoy the challenge of running a tiny little
weld bead on pieces of .028 channel. But then, I enjoy landing a Pitts,
so maybe I'm not a good barometer.

+++ #1757
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: [Bearhawk] Re: Brazing 

There is NO problem brazing the entire fuselage if you use fillets so
that the finished braze looks much like a welded joint.  There are some
fancy low temp nickle alloys with tensile strength that exceeds that of
welding with steel, but regular old blue flux coated brazing rod can
work just fine. The drawback is not strength, the problem is that in
structural assembly much more care is required to braze correctly than
to weld correctly. All brazing alloys contain copper. In a situation
where you may not have gotten enough flux on the joint you'll have a
tendency to push the process a little and the joint gets hotter, as you
try to get that one little void to close, all of a sudden the brazing
filler flows and closes up the joint. What has happened in that over
heated joint is that the grain structure of the steel opened up and the
copper in the alloy flowed between the grain boundaries of the steel. As
the copper infused steel cools the copper blocks normal contraction and
leads to micro cracks. Stress on that area causes those micro-cracks to
propagate eventually leading to larger cracks that endanger the
integrity of the structure. In tests on correctly brazed 4130 tube
tensile strength and fatigue life are equal to mild steel welded
fillets. There is an old saying among welders that if a weld looks good
it is good. That cannot be said of brazed joints (also cannot be said of
MIG welded joints, but that is another topic).

+++ #1767
From: budd davisson  <budd@g...> 
Subject: [Bearhawk] Re: Brazing 

I think it is irresponsible to make a blanket statement that brazing an
entire fuselage is okay. Given certain operating parameters it will
work, but we have a lot of people reading this who may not have your
obvious expertise and experience and a statment like that made on the
net is an invitation for someone to take you literally.

I seldom get on a soap box like this, but that kind of comment needs a
dozen caveats attached to it.

Get your hackles up if you want, but we need to watch what we say here.

+++ #1769
From: Donald Schindler  <t18skyguy@h...> 
Subject: [Bearhawk] Re: Brazing 

Easy Budd, but I understand where your coming from. I want to step in
and add a few qualifiers if I may. While alot of the things Frank said
are true, they only apply to mild steel if thats what your going to make
your airplane out of. Sure brazing can give you 90,000 PSI, which is
stronger than the 60,000 PSI of mild steel, but remember that race cars
are on the ground and not in the air. 4130 should never be brazed due to
the definite grain structure that opens at brazing temperatures. The
alloy flows in, but as the joint cools, the brass doesnt compress and it
forces cracks to form in 4130.  I have seen plenty of 4130 crack and
break after brazing. If you brazed your Bearhawk and tried to sell
someday, do you think anyone would want to buy it? Learning to weld well
is not any that much more difficult than learning to braze well. There
really arnt any short cuts, you just have to suffer through the pain of
practice practice before you do the real thing on your flying
machine. When I learned I was so embarassed in the beginning I wouldnt
let anyone see my practice pieces but after time pride starts to sneak
in.  Don #068

+++ #1770
From: Kelvin Gurney  <kgurney@k...> 
Subject: [Bearhawk] Tack welding 

While we are on the subject of brazing / welding I have a question about
tack welding.  What does the group think about using a MIG to tack weld
and then using a gas rig to do the final welding?  Would not re-welding
the tack welds with a gas rig alleviate the problems associated with MIG
welding of fuselages?

The main cautions I can think of would be to keep the tack welds to a
minimum and making sure the MIG filler metal was the same as the gas
welding filler metal.

It would seem to me that the fuselage jigging process would be smoother
with a welding rig that would be put down and pick-up with a minimum of
re-adjustments. (i.e. lighting, adjusting gases, etc.)

+++ #1771
From: Donald Schindler  <t18skyguy@h...> 
Subject: [Bearhawk] Re: Tack welding 

Kelvin, I think that you might just need to do more jigging before you
pick up your torch. If you've never tried Mig welding you may have a
tougher time with a tack than with gas, particularly on vertical tacks
and nearly impossible overhead. To help your jigging get a set of
Lowbuck adjustable tubing clamps(www.lowbucktools.com) they help alot. I
prefer TIG myself but it is a fact that Mig is employed by numerous
aircraft manufacturers(Kitfox, Mooney, Bellanca) for it's speed.  Don
068

+++ #1772
From: Lee H. Erb  <LeeErb@c...> 
Subject: [Bearhawk] Brazing 

I agee with you and your analysis of brazing. I remember when I started
at McDonnell Aircraft (not McDonnell- Douglas) 49 years ago next month
that there two things that probably could get me fired: 1) using what is
now 5052 on an aircraft structural part; and 2) brazing on a steel
aircraft structural part.

The latter was never fully explained to me other than brazing was a high
temperature soldering. It was, however, fully clear what would happen to
my career if I employed brazing on a structural part.

At Bell Helicopter we considered brazing as too unpredictable in fatigue.

+++ #1775
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: [Bearhawk] Brazing requires MORE skill than welding! 

I did qualify my blanket statement with both a warning about grain
structure cracking and highly stressed subassemblies such as the gear
and engine mount. I said IT TAKES MORE SKILL TO PROPERLY BRAZE A 4130
FUSELAGE TOGETHER THAN TO WELD IT TOGETHER!

+++ #1776
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: [Bearhawk] Re: Tack welding 

At the chance that I may be misread I'll tackle this one. Though many
commercially produced kit fuselages are fully MIG welded these days I
would advise a novice not to weld up a fuselage with MIG. BUT, MIG is an
excellent tool for tacking a structure together, particularly when
finishing welding process will be oxy/acet. It has the advantage of
allow a hand free to maintain parts alignment while tacking. It also has
low heat input helping to prevent distortion so correct alignment can be
maintained until the assembly is completed. The usual filler wire used
in MIG is E70S-6 which is fully compatible with ER70S-2(which is the
usual filler wire used for oxy/acet welding). There is no real
difference in the two except that the -6 contains higher percentages of
deoxidizers to remove impurities from the quickly solidifying MIG weld
puddle. In my experience I find that ER70S-6 cut lengths are superior
for both oxy/acet and TIG welding than ER70S-2. If you like RG45 or RG60
or Oxyweld #7 filler wire fine, but tacking with the MIG E70S-6 wire
meets all the FAA specs for mild steel filler and may produce a superior
weld due to its "fluxing" capability.

+++ #1782
From: Donald Schindler  <t18skyguy@h...> 
Subject: [Bearhawk] Re: Brazing requires MORE skill than welding! 

OK Bruce, all is well, but Im gonna hold firm that brazing is only for
mild steel and not 4130. Even if you brazed it and it held up you could
never get an inspector to sign it off, and then when you go to the
airshows other builders would be calling yur plane a skunk for what you
did. Welder's will tell you numerous stories of brazed 4130 actually
blowing apart after welding. It's not a skill thing, it's a metallurgy
thing. Mild steel and 4130 are two different critters. Don 068

+++ #1783
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: [Bearhawk] Donald, Gotta say one more thing about brazing 

> OK Bruce, all is well, but Im gonna hold firm that brazing is only for
> mild steel and not 4130. Even if you brazed it and it held up you
> could never get an inspector to sign it off, and then when you go to
> the airshows other builders would be calling yur plane a skunk for
> what you did. Welder's will tell you numerous stories of brazed 4130
> actually blowing apart after welding. It's not a skill thing, it's a
> metallurgy thing. Mild steel and 4130 are two different critters.

I have nothing to promote in the way of welding or brazing. I TIG weld
and post-heat my stuff. I MIG weld and post-heat my stuff. I have also
brazed (copper/zinc alloy) carbide chips onto blanks of both 4130 and
4140 and after millions of inches of lathe work with them none have
popped off. I have cut apart sections of 20 year old British road race
cars assembled with regular copper/zinc brazing alloy in the diagonals
and nickle alloy in the suspension hard points. No cracks observed
either in the fillets or the tube (all 4130). If the brazed 4130 joint
is not overheated in the process no cracking (or exploding) will ever
take place spontaneously in the material. I have demonstrated brazing
cracking and "exploding" failures in both 4130 and mild steel as a
welding instructor. Most modern weldors (trained in the last 40 years)
receive almost no training in brazing. They pick it up on the job from
other very good weldors who also have little training in brazing or at
best received 20 minutes of demonstration from their vocational school
instructor.

As for getting a sign-off on a brazed fuselage, in the last 15 years I
haven't heard an inspector even ask what method of assembly was
used. They don't even look at it until after it is painted. Truss type
fuselages such as the Bearhawk, Pipers, Maules, T-craft, and Airknockers
are significantly overbuilt particularly when fabricated from 4130. The
older planes used 1018 and 1025 steel with 4130 alloy types only in the
stressed areas such as gear mounts, engine mounts and firewall attach
points. Brazing, when done correctly is a bonding method SIMILAR to
soldering. The braze alloy does not penetrate into the 4130 or the mild
steel. It makes no metallurgical change to the base metal. If the bonded
surface area exceeds the wall thickness of the tube by 100% or more then
the bond strength exceeds that of the tube. Testing to failure of such a
joint breaks the tube not the braze. BUT, I WOULD NOT EVEN ASSEMBLE MY
OWN FUSELAGE THIS WAY, because, as I said, it requires more effort to
correctly braze weld than to TIG or oxy/acet weld a joint.

+++ #1789
From: budd davisson  <budd@g...> 
Subject: [Bearhawk] Re: Mig - TiG 

Tig/Mig, etc. 

Here's some information I picked up while doing some research for a
welding book: This all came from Eutictic Corp and the American
Petroleum Institute. Rather than make a big discourse out of this, I'll
just toss out random facts/comments.

Eutectic Corp doesn't like to see 4130 Mig welded for a number of
reasons but a prime one is that in some cases, including oil/moisture on
or in the tubes or a humid environment, Mig welding can proceed so
quickly it cooks the hydrogen in the atmosphere into the weld which
promotes embrittlment. They also don't like it because of the termal
stresses promoted by it heating and cooling so quickly, which 4130
really hates.

