+++ #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 GripsŪ, 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 GripsŪ 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 convenient
to transfer acetylene from my large bottle.  Is there any
practical was to do this safely?

+++ #4390
From: Larry  "lbhensley" <lbhensley@h...>
Subject:  Re: [Bearhawk] Digest Number 264

During my years as a welder/instructor, I have been exposed to
many 'bad' examples.  One as mentioned in another reply was the
draw or evacuation rate.  I have witnessed what happens when one
tries to 'steal' a little acetylene by simply running a tube
from one bottle to the next.  Without any regulation on either
bottle the tube started to turn red from the excessive
evacuation rate.

This is not a wise thing to do at home/shop under any situation.
It is best left to the local welding supply houses.  If you
would like more information on this subject just call your local
supplier and request to get some literature on the subject.
They should be more than happy to supply it to you.

Good luck and 'safety first'

+++ #4417
From: Leonard  mail-to-mo@j...
Subject:  Transferring acetylene

"I've been told that it is dangerous to transfer acetylene to
other bottles.  I have a small tank and it would be convenient
to transfer acetylene from my large bottle.  Is there any
practical was to do this safely?"

Well, it can be done, Joel, if you have the proper transfer
equipment and training.  It would also be possible to train in a
J-3 and climb into a DC-3 and you MIGHT get it up and down,
using the rationalization that airodynamic principles apply to
both.

It's not worth the risk. You are dealing with acetylene at over
15psi in a "free" state (gaseous - not absorbed in acetone) and
at over 15 psi it is not a stable gas. This is why the low side
gauge on the regulator had a big red band beginning at 15 psi,
which is more pressure than any acetylene tip I know of needs
anyway.

Of all the fuel gasses, acetylene is in a class by itself, and
safe enough if used properly, but also has the least forgiving
characteristics if mis-handled.

+++ #4418
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Transferring acetylene

> "I've been told that it is dangerous to transfer acetylene to
> other bottles.  I have a small tank and it would be convenient
> to transfer acetylene from my large bottle.  Is there any
> practical was to do this safely?"

It cannot be done with equipment available to the lay
person. Are you aware that there is a strict pressure max limit
on acetylene. At pressures as low as 30 psig acetylene can and
does self detonate. And I mean detonate.

The 300 psig you see on the acetylene cylinder regulator is that
obtainable over acetone. 99.99% of the acetylene in the cylinder
is adsorbed or the better word is dissolved in the
acetone. Trying to transfer 300 psig acetylene through a hose or
tube into another cylinder is virtually impossible without
special care and procedures.

+++ #4433
From:  Jim Ash <ashcan@m...>
Subject:  Re: [Bearhawk] Transferring acetylene

I always thought they had a way to bubble new acetylene through
the acetone and charge it up again, kinda like CO2 in water when
making soda. I've run acetylene tanks pretty fast into a
manifold system, and you could hear it bubbling out of solution.

I don't understand the comment about the 300 psi on the high
side gauge.  Does this imply that the cylinder is completely
filled with acetone and there's no space/volume for gas at the
top of the tank? I always thought it was weird that I could use
a regular pressure gauge to measure tank contents just like in a
compressed gas cylinder. I just took it on faith that the guys
giving me the tank weren't trying to set me up to be the lead
story on the 6 o'clock news.

Side question: How high can a regulator go? Will it go all the
way to 300 psi? I fabricated a car trailer for a friend with
equipment he borrowed (and which I didn't see first). Most of it
was stick welded, but when I needed to torch weld, the regulator
diaphragm valve leaked and allowed the pressure to build as soon
as the torch was shut off. I knew the gas is unstable at higher
pressures, so I did a lot of jumping to shut the bottle off as
soon as I was done to prevent it. But at home, I've left my
regulators on while I chip slag or grind. Is it possible there's
a risk here if my regulator takes a dump and I don't catch it?
Will the acetylene spontaneously react, or does it have to be in
the presence of oxygen to get it going?

+++ #4437
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Transferring acetylene

> I always thought they had a way to bubble new acetylene
> through the acetone and charge it up again, kinda like CO2 in
> water when making soda.

Correct.

> I don't understand the comment about the 300 psi on the high
> side gauge.

Yes, there is "high pressure" acetylene above the acetone in the
cylinder

> Side question: I knew the gas is unstable at higher pressures,
> so I did a lot of jumping to shut the bottle off as soon as I
> was done to prevent it.  Is it possible there's a risk here if
> my regulator takes a dump and I don't catch it? Will the
> acetylene spontaneously react, or does it have to be in the
> presence of oxygen to get it going?

If a regulator fails such that high pressure acetylene enters
the hoses there is extreme danger that the gas will
spontaneously detonate. I have seen it demonstrated by putting
80 psig in a standard welding hose; closing a valve and
completely removing the cylinder from the system (this was an
intentional demonstration--safety first). The pressurized hose
was lifted up and snapped on the floor like a whip. When it hit
the floor it detonated. Split the hose (20 ft) end to end with a
sound volume like a couple of sticks of dynamite. If the
cylinder had still been attached with no check valve (maybe even
with a check valve) the cylinder would also have likely
detonated, though I have seen a hose detonate with out involving
the cylinder (I have also seen the aftermath of when it did).

High pressure acetylene requires no oxygen present to detonate.

+++ #4466
From:  Steve Eldredge <steve@b...>
Subject:  Welding help

Just a little history before my question....

I learned to weld with a large victor set and got pretty good
with it.  Built all the steel fittings for the piet with it, but
now that Mike and I have started building BH parts Mike got a
Smith AW1A aircraft torch.  After using it for 10 minutes I
decided I was going to have one!  My wrists feel much better!
Welds turn out much nicer too.  Got it on Ebay, and picked up
all the tips you could ever use for $125.

The problem is this: I started with my steel parts and have had
a problem with tubing to sheet joints were the sheet edge gets
too hot and melts away.  Same problem I read about burning up
washers on the flap support spring post.  I have tried different
tips to vary the heat, and it helps a little.  I used a heat
sync on the thin edges with some success too, but still the weld
around the tube looks great on the side with more material and
uneven and higher buildup near the edges.  Often the puddle
looks like a doughnut and I end up adding more filler than
should be there fill the hole.  If I miss the hole a couple of
times it really gets bad.  Looking at Bill site at the same part
looks like its soldered compared to mine.  How do you get that
nice small radius bead down into the corner?

+++ #4469
From:  Bob Romanko <romanko@v...>
Subject:  RE: [Bearhawk] Welding help

Practice, practice, practice.  Then yours STILL won't look like
Bill Johnson's.  The man is a machine.  He's not human.  I saw
him cut himself while looking at the Bearhawk at the fly in.  He
didn't bleed.  Nuff said.

Seriously, if you want a small bead you need a small puddle.
The only way you'll get that is with a small tip and a focused
flame.  Practice on flat sheet just chasing puddles using a
small tip and less heat.  Don't worry about the filler, just
practice forming a small puddle then chase it down the sheet
making snail tracks as you go.  Use a 3"x5" sheet.  When you've
made a few puddles, cut the thing in half perpendicular to your
beads and check your penetration.  My guess is your puddle is to
big, and that may have a lot to do with learning with that big
'ol Victor torch you started out with.  Maybe you were swirling
the puddle with a bit more vigor than necessary.

I'm looking forward to the answers you get from some of the
welding experts in the group such as Kent White, Bill Johnson,
Bruce Frank, etc.  Man, I hate naming names 'cause I always end
up leaving out someone!

+++ #4482
From:  "Kent White" <kent@t...>
Subject:  RE: [Bearhawk] Welding help

Welding heavy to light:

Find a tip suitable for the heavy stuff, as if to weld it by
itself, and then go one size smaller, so as to have a
concentrated flame.  Set the tip-heat a bit hot, so's you can
hear it talking to you.  Now, as you try to weld heavy to light,
keep more of the heat directed onto the heavy, even angling the
flame onto or off of helps bounce or skip the flame from the
heavy back onto the thin stuff.  In this fashion, the residual
or bounced or indirect heat provides the welding puddle on the
thin stuff. Backhand may be preferable to forehand, too.  When
welding tinfoil to crankcases, it is a matter of heating the
heavy exclusively, with the torch angled away from the foil and
onto the case, and allowing only a tiny portion of the indirect
heat to nudge the foil into a molten state, sometimes even the
molten rod will raise the temp of the foil just enough to
sufficiently to weld it. Using the rod as a heat shield helps
greatly, and also using the rod as a heat sink to control the
puddle can give the control necessary.

So--try the tip size, the setting, the flame angle, and the
direction of the heat, and forehand and backhand. Then try the
rod as a fine-tune.  When the mojo is workin', you end up
welding everything in sight just to keep the feel.

+++ #4508
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Welding help

> Which is forehand, and which is backhand?  I ask someone
> occasionally when it dawns on me that I've forgotten again, to
> keep it clear what someone else is talking about.

Forehand and Backhand:

Forehand is moving the torch and puddle forward into unwelded
metal, pushing the puddle with the flame.

Backhand is moving the torch away from the puddle, drawing the
puddle "backwards" towards the torch, and pulling the puddle
along with the flame.

+++ #4526
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] media blasters

>> Oh foosh. Use Must For Rust.
>
> I assume this isn't a magic bullet against weld scale?  For
> that, you still need to blast?

Weldscale just happens.

While there are products like sprays and coatings which are
designed to reduce its occurrence during various welding
operations, for the guy making parts like we do, nada.  The MIG
guys may find an anti-spatter coat helpful to limit the metal
globule attachment around the welds, but they must still clean
the metal prior to paint.

MFR is a sort of magic bullet for post-weld cleanup, as it
knocks down most of the scale and all of the discoloration. The
little scale that is left is so tough that I either leave it on
there, or if doubtful, I give it a kiss with the wire wheel and
then re-wipe with the MFR. There are other similar products,
like Ospho, but I know this chemistry and the long industrial
history of the product. Like the painters, once I get onto a
particular chemical system it's tough to change over to another.

If the first (or only) coating is going to be the PPG black
oxide primer (awesome stuff, I have tested it for years), then I
am less apt to nitpick every bit of scale. The reason for this
"less than sterile" method is that the restoration work I have
done has routinely shown that the tenacious weld-scale remains
fastened tightly for decades, with the paint surface showing no
sign of its letting go.

+++ #4529
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Window frame forming

> "With respect to Russ's comments on how to form the rear
> window frame.  Use a "U" shaped block.  Heat areas that form a
> big wrinkle till orange and then hammer weld them down. ...."

OK..that's far enough, stop right there.  "Hammer weld" ???
"Hot shrinking" is what yer doing.  Cannot get the hammer hot
enough to weld with, cause the head just falls off.

+++ #4566
From:  budd davisson <budd@g...>
Subject:  Re: hammer welding

Re: Hammer welding

Russ is right about the blacksmith technique of beating redhot
iron together and I have bunches of old forged branding irons
that show how well it works.

another version of hammer welding is what we used ot use in the
hotrod field, expecially when chopping tops and working the
mid-frame flat and curved panels. There we'd weld about an inch
and, while the bead was red hot, hammer it flat with a hammer
and dolly. This greaty reduced the panel distortion.

+++ #4567
From:  Ken Beanlands <kbeanlan@s...>
Subject:  RE: [Bearhawk] Welding help

On the subject of welding, has anyone tried the Meco Midget
Torch? It looks pretty neat, but I was wondering how it compares
to a Henrob/Dillon? Is it big enough to handle the Bearhawk
welding?

+++ #4569
From: Rob Gaddy  zippydogg@a...
Subject:  RE: [Bearhawk] Welding help

Bought one, love it, haven't used others you mentioned.  Did
weld a fuselage with a Smith, the Meco is better, IMHO.

+++ #4571
From:  "Owen Davies" <owen@d...>
Subject:  Re: [Bearhawk] Welding help

> On the subject of welding, has anyone tried the Meco Midget
> Torch? It looks pretty neat, but I was wondering how it
> compares to a Henrob/Dillon? Is it big enough to handle the
> Bearhawk welding?

Can't say.  However, if it turns out you like the Dillon --
takes some adaptation if you're used to a standard torch --
there's yet another alternative you might want to consider.
Harris offers a $30 tip tube for the Aviator torch that, when
used with special tips, produces a soft, narrow, controlled
flame much like that of the Dillon.  Haven't used it yet, as my
"shop" needs an extensive cleaning before I can turn around in
it, much less dare to light an open flame.  However, I have seen
it in use, and the effect looks pretty much identical.  The
possible advantage over the Dillon is that you have a standard
torch handle instead of the pistol-grip.

+++ #4576
From:  "William & Delinda Johnson" <wjohnson@f...>
Subject:  023 Update

I have been lurking for the past 4 weeks without a post!  So,
here goes:

1.  Media Blasting - I use walnut shells and glass beads.  It
works so I keep doing it.

2.  Welding - don't weld more than is necessary.  For instance,
my washers which keep the spring on the support frame are just
tacked in four places.  The spring will break before those tacks
come apart.  Use some judgment; however, don't under weld in a
effort to make it look nice either.

3.  Window frames - Follow Bob's lead - he has found the easiest
way to get things done.

4.  In all cases, the Nike shoe slogan applies, 'Just do it!'

+++ #4580
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Window frame forming

>Come on, Kent!  I thought you, if anyone, would know about hammer welding. 

Sorry, old chap.  The method you refer to is "forge welding".
Hammer welding is a hotrod term, based on the mischief that if
you hammer on hot glowing steel that has been previously welded
with either torch or TIG, then you are "hammer welding"...you
see the logic? Hammering on a hot weld means hammer welding?

I never have figured out what they label it when I hammer hot
steel way far from a weld.  Traditional metalmen label
hotworking methods as, "hot planishing", where the metal is
smoothed when hot. "Hot shrinking" where the metal is shrunk,
and "hot stretching" where...you guessed it...the metal is
stretched.

These terms are used professionally by many, but "hammer
welding" is a cause for laughter amongst the true metalmen.

+++ #4585
From:  Russ Erb <erbman@c...>
Subject:  RE: [Bearhawk] Welding help

> On the subject of welding, has anyone tried the Meco Midget
> Torch? It looks pretty neat, but I was wondering how it
> compares to a Henrob/Dillon? Is it big enough to handle the
> Bearhawk welding?

I think Kent is a big proponent of the Meco torch.  budd likes
the Smith.  Before hearing of either of these I bought a Henrob
2000.  I like the small, soft flame.  I haven't used any other
torches except a "standard" big Victor-type torch.

The one possible drawback of the Henrob is its weight.  It is
noticeably heavier than the other torches.  Then again, a lot of
the weight seems to be in the hoses.  Kent sells some small,
lightweight hoses.

budd does like the cutting setup on the Henrob.

Then again, the books tell me I hold my torch in the wrong hand,
but I get better welds that way.

+++ #4590
From:  budd davisson <budd@g...>
Subject:  Re: torches

Henrob comment: 

I think it is unbelievably clumsy in a lot of fuselage
applications, although it welds okay.

We bought one of Kent's little torches, but I haven't had a
chance to try it. The only reason I'm sold on the Smith is it is
commonly available and super proven. It's the best of the
traditional torches.  I'm willing to bet I'm going to love Kents
little buggers.

+++ #4591
From:  "Kent White" <kent@t...>
Subject:  RE: [Bearhawk] Welding help

>I think Kent is a big proponent of the Meco torch.  budd likes the Smith. 

Kent is a big proponent of you using the torch you have and then
getting better at it.  If, however, you are unhappy with the big
bulky clumsy feel of that railway monster or whatever your Daddy
left you, then there are other choices.

+++ #4599
From:  Tim <tlc2@t...>
Subject:  Kent's Torches...

Has there a link with all of the Tinmans (Kent) torches laid out
for view. Interestingly is the Henrob 2000 (formerly Dillion)
lightened up with handle removed and beside that his Meco...>

http://www.tinmantech.com/html/torches.html>

+++ $#4602
From: Rob Gaddy  zippydogg@a...
Subject:  Re: [Bearhawk] Welding help

I bought the MECO, and I love it.  I've used it only on mild
steel so far.  I used a Smith to weld a fuselage and think the
MECO will be better, and lighter.  I haven't used other torches.
The MECO is the best money I've spent on tools so far.

+++ #4707
From: Frederic  nov222pa@c...
Subject:  Re: [Bearhawk] Building Status

I have a sack half full of tail ribs formed in cold roll steel
and a lot of respect for those building.

Did practiced welding at a shop bench after work tonight and can
pass on the advice I received to those working on their welding
skills:

Hold the rod very near the puddle end for better control.
Advance the rod through your fingers in tiny increments not
letting the rod wander away from the heat.

I was holding the filler rod 6"- 8" from the end to start.
Using it up to 3" away, then doing several of these big inch
worm reaches with my fingers to advance the rod.

+++ #4883
From:  Russ Erb <erbman@c...>
Subject:  Now I Get It...

Yesterday I as doing some welding on a barbecue grill of my own
design to help fill time while waiting for it to warm up enough
to alodine the skins outside.

As I was welding, I was thinking about something that bd had
said.  Prior to this, I would get the puddle going, let the
keyhole form, then ram the rod into it.  While bd would say this
"chills the puddle" (as if anything above 1000 degrees could be
considered "chilled"), my result half the time was that the rod
would get stuck there and I would have to melt it out.

This time I tried "pre-heating" the rod in the flame right above
the puddle, which resulted in a molten drop which I then pushed
into the puddle.  The molten drop went into the puddle no sweat
(except on my face) and the rod didn't stick.  Worked a lot
better.  However, the trick is to remember to keep the keyhole
going so that there is proper penetration.  Otherwise you'll end
up with a bunch of blobs of metal on the surface.

+++ #4884
From:  Bob Romanko <romanko@v...>
Subject:  RE: [Bearhawk] Now I Get It...

The way I was taught was to preheat the rod, and when the rod is
inserted into the puddle the puddle actually flows UP onto the
rod the instant the rod goes molten.  At least that's the visual
you should shoot for.  I only think I saw it happen a few times,
but it seems like a good goal.  In other words, the rod doesn't
drop into the puddle, it is wicked together with the puddle in a
molten state.

+++ #4886
From:  Budd Davisson <budd@g...>
Subject:  Re: [Bearhawk] Now I Get It...

Somewhere back in an earlier post I said part of the key was
keeping the end of the rod near the gap between the puddle and
the torch tip, then trying to just get it into that gap on the
way to the puddle so it was melting even as it got to the
puddle. Ideally, you won't touch the puddle with anything but
the molten end of the rod, which gets sucked into he puddle even
as you're bringing the rod back out.

the puddle should look like a little Pac Man, eating it's way
down the gap and you just dab the rod into its mouth and get it
back out ready to repeat it.

+++ #4887
From: Frederic Kess  nov222pa@c...
Subject:  Re: [Bearhawk] Now I Get It...

Try keeping the rod preheated just at the front edge of the "key
hole" and watch that metal know how to flow home to the puddle.

Were you holding the rod near the puddle end for better rod
control?

I've been practicing walking the rod through my fingers while at
my machine during work.  This has been reported as less
distracting to others than my twirling allen head wrenches or
screwdriver baton practice, and pointed out to be a more useful
skill too.

+++ #4888
From:  "Owen Davies" <owen@d...>
Subject:  Re: [Bearhawk] Now I Get It...

What I've never understood is how people get those neat
fishscales that everyone seems to feel are the mark of a really
professional weld.  I circle the flame constantly, handle the
rod just as Budd advised, get plenty of penetration, and find
that my joints pretty much always hold up fine when I hammer a
test piece -- if anything breaks, it's the wall of the tube that
rips, well outside the fillet.  But my welds usually wind up
looking kind of wavy, like water, with maybe just a slight chop
if I've been careless.  Sometimes the fillet is practically flat
along its length -- rounded in cross section, but with little of
the ridging or lumpiness that most welds seem to have, much less
neat little fishscales.  I can't imagine that it matters, so
long as the joints hold up, but it would be nice to understand
what makes the difference and how I could make welds that
someone else will think look good.

+++ #4889
From: Warren  "W. Shalm" <shalm@i...>
Subject:  Re: [Bearhawk] Circular welding puddle

I absolutely agree with Budd. A neat trick my welding teacher
told me was to use small circles with the tip to your
advantage. In addition to what Budd says below, hold your right
arm (torch hand for me) steady and with elbow braced against
your side. Grip the torch between your thumb and fingers with
the hose end against the heel of your palm. Then as your torch
moves along the weld, use your grip between you thumb and
fingers to move the tip of the torch in consistent 1/8"
circles. What this does is preheat the bottom tip of the rod on
the forward motion of the flame and then keeps the puddle molten
on the back stroke of the circular motion.

This gives you a beautiful consistent factory look weld where
the finished weld resembles a series of closely spaced 1/2 moons
in a consecutive row.  The problem with trying to move the torch
along without the circular motion is that it is jerky and you
are trying to preheat the rod and keep the puddle going at the
same time. The circular motion is smooth and allows you to flick
the flame ahead an extra 1/16 on each pass if your filler rod is
too cool or to shorten it up if it is too hot.

In short the front end of the circular motion controls the rod
heat and the back end of the circular motion controls the puddle
heat. In practice this happens quickly and repeatedly and once
learned, I found it very simple to control the weld especially
in vertical and overhead applications.

Now if the engine work was just that easy I'd be in business :-)

+++ #4890
From:  Budd Davisson <budd@g...>
Subject:  Re: Welding appearance

Re: weld strength and appearance

Go to Airbum.com and look up Zen and the Art of the Weld Puddle
in the articles section. I hope I make it clear there that the
strength of a weld is a function of how it looks going in, not
how it looks afterwards. I like clean, neat beads, but that's no
guarantee it has penetration. If the little Pac Man is eating
away the surface and flowing into it while the puddle is moving
forward, and if the puddle is tranquil, with a calm surface and
no activity on it or sparks indicating oxidation, you have a
good weld, regardless of how even it is or isn't.

Conversly, any good welder can run a quick, clean looking bead
across the surface of a piece of plate, let it cool and chip the
entire bead off with a screw driver in one piece. Penetration is
the name of the game and only you know its there when you see it
going in. Yeah, you will see some welds that are sligthly
undercut and know it penetrated, but you also know it reduced
the local strength slightly by the undercutting.

Just keep Mr. Pac Man nibbling away at the surface and let him
suck on a molten rod at regular intervals and you'll have a good
weld.

Incidentally, I've been giving welding forums at Oshkosh for
over 15 years and I've always started the forums off by asking
if anyone in the tent has ever seen a weld break in flight. Not
on a hard landing but in flight. I've never gotten an answer in
the affirmative and I've never seen one break that way. Plus,
I've seen some REALLY crappy welds flying. The design of steel
tube and the fittings attched to it is so over-done in terms of
weld length and safety factors, you just have to eliminate
oxidation sparks and let the Pac Man do his thing and you'll
have a strong fuselage.

+++ #4893
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  OT (add to January's total)inflight tubing breaks

While I lived in PA I hangared with Dianne Hackala (and I've
probably misspelled her name again) back in the days while she
was still flying a Pitts. The G's she pulled in competition
constantly broke rivets in the few places where there was
aluminum skin. The most significant damage from in air forces
was a broken tube. The welds didn't break, but a diagonal tube
in the floor of the cockpit area cracked right through the
middle. The area of the fracture was more than 10" from the
closest weld. This was a factory built fuselage and everyone was
impressed that Dianne could survive what the Pitts could not. (a
lot of good natured ribbing always went on in the hangar.

+++ #4907
From: Frederic  nov222pa@c...
Subject:  Re: [Bearhawk] Circular welding puddle

> I absolutely agree with Budd. A neat trick my welding teacher
> told me was to tip that flame up just a little and take a few
> degs off the puddle.

Hit the work with side of the flame to change rods or if
interrupted momentarily...and I'll add, just before you
anticipate saying ohh, I just burnt threw.

Don't have big flucations in the puddle temp, I think he meant.

+++ #4909
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Re: Welding appearance

For those wanting to watch some gas welding on 4130, through the
welding lens and close-up, I will be posting a video segment in
Real Player on the TM Tech website, www.tinmantech.com

This segment is an interview and welding demonstration with Joe
Young at Oshkosh, '99.  Joe is a very good teacher, has been a
welder for over 60 years, and his skill is remarkable.  The
tight even ripples of his gas welds look machine made, so photos
of the finished weld will also be posted along with the video.
He has taught in the Welding Workshop at Oshkosh for many years,
and tells some great stories, (like the one about the greased
midget welding the battleship armor).

+++ #4957
From:  Russ Erb <erbman@c...>
Subject:  RE: [Bearhawk] Status

> At least my welding has improved greatly with the input from
> the list.  One trouble I discovered when I got a new tank of
> Acetelyne...  Ac. burns much hotter than the acetone it is
> stabilized with.

What happened?  I was welding last weekend, running low on
acetylene, and stopped when the tank pressure gauge hit the zero
peg. (I usually don't push it that far) Wasn't quite to zero
pressure since it was still putting out at least 4 psi.  Does
acetone start coming out of the torch if you push it too far?  I
wasn't willing to find out by trial...

+++ #4961
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  RE: [Bearhawk] Status

> What happened?  I was welding last weekend, running low on
> acetylene, and stopped when the tank pressure gauge hit the
> zero peg. (I usually don't push it that far) Wasn't quite to
> zero pressure since it was still putting out at least 4 psi.

When you run the cylinder to "0" you can start to pull acetone,
what is called an "acetone blower." The most dramatic examples
are when someone tries to use an acetylene cylinder lying on its
side.

The re-filler checks the weight of the cylinder to determine
acetone content, but if you have pulled it so low as to get
acetone it is courtesy to tell them.

+++ #4966
From:  Steve Eldredge <steve@b...>
Subject:  RE: [Bearhawk] Status

Nothing traumatic, just that I started having trouble keeping my
torch adjusted at neutral and after I dropped below 4 psi it
took forever to get the material up to temp.  I didn't really
notice a difference until I got my new tank.  The world changed
for the better.  I assume that all many of my problems with edge
welds were due to the lack of heat focused on my parts.  I had
to increase the tip size to get enough heat, but lost the focus
of the smaller flame in the process.  After getting fresh tanks
I could go back to the small tip and concentrate a pinpoint
flame and my welds returned to what I was used too.
Contributing to the confusion, was that I switched to a Smith
airline torch from the big Victor about the time my tanks
started getting low.  Too many variables to really clue in to
what was happening.  Just an uneducated guess, but it seems that
either acetone burns cooler, or I just ran out of pressure.

+++ #4977
From:  Russ Erb <erbman@c...>
Subject:  Tighten Those Packing Nuts

Yet another thing that should be obvious but apparently isn't
since it took me this long to figure it out (I like to think
that I'm a little sharper than Planter Bob's bowling ball).

I had never considered the condition of the packing nuts on the
gas valves on my welding torch.  Silly me, I figured they should
be okay as it comes.  I had been having trouble with the mixture
of the gases changing as I welded.  Today I noticed that if I
pushed on the oxygen knob, the mixture would change.  After
this, I decided to check how tight the packing nuts around the
valves were.  Not surprisingly, they were rather loose.  I
tightened them up, and (not surprisingly) the control of the
gases improved.

Keep that in mind if your welding torch seems to not be able to
hold a mixture.

+++ #5042
From: John H Dugdale  jdug@p...
Subject:  OxyAcetaline Welding rods for 4130

What specs welding rods are you using for 4130?  The info I have
here is that I should be using AMS 6457 or AWS A5.18.  These
seem very difficult to obtain down here, or even in Australia.

+++ #5043
From:  "Owen Davies" <owen@d...>
Subject:  Re: [Bearhawk] OxyAcetaline Welding rods for 4130

>  What specs welding rods are you using for 4130?  The info I
> have here is that I should be using AMS 6457 or AWS A5.18.
> These seem very difficult to obtain down here, or even in
> Australia.

I understand CMS32 meets U.S. milspec, which seems to be about
as close to a viable standard as I can find.  Take a look at the
discussions of welding on the Biplane Hangar mailing list
archive, at http://gf24.de/biplane/ .  Somewhere there, you'll
find a file on welding, which contains many useful posts from
the mailing list.

+++ #5045
From:  Russ Erb <erbman@c...>
Subject:  Re: [Bearhawk] OxyAcetaline Welding rods for 4130

I'm using 32CMS, straight out of the Aircraft Spruce Catalog.

+++ #5071
From:  "Todd Chisum" <toddc@n...>
Subject:  Smith Rosebuds

Smith sells two different rosebud tips for the Airweight torch,
the AT603 (4 #65 holes, 24,500BTU) and the AT605 (6 #64 holes,
41,500BTU).  Which one should I buy for airplane building?

+++ #5072
From: Rod Smith  rsmith@a...
Subject:  Re: Smith Rosebuds

I'm sure the smaller one would be more than adequate. I'm still
trying to figure out a way to convert a small rosebud for use
with my Henrob torch. I use the #3 tip instead but it is less
than ideal for that purpose.

+++ #5073
From:  "DANFORD, GARY" <Gary.Danford@D...>
Subject:  RE: [Bearhawk] Re: Smith Rosebuds

Is the "Smith Airweight Torch" the lightweight torch listed in
the Aircraft Spruce Catalog that uses the "AW" tips?  Do you
know if the "AT" Rosebud tips will fit?

+++ #5075
From:  "Todd Chisum" <toddc@n...>
Subject:  RE: [Bearhawk] Re: Smith Rosebuds

It is the same torch, the AW1A.  The Smith catalog and brochure
says that the AT tips will fit the AW1A handle.

+++ #5077
From:  Benton Holzwarth <bcgh@t...>
Subject:  Another rosebud question

 I bought a Victor torch from a retiring plumber in the
neighborhood.  $125 for tanks (full!), handle, and a pretty wide
assortment of tips, including a couple rosebuds.

 Question is: The tanks are small with the acetylene being about
10-12" tall by about 5" diameter. One isn't supposed to draw
down the acetylene faster than 1/7th tank volume per hour.

 I've been concerned that a rosebud, or any of the larger tips
would exceed this.  Is there a table or further info on line
anywhere that I could reference to see what the limits would be
with these tanks, and what flow rate a particular tip would
need?  I couldn't find anything at the Victor site.

+++ #5078
From:  "Tim Anderson" <fuzzet@h...>
Subject:  Re: [Bearhawk] Another rosebud question

I don't have a Victor...but my Smith came with a small manual
that explained the requirements of each...ie, which rosebuds
needed a manifold set up of multiple tanks to eliminate that
problem.  Victor should have a simular manual.

+++ #5079
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Another rosebud question

You got "burglar bottles".  Good for tips up to #2, on Victor
J100, but no cutting heads or rosebuds.  Keep the bottles for
small jobs needing rapid portability.  Get a 60Ox and B acet. At
the minimum.

+++ #5081
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Smith Rosebuds

> Smith sells two different rosebud tips for the Airweight
> torch, the AT603 (4 #65 holes, 24,500BTU) and the AT605 (6 #64
> holes, 41,500BTU).  Which one should I buy for airplane
> building?

If the cylinder sizes that you have will support it, go with the
larger tip. The larger rosebud allows you to bring a complete
cluster up to temp quickly and easily. I have found that my
smaller rosebud could not pull a cluster of 5+ tubes up to a
uniform red heat.

+++ #5115
From:  Benton Holzwarth <bcgh@a...>
Subject:  Re: Another rosebud question

> I don't have a Victor...but my Smith came with a small manual
> that explained the requirements of each.

I picked my kit up used, and didn't get any manuals.  I had a
look at the Victor site but couldn't find anything useful.  I
was just remembering that the guy down at the welding supply
shop gave me a freebie "intro and safety" booklet last time I
was there.  I was just looking around for it, but no luck.  It
might have tank requirements in it.

> You got "burglar bottles".

Love it -- " burglar bottles".  They are handy!  The whole kit
is only a little bigger than a brief case.  (And lighter than
some I've hefted.)  And I do own 'em outright, no rent/lease
charges.  But then again, I've not tried to get 'em refilled
yet, and have heard there might be difficulty...)

> Good for tips up to #2, on Victor J100, but no cutting heads
> or rosebuds.  Keep the bottles for small jobs needing rapid
> portability.  Get a 60Ox and B acet. At the minimum.

Had another question, re: rosebuds.  For heating a cluster, I'm
presuming the rosebud plays over the front and then backside
while welding is in progress (I'd like to call a friend,
Regis!).  With tanks large enough to feed the rosebud I could
run the welding tip off the small tanks, or I could put together
a manifold to feed both rigs from larger tanks.  Would this
amount to just a pair of Y's?  It seems simple enough, what
should I expect it to cost?

+++ #5116
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Re: Another rosebud question

The last question first, the rosebud is used sometimes to
preheat, when you have a large cluster, to help bring the metal
to near welding temp so that the small welding tip can be
operated in its usual adjustment range---not having to over
drive it with excess flow which leads to reduced control of the
molten puddle.

Most use of the rosebud is to post heat a welded area. Since the
welding tip is relatively small, as one moves about a joint or
cluster, welding a bit here and a bit there, it is difficult to
maintain temperature uniformity. This uneven heating and cooling
leads to strain in the welded joint. That strain if left
unmodified can lead to cracks in 4130 tubing.  Regardless of
what Finch says about post heating, post heating can do two
things for you that will result in possibly a longer lived
fuselage. And I have not found that post heating causes problems
with the fuselage.

The first thing that post heating does is to bring the whole
cluster joint up to a plastic temperature point that allows the
tubes to align and relax relieving that welded-in
strain. Another benefit is to move the HAZ (heat affected zone)
further away from the welded joint.

The HAZ is the area of the tube where the transition from the
hot welded area to the cold tube takes place. This area is going
to have a higher likelihood of hard or brittle areas due to the
rapid removal of heat (quenching) caused by the conductivity of
the cold tube. If the HAZ is close to the joint, in the area
stressed by normal operational forces on the fuselage, there is
a greater chance of cracking.

This process is sometimes erroneously called "normalizing."
Normalizing is a process of taking 4130 tube up to a prescribed
temp and cooling at a precise rate. This removes all strain
created in the tube manufacturing process and allows the
uniforming or homogenization of the steel's grain structure (no
HAZ). This process cannot be easily done on a fuselage without
an oven large enough for the whole structure.

Remember that 4130 tube was developed for oxy/acet welding. It
was formulated to provide ease of welding and the strength
necessary for aircraft construction. Unless you are welding in a
20degF hangar (I used to) it is not likely that you'll really
need to use that rosebud very much. I incorporate post heating
only when TIG welding critical highly loaded structures such as
engine mounts and some parts of the landing gear.

You are not heating with a rosebud at the same time
(simultaneously)that you are welding. You cannot run two torches
off the same regulator with a "Y" connector. You are going to
find those small cylinders expensive to operate. First they will
run out quickly(usually on a weekend when you really want to get
something done). Second they will cost as much to refill as a
cylinder two to three times larger(its the labor you are paying
for,the gas in those size cylinders is inconsequential). Third,
it is not likely that your welding supplier has that size
cylinder in stock so that you could just swap them (I may be
wrong here, some refillers do maintain these size customer owned
cylinders in stock). If you have to actually have your cylinders
refilled then prepare to wait one to two weeks turn-around time.