They said Mig also has a tendency towards super high hardness changes
through out the weld and the Petroleum Institute won't allow harnesses
higher than 30 Rc on pipeline welds because imbrittlement is likely to
occur at levels higher than that. Oddly enough, however, the FAA allows
up to 47 Rc (if I remember correctly) in applications like Citabrias.

Bruce mentioned something very important with 4130 and that is the need
for post-welding stress relieving of critical joints, especially with
Tig. This is done with a rosebud torch. Even critical gas welds
(fittings, motor mounts, etc) should be stress relieved either as the
bead is completed, or by coming back later and going it.

And for another piece of welding trivia: T-6's and Stinson's were arc
welded!

+++ #1793
From: Bearhwk272  <Bearhwk272@a...> 
Subject: [Bearhawk] Re: Mig - TiG Random Bearhawk Thoughts 

There are three reasons that the API and NACE do not allow allow weld
areas to be above Rc 30.

1. Above Rc 30 Hydrogen Sulfide (H2S) contained in the product being
transported causes Hydrogen embrittlement.

2. The weld joints at the expansion loops are highly stressed when the
pipe is thermally active.

3.  With Mig welding it is difficult to achieve consistent weld
properties.  ( Were not talking about dedicated automated flux coated
wire fed machines that are certified for a specific application.) Maybe
Bob could build one for us. :-)?

Anthony what's his name of WW1 fame brazed his fuselages.

What's that got to do with building a Bearhawk?

Our regulatory authority is the FAA. They become concerned about
Hydrogen embrittlement as the result of welding and plating processes
and for 4130 material Rc47 is the crossover line. ( The FAA did not
invent this limit. )

Over the last 90 years of aviation history manufacturing methods and
materials have improved. There is a big difference between an Eindecker
III and a Bearhawk. Gas or Tig.... why step back in time and quality to
braze or Mig?

Remember>>........"The best material can be flawed in application
			if the quality of the craftsman is in question."
			( 1914 US Army Aircraft Riggers Handbook.)

+++ #1805
From: Russ Erb  <erbman@c...> 
Subject: [Bearhawk] Re: Tack welding 

> Hi, where does one learn to oxyacetylene weld, and what is the
> difference between brazing and welding with gas? Wayne.

Check at a local community college for welding classes. EAA has a bunch
of videos and books on the subject.

Brazing is like soldering. A metal (brass?) is melted over the parent
metal and bonds to it something like glue. The parent metal is never
melted. Welding melts the parent metal, which flows together, then
re-solidifies together, forming one continuous piece of metal.

+++ #1818
From: Zippydogg  <Zippydogg@a...> 
Subject: [Bearhawk] Re: Tack welding 

It would be very difficult to made a fuselage completely leak proof, so
I think that any inert gas would quickly leak out. However, if you think
that an inert gas would be an advantage, nitrogen, argon (from the TIG
welder), or CO2 would work. Maybe a little dry ice could provide a
convenient source of CO2. I certainly agree that any oxygen would
quickly combine, and if the tubes couldn't "breathe" by changing
altitudes, any rust would be inconsequential.

I'm not trying to invent a new (and by definition untried) system. It is
just that I've seen fuselages with oil leaking out of pin holes that
makes a royal mess with the fabric and paint. I would rather do without.

The objective of the pressure leak-down test (perhaps a starting with 50
psi and then reading the pressure after a couple of hours) would be to
detect cracks. If I suspected a crack, I would look for it. There are
several techniques that could be used, like a Freon sniffer, or
hydrocarbon sniffer from an emissions machine.

On a different approach, from my marine experience, any attempt to seal
a system will ensure that water will be trapped. Perhaps at the lowest
point of the fuselage a vent could be incorporated with would drain any
condensation. No water (as well as no oxygen) no rust.

For what it's worth.

+++ #1829
William & Delinda Johnson  <wjohnson@f...> 
Subject: [Bearhawk] Gas Welding 

I appreciate all the nice comments in my web site guest book as well as
the discussion group relating to my welding skills. I am certainly
humbled by the kind words.

While no expert on the science of welding, I though I would pass along
some of the art and thought pattern I use in approaching gas
welding. Please do not take me as the final, or for that matter, any
authority on this subject.  I only pass along these guidelines as my
approach to the welding art.

First, I use only traditional gas welding with the smith torch from
Spruce (may change when I do the gas tanks!). This is not from a lack of
equipment. We have a beautiful Miller tig machine and there are certain
areas where Tig could be very useful. I just need to practice. I am very
comfortable with gas and started gas welding in high school - hmm, 18
years ago. I feel old!

Anyway, most often used tip size is 201 with 1/16 rod from
Dillsburg. Tip 20 is used for light plate (.032) and T1-T3 tubes. You
will need 205 for large clusters like the gear attachment, 204 or 203
for fuselage wing attachment and engine mount. I tend to use 3/32 rod
for the large tip sizes or when I have large gaps.

I find puddle control is the key to gas (perhaps any) welding. To ensure
I get good consistent puddle flow, I do the following.

1. Adjust torch for no more than a light hissing sound. If heat is not
enough, go up one tip size. Keep the tips clean (I use a green scotch
brite pad) and welders cleaning files.

2. Preheat area and weld from area of light metal toward the area of
dense cluster. The light area welding will help to heat the dense area
making for a more consistent puddle. Warning - this is opposite of some
conventional thinking!

3. I weld tube clusters so that the final weld is a continuous flow
joining all the other welds. In other words, I try to have the last weld
be a continuous flow around the center tube of the cluster when
possible.

4. I sometimes use slightly higher heat and never remove the rod from
the puddle. This takes lots of practice and only useful for areas of
long flat welds. It does make a very nice looking weld but requires a
very steady hand. It is kind of a manual Mig process of continuous wire
feed with the benefits of gas.

5. I use the rod to shield the lighter material from the flame to keep
the penetration in both the thicker and lighter material equal.

As I complete the weld process, minimizing distortion and bending are my
concerns.

1. I remove the heat slowly to normalize and heat the backside of the
tube to compensate for the expected bend. ALWAYS ANTICIPATE THAT THE
MATERIAL WILL SHRINK MORE THAN IT EXPANDS. YOU WILL HAVE A SHORTER PART
AFTER WELDING! That is the reason for the bending - if you only heat one
side . .  .

2. I found that after welding the rudder pedal outer tube, the inner
tube was very hard to move. I inserted the inner tube and heated the 'V'
to a deep red to get the tubes in alignment. DON'T OVERHEAT. IF IT IS
ORANGE, YOU HAVE GONE TOO FAR. This process works great to get things in
alignment.  Pedals are only one example. The normalization process is an
art all to itself . . .

3 I almost always finish a weld cluster and let cool before welding the
other end of the tube. Often you will need to break the tack welds and
reposition due to the shrinkage or bending. I even had a tack break as
the tube cooled due to shrinkage. It scared the you know what out of me!
You will sometimes get a larger gap on the other end if you don't have a
tight fit to start . . .

4. Check alignment after every weld. Check alignment after every weld.
Check alignment after every weld. Check alignment after every weld.

When making parts that have a tube inside another tube, I do the
following:

1. Clean, clean, clean the inside of the outer tube. You want to
minimize the slag that forms on the backside of the metal being
welded. I try to sandblast before and after. It will really have an
impact on how smooth the inner tube or bearing functions.

Well, I hope this helps someone. Like I said, I am no expert. Just
passing along some of what I do which seems to work ok for me.

+++ #1886
From: Russ Erb  <erbman@c...> 
Subject: [Bearhawk] Re: other 

> > For you welding buffs, if you read Kent Moore's article on Aluminum
> > welding in the March Sport Aviation, check out his welding web site
> > (www.TMTechnologies.com) it's awesome, and made for folks like us.
> 
> Could you check that web address? This took me to a trade show
> consultants page.

If you meant Kent White, you're looking for www.tinmantech.com

+++ #2037
From: meldredge  <meldredge@a...> 
Subject: Which welding rig should I buy? 

I'm trying to decide on a welding set-up for my bearhawk fuse.  I've
heard good things about Henrob, Victor, and Smith sets, but I'm looking
for some input from people who have actually used them, or other brands.

I'm considering the Smith AW1A and the Victor J-28 torch bodies, and I'm
also interested in getting a whole rig together as a set.

Any comments would be greatly appreciated. 

+++ #2039
From: budd davisson  <budd@g...> 
Subject: Re: [Bearhawk] Which welding rig should I buy? 

No contest: go with the smith, tips 0,1,2,3,5 (for jigging) and a
rosebud.

Don't get swayed by the Dillon or something similar. It has a few
handling quirks and areas it doesn't work as well as it should. You'll
need the rosebud anyway, so stick withthe Smith.

+++ #2042
From: Donald Schindler  <t18skyguy@h...> 
Subject: Re: [Bearhawk] Which welding rig should I buy? 

Hi Mike, There are some other very well qualified folks on the site who
can advise you but I will give you my two cents. I am Tigging now but
used to use the Smith which is an outstanding torch. I know that Kent
Moore(www.Tinman.com) sells a fine micro torch but does not advise
switching if you already own the Smith. Im fairly sure his torch is even
lighter than the Smith. Good luck, Don 068

+++ #2050
From: William Johnson  <wjohnson@f...> 
Subject: Engine Mount & Wing Fitting Pics 

N720SF now has an engine mount and the wing fittings are welded to the
fuselage. Since the fuselage was jigged in a flight level position for
the engine mount work, it was easy to verify the +2 wing setting using a
propeller protractor.