I would upgrade to the next larger size cylinders. My next
suggestion is that you find a continuing education (tech school)
facility and take a welding course. I recommend a book called
"Metals and How to Weld Them."  This is an old book, but has
been used as a welding text for 50 years and is still hard to
beat. Finch's books can be some benefit, but a good hands on
instructor can better help you separate the wheat from the
chafe.

If your cylinder cannot support the discharge rate necessary for
your rosebud you'll find out quickly. The rosebud will just not
get hot enough or will start to pop and sputter (getting too hot
or acetone is actually coming out of the cylinder---gas flow
helps to cool the tip) If problems show up then try running the
rosebud with a smaller flame. If that doesn't provide the heat
needed then larger cylinders (particularly the acetylene
cylinder)are needed.

Hope this helps and I am sure that Kent and Budd will have
additional useful info.

+++ #5118
From:  Budd Davisson <budd@g...>
Subject:  Re: [Bearhawk] Re: Another rosebud question

Bruce summed the use of the rosebud and the need for post
heating up very nicely.

As a normal rule, unless you're putting the last tube or two on
a huge cluster, there's no need to pre-heat it with a rosebud as
you can pre-heat the affected area with the welding
torch. However, the rosebud will be needed to stress relieve it
(not normalize as Bruce points out), if you want to. I normally
stress releive while I'm welding the joint: as the bead is
finished and is still hot, I turn the torch up to a longer
feather, and play the heat around to the otherside and spread
the heat about an inch from the finished bead up on to the other
tubes, then back slowly away. Keep it dull red for five
seconds. You can also do the entire cluster with a rosebud, but
some consider that to be overkill.  For all fittings, I'd
definitely do a good job of stress relieving.

IN reality, one of the beauties of gas welding versus TIG or MIG
is that the heat affected zone is so much wider. So the hardness
changes in the weld has enough distance to change that there
isn't as much of an abrupt change. TIG and MIG both should be
preheated vigorously and post heated immediately because the HAZ
can be only 3/8 of an inch wide and the abrupt changes in
hardness can lead to fatigue cracking. That having been said,
Pitts TIGs their fuselages and American Champion MIG's their's
(Yeeeech!!) and neither stress relieve. I do it anyway.

FYI, if memory serves, the tubing charts we use to determine
wall thickness and sizes for truss layouts has a 15% margin
built into it that accounts for material changes introduced by
welding.

+++ #5120
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Re: Another rosebud question

Both Budd and Bruce are right on target with this thread.

I would also add that "normalizing" is done at a specific
measured temperature for an accurate length of time, and cannot
be done with the torch. Stress-relief is less precise, but is
also very forgiving and therefore can be done with the torch.
When metal men say "heat to a given color", they mean daylight
with the lights off in the shop, and not in a brightly-lit
environment. Think: dirt -floored dark blacksmith shop.

Also, the Kitfox and Maule are MIG welded and not
stress-relieved, and there are interesting stories, (which you
did not hear here, ....or on the 4130 Video tapes) about their
tube structures.

One aspect of TIG vs. torch is that there is a great temptation
to make tiny little precise beads with the TIG, which runs the
risk of leaving insufficient filler in the joint, and requires
more time to cut and fit the tube ends perfectly.  This is less
tempting with the torch because the Heat Affected Zone is
greater and it is natural to make a nice wide bead ---which also
covers those occasional gaps very well.

+++ #5125
From:  Russ Erb <erbman@c...>
Subject:  Re: Another rosebud question

Okay, you guys are forcing me to ask two questions that have
been floating around both brain cells for a while.


> You are not heating with a rosebud at the same time
> (simultaneously)that you are welding. You cannot run two
> torches off the same regulator with a "Y" connector.

And why not?  Unless it is a flow rate restriction in the
regulator, I don't immediately see why this would be a problem.
On the other hand, is a Y connector available that I could
connect two torches to the same bottles to use one at a time?
Otherwise it would be tough to heat a joint with a big tip (or
rosebud) and then weld with a small tip if I had to take the
time to swap tips or torches.

> When metal men say "heat to a given color", they mean daylight
> with the lights off in the shop, and not in a brightly-lit
> environment. Think: dirt -floored dark blacksmith shop.

I've also wondered is that the color as seen through the welding
goggles or without the goggles (which would seem hazardous)?

+++ #5127
From:  Budd Davisson <budd@g...>
Subject:  simple revelations

Re: I'm a slow learner

I've been welding since I was 15 years old and it's amazing to
me how many times I stumble into something that causes yet
another red spot in the forehead from slapping myself:

Saturday I was welding on the old grill shell for my roadster
and was trying to run a bead across some metal that couldn't
have been .015" thick, it had been ground so often. I could turn
the 00 tip down far enough that I wouldn't make the base metal
disappear, but then there was'nt enough heat to reliably melt
the 1/16" rod quickly enough to run a good looking bead. Then I
remembered something an old friend had said once. I grabbed a
role of safety wire and started using that for rod. It worked
like a champ! I don't nkow whether it would be a good idea for
structural welds, but it certainly worked in this application.

+++ #5129
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Re: Another rosebud question

>Okay, you guys are forcing me to ask two questions that have
>been floating around both brain cells for a while.

OK, the way to run two torches off one bottle is to install the
"Y" to the cylinder valve then install two regulators--- one
running one torch and one running the other torch.

If both torches were exactly the same then the setup might work,
but as one torch is adjusted it affects the flow of the other
torch. It's like balancing on a bolo board. I have tried it.

>> When metal men say "heat to a given color", they mean
>> daylight with the lights off in the shop...
> 
> I've also wondered is that the color as seen through the
> welding goggles or without the goggles (which would seem
> hazardous)?

You do need to see the true color so clear un-tinted safety
glasses under the shaded goggles. When brightness is getting
near, as viewed through the tinted lenses, lift the tinted
goggles and view the color through the clear lenses.

I once had a blacksmith book that claimed that to read the
colors properly you should not even wear safety glasses, even
clear ones. To protect your eyes you should just squint and sort
of look through your eyelashes. The book was written by an "old
timer" who had gotten away with such methods his whole
life. Maybe my unwillingness to adopt his method was why I never
was never able to forge weld and I eventually gave up the hobby.

+++ #5133
From:  "Todd Chisum" <toddc@n...>
Subject:  Re: [Bearhawk] simple revelations

You might also try gas welding with .030" MIG wire.  I tried
this with some ER70S-6 wire and the 000 tip on some thin sheet
just to see if I could do it, weld was great with a tiny little
bead.

+++ #5134
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Re: Another rosebud question

Bruce is right about the "y" balance for all of you wanting to
use two torches off one set of bottles.  Even two identical
torch- and- tip combinations are hard to balance, but they can
be done. Two different sized ones?---well....don't waste your
precious time.

+++ #5264
From:  Russ and Penny Erb <erbman@p...>
Subject:  RE: [Bearhawk] Plans, parts lists, construction tips, etc.

The vacuum melted rod is WAY overkill for what we're doing.
Besides that, if you don't keep the rods properly sealed at all
times, you'll lose the supposed benefit you paid for.  Go down a
couple of inches and get the 32CMS rod.  The size of the weld
bead from gas welding is larger than the thickness of the tubes
and generally stronger than the tubes.  You also want a milder
rod because it will harden as part of the cooling process (or
something like that).

+++ #5325
From: Rod Smith  rsmith@a...
Subject:  Tig Special - Sun and Fun

I've been in the market for a Tig machine for awhile and did a little 
research. At Sun and Fun you will be able to buy a Lincoln square 
wave 175 pro outfit for $1328. This includes shipping anywhere in the 
US (yes even Alaska! but not Canada Tim) and you dont have to pay 
Florida sales tax. They will have lower prices on demo units but you 
have to take it with you and you will pay Florida sales tax. The 
local dealer has the same machine on sale for $1399 until the end of 
March so I am taking this information to him to try to get the same 
price. Chances are I will buy it locally anyways for warrenty 
support, support the local economy, not worry about shipping damages 
etc., but wanted to pass the information along. List price on this 
package is in the $1700 dollar neighborhood. Incidently I started 
welding my fuselage with gas and will complete it through the cluster 
welds with gas. Once I get comfortable with the new machine I will 
probably use it for attaching the heavy fuselage weldments. I don't 
feel like this machine is necessary for this project, but have 
several other intended uses in mind.

+++ #5331
From:  "Bill Cox" <t18cox@f...>
Subject:  Re: [Bearhawk] Tig Special - Sun and Fun

I welded my fuel tanks with a 175 and fell in love with it. I'm
gas welding the 4130, but may borrow the 175 for a few heavy
parts.

+++ #5339
From:  rsmith@a...
Subject:  Re: Tig Special - Sun and Fun

> Does Lincoln or a dealer have a web site that describes this
> particular unit? I might be interested if it has all the
> do-dads I'm looking for. Is this unit water-cooled?

You can get good information on any of Lincolns products at
www.lincolnelectric.com. It does not come set up as watercooled,
that would involve buying a different torch/hose setup and a
cooler.

+++ #5352
From:  "Tony Chisum" <tonychisum@h...>
Subject:  Re: [Bearhawk] Tig Special - Sun and Fun

I have been looking at this same unit.  Go lincolnelectric.com
The 175 PRO is air cooled but they have a 235 amp. unit that
water cooled.

+++ #5353
From:  Jim Ash <ashcan@m...>
Subject:  Re: [Bearhawk] Tig Special - Sun and Fun

Can I get the 175 and then add on water-cooling as an option
later?

+++ #5354
From:  csdurham@q...
Subject:  Re: Tig Special - Sun and Fun

I had a long chat with my local welding repair folks about the
ins and outs of TIG. The word from them is unless you are
planning to do production type work (all day on heavy material)
a water cooled torch is unnecessary. The 175 would not be
appropriate for this type of work, which answers the question of
water cooling its torch. For any and all the welding on a
bearhawk it seems the 175 with an air-cooled torch would be
fine. They did caution me about the 175 being solid state, thus
expensive should repairs to the unit be necessary.

+++ #5355
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

I'll differ a little bit here. The 175 is an excellent piece of
equipment and the standard air cooled torch is adequate to
handle the output of the machine, but there are other reasons
for a water cooled torch. The WP-20 water cooled torch and all
its copies are about the most compact torches on the market. One
of them can handle 200 amps *because* it is water cooled. A
similarly sized air cooled torch can handle only about 80
amps. For the most part even that is well beyond what you'll use
on the Bearhawk. What I like about the small water cooled torch
is the ability to assemble it so you can get into just about any
tight space in any part of fabricating an aircraft. Over the
years my hand is adjusted to wrap around that small
torch. Anything else feels awkward to me.

Now a bit of the down side. This style torch complete with hoses
will cost about $100 to $120. If you want to keep the welders
portability then a coolant pump and heat exchanger are
necessary(commercial stainless unit can set you back
$300...Build one yourself for about $50). If you are only
welding in your shop then you can hook the water lead to a
faucet and just let the discharge from the torch run into a
drain or outside on the ground (it's a very small trickle).

Lincoln Electric does not put out short lived equipment. At the
price the 175 is one of the best pieces of welding equipment on
the market today. If it were not a solid state machine it would
be four times as large. There is no indication that these units
will not live for decades. When they first came on the market
they had a 3 year warranty just because the company knew that
welders did not trust the technology. The solid state machines
have taken over the market, almost every late model machine,
whether TIG, MIG, or Plasma, is solid state. And they are much
easier to use and produce better results because of it. BTW,
most of the solid state machines these days are repaired by just
replacing a circuit board.

For me, having been welding with TIG for almost 30 years, if I
were starting the Bearhawk today and I needed welding equipment
I would buy the Lincoln 175. If I were new to welding I would
buy the best quality oxy/acet outfit I could afford. The skills
developed with the Oxy/acet torch are those used when TIG
welding and are the best training for that step up.  When you
get ready to build the second Bearhawk you'll be ready for that
new TIG equipment.

+++ #5363
From:  "Rod Smith" <rsmith@a...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

Check out www.hi-techwelding.com, they are advertising highly
flexible tig torches, picture shows one wrapped around a welders
wrist. My understanding is they give a 25% discount to EAA
members. When I get my welder I will use the torch that comes
with it before deciding if I need something different.  One bit
of advice I got was to buy a 25' torch for fuselage welding. The
one that comes with the 175 is 12'. Bruce how long is the hose
on the WP-20?

+++ #5368
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

Any length is available, but I am so used to using the 25 foot
leads I never think about mentioning that. My welder sits in a
little cubby in the wall of the shop so I have a 25 foot lead on
mine allowing me to reach anywhere in the shop.

+++ #5373
From:  Jim Ash <ashcan@m...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

Torch size was one of the reasons I asked about the water
cooling. After doing aluminum mig with the big spool in the
handle, I like the lightest torch for the tig I can get. I've
already got a gas setup using the Henrob (was Dillon) torch
body, which I've used on 4130 tubing before and will probably
use for this fuselage. The tig would really be more for the
speciality stuff, in particular aluminum.

+++ #5374
From:  "Owen Davies" <owen@d...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

Rats!  I've lost track.  Was it this list where we've just had a
thread about how good gas torches are for welding aluminum?
Maybe it was wreck.aviation.homebuilt.

Take a look at your Henrob manual.  It has a very useful section
on how to weld aluminum with that torch.  Not terribly
difficult.  It's been a while since I used a Henrob, but I've
half an idea it even came with a mask filter suitable for
looking through the sodium glare of the flux.

+++ #5377
From:  csdurham@q...
Subject:  Hobart Tigmate

I just came across the Hobart TIGMATE complete package at
Welding- Supply.com. They want a little over $1,200.00 for
it. Is anyone familiar with this unit? It seems a pretty good
buy....

+++ #5378
From:  "Owen Davies" <owen@d...>
Subject:  Re: [Bearhawk] Hobart Tigmate

Never heard anything against it.  Seems to me the Miller 180SD
has a slightly lower bottom end on the amperage, which can be
useful, but it's more money.  For whatever it's worth,
www.brwelder.com offers the TIGMATE for $1199 with free
shipping, and they have a decent reputation.  I'd strongly
suggest asking at sci.engr.joining.welding (my mantra whenever
questions about welding come up!)  If no one else responds,
Ernie Leimkuhler is almost sure to have something useful to say.

+++ #5389
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Hobart Tigmate

I don't know whether to voice this opinion or not since it has
been about 12 years since I handled Hobart, but here is two
cents worth that may be worth less than that. While working as
an outside sales rep I sold Hobart, Lincoln, and Miller welding
machines. In four years of selling the ONLY machines that I sold
that needed repair or warrantee work were the Hobart
machines. Contact with friends who are still selling tell me
that they have a higher problem and return rate on Hobart than
Miller and Lincoln combined. Sorry I don't have a contact for
information on that particular machine.

+++ #5392
From:  Jim Ash <ashcan@m...>
Subject:  Re: [Bearhawk] Re: Tig Special - Sun and Fun

I got spoiled welding steel without having to do surface prep
first. I've done aluminum with the Henrob, but it had to be
cleaned and fluxed real well first or I had a really hard time
getting a good bead started.  Unfortunately, I haven't had a lot
of call for aluminum, and never got enough practice at it with
the Henrob to get any good at it.

I have a set of filters for my mask that I use doing aluminum.

+++ #5397
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Meco / biceps - Sun and Fun

TM Tech and Tin Man will be at SnF, space 55 across road from
end of Exhibit bldgs. Will be demonstrating forming and welding,
brazing, and soldering.

Have done the weld-offs with Blue and Red boys (Miller and
Lincoln) for many years, at many events.  Now that they are
attending the events in large forces these days, I am more often
"challenged" by the attendees.  They are always most impressed,
especially in the 20-40kt breezes.

Each particular welding method has its applications, advantages,
and drawbacks.  Like with the Bhawk, there is joy in choosing
appropriate technology.

+++ #5419
From:  Russ and Penny Erb <erbman@p...>
Subject:  Welding Heavy Stuff

A question from a user of the .357 Magnum torch (Henrob 2000):

Invariably, when your friends find out you know how to weld,
they will ask you to weld stuff for them.  "They" may also
include you or your spousal unit.  Of course, the items they
want welded are not thinwall 4130, but heavier steel stuff, like
trailers, lawn furniture, fences, and whatnot (especially
whatnot).  These items are well beyond the capability of our
little torches which work well on Bearhawk structures.

For those who have experience in this sort of thing, or just
have an opinion:

Assuming a Bearhawker has reasonable experience with gas
welding, which type of electric welder would be the best value
for use on this "other stuff", a stick welder or a MIG welder?
That being said, do you recommend a specific make and model?

I'm assuming a TiG would be more expensive than I was interested
in--besides, if I wanted to use one of those I would buy it to
use on the airplane.

+++ #5420
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: Welding Heavy Stuff

I get asked this question a lot. If you are always working at
about 3/16" thick material maximum I'd say the MIG would be just
fine.....won't be pretty welds for the most part, but things
will likely stay welded together. If I needed a welding process
that was inexpensive and absolutely trustworthy on thicker
material (and rusty and painted and so on) I would buy a "buzz
box"... an inexpensive AC stick electrode welder and ten pounds
of 1/8" E6011 and ten pounds of 1/8" E6013 welding rod. There
isn't much you cannot fix with that setup. If you have a little
experience welding with stick then maybe an AC/DC machine and
add a handful of 1/8" E7018 to your welding rod inventory.

If you know your way around a MIG welder then optional items
such as fluxcore wire and fancy cover-gas mixes can get you up
into the 1/2" thick mild steel range (small shop machine with
.045" wire). BUT supplies cost more and change over when you
need to go from welding thicker to thinner materials is
bothersome. This is where stick is absolutely the most
versatile. TIG will do it all (on clean material)but will cost
you 5 times what that stick machine does.