Here are some pictures:

Front Wing Fitting:
http://home.fuse.net/wjohnson/Mvc-900f.jpg

Rear Wing Fitting:
http://home.fuse.net/wjohnson/Mvc-901f.jpg

Engine Mount Bottom:
http://home.fuse.net/wjohnson/Mvc-904f.jpg

Engine Mount Top:
http://home.fuse.net/wjohnson/Mvc-905f.jpg

Engine Mount Left Side:
http://home.fuse.net/wjohnson/Mvc-906f.jpg

Engine Mount Right Side:
http://home.fuse.net/wjohnson/Mvc-907f.jpg

I was planning to write a summary of the process I used to construct the
mount and install the wing fittings but time is short. Sun & Fun waits
in Florida. However, I did add two tubes to the engine mount (see bottom
pic). I did not discuss with Bob so do this at your own risk - the rest
of the mount is per the newsletter.

Two recommendations:

Get a large tip for your torch. I used a smith #5 for all engine mount
welds. A smith #2 worked for the wing fittings.

Build your own motor mount ring instead of purchasing. Building will
give you confidence and a feel for welding the thick material.

Shelly, your cables are in the mail. Expect them Saturday.

+++ #2054
From: Donald Schindler  <t18skyguy@h...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

Hi Mike, Congrats on your step forward. When you get your tanks, dont
get the giant ones and dont get the teeny ones you see at Home Depot,
get the ones about hip height, they are a nice compromise and easy
enough to move.

+++ #2056
From: TheStones  <stonet@g...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

If I'm not mistaken, the hip height size are called "Q" bottles.  The
five foot or so size are "H" bottles.

+++ #2067
From: Donald Schindler  <t18skyguy@h...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

I forget the letter designations. I had a friend who used the tiny ones
on a small fuselage and he told me he filled them 22 times. Ive lugged
the bigs ones around, that gets just as old. Don 068

+++ #2069
From: John & Beverly Uecker  <jbuecker@n...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

I have the "Q & WQ tanks and they are just about right for a home
workshop. The acetylene bottle is 26"x7" and the oxygen is 36"x7".  Nice
to move around and handle when it's time for a refill.

+++ #2070
From: Russ Erb  <erbman@c...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

On the recommendation of the guy who sold me my Henrob 2000 torch, I got
the "B" size acetylene tank and a 58 cu. ft oxygen tank.  When I was
actively welding the wing steel parts, they seemed to last about a
month.

Note that the "B" size tank requires an adapter to attach the regulator
to.

+++ #2075
From: Rod Smith  <rsmith@a...> 
Subject: Henrob Torches 

> Russ, How do you like the Henrob? I have never had the chance to try
> one.

I have one also and I like it. I seem to make much nicer welds with it
than with the good sized victor torch that I used many years ago in
welding class. The smallest tips put out a very concentrated pencil lead
sized flame which I believe lets you make a more precise weld. Most
people that use one for aircraft work end up drilling out the smallest
tip with a #70 or #71 bit and that seems to be just about right for .035
to .049 tubing. I have never had a chance to use a Smith or a Micco
however which I hear very good things about and they are cheaper. It
weighs more than the Smith or Micco but I have never found that to be a
problem, perhaps because of the ergonomic pistol grip which works well
with my hand. Like someone mentioned, one drawback to the Henrob is that
their is no rosebud tip available that I am aware of. I have been
thinking of modifying one to work with the Henrob or just buying a used
victor to have that capability at home.

+++ #2083
From: Russ Erb  <erbman@c...> 
Subject: Re: [Bearhawk] Ordered a welding rig, any word on wing kits? 

> Russ, How do you like the Henrob? I have never had the chance to try
> one.

I like it, but I really don't have any experience to compare it to. I'm
not counting the welding class I took at a community college where we
used the standard big torches with who knows what size tip. We welded on
scraps (from the set for Waterworld), so I have no idea how it would
work on 4130 tubing.

I welded all of my wing steel parts you see on the website with it with
no problems (except those caused by the geometry of the part--the ends
on the flap and aileron drives make wonderful corner reflectors--what a
pain). I have found it to live up to all of the manufacturer's claims so
far. I've even tried welding aluminum, which needs some more practice.

I agree with everything Rod said in his previous message. I know what a
rosebud is in theory, but have never seen one. However, the #3 tip for
the Henrob is pretty big and seems to make a flame big enough to heat up
a cluster, although I can't verify that yet.

I bought mine at Sun'n Fun. I had already decided to buy one, but
watched the whole demonstration anyway. If you go to one of the big
shows you might be able to try one.

+++ #2094
From: rsmith  <rsmith@a...> 
Subject: Zen and the Art of the Weld Puddle 

Just read Budd's above article on his website. Great article! Some
insights that I hadn't read or heard before.

+++ #2096
From: budd davisson  <budd@g...> 
Subject: Re: tanks 

Yet another note about tank sizes. The medium tanks are the right size
unless you are doing other stuff than airplane building. Since all the
tanks we get have been recycled through a facility when refilled, I
theorize they originally had labels on them that read, "CONSUMER NOTE:
THIS TANK IS GUARANTEED TO RUN OUT SATURDAY AFTERNOON RIGHT AFTER THE
WELDING STORE CLOSES"

I've had that happen enough times I always go for the big tanks as I
sometimes do a fair amount of cutting which really uses up oxygen.

+++ #2098
From: budd davisson  <budd@g...> 
Subject: Re: More on Henrob Torches 

Some more non-essential comments on Henrobs. 

I own both a Smith and a Henrob. The Henrob does really great work,
sometimes better than the smith, but it's awkward to reach into nooks
and crannies because of its shape. Also, I guess because it uses such
low pressures, it tends to "sneeze" more when you get down into closed
spaces like theinside of a cluster or the inside corner of a square
fitting. I think that is because of the pressure of the flame being
bounced back. They make an extension to get the nose down inside
clusters but it still sneezes and is puts your hand a ways away from the
joint making it difficult to control it.

For outside joints, it's great but I still use the Smith much more. 

The cutting head on the Henrob is terrific! With its little wheels, and
concentrated flame, it's almost like having a plasma cutter, but that
doesn't help us when building airplanes.

+++ #2099
From: Forrest D. Ferdon A&P mailstuff  <theferdons@m...> 
Subject: Re: [Bearhawk] Re: More on Henrob Torches 

I agree with Bud on the Henrob torch. I use the Harris torch that is
made for aircraft, but I put the Tip Tube on it. It is a different tip
assembly and it does wonders for concentrating the flame. I can even
weld aluminum with it! Something I wrote off as impossible before this
set up. If you have a Harris, I highly recommend the tip tube. You have
to buy a different tube and different tips to fit on the end of the
tube, but it is well worth it. Most of the Harris reps don't know
anything about it, but if they ask the right people at Harris, the can
get the stock numbers. Before spending the precious cash on a welding
set up, get some local EAAers to let you try theirs. Torches are like
women, one is going to work out better for you than all the rest!

+++ #2213
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: Re: [Bearhawk] Brake Torque Plates & Brazing 

The easiest stuff to use is nickle-silver brazing alloy. There is no
adverse reaction with this process in 4130. Silver brazing is also up to
the job. The silver or nickle-silver alloy are expensive, but you'll
need only a few ounces.

>I need some wisdom and guidance. I am building a pair of brake torque
>plates for my dual puck brakes. The brakes were free but did not have
>any torque plates. See the following picture for a single puck brake
>torque plate. Notice the thick washers that brake housing pins slide
>into.
>
>http://home.fuse.net/wjohnson/torqueplate.jpg
>

>Question - can I braze the thick washers on both sides of the plate I
>am building? In looking at other plates, It would appear that is the
>procedure. However, Page 130 of performance welding says to never braze
>4130 due to grain structure - only braze mild steel.
>
>Also, is silver solder the same as brazing. Normal brazing is with
>brass I think. Thoughts?

+++ #2635
From: budd davisson  <budd@g...> 
Subject: Re: [Bearhawk] Seeds, Skinning Cats, and Brown Trucks 

Doug Re: Tig welding 4130

Although a lot of welders Tigging 4130 treat it jus tlike 1020 and
get away with it, the smart money stress relieves each joint as they
go.  4130 hates thermal shock (can develop micro-cracks in the weld
from thermal stress) so the best bet is to pre heat it, weld it,
stress relieve it on the spot with a rose bud.For the preheating, if
you don't want ot use a torch, just keep the heat down for a few
seconds giving it a chance to warm up before stepping it up to
welding temp.

Waiting too long to stress relieve 4130 is a subject of some
controversy, some say it needs to be done within a day or
two. eutectic Corp says it's possible to get hydrogen embrittlement
if the weld is done on a tube with some moisture or in a high humidy
environment, if the weld is rushed. So, they say relieve it as
quickly as is practical.

On the other hand, a lot of folks, Aviat among them, don't stress
relieve anything. So....?

+++ #2658
Doug Knight  <metalfab@p...> 
Subject: Re: [Bearhawk] Seeds, Skinning Cats, and Brown Trucks 

OK, I think I'm on the same page with you now. You have raise some
valid points that have jogged my memory. Years ago I had the head
bearing crack off of a 4130 motorcycle frame. I had it rewelded and
then it cracked again. Neither the original or the repair where
stress relieved to my knowledge. Since this motorcycle was just the
first handful to enter the country, the manufacturer replaced the
frame sans labor because of the flawed process.

At work we store our lo-hi rod in a rod oven per AWS and structural
code specs. Welding with wet lo-hi is sufficient cause for hydrogen
embattlement. If you visualize the gas welding process of what is
happening. When you heat the joint you are chasing out all the
latent moisture in the metal. Then again, water is a by product of
the gas combustion from the torch. Go figure.

I concur with the pre heating and post joint stress relieving. I
plan to build my fuse at my hangar, then trailer it to work for the
final weld out. My hangar has only 110, while at work I have access
to a Dynasty DX w/pulser. Both have different micro climates that
really suck, the hangar hot and dry in summer while cold and damp in
the winter. The shop, well, cool and damp all year around, right on
a saltwater estuary.  So I have some challenges ahead of me but that
will have to wait till next year. Wings first.

As far as pre and post heating, I have a weed burning propane
torch. I hate burning up acetylene just for a heating
process. Propane is cheaper too.