+++ #5422
From:  Bob Romanko <romanko@v...>
Subject:  RE: Welding Heavy Stuff

I swapped my brother an old Reznor heator for a just-as-old
Lincoln 225 buzz box.  TIG's nice, but the 'ol buzz box was
cheap (free), welds a good amount of stuff that breaks around
the house, and I think I'd have a hard time justifying the
expense of a TIG outfit to Mrs. Planter to just weld whatnots
with.  Then again, if it works for YOUR spousal unit, I'd say go
for it!

+++ #5423
From:  Tim <tlc2@t...>
Subject:  Re: Welding Heavy Stuff

My brother Dean converted his similar Buzz box with a homemade
adjustable resistor (?) and added a bottle of Argon which gave
it an inexspensive tig capibility...He's been using it for quite
some time now...Perhaps he will comment?

+++ #5424
From: Del Rawlins  "Float-By Shooter" <del@n...>
Subject:  Re: [Bearhawk] Welding Heavy Stuff

> Assuming a Bearhawker has reasonable experience with gas
> welding, which type of electric welder would be the best value
> for use on this "other stuff", a stick welder or a MIG welder?
> That being said, do you recommend a specific make and model?

Russ, I've fabricated and repaired all kinds of needed items
(including a flatbed trailer) using an old Miller "buzz box"
stick welder which my dad bought used in the early 70's.  I may
buy a MIG welder sometime after the Bearhawk is finished, but
only because I will be doing automotive restorations involving a
lot of bodywork.  MIG units typically have automated features
such as spot and stitch welding which make them ideal for
welding thin steel panels together.  The MIG welder will also
perform the same tasks as the stick welder (with less skill
required) but unless you see yourself doing bodywork I wouldn't
bother spending the extra money on one.  With all the practice
you're getting welding on the bearhawk with oxy- acetylene
equipment mastering the stick machine shouldn't be a big deal.

I can't recommend any specific machine; the old one works so
well we've never had reason to look into replacing it.  Probably
the first thing you should do is figure out what sort of power
source you will need to run it.  I doubt if you have 220 in the
famous one car garage workshop, which will limit your selection
somewhat.

> I'm assuming a TiG would be more expensive than I was
> interested in--besides, if I wanted to use one of those I
> would buy it to use on the airplane.

Whenever I've used my TIG machine for the sort of tasks you
described, I always used it in stick mode anyway.  I think in
stick mode it welds nicer than the buzzbox, but then again, I
would be disappointed if it didn't.  Either machine will produce
better quality welds than I typically can, so it really doesn't
matter.

+++ #5425
From:  Donald Schindler <t18skyguy@y...>
Subject:  Re: [Bearhawk] Welding Heavy Stuff

I think Bruce is right on with his advice. If I was a new
Bearhawk builder and had $1500 to burn, instead of a TIG, Id get
a Meco and a pair of Kent's best goggles and use the balance of
the money for a shear or something on that order.

+++ #5428
From: Rob Gaddy  zipppydoggg@y...
Subject:  Re: Welding Heavy Stuff

> capability of our little torches which work well on Bearhawk
> structures.

I bought a Meco for the aircraft welding, and use it for some
home projects.  I also have a larger gas torch that is useful
for those "intermediate" jobs around the house (Home Depot).
Finally I have an old Sears "buzz box".  I just finished
building a front bumper for my old truck, after a kid ran a stop
sign and customized it in the middle of a 4-way-stop
intersection.  The bumper is made of 10 inch channel iron (15
lbs per foot, I don't think this one will bend).

Dell hit the nail on the head.  The problem is the power source
for the "buzz box", it is a special-run 50 amp (the plug alone
was expensive)220 Volt circuit I installed in my garage.  Great
for projects that are within about 25 feet of the plug, but
useless outside the radius of the welding leads.  I think that
if I had the money and was starting I would get the best "basic"
mig unit that I could afford that runs on 110 volts.  I would
add the gas and other accessories as I needed/wanted them.  This
unit has the advantage of portability which my Sears stick unit
doesn't have.  Anyway, you can always find someone with a stick
welder if you need to weld something that heavy.  A good mig
unit could be set-up for aluminum welding.  I was talking to the
guys at the local welding supply and they don't advise a "cheap"
unit for welding aluminum.

+++ #5430
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  Re: [Bearhawk] Re: Welding Heavy Stuff

I have 100ft leads on my "stick" machine. That's the nice part,
you don't have to haul the whole welder out into the driveway to
fix the trailer frame.

+++ #5433
From:  Budd Davisson <budd@g...>
Subject:  Welding Heavy Stuff

Re: Welding heavy stuff

I've been off line for a day and a half because my server took a
dump, so I don't now what others have said in regard's to Russ's
question about welding heavier stuff.

First, I routinely weld up to 1/4 with my little Smith by using
a No. 7 tip and 3/32 rod. It just a little longer to heat up but
welds the same.

Stick welder vesus Mig: Stick is much cheaper, Mig is much
cleaner. A old stick buzz box will weld anything and, although I
haven't checked, I imagine you can get a cheap 200 amp unit for
under $200. A good electronic welding hood is a must.

Since you wont' use it that much, if you're going to get a Mig,
one of the flux-wire type is probably a good idea as you don't
need the gas bottle. If you get the gas type, most of them will
function as a stick welder with no gas. However, the lower end
Mig units generally poop out as they go past 3/16 plate moving
you up to a more expensive welder.

For occassional, heavy plate, it's hard to beat the old Stick
machines on a dollar to dollar basis, but don't expect much of
your gas welding expertise to help you out. It's another skill
to be learned.

+++ #5445
From:  Jim Ash <ashcan@m...>
Subject:  Re: Welding Heavy Stuff

I second Rob's and Bruce's opinions.  My wife went into
Builder's Square and just pointed at the biggest buzz box they
had one year for Christmas.  It does both AC and DC. I pulled
50-amp 220 to an outlet box in my garage for it. I also made an
'extension cord' from 3 lengths of 6 gauge wire to overcome the
lead length thing (I like having the welder close by so I can
fool with it). I used that welder to build a fancy race-car
trailer out of 2x4 box for a co-worker at his house by tapping
into the panel in his garage (He didn't have an oven for 3
weekends). I used E7018 reverse-DC, my personal preference for
thick mild steel jobs like that. But if you don't weld a lot of
heavy steel, such things might not be your thing.

MIG doesn't make welds quite as strong as stick, if ultimate
strength is your goal, but it's a whole lot easier to use, and
you don't have those annoying stops and starts when you're doing
a long run. It's a lot easier to get around those bends when
doing small-diameter tubing, too. But beware of the cheap MIG
machines, or used ones. Don't commit to purchasing one until you
know it works to your satisfaction. I welded a new set of floor
panels into an El-Camino for another friend with a MIG he
borrowed for the job. The wire feed mechanism was cheap plastic;
I never did manage to get it to feed smoothly enough to get a
good bead out of it. It was also a small machine, so it would
cut out when I tried to push it too hard. I took the sheet metal
off it and set a floor fan next to it to try and get more cycle
time out of it. That job probably went 2-3 times longer because
of the time I spent attempting welder repair.

Most MIG steel units push the wire through a tube from the box
up to the stinger. Steel filler is stiff enough to pull this
off. But if you want to do MIG aluminum, the units I've seen all
have a spool in the handle instead, because the wire will fold
up inside the normal tubing if you try to push it through from
the bottom. The handle end of these things looks like the big
commercial tape dispensers used to seal boxes. It's large and
heavy. Not great for fine work. Great for biceps.

Summary: Get the MIG and make deals for the stick welding as
needed, like Rob said. There's a place locally called Daytona
MIG that sells a reportedly good 110v portable unit that can run
either flux-core or gas.  I've seen their machine, but haven't
welded with it.

+++ #5465
From:  "Kent White" <kent@t...>
Subject:  Re: [Bearhawk] Welding Heavy Stuff

Tin Man responds:

Gone to make stuff for the H1 for a week, and just back now.

Heavy stuff like you mention is ideal for a good buzzbox
junkyard-style AC stick welder. 200A, $350 at most, and try to
get one with the variable amp adjustment ---and Not the
clickswitch model with only 5 choices of heat.

Miller used to make a good one that I used for 15 years doing
all of the neighborhood thingummies.  Cast iron, heavy plate up
to 3/8, -----but no aluminum...must have DC for that.  But doing
aluminum on 1/8 up to 1/4 is a breeze with the DC stick and
looks really nice.

TIG is great for nicely detailed stuff and the MIG will splash
steel together quick.  Forget about the MIG for aluminum. Unless
doing 1/8 to 1/4" stuff.  Even the $4000 HP machines which are
regarded by the "National Aluminum Specialists" as the best can
do only .063" ....and only on an outside corner...and only with
the finest virtuoso at the controls.

Use dryer circuit, and #8 wire for the 10 ft. needed. If longer
go to #6.  Do Not Starve The Welding Machine For Its Electric
Current. ..........Period.

IMHO,
Kent White

+++ #5647
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  [Bearhawk] Welding Heavy Stuff (by Rube Goldburg)

>Bug your brother and get him to gift us garage tinkerin' tight
>wads with the details of the home made TIG set up. The resistor
>trick alone would provide a way to fine tune the amp setting on
>one of those 5 amp settings to choose from buzz boxes.

Any "Buzz box" or any stick electrode welding machine can be
made into a TIG machine, but let me give you some insight into
the advantages and disadvantages of such a setup. First if you
have a later model machine with an electronic controller board
the amperage control may be setup to be adjustable with a
variable potentiometer. This may have a slight advantage if you
have one of the machines that does not offer fully variable
amperage. A standard TIG machine offers that control adjustable
on the fly with a foot or finger-tip control. That is the major
advantage of TIG in the first place.

Another thing offered by a full fledged TIG machine is the high
frequency circuit. This provides for a ionized path to "start"
the welding arc without having to touch the work with the
tungsten. Touching the work with the tungsten may do two things;
contaminate the tungsten so the arc doesn't form correctly and
actually sticking the tungsten to the work contaminating both
the tungsten and the work. Steel contaminated with tungsten may
cause extremely brittle points in the weld leading to crack
formation. Steel is welded with DC negative with TIG.

AC is used to weld aluminum. The reverse polarity side of the
circuit actually cleans the surface of the aluminum. Because of
the condition of the surface of aluminum, always some oxidation,
when the polarity reverses, the arc will go out... just
quit. The high frequency circuit runs continuously when welding
aluminum to maintain that ionized path to keep the AC arc
established through the polarity reversal. It is almost
impossible to TIG weld aluminum without HF.

One last thing, one of the more expensive consumables of TIG
welding is the cover gas. A TIG machine has automatic solenoid
valves that start and stop the gas flow when starting and
stopping the weld, saving big on gas consumption.

I have one of these add-on TIG units myself and found it limited
in usefulness when doing on-site work when I had only my AC/DC
gasoline powered stick welding machine. I cannot see any
advantage with a setup like this, over oxy/acet, for welding a
tube fuselage.

A last bit of information, there used to be add-on boxes, into
which you plugged the stick machine, that provided the high
frequency and some even provided the automatic solenoid
valves. This was useful if you had a high dollar portable
welding machine with which you made you living. Last time I
looked I couldn't find anyone still making those add-on
units. Their price began to approach that of a good quality
portable TIG like the Lincoln 175.

+++ #5935
From:  "Kent White" <kent@t...>
Subject:  RE: [Bearhawk] Re: Fuel Tanks

Re: Brazing the rivet heads.

I have researched the aluminum brazing industry, even going back
to WW2 when it was first developed. The original material is
still around, but over priced. We supply what Ford Motor
Co. uses in their experimental shops for assembling engines. It
is a beautiful product. Very high quality. And reasonably priced
(yeehaw).  The flux and the rod are sold together, and must be
used together.

Clean rod with scotch brite. Mix flux with clean bottled spring
water (Evian). Clean parts first with alcohol, then with SS
brush.  Flux both part and rod.  Heat with soft flame till flux
runs wet, then touch rod to part.  When temp is right, rod will
run like water and vanish into seam/joint.  When done well, no
great evidence of filler seen, unless closely inspected.

Do not overheat, as temp for braze is only 40F less than melting
of aluminum. If overheated, the rod stops flowing as the flux is
burnt and the aluminum surface is thus oxidized. If this
happens, Stop. Clean and scrub back to bright, and begin
again. Most distortion comes from surface shrinkage (net change
in surface area) as metal contracts to solid from the molten
state.

Distortion: Limit warp by beading along rivet line on each
side. This traps the baffle too, if beads go down. Bead either
up or down, even a quarter inch bead will help
significantly. Same with bungs/fittings. Press up or down around
the fitting area, even to make a platform or mesa (bd)
inhibiting the warp of the heated joint.  BTW, We are still
planning the video on tanks.

Kent "tin man" White

+++ #5957
From:  "Tim Anderson" <fuzzet@h...>
Subject:  Cracked welds

I built my flap torque tube/spring arms several weeks - strike
that - month or two ago.  Had them just sitting on the table,
resting, taking it easy, no stress.  This past weekend I
finished a few other steel parts and was anxious to try out the
new media blaster and my blasting cabinet when...oh my
god....one of the flap arms was cracked right across the weld on
the top side of the slip tube.  The weld was cracked, not the
steel part.  My welds looked OK, but maybe a tad bit on the thin
side.  Anyway, it got the torch treatment again, with some extra
filler.  To all you welding experts, what did I do wrong, so I
don't do it again.  No, I didn't shock cool it.

On a side note, I bought an el-cheapo portable roller stand at
harbor freight, commonly used with a table saw.  It has a 12
inch roller top that is adjustable up and down.  It makes a
dandy portable/adjustable arm rest for welding.  My welds
improved by quantum leaps and bounds. I need all the help I can
get.

Tim #398

+++ #5959
From:  "Kent White" <kent@t...>
Subject:  RE: [Bearhawk] Cracked welds

Could it be a mixup in the filler rod dept?  Perhaps central
supply mixed in one or two errant sticks of Tig-only material?

Kent "been tricked before" White

+++ #5960
From:  "Tim Anderson" <fuzzet@h...>
Subject:  RE: [Bearhawk] Cracked welds

I used RG45..I do have some ER 70S-06 around, but I don't think
I grabbed one of those.  Have to double check my rod container
and see if some commy-picko store-aways got in by mistake.

Tim

+++ #5965
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  RE: [Bearhawk] Cracked welds

That er70s-6 will work just fine with oxy/acet. My thought is
that you've run a small bead therefore not getting enough heat
into the process. Next question is: were your finish puddles
filled so when cooled there is no concave crater? 99% of the
cracks I have observed on 4130 started from a poorly filled
crater with a spot of porosity at the bottom. Another
possibility is that with a small bead sometimes the material is
not fully melted to get a 100% penetration. When two pieces of
4130 are butted hard against each other (no gap) and the weld
does not fuse all the way through, the back side can act as a
restraint so the normal shrinkage that takes place upon
solidification of the puddle causes the filler metal to crack.
The weld bead has to be large enough to provide the
give/stretch/elasticity needed during normal shrinkage of a
cooling weld. Heavy restraint of the pieces combined with a
small fillet can precipitate cracking. Don't be afraid to
deposit a good size bead. Look at some of the older Piper welds,
welding .035 wall tube, but the fillet is 1/4" across the
face. Don't try to weld as small a bead as possible.

Bruce A. Frank

+++ #6276
From:  "Dave Visser" <dave@a...>
Subject:  RE: [Bearhawk] 4130 TIG welding rod

Can anyone tell me the best rod to use to TIG weld my 4130
fuselage together with. I've read in building manuals that I
should be using 4130 rod and then normalize, but I called
Wagaero and they recommended that I use ER80S-02 (which is a
mild steel rod) and I don't normalize. I have my fuselage
completely tack welded, and I hope to do the finish welding this
weekend (wife is out of town). I don't want to start a
discussion about TIG welding vs. gas welding, because I am going
to use TIG. Any advice or comments would be appreciated.

Dave Visser

+++ #6277
From:  rsmith@a...
Subject:  Re: 4130 TIG welding rod

First of all, dont use 4130 rod unless you are going to be heat
treating the piece afterwards for high strength. There are no
parts on the Bearhawk that require that. Bruce Frank (on the
list) recommends the ER70S-D6. I use that and it works well for
me, both with Tig and with gas. When gas welding I remove the
copper coating so that it melts easier. Kevin Kimball who puts
out the Pitts model 12 kits recommends the ER80S-D2 for tig
welding. He says that is the only rod that you can reweld over
without the filler metal bubbling.  I dont know about that as I
haven't tried it. I can buy the 70S-D6 locally but not the
80S-D2. I know you can order it through www.hi- techwelding.com

Rod Smith #246

+++ #6280
From:  "Bruce A. Frank" <bafrank@w...>
Subject:  RE: [Bearhawk] 4130 TIG welding rod

Some will disagree with me but I recommend ER70s-6 for TIG (and
oxy/acet too). Dash 6 filler was originally developed for MIG
welding. It has a higher percentage of deoxidizers so bubbles
and pin holes are almost non-existent. It flows and "wets out"
better than -2. I have met few who don't agree with me once they
have tried it (beats RG45, RG60 and all of the others, even some
of the fancy stainless derivitives) Mild steel rod is the only
filler you should with 4130 UNLESS there are specific
instructions specified by the designer for building a part that
will be heat treated.

If using it with Oxy/acet it behaves better if you Scotch Brite
the copper plating off before welding with it. The copper plate
caused no problem when TIG welding, but even there it is
smoother welding with clean Scotch Brited rod.

Bruce A. Frank, Editor 

+++ #6464
From:  "dean robert cramb" <shoptalk47@t...>
Subject:  175

What pricing did you guy's get on the Lincoln 175 Pro?
The local dealer here Quoted me $2,200 Cdn.

+++ #6465
From:  rsmith@a...
Subject:  Re: 175

$1328 US at Sun&Fun, dont know if there will be a similar deal
or not at Arlington.

Rod Smith #246

+++ #6532
From:  "Mark and Tina Lapierre" <lapierre@s...>
Subject:  Re: [Bearhawk] Kind of flying

Go to www.tinmantech.com , that's Kent's web site.

I bought one of these too. It's not terribly expensive and it's
worth every penny of the price and more.

Mark Lapierre
#493

+++ #6810
Date: Wed, 11 Jul 2001 18:37:28 -0700
From: Russ and Penny Erb erbman@
Subject: More welding tips

One of the running themes in our welding discussions is when
possible, leave a part long and trim as required after welding.
Same goes for drilling holes after welding.  Usually the issue
is that the piece will shrink as the weld cools.

Today's job was to weld in the bushings in the horizontal
stabilizer for the forward strut and the elevator hinges.  Per
the plan, these bushings are only 1" long in a 7/8" tube.
That's only 1/16" sticking out of either side.  I could see that
melting away real quick and causing a problem.
 Therefore I left about 1/2" hangin' out both sides to weld it in.  Now 
I'll go back with a cutting wheel and trim it to size.

A question for Bill Johnson: I was reviewing the picture of your
rudder stops.  They have a nice head on them, as though you used
16d nail heads.

 Is that what you did, or how did you make the heads?

Russ Erb

+++ #6812
Date: Wed, 11 Jul 2001 21:42:41 -0700
From: Russ and Penny Erb erbman@
Subject: Done!

Then at last...I have "finished" my first major tubing structure
outside of the wing--a horizontal stabilizer.  Which one? Don't
know--they're identical.  It even still fit in the jig, so the
distortion was minimal.

I say "finished" because there are several operations that won't happen 
until it is matched up with other parts.  For instance, the root ends won't 
be trimmed or the holes drilled until there is a fuselage to mate them to. 
 The bearings for the trim tab torque tube only have a single tack on them. 
 That way they can be properly aligned when both stabilizers are
on the fuselage and the two torque tubes are together.  Wouldn't
want them finish welded and not aligned!  The hinge support V's
will be trimmed when the elevator and hinges exist.  Much of
this guidance came from Bill Johnson's tips (available on his
web site and the Bearhawk CD)

While I can't prove it, the distortion may have been reduced by
using another technique I think has been mentioned in this
forum.  The basic concept is that distortion occurs when you
pump too much heat energy into one area of a structure.  To
avoid this, weld one end of one rib, then jump to the other side
of the structure on another rib.  Sort of like tightening lug
nuts on your car--you don't just go around the circle--you
criss-cross between lugs.

On a similar note, someone was talking to me about welding fuel
tank.  I think he was showing me one that had virtually no
distortion.  He said that he did not just weld the seam from one
end to another.  He welded in short beads of about 2 inches and
jumped around such that the beads were evenly spaced.  That way
no section of the tank got too much heat (and thus expand too
much) and all of the panels became well supported, much like
having a whole mess of tack welds.

All for now...

Russ Erb

+++ #6813
Date: Wed, 11 Jul 2001 22:15:45 -0700
From: Budd Davisson buddairbum@
Subject: Re: distortion

A lot of distortion also comes from the weld being on one side
of the tube only and causing that area to shrink. When finished
with the bead, keep the area hot and move around to the outside
of the tube and heat it almost up to welding temperature and let
it shrink with the other side. Won't eliminate all distortion,
but keeps it within limits, especialy, when welding tabs nd
stuff on.

Owning a really big rubber mallet also helps.

bd

+++ #6814
Date: Wed, 11 Jul 2001 23:04:22 -0700
From: "Kent White" kent@
Subject: RE: Done!

One method of "controlling" distortion is not to encourage its
accumulation.  So: balance the stresses. Weld opposite when
possible. Weld in segments, and opposite each other when
possible.  When welding one side of a tube, heat the other side
too, to balance the stress.

I have a method for installing a filler neck in a flat polished
tank surface, with no distortion. Yes, it is welded. It boggles
a few to view it, but it can be done.

Kent White

+++ #6815

Date: Thu, 12 Jul 2001 00:44:48 -0700
From: "Bruce A. Frank" bafrank@
Subject: RE: Done!

> One method of "controlling" distortion is not to encourage its
> accumulation.  So: balance the stresses. Weld opposite when
> possible. Weld in segments, and opposite each other when
> possible.

Have you put this distortion free filler neck installation on
tape? I want to know how! I am building tanks right now in which
the tops of the tanks are airfoil shaped and are intended to be
the top of the wing in the tank bay. As careful as I was,
welding a flange extension to the top edge of the tank, to
provide for screw mounting similar to the way the tank cover on
a Piper wing is screwed down (not the only method of holding
this tank in place), my final few inches of weld caused an
oil-can like dimple. Small and easily filled, but extremely
irritating to one who prides himself on distortion free
welding. That incident frustrated me so that I riveted the
filler rather that attempt to weld it. My materials are .065"
5052 aluminum welded with TIG. I welded 1" segments using the
back-step method (usually reserved for stainless, but I've found
effective for large expanses of aluminum also) alternating from
one edge to the opposite edge after each 1" of weld. I allowed
cooling between passes so that temperatures, though too warm for
contact with a bare hand, never became uncomfortable for my
thinly gloved hand to lie directly on the previous weld to make
the next 1" section of weld. The whole top of the tank was tack
welded every 1" or less to the flange extension. The tank top
had previously been welded to the body of the tank using the
edge of the outside flange melt method (3/8" flange top to side
of tank, well clamped and tack-welded before melt welding the
edge) No distortion was visible when the flange extension
attachment was started. No distortion was apparent until the
final few inches of welding the extension. The tank top to
flange extension was not welded all in one sitting. About 1/3
done each day over three days. This has stymied me to the point
of not finishing the second tank after six months now.

Additional info: The top of the tank was rolled to the USA35B
airfoil section, not just clamped down the tank's sidewalls,
before welding began.

Bruce A. Frank

+++ #6821
Date: Fri, 13 Jul 2001 12:15:47 -0000
From: bearhawk260@
Subject: Re: Done!

> concept is that distortion occurs when you pump too much heat
> energy into one area of a structure.  To avoid this, weld one
> end of one rib, then jump to the other

Yep great technique.  My father was and still is for that matter
a professional (was certified) welder and frequently uses this
technique to weld without distortion.  Had all his co-workers
asking how he did such a great job without warping the metal.
Its all in experience and technique.

ht

+++ #6864
Date: Mon, 16 Jul 2001 23:25:43 -0800
From: "Float-By Shooter" del@
Subject: Re: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

> As a note Mr. Pat Fagan, there was a Square Wave 175pro on
> wheels in his shop.....Yes, he welded most of the fuse with it
> and commented, "I love it, it is the nicest welder I've
> used".....Maybe I should have stayed until Sunday Close ;-)

I really love my 175.  The one thing that I would change, would
be to add controls to regulate the argon post-flow time.  It is
permanently set for 15 seconds which is often way longer than
needed and unnecessarily wasteful of gas.  Now for 4130 I'd
probably keep it adjusted for a good healthy post-flow just to
be sure to protect the cooling puddle, but a lot of the stuff I
weld is non-critical mild steel (like body panels) and 15
seconds is just overkill.  The other thing I'm going to change
will be to get a longer cable and hose!  That is one serious
advantage that an O-A rig has; it is much more easily wheeled
around a large project like a fuselage.  The 175 wheels just
fine, but it's tied to its outlet.

Please forgive me if I start the debate again, but I was
commenting to somebody the other day about how everybody says
not to buy the TIG just to weld one airplane together, but the
thing is, you don't just use it for that.  It has come in really
handy a number of times, most notably earlier this summer when
the inside driver door handle on one of our delivery trucks came
off; the underlying metal failed due to fatigue.  I was able to
get away with just removing the door panel, tigging in a repair
piece, and get the truck back in service within an hour or so,
instead of farming it out to a local welding shop who would have
finished it who knows when.  I would never have dared to make
that repair with an oxyacetylene torch for a couple of reasons,
the metal was extremely thin and I'd be afraid of burning it up,
and the fear of setting the door internals afire.  The
concentrated heat of the tig kept the collateral damage to a
minimum, just a little localized scorched paint.

Del Rawlins--

+++ #6876
Date: Wed, 18 Jul 2001 09:31:17 -0700
From: "Kent White" kent@
Subject: RE: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

Re: post-weld gas flow for TIG on 4130.

For best brittleness be sure to have high flow rates and long
time for flow.

For best toughness and durability, .25 second and 5cf/hr.

You see, if you can gas weld the stuff without a flux and
without an inert gas shield, then why be all concerned about
protecting the puddle using TIG?  If you think about it, there
is a thread of "common" sense in the process.

Kent "see you at the Osh Workshops" White

+++ #6882
Date: Wed, 18 Jul 2001 17:56:40 -0700
From: "Owen Davies" owen@
Subject: Re: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

> Re: post-weld gas flow for TIG on 4130.
>
> For best brittleness be sure to have high flow rates and long time for
> flow.
>
> For best toughness and durability, .25 second and 5cf/hr.
>
> You see, if you can gas weld the stuff without a flux and without an inert
> gas shield, then why be all concerned about protecting the puddle using
> TIG?
> If you think about it, there is a thread of "common" sense in the process.

I posted the above (without attribution) to
sci.engr.joining.welding for a response from some heavy-duty
weldors.  My own thought was that I'd rather keep the gas
flowing than expose the hot steel to the air so as to avoid any
risk of scale formation; thus I could just use an etching
primer, rather than having to sandblast a tube structure
approaching 20 feet long.  However, this is what Ernie
Leimkuhler (a pro weldor who supplies a lot of good info on
s.e.j.w. and rec.metalworking) had to say:

> Gwyn [Phillips] gave my answer.
> 
> The gas shield is there to protect the tungsten more than the
> steel.  A 7-10 second flow is pretty standard on a 3/32"
> tungsten, a little shorter for a 1/16" tungsten.  The gas
> shield can prevent some oxide formation, and really can't hurt
> anything.  If the flow is too long you will just be wasting
> gas.  On stainless steel welds I often up the flow to 15-20
> seconds to help prevent oxide formation.

Sounds right to me.  I'd be much surprised if even 15 seconds of
post-weld gas flow at normal rates would chill the steel enough
to cause brittleness.

Owen Davies

+++ #6883
Date: Wed, 18 Jul 2001 18:26:34 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

> The gas shield is there to protect the tungsten more than the
> steel.  A 7-10 second flow is pretty standard on a 3/32"
> tungsten, a little shorter for a 1/16" tungsten.

I am going to have to put in my two cents worth here on the
chance that some might think I am picking nits. The tungsten has
to be protected from the atmosphere while glowing hot. Now on to
the molten puddle. When oxy/acet welding the molten puddle
actually in enveloped in a protective bubble of gas... the
envelope of the flame protects the molten steel from atmospheric
oxidation. As you move on the puddle chills and solidifies and
as the flame envelope gradually moves off exposing the still
read hot metal to the atmosphere just a thin layer of oxide
forms on the surface.

If the heat to melt the base metal and the filler rod could be
generated any other way there would still have to be a
protective envelope over the molten puddle. Post flow on
machines that have adjustments are worked out not just to
provide cover for the tungsten, but to provide cover long enough
for the puddle to solidify after the arc is stopped.

Bruce A. Frank

+++ #6886
Date: Wed, 18 Jul 2001 20:58:21 -0700
From: Russ and Penny Erb erbman@
Subject: RE: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

> For best brittleness be sure to have high flow rates and long
> time for flow.

Here's my interpretation of what Kent was trying to say:

We've all heard that welding in a draft is bad, because 4130 is
air-hardening.  To keep it near a "normalized" condition, it
must air cool in still air.  It seems to me that having argon
blowing over hot 4130 for 15 seconds would have the same effect
as having air blowing over it.
 Hence, Kent's comment about brittleness (in case you missed it, that's 
bad)

So based on my non-professional welder's analysis, it would seem
the answer if TIG welding would be when finishing a weld, stop
the current, slowly withdraw the torch as you would slowly
withdraw the welding flame as the metal solidifies, then move
the torch away from the joint and let the argon flow as long as
required to let the tungsten cool.

Russ "Just a Dirt Farmer's Understanding of Welding" Erb

+++ #6887
Date: Wed, 18 Jul 2001 21:26:37 -0800
From: "Float-By Shooter" del@
Subject: argon flow


> We've all heard that welding in a draft is bad, because 4130
> is air-hardening.  To keep it near a "normalized" condition,
> it must air cool in still air.  It seems to me that having
> argon blowing over hot 4130 for 15 seconds would have the same
> effect as having air blowing over it.  Hence, Kent's comment
> about brittleness (in case you missed it, that's bad)

Yup, that's exactly why I'm planning on stress relieving some of
the more highly stressed areas with an oxy-acetylene rosebud,
per Bruce's past recommendation.  It's definitely something I've
thought about.

> So based on my non-professional welder's analysis, it would
> seem the answer if TIG welding would be when finishing a weld,
> stop the current, slowly withdraw the torch as you would
> slowly withdraw the welding flame as the metal solidifies,
> then move the torch away from the joint and let the argon flow
> as long as required to let the tungsten cool.

Well, what I've been doing at this point (on non aviation items
it should be noted) is finishing the weld, and as soon as the
puddle has solidified I move on to the next weld if possible, in
order not to waste so much gas on post-flow.  It usually doesn't
take more than a few seconds for that to happen, so 10 or more
seconds of argon flow is wasted.  Considering that I need to
have this stuff shipped in, its mildly annoying.  I'm eventually
going to experiment with the flow rates some more to find the
minimum I can get away with under different conditions.  I might
also buy a gas lens for my torch to replace the cup with, which
might give better argon distribution and should allow me to work
around clusters more effectively.

After reading some of the varying opinions, I'm beginning to
think that Lincoln made the post flow on my machine (SWT 175)
non- adjustable so that an amateur welder like me (its apparent
target market) wouldn't be able to adjust it wrong.  Can't
really argue with that logic, I guess.

Del Rawlins--

+++ #6889
Date: Thu, 19 Jul 2001 00:07:08 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: argon flow

> After reading some of the varying opinions, I'm beginning to
> think that Lincoln made the post flow on my machine (SWT 175)
> non- adjustable so that an amateur welder like me (its
> apparent target market) wouldn't be able to adjust it wrong.
> Can't really argue with that logic, I guess.

I can argue with that logic. If the post flow is adjusted
incorrectly there is little impact on anything other than the
contamination of a tungsten or the possibility of adjusting flow
even higher. Things even a novice will pick up on fairly
quickly. But, with it permanently set at 15 seconds there is a
significant drain on the most difficult to obtain consumable.

There are wheel type valves designed to be installed in the gas
line right below the torch. This might be a solution. You can
bypass the gas solenoid valve and plumb directly to the
torch. The draw back is that I invariably forget to turn it on
again.

Del, I don't know how handy you are, but on an early machine I
had the timer die. I installed (taped) a micro toggle switch on
the torch body wired directly to solenoid gas control valve to
cut the gas on and off manually bypassing the machine
electronics. It worked well for several years. Since my switch
setup carried the full electrical load of the solenoid valve I
had to replace it several times. Probably a small relay designed
to handle the relatively light electrical load would have
eliminated the wear on the micro switch. ( I could easily flick
the switch with the welding hand, but the wheel type gas control
valve required my other hand to operate it...which is why I
probably forgot to turn it on all the time. The wheel valve and
switch have the hazard of being left open/on and draining the
cylinder of argon)

A gas lens helps some, particularly in tight areas like a
cluster. The lens will allow you to extend the tungsten a bit to
reach down into a tight area. I have never tried actually
reducing the flow rate and allowing the lens to make up for that
reduced flow. Let me know if it works. In general I find a lens
to improve the function of the torch, but the somewhat larger
size of the nozzle gets in my way when working in tight tube
clusters. Then again, I am very hooked on the WP20 type water
cooled torch because of its very small size, so my assessment of
the bulk of the lens type may be flawed.

  -- Bruce A. Frank

+++ #6893
Date: Thu, 19 Jul 2001 06:59:57 -0700
From: "Owen Davies" owen@
Subject: Re: Builders/Arlington/Oh Yeah - And 4.6 230cu.in. BHawk 

> So based on my non-professional welder's analysis, it would
> seem the answer if TIG welding would be when finishing a weld,
> stop the current, slowly withdraw the torch as you would
> slowly withdraw the welding flame as the metal solidifies,
> then move the torch away from the joint and let the argon flow
> as long as required to let the tungsten cool.

If I understand correctly, you would physically pull the TIG
"torch" back from the puddle, much as you would slowly remove an
O/A torch?  If so, you may be in for some disappointment.  The
cases are not really similar.  Pulling the tungsten back does
not reduce the heat smoothly and evenly, as it would with a gas
torch.  Instead, it makes the arc weak and irregular.  The heat
remains as intense where the arc hits, but it is no longer
distributed well, and the surrounding metal tends to chill the
puddle in the unheated areas.  Or so I interpret what was said
in a recent thread on the welding newsgroup.  Whatever the exact
mechanism, the result is a depressed surface at the end of the
weld, with an appearance of crazing.

Among other activities, Ernie Leimkuhler teaches welding at a
community college in the Seattle area.  He commented that when
teaching TIG to gas weldors, he often has to break them of the
habit of removing the torch from the puddle.

I believe, but do not know from experience (not yet being a TIG
weldor myself), that the TIG equivalent would be to back off
slightly on the amperage at the end of the weld.  Makes sense if
you think about it for a minute.  Of course, so do many things
that are wrong.