At some point I guess we can't afford to be anal and just get on
with the building process.

+++ #2665
From: budd davisson  <budd@g...> 
Subject: Re: [Bearhawk] 2nd-hand gas rigs 

Here's my opinion on used gas rigs. 

There is "used" and there is "USED." It depends very much on the age
and vintage of the equipment. Diaphrams go bad if they are really
old or really used a lot. I don't know what a regulator reguild is
these days, but I used to pay about $50. Also, you may not be able
to tell if they are single or two stage regulators, not that it
makes much difference for our use.

Also, if it isn't one of the small torches like a Smith Airline,
don't bother. Also, it's doubtful the smaller tips will be with it,
since no many use the small sizes we do. You'd be amazed how much
easier the small torches and hoses are to use. I built a couple of
planes using my old bridge-building Purox and didn't realize how
much fatigue was involved until I finally switched over to a Smith.

Having the right torch with good hoses and clean undamaged tips is
worth paying the extra bucks.

There it is...another opinion that may or may not be worth anything.

+++ #2666
Bob Romanko  <romanko@v...> 
Subject: RE: [Bearhawk] 2nd-hand gas rigs 

> From: John Morrison [mailto:johnm@v...]
> 
> Hey all, 
> I have the chance to pick up a gas rig in parts (the welding
> torch, regulators, hoses, tips etc all avaiable seperatly) from a
> used tool shop.  What to watch for? I think I'll buy brand new
> tips, but do regulators, hoses and torches stand up over the
> years? A brand new Lincoln Electric gas rig is $350, and I hate to
> pay for the cutting torch, cheapo safety glasses etc.
> The store owner asked if I needed anything else, I said:
> 
> "No tanks..."

Ouch! I didn't even see that "No tanks..." coming. And so close to
my lunch, too.

Our local welding supplier has a basic setup from Victor for around
$500. That's new tanks, regs, torch, the whole enchilada. The neat
part of the deal is instead of the medium size Victor torch, he'll
include a Meco Midget for LESS money! That's right, a whole rig "all
up" new outta the box with an awesome torch for only around
$460. Not too shabby, really. About the only thing good that came
out of Victor buying out Meco (and trashing the ENTIRE product line,
except for the Midget) was this particular deal you can get. If you
have a local Victor dealer you'd probably be able to get a similar
package.

Used gas equipment frightens me. Nasty things can and do happen with
used gas equipment. Some problems are more obvious than others. You
should have someone VERY well-versed look over the equipment before
you buy. Still, You have no way of knowing some things without
firing up the torch. For example, did someone in the rig's past lay
a tank on its side? That can put acetone in the whole rig, and
you'll have a purplish flame when you light the torch. Diaphragms
can dry out, and hoses can fatigue. Sure, they can be repaired for a
reasonable expense, but do you really want to take your time away
from building to go through the hassle? For the money you'd be
saving, I'm not sure it's worth the worry to go over
everything. You're going to be using your torch and tips quite a
bit, so I'd pick out a rig that you really feel comfortable with for
our application, not the used rig that is a "good deal". Nearly
every used torch I've seen out there locally is too big for our
application. Heck, they'll work, but the torch will work you rather
than you work the torch.

Buy a new rig. You'll find plenty to do around the shop with it
after your Bearhawk's finished.

+++ #2699
From: Marc Labbé  <mlabbe@i...> 
Subject: Re: [Bearhawk] Welding 4130 

Warning,

I am writng this by memory only. I did not have the courage or the
will to dig in my storage.

Welding 4130 with mild steel rods might be okay if the weld part or
piece is not subjected to cyclical high stress (fatigue) otherwise
consult with the Canadian Welding Bureau or US equivalent.

More, with heavy and thick piece, cooling time is very important
(change in cristaline structure).

To avoid problems use 4130 when there are no alternative.

+++ #2700
From: budd davisson  <budd@g...> 
Subject: Re: [Bearhawk] Welding 4130 

General fact: 99.9999999% of homebuilts welded use copper coated
mild steel rod. A few of the specialty builders use 308 stainless
for its ductility. 4130 rod is so tempermental to use, your chances
of getting a worse weld, dispite the better rod, are too high to
justify using 4130. Some worry about the lower tensile strengh of
the rod and/or the contamination by the copper, but none of that is
important when gaged against the overall length of the weld, which
in most clusters is three or four times what's needed. Mild steel is
so easy to easy compared to 4130, it's hard to get a truly unsafe
weld.

+++ #2702
From: Bruce A. Frank  <BAFRANK@w...> 
Subject: Re: [Bearhawk] Welding 4130 

You have said it correctly, the only time 4130 should be used as
filler is when the whole welded part is going to be heat treated to
a specific temper. Inexperienced use of 4130 as filler can lead to
serious problems, some not easily detected, in the finished weld.

Welders who doubt the strength of their mild steel weld should make
a simple fish-mouthed (coped) "T" joint. After air cooling, place
the piece tightly in the vise and try to beat it apart with an good
ball-peen hammer.  If you succeed in beating it apart, the majority,
if not all, tears and breaks will be in the tubes, not in the welds.

The FAA manual on welding 4130 also states to use mild steel as the
filler.  Whether using RG45, #7, ER70S-2, ER70S-6 (my rod of choice)
or stainless the end result will be superior and easier to
accomplish than a weld done using 4130 as the filler.

+++ #2708
From: William Johnson  <wjohnson@f...> 
Subject: FW: [Bearhawk] fuselage welding 

Pat, sorry for the delay in responding.  You may be well into the
welding process by now.

I welded my fuselage from the tail forward finishing each cluster as
I went.  Since you can not prevent shrinkage, the idea is to make
sure you have an equal amount of shrinkage in all directions.  The
bending and strange twisting of longerons as you weld is due to
uneven shrinkage.

Here is what I recommend.  Preheat cluster on side opposite of where
you intend to weld until light orange.  Move torch to weld area,
preheat and begin welding.  Don't stop until entire cluster is done.
Once done, slowly move torch around to all sides, bring entire
cluster to cherry red, sloooowly remove and let cool.  Once cool,
check alignment.  Weld the next cluster moving in a circular pattern
toward the front.  You will need really good tack welds or some may
break.

Good puddle control and working to get even shrinkage are the keys
to great accurate welding.  Before every weld, think about the
effect of shrinkage and work to get equal amounts on all sides.  We
need to have another discussion once your done with your clusters.
Welding tabs, fairlead tubes, brackets, etc. requires a slightly
different approach.  Let me know when you get that far.

+++ #2802
From: Tim Anderson  <fuzzet@h...> 
Subject: Cutting Torch !@#$% 

BHawkers - I know there are torch experts out there, who could point me
in the right direction.

I spent the weekend building a table for my new habor freight special
milling machine.  Has to be good and sturdy, because of the weight.  I
picked up a sheet of scrap 1/4 inch plate for the top.  I started the
cutting torch and after a few minutes of adjusting, got it to cut.  Then
I shut down momentarily.  Upon my attempt to re-start the cutting, the
blasted metel wouldn't cut.  I fiddled with the controls and heated it
until I was red in the face.  The sheet was fairly rusty, if that makes
a big difference on cutting.

What started out to be a one day job, is still unfinished after three
days and taking up valuable room in the work shop.  It is also VERY
heavy, and airplane building has ceased until this project is done.  My
spar's are feeling a bit lonely, just sitting there about 75% done.

The oxy control seems to be VERY sensitive, maybe I overblasted with
oxygen.  As you can tell, I'm a new-by torch man.

Any suggestions?

+++ #2803
From: budd davisson  <budd@g...> 
Subject: Re: [Bearhawk] Cutting Torch !@#$% 

Rusty iron cuts "almost" as well as clean, but clean cuts better and
doesn't give off the crappy odor. If it has scale, as opposed to fuzzy
surface, it'll be really hard to cut because you're heting the scale and
not the metal.

My guess is you've got something in the oxygen orifice of the tip. Try
cleaning it. 

All a cutting torch does is heat the stuff to near melting then you
oxydize a path through it with pure 02. Make sure the 02 is at about 18
pounds and the acylene at about 8-10 pounds. Adjust the tip so the
little cones are nice and blue and not particularly sharp, amost exactly
like aneutral welding flame. Their only function is to heat, not cut.
You'll know you've got them set right when the back side of the cut has
little or no slag. Get it set right and you can slice 1/16 slivers off
without melting them. Really cool...er...or something!

Apropos of nothing, but the Dillon cutting torch is unbelievably good.
If you do much heavy steel cutting, that's a good enough reason to own a
Dillon, although I don't like to weld with them.

+++ #2804
From: Russ Erb  <erbman@c...> 
Subject: Re: [Bearhawk] Cutting Torch !@#$% 

> Apropos of nothing, but the Dillon cutting torch is unbelievably good.
> If you do much heavy steel cutting, that's a good enough reason to own
> a Dillon, although I don't like to weld with them.

budd gives good advice, but may not be hip to the various name changes
that take place with time. For those who haven't been keeping up, the
Dillon torch is now sold as the Henrob 2000, the pistol looking one. I
have no idea why the name changed, just that it did.

+++ #2805
From: Donald Schindler  <t18skyguy@h...> 
Subject: Re: [Bearhawk] Cutting Torch !@#$% 

Tim, Im no torch expert but I will give you what usually works. Adjust
your regulators for about 1-2 psi acetylene and 10-15 psi oxygen.(oxygen
does all the work) Next, preadjust the cutting tip. Shut off the oxygen
valve on the cutting tip and fully open the oxygen valve on the torch
handle. Open the acetylene valve one turn and light the torch. Add
oxygen by opening at the cutting tip until there is a neutral
flame. Start the cut by heating the edge of the plate, when you get a
puddle, press the oxygen lever and it should begin to blow away the
metal. If it doesnt, then your puddle is not good. With 1/4 plate you
should move about 1 inch every three seconds. Too many sparks means your
moving too fast. Keep your tip clean. If all else fails, that cut is
only a five minute job at a welding shop with a plasma cutter. Bruce
Frank is another in our group that can give real solid advice on this
topic also. Good luck

+++ #2975
From: Rod Smith  <rsmith@a...>
Subject: Welding Stress Relief by Vibration

Just read an interesting article in the August Custom Planes
magazine. It describes a process of relieving welding induced stress in
welded structures by the use of high frequency vibration. It can be done
either during the welding process or post weld. It is accomplished by
clamping a vibrator, controlled by a computer to a weld table to which
the weldment is securely attached. When applied during welding benefits
claimed are less weld cracking, longer fatigue life, less weld
distortion and less porosity. Probably not applicable to our project but
a very interesting article.