Owen Davies

+++ #6894
Date: Thu, 19 Jul 2001 07:16:25 -0700
From: "Owen Davies" owen@
Subject: Re: argon flow

> Yup, that's exactly why I'm planning on stress relieving some
> of the more highly stressed areas with an oxy-acetylene
> rosebud, per Bruce's past recommendation.  It's definitely
> something I've thought about.

You know, that was originally my plan, but much as I respect
Bruce's views on the matter I've had to reconsider post-weld
heating, .  Two or three days ago, I exchanged messages with
Kevin Kimball on this subject.  He reports that in restoring
many airplanes and building the Pitts Model 12, which the
Kimballs market, they have decided against "stress relieving,"
as it cannot be done to adequate tolerances in any normal
aircraft shop.  The risk of messing up the steel even worse
apparently outweighs any hope of improving things.  (Richard
Finch makes this point at some length in his book, "Performance
Welding.")  I believe Aviat also does without post-weld heating,
and I've heard of no problems with their S1 and S2 models.  The
Kimballs and Aviat both use TIG.

My own rather casual observation is that it's usually the self-
taught traditionalists who want to "stress relieve" their welds.
The more weldors know about metallurgy, the less likely they are
to endorse this practice.  Or so it has been in my experience of
asking about this issue at every opportunity for something like
ten years.

Owen Davies

+++ #6895
Date: Thu, 19 Jul 2001 05:37:37 -0700
From: "Kent White" kent@
Subject: RE: argon flow

Watch out when quoting Finch.  Some of his facts are good, some
are a little shakey.

Kent White

+++ #6897
Date: Thu, 19 Jul 2001 09:06:23 -0400
From: Bob Romanko romanko@
Subject: RE: argon flow

At PIA I had a VERY GOOD welding instructor.  This guy lived and
breathed welding.  We restored quite a few rag 'n tube fuselages
there, and the practice we were taught is one often repeated
here.  He did NOT stress stress relieving without a big honkin'
oven.  He did not recommend playing around with rose bud tips.
Claimed you would do more harm than good.
 
I was taught "Take your back 'round the patch" when finishing a
gas weld.  What it means is that when welding a cluster you need
to heat the backside of the cluster as well and finish off the
weld by taking the flame around the cluster.  Never pulling the
torch away quickly.
 
I'm nowhere near the expert welders that Kent White, Bruce Frank
or Budd Davisson are, but this simple saying is a reminder to
keep the cluster evenly heated and gradually remove the flame.
It works for we metallurgicly challenged folks.
 
Nothin' fancy, but got me through a six-tube cluster on my FAA
Practical Exam for the "P" part of my A&P ticket!  That one weld
had more stress in it than I could ever relieve anyhow (grin).
 
For what it's worth...
 
Planter Bob

+++ #6898
Date: Thu, 19 Jul 2001 09:41:52 -0400
From: "Mike Carriere" mcarrier@
Subject: Re: argon flow

> Watch out when quoting Finch.
> Some of his facts are good, some are a little shakey.

While I agree with Ken about Finch's facts the man is not wrong
when it come to stress relieving. We are in the quench and
temper steel busines (granted much thicker sections) it is a
very controlled process of time and temperature.  I don't
believe a rosebud could properly do the job without making a
cabinet and control the ramp up temperature and cooling rate.

+++ #6900
Date: Thu, 19 Jul 2001 06:50:45 -0700
From: Budd Davisson buddairbum@
Subject: Stress relieving

Here's the drill on stress relieving from a self-taught
traditionalist who has done a lot of research and still hasn't
gotten a clear answer:

A problem with both TIG and MIG is that they bring a very narrow
area up to welding temperature almost immediately. This
introduces thermal shocks of it's own, but then, when the weld
is done, because the surrounding area wasn't pre-heated, it acts
as a sponge and sucks the heat out of the welded area very fast,
ntroducing some more stresses from contraction, plus it raises
the Rockwell hardness of the weld by a measurable amount.

According to the tech department of Eutectic corp, who, among
other things makes alot of our welding rod, you can see hardness
get as high as 45 Rc in a MIG weld and 40 Rc on a TIG. That's
almost glass-hard. This, according to Eutectic, is the result of
martinzite build-up from too-rapid cooling rates.  Done
correctly, however, 28-40 Rc is more normal. Still pretty high.

The real problem is that while the weld is hard, the tubing next
to it has gone from its natural state of around 19-23 Rc to
under 5 next to the weld where it has been heated then back up
to what ever the weld is, so there is a hardness discontinuity
that can lead to fatigue cracking next to the weld.  A gas weld
is down around 1-2 Rc next to the weld and 20-25 in the weld.

A gas weld spreads the heat out much further and can't get
nearly as hard so the hardness discontinuity isn't nearly as
profound. Also, the act of preheating, which is critical to a
good gas weld to get the bead flowing easily, heat-soaks the
surrounding area so it doesn't have as much of a "sinking"
tendency and doesn't suck as much of the heat out so quickly. If
that were done for TIG welds, the hardness and distribution of
locked-in stresses would be better, but then you'd lose some of
the convenience of using a TIG in the first place. MIG is really
bad in this area because it's you basicaly have zero control of
over the heat build-up.

Eutectic also tossed something else into the mix. They said the
Petroleum Institute won't let a MIG pipeline weld be harder than
30 Rc because the chances of hydrogen embrittlement of the weld
go up quickly as you pass that hardness. Also, they don't want
that much martinzite in the weld. They say rapid welding,
including TIG, but primarily MIG can capture moisture out of the
air or from the material locking the hydrogen into the weld
causing microscopic cracks in a coupe of days. They say even TIG
will do that if welding quickly, with a little too much heat, on
a very humid day.

Eutectic strongly recommends both pre- and post-heating not only
to stress relieve but to cook the hydrogen out.

All that having been said, Pitts doesn't stress relieve, and the
only fractures we've seen have been the result of overstressing
the airplanes.  However, those fractures are almost all right at
the edge of the weld in the hardness band. American Champion
MIGs their fuselages and the FAA okays a hardness of 38-41
Rc. Go figure!

My own, traditionalist-driven practice, is to pay attention to
cooling rates of all welds and I pre-heat, then stress relieve
while I'm welding, reheating the cluster or fitting, as I finish
the weld and it's still hot and let it cool down sightly.

It's important we keep the terms "stress relieving" and
"normalizing" separate. Normalizing is a specific heating
schedule that controls the martinzite and pearlite (both
crystaline changes in the material) build-up.  Stress-relieving
is a much cruder situation that simply "relaxes" the stresses
captured in the part by rapid heating and cooling. This takes
little or no technology and only basic understanding: heat the
entire area dull red, hold there for a few seconds and play the
torch on it while it cools slowly.

We are gas welding AviPro fuselages but TIGing tails and landing
gear and we're stress relieving all critical welds. We can't
prove it does any good, but we know it's not hurting
anything. Also, we're welding everything that can be reached
while it's still clamped in the steel jig. We've found
everything stays much, much straighter that way.

sorry, didn't mean to ramble.

bd

+++ #6902
Date: Thu, 19 Jul 2001 10:36:11 -0700
From: "Owen Davies" owen@
Subject: Re: argon flow

> Watch out when quoting Finch.
> Some of his facts are good, some are a little shakey.

Yup.  However, his comments about stress relieving are one part
about which I've found credible criticism to be at a minimum.
Budd's comments this morning are the first reasonably
authoritative statement I've heard in favor of stress relieving.
Even there, however, I have to wonder whether Eutectic was
thinking of going at a large structure with a rosebud or
imagined that they were discussing a more controlled process.
Checking that point with them just went on my to-do list, unless
Budd can confirm that they understood exactly what was intended.

Owen Davies

+++ #6903
Date: Thu, 19 Jul 2001 07:35:00 -0700
From: Budd Davisson buddairbum@
Subject: Re: stress relieving vs normalizing

I think we're confusing stress relieving with normalizing
here. In fact, way too many times we see the two terms used
interchangeably and they aren't.

As per my last e-comm, as I was taught in materials classes,
normalizing is a controlled heating process aimed at controlling
crystalline change while stress relieving is aimed at relaxing
locked-in stresses caused by expansion/contraction, not material
change.

There is no way normalizing can be done outside of a cabinet,
but stress relieving only requires the judicious application of
heat.

bd

+++ #6904
Date: Thu, 19 Jul 2001 07:40:53 -0700
From: Budd Davisson buddairbum@
Subject: Re: argon flow

When I did the interview with the VP of Technology at Eutectic,
he understood exactly what I was talking about. We talked about
the exact types of structures in detail. Also, here again, we
have to keep normalizing and stress relieving separate in our
minds and our conversations. Two different processes aimed at
two different goals.

When welding high-carbon steels, Eutectic was emphatic about
both pre-heating and post heating.

I personally watched a TIG bead being laid into the gear box of
a 195 Cessna. About five inches of weld in a 90 degree
fillet. He jumped right on it with the heat up, shut down at the
end, and as we watched it cool, a crack started at one end and
worked its way all the way to the other end.  Wierdest thing i
ever saw. We could take the pieces apart with our fingers, when
cool.

That one incident is what got me started on the pre/post heat
band wagon.

bd

+++ #6906
Date: Thu, 19 Jul 2001 15:37:25 -0000
From: rsmith@
Subject: Re: argon flow

The lack of an adjustable post weld purge timer seems to be the
only complaint heard about the Lincoln SW 175 welder. Sure seems
that someone would be able to design an add on to provide that
function. I have been using a gas lens and a flow rate of 8cfh
without any noticeable oxidation. The gas lens is definately
larger and I switch back to the normal head when welding tight
clusters. Even then I find that you have to extend the electrode
and jack up the flow rate to compensate. Del, I also needed a
longer torch cable and went with the WP20 water cooled torch
with 25' cable. You dont need a water cooler if you have a water
tap in your shop. The torch only needs about a quart a minute
and as Bruce mentioned is more compact than an air cooled
torch. Found mine on E-Bay.

Rod Smith #246

+++ #6907
Date: Thu, 19 Jul 2001 10:04:42 -0700
From: "Kent White" kent@
Subject: RE: Re: stress relieving vs normalizing

Re: stress relieving vs normalizing

Once the confusion about stress-releif and normalizing are
settled, then the choice of one's method of stress-relief
remains.

Bob R's method of "back around the patch" is the same used by
Budd, and the one we use on our 4130 film. Mr. Finch, esteemed
scholar though he may be, stomps all stress-relief flat, never
admitting that one traditional and proven method just might be
acceptable. I do not know of any aircraft builder who uses the
rosebud method, nor of any factory who did.

I do know of the Maule and Kitfox problems with their MIG welded
joints.  Also, what the engineers, FAA, and insurance companies
agree to insofar as method is a matter of their liability for
that particular design...and is in no way a yardstick for the
rest of us.

One weld engineer for a large commercial builder told me the
method they devised for TIG welding 4130 tube that needed no
stress relief, and passed all bend and Rockwell tests: Use
minimum amps (80 for thin sections), gas flow at 4-6, and purge
time at .25 seconds.

Weld in still warm air, be aware of excessive humidity (does the
tube sweat ahead of the weld?), and allow for a very gentle
cooling rate.

Now, about that vacuum-melt high-buck filler rod.......

Kent White

+++ #6908
Date: Thu, 19 Jul 2001 09:22:59 -0800
From: "Float-By Shooter" del@
Subject: Re: Stress relieving

> We are gas welding AviPro fuselages but TIGing tails and
> landing gear and we're stress relieving all critical welds. We
> can't prove it does any good, but we know it's not hurting
> anything. Also, we're welding everything that can be reached
> while it's still clamped in the steel jig. We've found
> everything stays much, much straighter that way.

Wow.  Thanks to everybody for the excellent round of posts on
stress relief/normalizing.  I sure didn't mean to start that up
again, but it seems to have been worth it.  8^) With all the
discussion on this topic over the years, both here and on
rec.aviation.homebuilt, there is still one thing which I do not
quite understand.  Some people, like Budd here, say that post
weld heating for stress relief might not do any good, but
doesn't hurt anything, while others claim that it can or will
make things worse.  I'm not sure how heating a joint to a dull
red (or maybe even hotter) with oxy-acetylene is going to hurt
anything, considering that it is okay to weld it with o/a in the
first place.  It just seems like 2 different ways of arriving at
the same result to me, but admittedly I only have a limited
understanding of the metallurgy involved.  FWIW, I'm not
planning on stress-relieving every cluster, only places like the
gear/float mounts, spar and strut attach points, tailwheel area,
and where the engine mount attaches on the firewall.

It should be noted that I can weld up my Bearhawk either way,
with tig or o/a.  I'm not a zealot or anything; if I were to
become convinced that o/a was a better way to go, I'd for sure
be going that route.  There are various reasons why I have the
tig machine, but probably as much as anything I like learning
new skills.  Having used the tig enough to get comfortable with
it, I find that the cleanliness amount of control over the
process are also appealing.  The downside is the cost and the
extra space it takes up, but as i've mentioned before, somebody
my age (late 20's) can't go wrong buying nice equipment since
I'll have it a while.  The SWT 175 also doesn't take up any more
space than the buzz box which it does double duty for, and which
I would have anyway.  The extra cost and space of the O/A rig is
a non issue as well, since I would want one for a cutting torch
(not for aircraft use, LOL).

Del Rawlins--

+++ #6911
Date: Thu, 19 Jul 2001 11:02:16 -0700
From: Budd Davisson buddairbum@
Subject: Re: Re: MIG

> I do know of the Maule and Kitfox problems with their MIG
> welded joints.

You only have to spend about two minutes on the Maule production
line to know why they have problems. They treat the welding as
if they are working 1018 steel in a cow feeding rack. My friend,
Jim Clevenger, called me after his plant tour (I'd seen similar
on my tour) where he watched one welder who wasn't even using a
helmet. He just turned his head as soon as the arc started and
wandered back and forth until the valley was full of weld.

They have one person on each fuselage jig position with a 4"
grinder and it is his job to go back after the fuselage is
welded and knock down all the high points that might show
through the covering. Nice!

TIG has a few areas of caution, when welding 4130, but MIG is so
operator-dependent, both for technique and understanding, that
I'd prefer to never see it used on aircraft, even though I know
it is. Among other things, it is much worse than TIG in terms of
locking in stresses. Bam! The steel is melting. Bam! No more
heat is going in and the rest of the strucure is sucking heat
out of it as fast as it can. Not good!

bd

PS - And then there were Stinsons and T-6's which were both
stick welded. Now THAT I'd like to see how it's done.

+++ #6912
Date: Thu, 19 Jul 2001 11:14:41 -0700
From: Budd Davisson buddairbum@
Subject: Re: Stress relieving

Del: two points

First: We don't want to hear that you're in your late 20's. I'm
wearing boots older than you are. gheez! Give us a break.

Second: one reason I preach gas over TIG for one-time airplane
builders is that you're gong to need the gas for bending and
pre/post heating (although propane can do that) anyway, so why
not weld with it?

TIG also requires a much tighter tolerance on the tube
fitting. Not that I'm preaching sloppy fits, it's just that gas
is more tolerant in that area.  Actually, gas is more tolerant
in general so the guy who doesn't weld a lot is less likely to
have problems.

That having been said, having a TIG around the shop can't be
beaten for a lot of work.

bd

+++ #6924
Date: Thu, 19 Jul 2001 18:19:04 -0700
From: "Bruce A. Frank" bafrank@
Subject: Post-Flow "chilling"

First off, everyone should take Finch's book and opinions about
welding with a LARGE grain of salt. I do not strain relieve my
TIG welds. I do strain relieve SOME of my MIG welds (yes, I
think MIG acceptable on 4130 in some applications). My opinion
is that all welded tube fuselages built from 4130 are over-built
to the point that no single point gets loaded to the level that
strain relieving is necessary. (But, when I used to share the
Ghetto Hangar at New Garden Airport with Diann Hackala(sp?) I
saw several cracked welds in her factory built Pitts caused by
her off-the-scale acro routine...she flies a Stoddaker(sp?) 300
now I think)

If 4130 can be welded successfully with oxy/acet then going
after welds with a rosebud to gently postheat is not going to
cause problems with the fuselage....Finch is incorrect on this
point in his book. Post heating can be done VERY precisely if
needed by using welder's temp sticks (crayons that melt as
specified temperatures). But I think it seldom necessary.

Let me pass along another observation. When you let off on the
peddle when TIG welding, the argon coming out of the nozzle is
not cool, it is not chilling the weld. The gas is coming through
a ceramic cup past a tungsten which are still 2000+ degrees. The
gas, even at 20 cf/hr, is superheated as it "cools" the torch
and tungsten. Years ago I had access to optical type
pyrometer. I and several others were welding stainless and we
needed to keep overall temperature of the machined part low to
reduce dimentional change. We'd weld a little then let it cool
before welding on the part again. We were using 1/8" diameter
tungsten and the post-flow was set for 20 seconds. When I was
using the pyrometer I remember that the temperature of the weld
varied very little whether the torch was removed or was held so
that the post flow argon bathed the weld. From one weld to the
next, temperature of the welded metal varied as much a 300
degrees F at the 20 second point. Holding the torch gas post
flow on the cooling bead had only about a 30 degree effect
during that 20 second flow (Delta 'temperature' was only 30
degrees greater change with gas flow than without). The job was
welding .035 wall 1/8" diameter round tube through a hole in an
.049" diaphram. At another time I saw similar temperatures with
carbon steel.

Brittleness is caused by very rapid cooling from the red heat
level... such as that obtained from immersion of the still red
hot part in a bucket of water. The cooling rate I saw under the
torch's gas post flow came no where near the changes needed to
embrittle a weld in 4130... even in very thin sections (.025" to
.035").

Bruce A. Frank

+++ #6929
Date: Thu, 19 Jul 2001 19:42:17 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Stress relieving

That wasn't a "ramble", that was a darn good article.

To add just a little and clarify things for some. That heat
affected zone, that brittle transition point, is always
there(unless you can insert the whole weldment in an oven). Post
heating tends to push it further away from the high stress area
right around the weld. The main thing desired is strain relief,
actually removing the stress that is caused by the normal
contractions of the filler metal. By post heating the tube to a
red heat it becomes rather plastic and "gives" where the strain
pulls it. This removes the concentration of load that might
eventually cause a crack in the nearest transition zone or
embrittled area.

Bruce A. Frank

+++ #6982
Date: Thu, 19 Jul 2001 22:01:24 -0800
From: "Float-By Shooter" del@
Subject: Re: argon flow

> Why not oxyacetylene weld and stress relieve as you weld?

Because I really like using the tig unit, and I think it does at
least as good a job.  8^) Like I said, I'm not going to hit
every joint with the rosebud, just a few critical ones.  I doubt
if it will add an hour to my overall build time.

Del Rawlins--

+++ #6942
Date: Fri, 20 Jul 2001 00:05:28 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Post-Flow "chilling"

I have given some detail on how several times. And at times I
may have leaned that way also, but I have tested my TIG welds to
destruction many times, some myself and others at testing labs,
and am satisfied with the non-post heated results. I probably
overstated when I implied "never".  Because of the size of the
tubes and some dependency on single welds to carry the load I DO
post heat my TIG welds in the engine mounts I build, including
the one I built for myself.

Someone asked about use of MIG. I tack weld with MIG and I fully
welded my main gear with MIG. I have said before that most
people should not MIG weld their fuselage unless they have many
year of experience. The process requires setting up and running
the machine on the ragged edge of melt through and on 4130 I
always post heat. Tube that has been bead blasted and a
too-hot-to-touch-with-the-bare-hand pre-heat has taken
everything I or my testing lab could dish out. I also think MIG
makes it easy to fill gaps in difficult cluster fit-ups,
followed by your chosen method (oxy/acet or TIG).

Bruce A. Frank

+++ #6948
Date: Fri, 20 Jul 2001 08:47:28 -0500
From: John Thompson rcav8r@
Subject: TIG welding/stress relieving/etc

Well you guys have really gotten me confused on the sress relief
issue when using TIG. My TIG experience to date is fixing
"mistakes" on aluminum molds, so stress relief is not a issue
there.  Actually, while TIG would be a nice tool to have in the
shop, I can't really see using it on a airframe myself,
especially around those tight clusters. Its hard to get in those
tight spaces with a TIG gun.

Lets just say that all this discussion just drives me more into
the O/A camp....just basically weld it up, and play the torch
over it to stress relieve. (in a nutshell).

John

+++ #6951
Date: Fri, 20 Jul 2001 11:18:33 -0700
From: "Owen Davies" owen@
Subject: Re: argon flow

> Why not oxyacetylene weld and stress relieve as you weld?

TIG is a bit faster. Of course, that only counts if you are
doing it as a job--in which case you probably want to use TIG
anyway, because it seems to impress the customers.

My reason would be cleanliness.  Sand blasting is one of the
least pleasant jobs I know, and TIG doesn't leave any scale to
remove.  Just wash the airframe down with solvent, and use a
good etching primer.  Done!

Owen Davies

+++ #6953
Date: Fri, 20 Jul 2001 11:32:06 -0700
From: "Owen Davies" owen@
Subject: Re: Post-Flow "chilling"

> Someone asked about use of MIG. I tack weld with MIG and I
> fully welded my main gear with MIG...

I'd like to hear more about your use of MIG.  I've always
thought of it as being strictly for tacking, places like Maule
(!) and Skystar not withstanding.  Your success with something
as heavily stressed as the mains could get me to rethink that.
Though what with the prep work and post-heating, it sounds like
it could be quicker and easier just to use O/A or TIG.  Do you
find any advantages beyond the ease of filling gaps?  What
conditions do you use?

Many thanks.

Owen Davies

+++ #6958
Date: 20 Jul 2001 12:29:05 EDT
From: charles.k.scott@
Subject: Stress relieving

I don't know about you guys, but when I weld a joint or cluster
on my fuselage, by the time I'm finished, the entire joint
and/or cluster is pretty much the same red color.  Tony
Bingellis has said in print that this is the reason he doesn't
think gas welding requires stress relief.

Sure you can do it, but next time you weld using a torch, notice
just how hot everything is getting.

Corky Scott

+++ #6960
Date: Fri, 20 Jul 2001 09:40:47 -0800
From: "Float-By Shooter" del@
Subject: Re: argon flow

> My reason would be cleanliness. 

Doesn't the tubing have mill scale on it, which must also be
removed?  Or is that just before welding?

Del Rawlins--

+++ #6962
Date: Fri, 20 Jul 2001 14:28:44 -0700
From: "Owen Davies" owen@
Subject: Re: argon flow

> > My reason would be cleanliness.
> Doesn't the tubing have mill scale on it, which must also be
> removed?  Or is that just before welding?

So far as I know, it doesn't cause a problem.  I should have
said that this was strictly my reasoning, based on the reports
of others, and not a statement of experience.  While I trust the
sources, I could have misunderstood them.

Maybe this is time for one of my periodic disclaimers (which,
now that I think about it, I may not yet have posted to this
list.)  Though I am a decent O/A weldor, with experience almost
solely on 4130 thin-wall, and am extremely interested in
welding, which is an activity I enjoy A LOT, there are many,
many people who know much more about this stuff than I do.  Budd
and Bruce are clearly among them, to say nothing of virtually
everyone at the welding newsgroup.  When I talk about MIG or
TIG, it is almost always second-hand information, and I usually
try to remember to label it appropriately.  Though I can
sometimes offer advice that might be of use to someone, my
primary goal in discussions of welding is to learn from those
who are more experienced than I am.

Bruce and a few other familiar names here have probably seen
this sort of statement on wreck.aviation.homebuilt, where I hung
out for years (until I gave in to despair over the low
signal-to-noise ratio), or on one of the other tube-and-fabric
oriented mailing lists.  I had forgotten that others might not
know how to evaluate my comments.

Owen Davies

+++ #6963
Date: Fri, 20 Jul 2001 11:39:47 -0700
From: Budd Davisson buddairbum@
Subject: Re: argon flow

It is seldom you see 4130 tubing that actually has mill scale on
it.  Sometimes the sheet does, but not the tubing. Any scale you
get on it comes from welding and that should be minimal, if you
clean the tubing and don't overheat it. A well done gas weld is
nearly, but not quite, as clean as TIG.  Cook it, however, and
you'll have scale and oxidation to deal with.

Of course, I've only gotten tubing from Dillsburg (Charlie
Vogelsong), which is also the supplier for most of the other
sport av supply houses (Wicks, aircraft Spruce, etc). Maybe
other suppliers do have tubing with mill scale, i don't know.

bd

+++ #6964
Date: Fri, 20 Jul 2001 17:40:31 EDT
From: supermexgarza@
Subject: Re: Elevator Hinges

some thing else that a person can do minimize the bild up of
scale on the other side of a weld is to purge the inside of the
pipe with an inert gas (nitrogen, argon) thus reducing the risk
of exposing the material to oxigen.  After all if you are
creating a small atmosphere were to weld with the gas , you must
think about the oposite side of what you are welding.

.02 ct

javier garza

+++ #6965
From:  Jerry Russell <jerry@t...>
Date:  Fri Jul 20, 2001  3:01 pm
Subject:  Re: Elevator Hinges

If you use a backup gas it should be totally inert!  Gaseous
Nitrogen (GN2) is NOT totally Inert!  Nitrogen will decompose at
700 degrees F and precipitate out a BROWN Residue. I belive it
is Nitrous Oxide.

Welding gases such as Argon, helium. and Argon/Co2 mix should be
used.  Pure Helium is the best because it will absorb more heat
per liter but is the most expensive. (plus it makes you sound
funny)

Jerry Russell

+++ #6967
Date: Fri, 20 Jul 2001 22:43:28 -0700
From: "Bruce A. Frank" bafrank@
Subject: MIG Advisory- Confessions of a Practical Weldor

OK, confession time, and I don't recommend anyone else following
my example.

I run .035" ER70s-6 wire with argon/co2 gas mix.  I set myself
up physically, meaning no obstructions in direction of travel
and making sure that I can move the MIG gun smoothly, quickly
and rotate it in my hand to follow the contour of the shape I am
welding. I make several practise welds without energizing the
gun to check my position. One of the most common welds I make on
4130 is to install finger reinforcements, finger like pieces of
4130 overlaying a weld that heavily loaded or to reinforce a
corner or bend on a tube. Fit up is tight, parts are made to
conform to each other by heating with the oxy/acet torch and
judicious work with a very small ball peen hammer. I don't bead
blast everything, but it is easier to weld because you can see
what is going much more clearly than when the material is
black. I also wipe everything with acetone first. I also light
the area well. It may sound funny because you'd think working in
the light of the arc would be more than enough. I find a bright
light on the work helps me align better before I energize the
gun.

On occasion when welding heavier parts such as an axle to the
support tubes I will use a weave to help flatten the
reinforcement of the weld (the word reinforcement used in this
context means the build up or height of the weld bead). But when
welding tube (or a finger reinforcement onto a tube) such as one
tube fish-mouthed into the side of another (typical diagonal
brace between longerons) I run a straight non-weaving bead
wrapping 180 degrees around the junction (in the case of a
finger reinforcement I follow the line of the edge of the
contact line). My settings are hot enough that I have to move
about 1" in no more than 3 seconds or I will melt a hole through
the tube wall. I limit this style of MIG welding to .049" or
thicker wall. I then reposition myself to weld the other 180
degree half of the joint. Good parts fit is required.

My other method is using the MIG gun like a spot welder, in a
sense. When there are gaps I pull the trigger in a short burst
to leave a small deposit of filler wire like a tack weld. I will
stitch along a joint filling the gap with short "tacks" until
the joint is fully welded with the final few "stitches" turning
into a more extended duration weld to tie it all together. At
times when I have a good tight fit-up but cannot access the
joint to make my wrap around weld described above I will set the
machine hot and develop a puddle on the joint...stopping just
short of melt-through; then move a bit along the joint and do
the same thing again then again. The finished weld looks like
little overlapping pancakes. These are full penetration fillets
welding the whole joint. Care must be taken to modulate the
trigger to prevent a bubble from forming in the center of the
center of each of those "pancake" deposits. Care must be taken
to stop just short of melt through. If you look at MIG welded
fuselages, no matter who the manufacturer, you'll see a lot of
"build-up" or these "overlapping pancake" welds in difficult to
access areas.

If I do melt through, I stop to let things cool a bit, then
begin stitching around the edge of the hole, eventually closing
it making a uniform over-weld to finish it off. There is no
effort on my part to keep these types of welds small. A typical
MIG weld like this will measure 1/4"+ across the face. There are
a couple of reasons for this; the start, when the energized wire
first makes contact with the metal being welded, that spot is
relatively ice cold. The first milliseconds of weld do not
actually fuse the filler metal into the base metal. The MIG
welding machine is design to start "hot", but there is still the
necessity to hold the gun in place to develop a molten
puddle. The heat electrically created as the puddle grows pulls
that initial contact spot into the melt acquiring fusion of the
filler to the base metal. You have to allow the puddle to grow
enough to create the heat for fusion. It is a ballet between
fusion, melt through, and cold lap.

Another thing that the larger bead does is help to overcome the
quenching effect of all the surrounding metal which is trying to
chill the weld and make it brittle. MIG welding a cluster
generates enough heat that things glow for a while after you
finish, just as it does with oxy/acet, strain relieving the
weld. Problems can arise when tubes come together in a single
joint... such a "cold" joint has a greater chance of being
brittle.

In the truss design of fuselage no single joint carries a high
load, so correctly MIG welded joints can do the job with low
risk of any kind of failure. The areas that are critical when
MIG welding are axle to gear legs, gear mount points on the
fuselage and the engine mount. MIG welds, because of their cold
start and quick solidification of the weld puddle have a higher
chance of embrittlement from both normal carbon steel chemistry
and hydrogen absorption (with any moisture present there is
always dissolved H in the molten puddle. It will come out unless
the puddle chills and solidifies too quickly. A MIG weld pushes
that limit point hard.)

Post heating MIG welds can "temper" the crystal structure to
reduce the brittle heat affected zone. Post heating has been
shown to reduce hydrogen embrittlement also. Now it is not
likely that I have said much here to make you more confident in
MIG welds or your own MIG welding. I may not have as much
finesse at welding delicate and critical structures as Kent and
Budd, but I have been handling structural, race car, boiler,
pressure vessel, reaction chambers and gas chromatography
plumbing for about 25 years now.  As the old saying goes "MIG is
the easiest weld to make look good and the most difficult to do
correctly."

When I MIG weld on aircraft parts, my oxy/acet with a rosebud
attached is always close at hand. I do not think the additional
time used to post heat MIG work adds significantly to the time
involved. I post heat all critical structures.

Bruce A. Frank

+++ #6972
Date: Sat, 21 Jul 2001 10:32:25 -0700
From: "Owen Davies" owen@
Subject: Re: MIG Advisory- Confessions of a Practical Weldor

> Bruce A. Frank explained his use of MIG in extremely helpful
> detail.

For which, many thanks.  That was a lot more than I've ever
heard about how to MIG work in the kind of applications that
interest us.  However, it was a little disappointing in one
respect.  I've always thought that the big advantage of MIG is
its speed--hence its value in tacking, compared with fumbling
with an O/A torch.  Your account sounds like it can't be much
quicker to do a finished weld than it would be with TIG.  Is
there some other benefit that makes it worthwhile, or does it
just take longer to describe than to do?

Thanks again.

Owen Davies

+++ #6973
Date: Sat, 21 Jul 2001 09:49:54 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: MIG Advisory- Confessions of a Practical Weldor

It takes a lot longer to describe than do. It is fast and
particularly useful when fit up is less than perfect.

Bruce A. Frank

+++ #6974
Date: Sat, 21 Jul 2001 15:04:49 -0700
From: Budd Davisson buddairbum@
Subject: Re: MIG Advisory- Confessions of a Practical Weldor

I think what Bruce is trying to say below is, "Don't try this at
home, kids."

In my humble opinion, MIG and 4130 must be mixed with
professional level skill and an understanding of the potential
problems and how to avoid them. Personally, I recommend against
it's use by us mere mortals.

bd

+++ #6975
Date: Sat, 21 Jul 2001 16:23:05 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: MIG Advisory- Confessions of a Practical Weldor


> I think what Bruce is trying to say below is, "Don't try this
> at home, kids."  In my humble opinion, MIG and 4130 must be
> mixed with professional level skill and an understanding of
> the potential problems and how to avoid them.  Personally, I
> recommend against it's use by us mere mortals.  bd

I'll put it this way, if you have been using MIG for years and
understand the process, the limitations and ALREADY have a MIG
machine then use that tool. If you are a pretty good welder, can
handle an oxy/acet outfit fairly well and want to buy a new
piece of equipment then buy a TIG outfit.

You cannot go wrong with an oxy/acet outfit as a first
purchash. The skill developed with oxy/acet applies directly to
TIG welding. You will likely need an oxy/acet setup
anyway. Start with it, learn it, then branch out.  Unless you
want it to build jigs, benches, and do some autobody work don't
buy a MIG unit. If you want to buy a MIG unit anyway because, by
heaven, you are going to weld your fuselage, buy the BEST unit
you can get. Do not expect the $250 unit to be up to the job.

Bruce A. Frank

+++ #7013
Date: Sun, 29 Jul 2001 23:04:44 EDT
From: petz187@
Subject: Re: Re: stress relieving vs normalizing

Gentelmen, READ the whole book. Then discuss those two subjects
again. Weld your parts and then blast them. I have welded up
some of my hinge fittings with both TIG and MIG.
 
Thanks       
HAL # 355

+++ #7256
Date: Thu, 16 Aug 2001 17:54:16 -0000
From: "Bubba jones" bubba98042@
Subject: Weld filler rods

I recently attended the lincoln TIG worskhop at Arlington. I was
pretty impressed with the setup and use of the SQ Wave 175. My
question to you weldment experts is the choice of filler rod.

The expert that lincoln had ( I forget his name) seemed to have
years of experience welding and bulding parts for LMT
Skunkworks. He was a consultant on the design of the SQW 175. He
suggested the use of the following rods for welding 4130 tubes
in order of preference

ER80SD2  Best
ER70S2   Next Best
ER70S6   In event the other two are not available

Could you experts kindly comment on the choice of the rods and
or SQW175

Varun #505 Khanna

+++ #7257
Date: Thu, 16 Aug 2001 12:11:10 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Weld filler rods

I hate to get into conflict with an expert, but I might ask how
many 4130 structures he has built? Any race cars, any fuselages,
engine mounts or landing gear?

ER80sD-2 not bad, but it is a specialty rod that I have never
been able to find locally. Many welding supply places just
scratch their heads when you ask for it.

ER70s-2 is the rod that all welding supply houses will have on
the shelf.  It is ok and most people use it for both TIG and
oxy/acet. It has a tendency to spark under the TIG torch and
contaminate the tungsten. It has a tendency to spark under the
oxy/acet torch clogging the tip and causing the tip to pop.