+++ #2977
From:   <newbegin@i...>
Subject: Re: [Bearhawk] Welding Stress Relief by Vibration

Funny you should bring this up, my neighbor just had a motor mount break
on his Whitman-10 I t broke about 1/2 inch from the cluster at the
longeron end. The guy knows about gas welding and releiving and was very
suprised.

+++ #3116
Subject: A couple good tips from Airbum.com
From: Rod Smith  <rsmith@a...>

In Budd's article "Zen and the Weld Puddle" he recommends using a
cheap set of reading glasses while welding to better see the puddle.
I finally bought a pair marked as 1.75. Wow. Now I know exactly what
the puddle is doing instead of having a vague idea. The appearance
of my welds has improved noticeably using them, and according to my
eye doctor my near vision is still 20-20. 2nd tip comes from his
article on flying wires. Those of you who are admiring your new high
dollar,streamlined, stainless, rolled thread tailwires and stainless
clevis forks, like I am, don't forget when the time comes to use
some moly-disulphide lubricant on the threads. Stainless on
stainless will gall otherwise, possibly causing a wire to break.

+++ #3130
Subject: Seeing to weld
From: Kent White  <kent@t...>

I encourage everyone who wants to weld decently to get their eyes
tested (like the surgeons do) for depth perception and clarity at
the reading distance. If you cannot see, you cannot weld.  Many
students have told me that after they dedicated cheap accurate
correctives (cheaters, readers, whatever) their welds improved by a
considerable (read:drastic) margin. You will not need trifocals,
bifocals, Serengeti Drivers, etc. to weld. At all. Ever. Fix your
eyewear, and your welding will improve, and your frustration and
tension will markedly decrease.  Be comfortable, and your energy
will increase. This is a "must-do" to finish large projects.

+++ #3131
Subject: RE: [Bearhawk] Seeing to weld
From: Bob Romanko  <romanko@v...>

Kent, you missed one other really important point if one wants
professional welds.  They need to buy your video, "4130 Chromemoly
Airframe Construction"!

I received mine from you about two weeks ago.  What a wonderful
piece of work!  Thank you so much for putting this together.  Folks,
there is SO MUCH MORE in this video than just welding technique.  If
you don't buy this thing you deserve every crater you get (grin)!

Here's the URL:

http://www.tinmantech.com

From there select "Products", then "Videos by the Tin Man".  It's a
full two-volumes, and on sale now for only $70!  I'm in no way
associated with Kent or his company, other than I'm delighted with
this video.  The instruction is top-notch, video quality excellent,
and value the best I've seen for instructional video.

+++ #3135
Subject: Re: [Bearhawk] Seeing to weld
From: Bruce A. Frank  <BAFRANK@w...>

I didn't mean to imply that one needed tri-focals for welding. I
already have the tri-focals to see, but I still required an
additional lens to improve the vision for welding.

+++ #3137
Subject: Re: [Bearhawk] Seeing to weld
From: Donald Schindler  <t18skyguy@h...>

I have the blended bifocals and after straining to keep the bead in
that narrow area of the lens I said "I CANT GO ON LIKE THIS" So I
went and had a big pair of glasses made in my prescription for close
work only. I call them my welding specs. Made it alot easier.

+++ #3345
Subject: Welding practice w/ EMT
From: Benton Holzwarth  <bcgh@t...>

I'd remembered in Richard Finch's book, "Welder's Handbook", he
talked about mocking up an engine mount with 'EMT' (galvanized steel
electrical conduit.) Pgs 39-40.

Question to the welding experts: Does this EMT weld like thinwall
4130? Would it be a cheap/available material to practice with, in
advance of my first order from Dillsburg?

Also, does the galvanizing (zinc) present the health/safety issues
that welding Cad-plated HW does, e.g. using a cad-plated nut for one
of the weld-on grease fittings. I'm presuming not, but was far from
certain.

+++ #3347
Subject: Re: [Bearhawk] Welding practice w/ EMT
From: Kent White  <kent@t...>

Cough cough!!  Yes the zinc coating on the EMT is toxic. Wire wheel
it off the weld areas or sand it or acid etch it clean before
welding it. Weld it with RG45 (gas) or 70S (tig). Welds fine, like
real steel. Ventilate room well, just in case. If you see a
yellowy-brown smut in the post-weld area you got zinc. If you see
white smoke or streamers in the air during welding--you got zinc. If
you get chills, fever, dry throat, or a naggy hack a few hours after
welding--you been "zinked".

+++ #3350
Subject: Re: [Bearhawk] Welding practice w/ EMT
From: Russ Erb  <erbman@c...>

Remember that Aircraft Spruce will sell you a pile of leftover 4130
at a reasonable price.  "At least 20 ft. of tubing in assorted sizes
and wall thicknesses."  P/N 03-15900 $35.  You may have to wait a
little while to get it while they accumulate cutoff pieces.  Might
as well learn on the real stuff, and much less health hazard.

+++ #3352
Subject: Re: [Bearhawk] Welding practice w/ EMT
From: Bruce A. Frank  <BAFRANK@w...>

EMT is a pain to weld because of the galvanize. Zinc fumes are a
very minor heavy metal intoxicant. You feel like you have a bad case
of the flu with badly aching joints. It passes in a few
hours. Drinking milk is supposed to help. If you sleep it off and
sweat with the mild fever the sheets are stained yellow.

Galvanized (and sometimes zinc-rich painted) EMT pops and sputters
and throws flaming bits of very hot molten zinc down your shirt
collar. I used to use it for test structures of peddle cycle
designs. If you can sand blast the areas to be welded it might be
useful. It is very inexpensive.  Wall thickness for 1/2" through
1"is similar running about.035" up to .049" so you will get the idea
when trying to weld it.

But, you may find that ten feet of 4130 so much easier to cut up and
practise with, that the cost becomes insignifiant.

+++ #3356
Subject: Re: [Bearhawk] Welding practice w/ EMT
From: budd davisson  <budd@g...>

As one who suffered lung damage at a very early age from
welding/brazing galvanized conduit, I can categorically say that
it's a lousy idea unless you grind all the coating off for at least
an inch from the weld.

+++ #3444
Subject: Re: [Bearhawk] fuel tanks
From: Kelvin  <kgurney@k...>

   In addition to Kent's "Gas Welding Aluminum" I also have "Edge
Those Panels".  It is another of his videos I would recommend.
"Edge Those Panels" has good information on forming edges that would
simplify welding and add to a tanks durability.

+++ #3545
From: Tom & Michelle Brant  <tmbrant@u...>
Subject: welding 4130

Does anyone out there who's knowledgeable on welding know if welding
4130 with a different alloy filler rod is a bad thing?  4130 rod from
Spruce is pretty spendy and I can get "chrome-molly" filler rod for
about a 4th of the cost.  I can't find anything that specifies whether
it's 4130 or not.  Maybe they're the same thing.  I don't know.

Fuselage #324 has been started...  and restarted.  I bent the lower
longerons exactly as the plans are drawn...  IE: the bends are
straight and do not form a smooth radius.  I got home from the shop
and something dawned on me that I had read in the past...  The
newsletter showing that they are supposed to be a smooth radius.  So I
formed up new longerons.  This weekend we'll be adding in the cross
members and diagonals on the fuse bottom.

I would assume the top longerons receive the same kind of smooth
radius bend.  Is that correct?  I haven't seen anything related
directly to the top fuse in the newsletters and it's hard to tell from
photos of other builders.

+++ #3546
From: Bruce A. Frank  <BAFRANK@w...>
Subject: Re: [Bearhawk] welding 4130

>Does anyone out there who's knowledgeable on welding know if welding
>4130 with a different alloy filler rod is a bad thing?

It is recommend that one "NOT" use 4130 alloy as the filler rod for
welding 4130 (4130 and chromolly are the same material).  The correct
filler rod is mild steel: ER70S-2 is usual, ER70S-3 will work OK, I
like best ER70S-6. Welding with 4130 filler usually leads to cracking
problems in the hands of the low experienced weldor. In fact a lot of
professional weldors have trouble with it. The strength of the mild
steel fillet exceeds the strength of the tube and it is a straight
forward process to get an adequate weld. The vacuum melt filler rod is
nice but very expensive. The de-oxidizers in the -6 filler rod make
the puddle just about as quiet as when welding with the expensive
vacuum melt filler.

+++ #3547
From: Tom & Michelle Brant  <tmbrant@u...>
Subject: Re: [Bearhawk] welding 4130

Is this still recomended with TIG welding?  That's waht I'm doing on
the fuse (my brother is the welder).

+++ #3550
From: Russ Erb  <erbman@c...>
Subject: [Bearhawk] welding 4130

> Does anyone out there who's knowledgeable on welding know if welding 4130
> with a different alloy filler rod is a bad thing? 4130 rod from Spruce is
> pretty spendy and I can get "chrome-molly" filler rod for about a 4th of
> the cost. I can't find anything that specifies whether it's 4130 or not. 
> Maybe they're the same thing. I don't know.

I've been using "32CMS" directly out of the Spruce catalog. The
caption says "Recommended for 4130 steel structures for most
satisfactory results.  This rod is heat-treatable after welding."

+++ #3552
From: Bruce A. Frank  <BAFRANK@w...>
Subject: Re: [Bearhawk] welding 4130

>Is this still recomended with TIG welding?  That's waht I'm doing on the
>fuse (my brother is the welder).

Yes, good for both oxy/acet and TIG.

+++ #3553
From: Rod Smith  <rsmith@a...>
Subject: Re: welding 4130

I may be mistaken but I believe ER70S-6 is meant to be used for Tig
welding. It is what I use when Tig welding and I get very good results
with it. The guys up the road that build FAA approved replacement
frames for Super Cubs tig weld their frames with it. I believe Bruce
also recommends it for gas welding. For me it doesn't flow as well
when gas welding and I use RG60 for that. Some people think the copper
coating contaminates the weld and sand it off.  Others believe it
vaporizes and never gets in the weld. Then there is the whole question
of whether or not to stress relieve with heat.  Most experts agree
though not to use 4130 rod as a filler unless you are going to heat
treat the weldment afterwards. You missed our lively welding
discussions of a few years back.  I am not aware of any area of
technical expertise that seems to have less consensus on methodology
than welding 4130. I guess the proof is in the pudding though and even
what looks like very mediocre welding jobs seem to hold together just
fine.

+++ #3554
From: Bruce A. Frank  <BAFRANK@w...>
Subject: Re: [Bearhawk] Re: welding 4130

>I may be mistaken but I believe ER70S-6 is meant to be used for Tig
>welding.

RG45 works OK also. Most of my welding these days is with TIG, but a
few months ago I tried a little oxy/acet just to keep in practise. I
still like the -6 best for my oxy/acet welding also for its quiet
puddle, but RG60 flows a bit more easily. I Scotch-Brite off the
copper when oxy/acet welding.

Back in the days when I maintained my membership in the American
Welding Society they reported on extensive testing on copper plated
vs. bare TIG wire filler. There was no detectable copper in any TIG
welds done with the copper plated stuff. I do find sometimes that the
-6 seems to melt and flow more uniformly if I remove the copper before
using it for TIG. I remove it from wire before oxy/acet welding
because the limited heat available from the acetylene torch, compared
to TIG, seems to melt the bare steel more quickly.

+++ #3555
From: Bob Romanko  <romanko@v...>
Subject: RE: [Bearhawk] Re: welding 4130

To further on the "dead horse beating" welding discussion...

One thing I found in my humble beginnings as a welder in '81 is that
ugly welds with gas ARE usually still good welds.  I found that
comforting at the time!  By the time I had to weld for the FAA
examiner, I had it down to where they also looked good.  They weren't
on Bill Johnson or Kent Whites caliber, but they passed the examiner's
scrutiny.  I like gas.  Gas is much more forgiving than TIG, as the
consensus is TIG welds can look great, but still crack.  Also, TIG can
be pretty deceiving as far the depth of the weld.  It can look good
but not have the penetration to create a strong union of the material.

Of course, the above "gotchas" are for neophyte TIG welders.
("Neophyte" has nothing to do with sexual preference, it means you're
new at somethin'...SHEESH!)

Having said that, I think we're all pretty safe to suggest to new
welders they stick with gas.  Of course, if you have someone else with
experience weld your fuselage FOR you (I shudder at the thought), that
doesn't apply.

Gas is good.  Gas is forgiving.  Gas is easy to master (with the
proper equipment).  Gas is natural.  Gas comes from GOD.  I'm not sure
about TIG.  Just too much physics goin' on to make me feel at ease
with it.

+++ #3601
From: Rob Gaddy  <zippydogg@a...>
Subject: Welding practice

For what it's worth, I've read discussion about practiseing gas
welding on electrical conduit.

I bought one on those $200 vertical/horizontal bandsaws (mine made by
JET). I highly recommend this tool, but the base was flimsly and too
low for by back. I bought some 1 inch square tubing that is used to
make "wroght iron" fences (like the ones used to fence out swimming
pools). This material is very reasonable priced, comes in 20 ft
lengths (for about $12 locally), and made an excellent base for the
saw. I made my base higher, and wider to be more stable. I fitted a
tray to catch the cuttings, and a shelf for storage under the saw. I
welded it togeather with gas which is good practice for later aircraft
work. I've also made work tables and material holding shelves with the
same material. Very good stuff.

+++ #3608
From:   <pfflyerz@c...>
Subject: Re: [Bearhawk] Copperstate observations

A thought on practice welding, at some point you just have to dive
into the real stuff.  I practiced a lot on 4130, and felt that I was
pretty good, but once I began work on the actual tiny parts for the
wing hardware I burned off the edges of one piece after another.  I
just kept making more pieces until I finally learned how to control
the process and now I can manage most anything, but you won't get that
finesse working on large practice pieces.

I heaved a huge sigh of relief last Thursday when my wife and I hung
the wings on our fuselage, and they not only slipped right in, but
they came out straight!  What a thrill to see them in place.

+++ #3682
From: Rod Smith  <rsmith@a...>
Subject: Welding with ER70-S6

Just a month ago we were discussing which rod to use for welding
4130. Bruce Frank recommended ER70-S6 both for Tig and gas welding
use. I replied that although that was what I used for Tig welding, I
couldn't get it to flow well when gas welding. Bruce recommended
sanding off the copper coat when gas welding. I gave this a try this
past week and WOW! I can not believe how quiet the weld puddle is. It
flows very well and makes it easier to see and control what is
happening. I now have found my rod of choice for the rest of the
project. Someone told me you can special order it without the copper
coating. I will look into this and report what I find out. The only
down side is that I still have several pounds of RG60 which I will not
be using, mostly 1/16" and a pound or two of 3/32". If someone wants
it I will send it to you for what it costs to mail it. By the way, be
sure to get out and vote. Republicans vote on Nov 7th and Democrats on
Nov 8th :^)

+++ #3683
From: Bruce A. Frank  <BAFRANK@w...>
Subject: Re: [Bearhawk] Welding with ER70-S6

Glad someone agrees with my assessment. If you can locate uncoated rod
keep it in a plastic sleeve to prevent rust. Some of the unplated rod
comes coated with a light oil film. Wipe it with a rag wet with
acetone before using it.

+++ #3686
From: Rob Gaddy  <zippydogg@a...>
Subject: MECO torch

I recently bought the MECO (spelling?) torch, as seen on Kent White's
Tinman web site. What a joy to use. Small and light in the hand, easy
to light and adjust, with one hand, and the tip (I bought all the
sizes) seems to do a better job than my Victor. The Victor is a
general purpose home unit, suitable for post welding heat treat,
pre-heating, etc, but I don't think one could ask for a better thin
wall steel welding torch than the MECO (especially for the price!!).
I'm saving up for the special filter to weld aluminum. The little
torch has given me the confidence to try. Wouldn't an all aluminum
cowling and wheel pants look great! I might even think about welding
the fuel tanks, what a concept!

Thanks to Kent for a great product. (I have no financial interest or
agenda, I'm just a very satisified customer).

+++ #3693
From: Kent White  <kent@t...>
Subject: Re: [Bearhawk] re: MECO torch

On Tue, 07 Nov 2000 20:29:27 -0800, Benton Holzwarth wrote: 



>>   I'm saving up for the special filter to weld aluminum.
> 
> That last bit jarred a thought loose.  The idea of brazing steel (on
> the fuselage) has gone around with, I think, the concensus being that
> it's a bad idea for the novice, due to risk of embrittlement if not
> done right, but what about brazing Aluminum?
> 
> It seems like the tanks, being riveted, don't require the full
> strength that a weld would develop; the weld is there primarily to
> 'seal the deal'.  (No?)  Would brazing seal adequately and reliably,
> while providing reduced risk of melt-through?  Would that be easier
> for a novice to do than a full-heat weld.  What are the up and
> downsides to brazing Al?

Brazing Aluminum: 

Was done on many wartime tanks from Ryan, Lockheed, Northrup, North
American, etc. Usually the seams were welded with the rivets and bungs
(fittings) brazed in. The practice still continues. I am releasing a
new video, "Aluminum Welding Methods" by ALCOA, 1941. It shows all
methods of aircraft welding and brazing for the War. (Also is a new
historic film on Plexiglas working, and 3 more on the J3 Cub)

+++ #3718
From: Mike Eldredge  <meldredge@a...>
Subject: Rudder pedals welded

#427 now has (is) four brand spankin new rudder pedals!

My first foray into welding real parts produced four servicable 'T's.
The fourth one looks better than the first, which is a good trend.

I'm still trying to figure out the right way to apply heat to the
opposite side of the weld to straighten out the tube after welding.
I've sent off for Kent's video on the subject, also ordered his video
on aluminum welding.

I'm getting a significant amount of scale when I weld, and it's tough
to clean off. I have a wire brush wheel on my bench grinder, but it
bogs down too easily, and I have to wait for it to spin up for 5
seconds after each half second of contact with the part.

Does anybody clean out the inside of the tube before welding? I'm not
too concerned about the parts I've welded so far, but when I weld the
pedals to the rudder pedal torque tube, the inside of the outer tube
will need to be clean so the inner tube will fit and turn smoothly.
Hopefully Kent's videos will have some tips on how to take care of
those issues.

I'm also planning to be done on Saturday. :)

+++ #3719
From: Russ Erb  <erbman@c...>
Subject: [Bearhawk] Rudder pedals welded

Good move. I've been watching Kent's video on welding--it deals
DIRECTLY with the rudder pedal issue.

+++ #3720
From: Float-By Shooter  <packrat@c...>
Subject: Re: [Bearhawk] Rudder pedals welded

> I'm getting a significant amount of scale when I weld, and it's
> tough to clean off. I have a wire brush wheel on my bench grinder,
> but it bogs down too easily, and I have to wait for it to spin up
> for 5 seconds after each half second of contact with the part.

If you have an air compressor, maybe get one of those benchtop
beadblast cabinets. Or a small sandblaster, if you can stand the mess
(plus you will have a lot of parts you can use it on, including the
fuselage).

> Does anybody clean out the inside of the tube before welding? I'm
> not too concerned about the parts I've welded so far, but when I
> weld the pedals to the rudder pedal torque tube, the inside of the
> outer tube

I didn't on my flap levers, and regretted it. Had to ream them out
considerably to make them fit over the torque tube. Fortunately they
don't have to rotate on the tube; in the future I will be sure to hone
the insides of such parts out with a little cylinder hone and wipe
them with a solvent.

+++ #3722
From:   <pfflyerz@c...>
Subject: Re: [Bearhawk] Rudder pedals welded

The best thing I have found for keeping down scale build up inside a
tube is to insert another tube inside the first.  This protects the
back side of the tube you are welding from the atmosphere which helps
to eliminate the scale.  It can also help to keep those bearing tubes
round when you weld the bracket to the bottom.  Can also help to
control some of that distortion you got welding the rudder Ts.  Just
be sure the fit isn't too tight and that you leave some means of
grabbing a hold of the parts to pull them apart, as what scale does
form can make it tough to seperate the parts.  It can help to grind a
flat on the insert tube to preclude a full 360 degrees of contact.

+++ #3731
From: Bruce A. Frank  <BAFRANK@w...>
Subject: Re: [Bearhawk] Rudder pedals welded

Rather than another piece of tube, I like to insert a section of solid
bar stock. The bar stock has enough mass (stays cooler) that it can't
get involved with the weld. If the tube does get tight the solid bar
is easier to drive out.  Several years ago I bought a set to
inexpensive used reamers just to fix this type of interference
problem.

+++ #3732
From: budd davisson  <budd@g...>
Subject: Re: scaling

Some thoughts on scaling, etc: 

The cleaner the material the less it scales. If the inside of the tube
is to be inserted over another piece, either to rotate or whatever,
clean the h--l out of the inside, first with a solvent (lacquer
thinner, etc), then hone or sand it using one of the little flapper
sanding gizmos.

Someone mentioned inserting tubing inside of it: you can weld short
bushings better (I always leave them long and trim them back after
welding) and not burn the edges by putting a heat sink inside them
which can be nothing more than a bolt that fits inside with just a
little clearance. Grind a couple flats on the bolt to facilitate
breaking it loose after welding. Having the bolt head to grip with a
wrench makes taking it out a ton easier. Take the plating off the bolt
before you use it so it doesn't bubble up and glue the bolt in place.

+++ #4101
From:  "Robert L. Thomasson" <bobthomasson@c...>
Subject:  Welding - Again

Here is an excerpt from the "Education Thru Airror" section in
the December 2000 EAA Experimenter magazine:

(After a non-injury RV-6 accident) <<...examination of the
airplane's rudder controls revealed that a fracture had occurred
just outside of the weld attaching the base of a T-shaped bar to
the torque tube connecting the left and right seat rudder
pedals.  Further examination of the broken parts revealed a
fatigue crack on the torque tube, originating on the rear
outside portion of the fracture.>>

Just wondering if anyone knows how the parts were welded, ie.,
OA, TIG or MIG?  Or any other details of the failure?  I know
we've covered welding pretty thoroughly in the past, and I'm
convinced that when it comes to Bearhawk fuselage welding, there
is enough over design in the joints that I could botch them all
and it would probably hold together.  However, after reading the
above, the control parts may be another case all together.
Although I hesitate to reopen the TIG vs OA discussion, the
failure sounds like it *might* be a case of brittleness due to
poor or no post weld heat treatment.  Of course that is pure
conjecture based on a paragraph of a preliminary accident
report.

+++ #4210
From:  budd davisson <budd@g...>
Subject:  Re: welding tanks

Re: welding tanks, etc. 

Apropos of the conversation thread on welding tanks: An
absolute, never to be violated rule is to never leave your tanks
standing anywhere without the regulators removed and the caps on
them. If you're using them, chain them to your cart, a wall or a
lally column.

I watched an oxygen tank launch itself through the knee wall
foundation of a metal building, scoot under a bunch of trucks
and finally skip up and torpedo a van about 50 yards away on the
other side of the parking lot. They were changing tanks and took
the cap off the new one while they were still removing the other
one from the cart and they backed into the new one, knocking it
over.

No one was hurt but a couple pair of underwear, including mine,
bit the dust.

Put the cap on the old one before unchaining and don't take the
cap off the new one until it's safely in the cart.

+++ #4213
From:  BruceAFrank@a...
Subject:  High Pressure Cylinder Rockets

When My family first moved to SC in the mid 1950s the process of
filling the Clark's Hill Reservoir ( now the Strom Thurmond
Res.) was near completion. As the final work was being done on
the dam there was a large cache of oxygen and acetylene
cylinders(200+) kept in a fenced area near the guard house.
Inventory began to show a shortage of 5 or 6 cylinders a
day. After a lot of finger pointing and investigation the
contractor secretly setup a guard to watch the guard.

They discovered that, in his late night boredom, the security
guard would unlock the gated storage and roll several full
oxygen cylinders down to the edge of the partially filled
lake. He'd point the base of the cylinder towards the center of
the lake and with a sledge hammer break the valve off.  The
cylinder would rocket across the surface for several hundred
yards then sink.

After they arrested the guard they dredged the lake to find over
300 cylinders. The cylinder supplier was surprised that the
guard had been lucky enough to never have an unguided cylinder
come back his way.

+++ #4214
From:  budd davisson <budd@g...>
Subject:  Re: [Bearhawk] Re: welding tanks

> Hence my question: Do the caps structurally screw onto the
> tank such that they can take an impact and leave the valve
> untouched?  Is this the point?

Yes, the caps screw onto about a four inch diameter, one inch
deep threaded boss around the top of the tank and I think you
could drop it off a four story building and not hurt it.

+++ #4216
From: Warren  "W. Shalm" <shalm@i...>
Subject:  Re: [Bearhawk] Re: welding tanks

You got it exactly. The caps are a heavy enough gauge to
withstand a pretty severe blow and yes they screw onto threads
that are integral to the tank.

It's interesting that at the factory they lay the Oxygen tanks
down and I've seen them roll a hundred or so of them down off a
truck with no caps on, but as dangerous as this sounds, they
have a system of doing it that prevents the valves from being
touched (a definite "don't try this at home" procedure).

Even though lots of guys lay their acetylene tanks down for
transportation in the back of the truck we were always told
never to weld with them in this position as the acetone can
transfer into the regulator. Oxygen tanks are just hollow
cylinders but acetylene tanks are filled with specific layers of
such things as fine and coarse asbestos, and charcoal or balsa
wood fillers that are saturated with acetone (used to dissolve
and absorb acetylene).

If you have ever wondered about the importance of oxygen in a
perfect mix with acetylene, the following little experiment will
cause you to forever respect these gases. Take a balloon and
fill it with only acetylene from an UNLIT torch to the size of a
tennis ball. Tie it off and then light your torch as usual and
let the flame ignite the balloon. Pop!

Now take the other balloon and a properly adjusted neutral
flame. Blow out the flame or knock it out with a quick motion of
your finger (better to wear a leather glove if you're not adept
at such things). Fill the balloon to the size of a GOLF BALL
with the unlit torch that is giving out a neutral mixture of OA
gas through the tip. Tie it off. Please don't think you can fill
it bigger and get away with it. Now re-light your torch and
ignite the balloon. KA-BANG!!! And you thought a shotgun was
loud.

ADDITIONAL PRECAUTIONS (for your safety and my liability): Don't
do this near houses or inside. Wear good hearing protection,
gloves and safety glasses. Do it in an open, ventilated space as
the noise is verrry loud.  Don't make the balloon bigger than a
golf ball. Don't use this as a prank, I'm only describing this
to give you an understanding of how dangerous the neutral
mixture can be if the flame is knocked out while welding in a
confined space. My high school welding teacher did this for our
class years ago except he did it in the welding shop. The entire
tech wing of about 20 classrooms thought the building had blown
up and that was after he had warned them about what he was
doing.

+++ #4294
From:  budd davisson <budd@g...>
Subject:  Re: welding position

> the only acceptable way to weld was in position, take it the
> way it falls.

I know there are a lot of schools of thought on welding stuff in
the position it happens to be in, but, as a long time
welder/welder instructor, I try to get my students to do
everything they possibly can to approximate a steady, well
rested, right to left (for righties), horizonal welding
situation. Your chances of getting perfect puddles/beads
multiplies by the square of the steadiness of your hands and the
ease of the position. If you don't want to build a rotisserie,
at least rotate it on saw horses.

Of course, that's just another opinion. 

+++ #4299
From:  Bob Romanko <romanko@v...>
Subject:  RE: [Bearhawk] Re: welding position

Building a Bearhawk is easy, it's all the parts you have to
build to build a Bearhawk that's a bear.

Say that real fast ten times...

I couldn't imagine putting a Bearhawk fuselage together without
a rotisserie.  I'm not much of contortionist, and the time it
takes to assemble a decent rotisserie pales in comparison to the
time it will save you.  In addition, think of all the money
you'll save in pain killers.

+++ #4300
From:  "Tim Anderson" <fuzzet@h...>
Subject:  RE: [Bearhawk] Re: welding position

I made a very inexpensive "rotisserie" when covering my
kitfox...just would have to be enlarged slightly.  Bolt two
2X4's in each direction (total of four) onto the engine mount
holes.  The boards need to be long enough to clear the fuselage
top when inverted.  Build a rear swivel from something.  gives
the fuselage a quarter turn direction.  Good for welding or
fabric work.

+++ #4302
From:  budd davisson <budd@g...>
Subject:  Re: [Bearhawk] Re: welding position

Rotesseries, etc: 

I usually make up a Dutchman clamp that clamps on to the rudder
post inside the fuselage that has a piece of 1" heavy wall
tubing attached to it. I drill a hole in a wall stud and put a
saw horse at the other end.  That way I can rotate it by myself
without have to have a big rotary thang to pivot it on.

+++ #4306
From:  Russ Erb <erbman@c...>
Subject:  [Bearhawk] Re: welding position

> I try to get my students to do everything they possibly can to
> approximate a steady, well rested, right to left (for
> righties), horizonal welding situation.

So budd--which hand is the torch in?  I'm right handed, so I was
told (by my instructor and several books) that I should hold the
torch in my right hand and the rod in my left.  However, I've
found I get significantly better results if I hold the torch in
my left hand and the rod in my right hand.

Now I've been called perverse before...that's PERVERSE! Not what
you were thinking, Planter Bob!  Sheesh!

It seems to me that the higher pointing accuracy requirement is
in the rod, not the flame.  I can keep the flame in the correct
general area with my left hand okay.  Holding the rod far enough
from the puddle to not burn my fingers means that in my right
hand I can put the end of the rod close enough to where I wanted
it most of the time (how's that for weasel wording?).  In my
left hand I miss the puddle half the time or more.

Thus, generally my easiest direction to weld is left to right.

I know of at least one other right handed welder that welds
"backwards".  Whatcha got to say about that, budd?  Have you run
into any other perverse folks like me?  (Let's try to keep the
discussion to welding techniques--I know that was an
irresistable straight line...)

+++ #4308
From:  budd davisson <budd@g...>
Subject:  Re: [Bearhawk] Re: welding position

> Whatcha got to say about that, budd?  Have you run into any
> other perverse folks like me?

I made my living through most of the '60's as a guitar player,
so I know the meaning of "perverse". Or was that pervert?

As for holding the rod/torch. I supposed it's an individual
thing, but I hold the torch in the right hand and always weld
with tight fitting leather gloves which allows me to hold the
rod closer to the end for better control. Also, the second a
bundle of rod comes out of the tube, I cut it in half so I'm
only working with 18" pieces which are easier to control. Being
a cheap skate, I save all the short ends and either weld them
back together to be used, or at least save them to make "S"
hooks to hold painted parts or to make "V" bent pieces to space
pieces I'm welding up from the fire brick.

One method of controlling placement of the rod is to keep it
close to the gap between the flame and the puddle so it never
really gets cool, so it melts more qickly and evenly the instant
it is placed in the gap.  Try not to touch the puddle with the
rod, as itis a heat sink and cools every thing off, but you've
probably already figured that out by building in a lot of little
short antennae.

the other day I had to weld a good sized finger gusset on the
bend in my tow bar which was cracking. They don't always work
out perfect, but this one did and I couldn't bring myself to
paint it because I think an even, clean weld bead is a tiny
little work of art.

enough rambling. 

+++ #4310
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] welding position

My day job boss walked out into the shop a few weeks ago while I
was welding a tube frame together. He stood and stared for a
couple of beats then said, "Are you right handed or left handed
(I have only been working there 3 years now)?" I answered right
handed so he followed up with, "Then how do you weld with the
torch in your left hand?"  I told him I was taught that a "good"
welder had to be able to weld with either hand, because many
times you couldn't reach a weld if you didn't swap hands. Manys
the time when I could have stopped; walked around the other side
and continued the weld with the torch in my right hand (the
usual right handed person's hold), but, "that little bit of weld
is all that's left," so I switch hands and complete it. My
"left-handed" welds are not as nice as I can make
"right-handed", but there are adequate.

As for a "righty" welding with the torch in his left as the
primary method, it is not unusual for a person to continue to
use a "reverse grip" to do certain jobs if that was the way they
started a new process. My older sister, a "lefty", had never
cast a fishing rod before and after watching my father and I
fish asked to try it. He, a righty, placed the rod in her right
hand and she made several dozen casts before she realized she
was using the "wrong" hand. She switched, but could not cast the
rod--- at all--- could not coordinate the line release with the
arc of the rod tip.  Frustrated she switched back to the right
hand hold and caught several 3 lb bass over the next couple of
hours. . . flawlessly.

It is also not uncommon that a person performing a task with the
non-dominant hand, once perfected, may do it better than done
with the "proper" hand. . . particularly deft mechanical
skills. It has been noted that baseball players who have
recently perfected left-handed batting will run a higher batting
average left-handed than they ever did right-handed.  Even if
they switch back and forth, so's not to neglect the skills of
the right hand, sometimes in the first few years they retain a
better "lefty" average than they ever hit or can then hit as a
"righty."

+++ #4311
From: Corky Scott  charles.k.scott@d...
Subject:  Re: [Bearhawk] Digest Number 264

> I know there are a lot of schools of thought on welding stuff
> in the position it happens to be in, but, as a long time
> welder/welder instructor, I try to get my students to do
> everything they possibly can to approximate a steady, well
> rested, right to left (for righties), horizonal welding
> situation. Your chances of getting perfect puddles/beads
> multiplies by the square of the steadiness of your hands and
> the ease of the position. If you don't want to build a
> rotisserie, at least rotate it on saw horses.

Seconded by me.  I've found that whenever I manage to get my
arms supported it's always much easier to do good welds.  The
toughest welding is when you are unsupported and hanging over
something and it's taking a long time to get the work up to
temperature.

I also agree with Bud that sometimes a really good looking bead
is a work of art.  Unfortunately only someone who has welded
would know it though.  Laymen would not know or care.

On another note, I've had my Christavia fuselage suspended from
a rotissery for more than a year now.  It's just too conveniant
to simply loosen the pinch bolt and turn it a bit to get where I
need to get.

Especially now that the fuselage has most of it's metal attached
and it's getting to be a significant weight.

+++ #4321
From:  "Kent White" <kent@t...>
Subject:  RE: [Bearhawk] welding position, take 9

Hold the torch with your lips and the rod with your toes, unless
doing backhand inverted on thin stuff, at which time you must go
forehand.

You guys are making this much too difficult. Find out which way
the stoont favors to hold the torch.  Teach backhand and
forehand, the former is better on thick material.  It makes no
difference at all, IMHO, because there are always some parts
which must be gotten at from the left going right, forehand.

I enjoy teaching, and I teach and talk to a sizeable number of
skilled instructors every year. We all chat about the different
methods of starting the torch, welding methods, positions, and
shutting it off.  Most of us agree on one general set of
guidelines, and so that is what I teach.

I get the most elongated eyeballs when I right- forehand weld an
8" bead, and then switch over in order to weld left-backhand to
finish. Overhead (inverted) is another story. Seriously, try to
find which is most comfortable and successful For You.

I received a lot of ridicule many years ago when I showed up at
a restoration shop and was simply welding right-backhanded,
after having attended a good school to learn welding. The
instructor at that school simply told me I was a good welder,
and never mentioned that I was a natural backhander.

+++ #4327
From:  "Robert L. Thomasson" <bobthomasson@c...>
Subject:  [Bearhawk] Re: Kit update

> Just so everyone knows: the fuselages are gas welded and the
> tails/landing gear, etc will be TIG'd with stress points
> stress relieved.

Could you give us a brief review of the decision making process
that led to the choice of welding processes?  Don't have any
strong opinions or agenda on the subject, I just find the
endless discussions about OA vs TIG, and welding in general to
be interesting.

+++ #4331
From:  budd davisson <budd@g...>
Subject:  Re: kit welding

> Could you give us a brief review of the decision making
> process that led to the choice of welding processes?

We may eventually go over to TIG all the way through, but right
now we aren't hard tooled for each of the pieces of tubing so
they'll be hand fit. TIG likes a much tighter fit than gas and
gas is much more forgiving in almost all areas, although it is
much slower in a production application. We'll be TIGing the
smaller pieces because we're hard tooled for those and it is
easier to control the welding position and therefore guarantee
good beads.

As we get deeper into this thing, we'll probably wind up
switching to TIG.

+++ #4336
From:  petz187@a...
Subject:  Re: [Bearhawk] Re: welding position

I usually don't get in to these discussions. You use which ever
hand you want to when you're welding. Some times you have to
switch hands to get the job done.

+++ #4342
From: Leonard W. Molberg  mail-to-mo@j...
Subject:  Re: [Bearhawk] Digest Number 264

Some thoughts on recent topics:

On torch welding...it's the torch flame that does the welding,
not the filler rod, and the motion of the torch that controls
the puddle, so it seems to me that the dominant hand should hold
the torch.  Of course that's only my opinion, based on 45 years
or so of using one. Some welds can be done with no filler rod
whatsoever, but when necessary, the rod should be added to the
puddle and the puddle worked to get the desired penetration and
build.

Having the welded item rotatable to accommodate gravity is a big
plus, (unless you forgot to pay your gravity bill).  The best
welds, of course, are made when the welder is in a comfortable
position and not in a hurry to finish because of discomfort.

One thing not mentioned in recent discussions on acetylene
bottles is that the "rule of thumb" for bottle size is that you
should never draw more than one-seventh of the capacity of the
bottle per hour to avoid drawing acetone from the "honeycomb".
Guys with small bottles are pushing that limit.

I have a 300 cubic foot acetylene bottle on my main torch set,
and the smallest "rosebud" heating tip available for my Smith
Silver Star series torch would not be within the safe capacity
of that bottle.  As a former plant engineer in a heavy equipment
manufacturing and fabrication shop, I've seen accidents from
overdrawing acetylene bottles.  You could hear the problem clear
across the plant when someone's torch started sounding like a
machine gun - just before the "big bang".  Rosebud heating tips
can be had to run on propane, and propane doesn't have the draw
rate restriction.

Oxygen bottles do not have that draw rate restriction either, so
a small oxygen bottle is safe, if not very economical.

So keep that acetylene draw rate safety margin in mind, please.

As to Budd's comments on removing the back seats - here in
Colorado we don't consider too many "4-place" airplanes to be
more than a 2 seater anyway. Not if we wish to become "old
pilots".  My home airport is 5680 msl, higher than some of you
regularly cruise. Then we've got these big rocks to work around,
so...

+++ #4343
From:  Joel Mayhall <jmay2174@y...>
Subject:  Re: [Bearhawk] Digest Number 264

I've been told that it is dangerous to transfer acetylene to
other bottles.  I have a small tank and it would be con