ER70s-6 is my choice for several reasons: It "wets" and flows
well giving smooth "stack of dimes" welds. It contains higher
levels of silicon and other de-oxidizers that very effectively
"kill" the molten puddle...no sparks or sputtering and virtually
no porosity in the cooling puddle as you move along. The
designation -6 is a formulation developed for MIG welding.  The
high de-oxidizing chemical content was designed to control
contamination in an environment where the molten metal is
solidifying almost too quickly for the impurities to boil
out. If you bead blast or sand paper every joint to make them
nice and shiny then wipe with acetone before you weld, just
about any mild steel filler rod can be used. Every single
experienced 4130 welder to whom I have introduced -6 has raved
about it and switched to the -6 filler.

There are some super "vacuum melt" or triple deoxidized rods out
there that are slightly easier to use that cost nearly $50 a
pound. Some will argue that you are only using a pound or two
and one "should not cut corners (save $) on such an important
thing". The finished product with -6 tests to exactly the same
standard as those very expensive filler rods You give up nothing
with -6 and ease of use is virtually identical. And the most
important point to me is that most welding suppliers have it or
can get it and it costs only a few cents more per pound than -2.

I have tried just about every possible ferrous (and non-ferrous)
filler rod available for TIG and oxy/acet welding of 4130. Some
have touted stainless and other exotic fillers. You will not be
disappointed with ER70s-6. The only caviat I can make is that if
you obtain copper plated rod (the copper is there only to reduce
rusting of the rod in storage) you might want to Scotch Brite
the copper off before oxy/acet welding. The copper forms a
slightly scummy surface on the molten puddle so many find
removing the copper first eliminates that minor interference.

BTW, for most of my 4130 tube welding I find 1/16" diameter
works best and is the easiest to find.

Bruce A. Frank

+++ #7261
Date: Sun, 19 Aug 2001 19:40:02 -0700
From: "Joe Hemmer" kiote1012@
Subject: Re: Weld filler rods

Bruce, thanks very much for the welding tip.  My previous
testing resulted in such poor welds that I have been using
bicycle technology, sticking 4130 together with silver braze.
It makes for a very strong joint, but cleaning up the flux is a
nasty mess.

So Friday I bought a roll of 0.045 MIG wire in ER70s-6, ($6 for
2 pounds) and today I cleaned a 45 degree test joint and welded
it up.  Not particularly good fitup, and not particularly
cosmetic weld.

And the stuff works!  Fantastic!!  When I attempted to pound the
joint to destruction, formerly a realtively easy task, I could
not get the weld to break.  Very ductile.  And there was no
problem with heat-affected zones near the weld either.

Thanks, Bruce!!

+++ #7305
Date: Tue, 21 Aug 2001 19:16:31 -0700
From: "Joe Hemmer" kiote1012@
Subject: Re: Weld filler rods

You quoted my thanks to Bruce for prescribing the ER70s-6
welding rod for chrome-molly tubing; did you mean to ask a
question or make further comment?  I must have missed something,
as usual.

I did want to clarify that even though I used MIG wire, the
welding was done with an oxy-acetelene torch.  I used the MIG
wire because that was all I could find in ER70s-6 locally.  And
it works like a charm; just put the roll in your pocket and
unreel what you need.  You have to fight the 0.045 a little, it
is stiff.

I have had very poor results with MIG on airframes, somewhat
moderated if you flame soften the quench area around the weld
afterward.  I much prefer the acetelene torch, thank you.

Joe Hemmer

+++ #7520
Date: Sun, 02 Sep 2001 06:49:56 -0700
From: Budd Davisson <buddairbum@home.com>
Subject: Re: Smith torches

Re: Smith AW-1A torches

We're having fits with a batch of brand new Smith AW-1A
torches. The valves all have areas of reverse command, they
won't hold a setting and on one of them the valves wobble in the
packing nut and cause the flame to change.

Has any one else had problems with the Smith? The factory has
been super supportive, but says they have never had these
problems before. More frustrating, when we sent one back, they
said it tested perfect in their lab.

Also, the AW-1A, as opposed to the old AW-1 "airline" torch has
vaguely rectangular knobs rather than round ones and are harder
to adjust with a thumb.

I find this very frustrating because I've always pushed the
Smith at my forums, now I'm going to have to reevaluate my
position.

Any comments?

bd

+++ #7551
Date: Tue, 04 Sep 2001 20:01:00 -0000
From: zipppydoggg@
Subject: Re: Smith torches

Probably too late to help, but I love my Meco from Tinman.

Rob Gaddy

+++ #7569
Date: Wed, 05 Sep 2001 09:08:52 -0700
From: "Bruce A. Frank" bafrank@
Subject: RE: Bearhawk CD

> I was using silver braze, which leaves a nasty mess of flux to
> clean up.

Couldn't the flux just be left in place after the brazing then
sandblasted away when the fuselage was preped for painting?

Bruce A. Frank

+++ #7571
Date: Wed, 05 Sep 2001 10:27:01 -0700
From: "Joe Hemmer" kiote1012@
Subject: Sandblasting?

Bruce, yes, sandblasting would easily take care of the flux,
except that this fuselage is not going to get sandblasted.  Just
hot water.

I will be using the AFS water-carried finsihing system supplied
by Noel at Blue Sky Aviation, and it includes a water-borne
fabric adhesive.  Which does not require MEK to activate!  Also
does not require special breathing systems during painting.

Which means that I can use something other than the evil
two-component epoxy primer on the tubes, since the paint does
not need to be defended from MEK.

And I really, really, really do not like two-component epoxy
primer!  Don't care much for MEK, either, now that you mention
it.  You see, I am a devout coward.

So after surface treatment with Jabsco metal etch and rinsing,
this thing will be painted with Rustoleum!  Presuming that my
test samples actually stick to the Rustoleum, and the Rustoleum
actually siticks to the steel tubing.  Don't laugh, I have had
excellent service from Rustoleum!

I expect to get back to you with a report on how it worked in 20
years or so.  (He says confidently, not actually having a clue
as to what is going on).

Joe Hemmer

+++ #7572
Date: Wed, 05 Sep 2001 11:18:51 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Sandblasting?

Over the years of building many utility trailers and several
dozen fuel tanks for off-road vehicles I have come to depend on
bead or sandblasting as the most practical and fast method
available to me. My question then is how do you handle the scale
that forms around the welded areas? None of the prep etches that
I have used do much of anything to modify the weld scale.  The
nice uniform blue/black mill scale that comes on most 4130 tube
is very tenacious and if the paint can adhere to that, it will
stay on the metal very well. But, the scale that forms around
the oxy/acet welded areas is not smooth or solid and is usually
quite rough. Items that I have built, though cleaned and painted
very well, when they eventually develop rust, given enough time,
always start in those weld scale areas. I like to avoid water
based products on steel and prefer etching primers after a wipe
down with my personal mix of acetone and MEK. I do this outside
with a organic filter (paint) mask and industrial solvent
gloves.

Bruce A. Frank

+++ #7575
Date: Wed, 05 Sep 2001 12:34:06 -0700
From: "Joe Hemmer" kiote1012@
Subject: Re: Sandblasting?

Welding scale comes off fairly well with a rat-tailed file, and
then a good shot of the fish-oil based red-brown Rustoleum
primer takes care of whatever is left.  Contrasting finsh coat
of white or black seals it well enough that I have had no
problem so far.

I do preliminary cleanup with a braided wire brush in the 4"
sidewinder grinder, but it will not reach into the corners;
hence the rat-tailed file.

Cleaning up in the corners after arc or Mig welding is more
difficult, the spatter needs to be chisled off.  Again, the
red-brown primer so far has sealed things just fine.  But please
remember, I do not live in a coastal climate!

Yes, sandblasting would still be preferable, if I had a
sandblasting setup.

Joe Hemmer

+++ #7576
Date: Wed, 05 Sep 2001 12:58:57 -0700
From: Budd Davisson buddairbum@
Subject: Re: Sandblasting?

go to TPtools.com. They sell a really good little pressure
sandblaster that works like a charm and is well worth the
investment..

bd

+++ #7577
Date: Wed, 05 Sep 2001 13:38:55 -0700
From: "Joe Hemmer" kiote1012@
Subject: Re: Sandblasting?

Thanks, Budd

Both of those little ones look good for our joints.  I will give
one a try.

Joe

+++ #7580
Date: Wed, 5 Sep 2001 14:20:34 -0700
From: "Kent White" kent@
Subject: RE: fuselage welding

This fellow has the essence of it: Plan carefully.  Work
comfortably.  Keep mental notes to guage both progress and
quality.

And...rest when tired. Pushing will degrade both joy and
results.

Kent "oh! the sound of a hot one defoliating the right ear
canal..." White

+++ #7583
Date: Wed, 5 Sep 2001 16:25:45 -0600 (MDT)
From: Ken Beanlands kbeanlan@
Subject: Re: Sandblasting?

Budd, which one were you talking about? There are two on this
page and I'd love to pick one up:

  http://www.tptools.com/prod_list_display.asp?dept%5Fid=L2%7E56&dept%5Fname%5Fp=Abrasive+Blast+Cabinets&mscssid=F0XEAS13LAS92NS500N0SFRP64E3409F

Ken Beanlands B.Eng (Aerospace)

+++ #7584
Date: Wed, 05 Sep 2001 15:44:06 -0700
From: Budd Davisson buddairbum@
Subject: Re: Wrong Sandblaster

Okay guys, I lied. But, I didn't know it. I gave you the wrong
URL for the wrong sandblaster company.

Sorry.

Mine is made by Trumans. It's the 99-S and it works beautifully.

www.san-blast.com

bd

+++ #7587
Date: Wed, 5 Sep 2001 18:41:28 -0800
From: "Float-By Shooter" del@
Subject: Re: Re: Wrong Sandblaster

> Mine is made by Trumans. It's the 99-S and it works
> beautifully.

I've got the same model and I will never go back to a siphon
blaster again (excluding blast cabinets of course).

Del Rawlins--

+++ #7588
Date: Wed, 05 Sep 2001 20:51:56 -0700
From: "Joe Hemmer" kiote1012@
Subject: Re: Re: Wrong Sandblaster

OK, Budd

The 99-S is a mite expensive; but if that is what it takes, that
is what we should do.

But how about the siphon blasters on the next page, the 8001-50
and the 8001-30?  Are will they do the job?  Slow is OK, if they
will take off the scale.

My only experience is with cabinet siphon blasters; will these
little ones work for us?

Joe Hemmer

+++ #7590
Date: Wed, 05 Sep 2001 21:38:33 -0700
From: Budd Davisson buddairbum@
Subject: Re: Re: Wrong Sandblaster

siphon blasters work after a fashion. Blasters in general clog
up ALOT. Dry air is critical as is dry sand and well-sifted
sand. Siphon blasters don't have anything pushing the sand
through the hose so they have yet another place that can get
clogged. Once you've used a pressure blaster, and it doesn't
make any difference how small it is, you'll never go back. Those
little spot blasters guns they list may work for
clusters. You'll just have to reload them more often, which is
no big deal.

bd

+++ #7591
Date: Wed, 5 Sep 2001 21:26:45 -0800
From: "Float-By Shooter" del@
Subject: Re: Re: Wrong Sandblaster

> siphon blasters work after a fashion. Blasters in general clog
> up ALOT. Dry air is critical as is dry sand and well-sifted
> sand.

I dumped a bag of new, unused commercial sandblast sand into my
new pressure blaster when I first got it, and after about 30
seconds of mind-boggling good rust cleaning action, it just up
and quit.  Turned out the nozzle plugged up with some larger
pieces of grit.  I started sifting everything after that, even
fresh sand out of the bag, and haven't had problems since (other
than getting halfway through and realizing I didn't sift enough
sand).

The best thing that can be said about siphon blasters is that
they are cheap.  For use on one project its probably not a bad
choice but with at least one airplane project, several planned
automotive projects plus all around use on other stuff, the
pressure blaster was a no-brainer for me.  I try to keep mine
out of sight when not using it, otherwise people are always
asking to rent or borrow it.

Del Rawlins--

+++ #7593
Date: Wed, 05 Sep 2001 22:33:32 -0700
From: "Bruce A. Frank" bafrank@
Subject: Re: Re: Wrong Sandblaster

There is a problem with siphon blaster. It may not be as
significant in some climates as others. When I lived in Utah
with a relative humidity of about minus 15% my cheap Harbor
Freight 40 lb hopper siphon blaster ran for days with never a
clog. When I moved to PA the siphon sand blaster became next to
useless. The low pressure created in the gun (that sucks the
sand from the bottom feed on my hopper) would create enough
condensation to wet the sand and stop the flow. My shop
compressor (7cfm at 100psi) could not "suck" the wet plug of
sand through the feed nozzle.

I later borrowed a friend's pressure feed unit, was blasting two
or three pairs of gear legs a day. Nearly cried when I had to
give it back. My old hopper feed sits in the corner gathering
cobwebs even though the humidity here in the Silicon Valley if
usually low. I was so impressed with that 99-S, which appears
similar to the pressure feed I used in PA, that I just ordered
one. Budd, thanks for the tip.

Bruce A. Frank

+++ #7594
Date: Wed, 5 Sep 2001 21:41:45 -0800
From: "Float-By Shooter" del@
Subject: Re: Re: Wrong Sandblaster

> But how about the siphon blasters on the next page, the
> 8001-50 and the 8001-30?  Are will they do the job?  Slow is
> OK, if they will take off the scale.

One of the local A&P's has one that looks just like the 8001-50
and he swears by it.  He and his son recently blasted and
painted a Super Cub frame and it seems to have done the job.
However, having seen his previous sandblast equipment, anything
new would probably have been an improvement.

Personally, I don't like sandblasting much and am in favor of
anything that gets it over with faster.

Del Rawlins--

+++ #7597
Date: Thu, 06 Sep 2001 14:11:47 -0000
From: daniel_fox@
Subject: Re: Wrong Sandblaster

Getting slightly off topic w/ this blaster thing, but I was
comparing Tip Tools w/ San-blast on the Web, and I noticed that
they have essentially next-door-neighbor addresses ( 7075 vs
7079 State Route whatnot...).

Does anyone know if they are actually the same outfit?

OTOH, there is very little crossover in product line. Belay that
last.

--dan fox

+++ #7598
Date: Thu, 6 Sep 2001 11:38:18 EDT
From: pfflyerz@
Subject: Re: Re: Wrong Sandblaster

> Mine is made by Trumans. It's the 99-S and it works
> beautifully.  www.san-blast.com

I recently bought the same unit and really like it, especially
the pistol grip nozzle that comes with it.  I first used it to
blast my tail feathers and was dissappointed with the speed.  It
wasn't until I blasted something with more surface area, like
the shock struts, that I got an appreciation for how much faster
it works than a siphon blaster.  Trumans is a quality
manufacturer with excellent support.
            Pat Fagan   #232 Pearblossom CA

+++ #7599
Date: Thu, 6 Sep 2001 11:45:30 EDT
From: pfflyerz@
Subject: Re: Re: Wrong Sandblaster

> I was comparing Tip Tools w/ San-blast on the Web, and I
> noticed that they have essentially next-door-neighbor
> addresses

They were the same company until just recently.  For whatever
reason, Tip Tools now makes blast cabinets and San-Blast makes
pressure blasters.
            Pat Fagan  #232  Pearblossom CA

+++ #7600
Date: Thu, 06 Sep 2001 08:45:43 -0700
From: Budd Davisson buddairbum@
Subject: Re: Re: Wrong Sandblaster

TP tools used to make a 99-C type pressure blaster but stopped
making it a few years back to concentrate on blasting cabinets
and other stuff. I'm guessing one of their employees saw it as a
viable market and picked it up.  They changed the nozzle/valving
to a "deadman" plug type of arrangement that eliminates the shut
off valve at the nozzle that always wears out. I had a TP unit,
traded it off, then couldn't live without one and bought the
San-blast unit. Same unit. Different valve.

bd

+++ #7602
Date: Thu, 6 Sep 2001 13:25:20 -0500
From: "Tony Chisum" tonychisum@
Subject: Wrong sandblaster

Harbor Freight has two 20# pressure blasters for $59.95
each. One comes with a hood and funnel.  I also saw a larger one
at the store for $100.00.  My brother in law has one of the 20#
blasters and it works just fine.  I intend to pick up one this
weekend.  Its a lot cheaper than the San-Blast unit.  Check it
out www.harborfreight.com

Tony

+++ #7605
Date: Thu, 6 Sep 2001 12:14:57 -0800 (AKDT)
From: Float-By Shooter del@
Subject: Re: Wrong sandblaster

I just remembered that the EAA aircraft welding book has
instructions for making a small pressure sandblaster.

Del Rawlins--

+++ #7606
Date: Thu, 06 Sep 2001 21:35:48 -0000
From: meldredge@
Subject: Re: Wrong sandblaster

I inherited what looks to me like a Harbor Freight pressure
sandblaster that has some worn out parts.  (the ball valve at
the nozzle being foremost)

Can that ball valve be replaced with a ball valve like you would
buy at Home Despot for plumbing?  Looks to me to be the same
unit.

-Mike Eldredge

+++ #7607
Date: Thu, 06 Sep 2001 15:53:39 -0700
From: Budd Davisson buddairbum@
Subject: sandblaster

Those ball valves wear out really quickly, especially if used
wrong. You're supposed to quickly transition from full closed to
full open and not use them to meter the sand. I've never liked
them and yes, they look exactly like a plumbing valve to
me. It'll be more expensive, but the new deadman unit that
San-Blast uses is better all the way around. It's a one hand,
pistol grip operation and forces you to go full open. The pad
that slams shut on the end of the gun doesn't seem to wear very
quickly and you can rotate it for four more positions before
replacing it. Even then, I doubt if it costs five bucks.

Incidentally, I read a warning somewhere that you're not
supposed to sand blast with silicon sand because it releases so
much silica that it can cause silicosis of the lungs. I'd think
a good mask under the hood would prevent that. If you're not
dong a huge amount I don't think I'd worry about the silica
sand, except it's not very uniform and absolutely has to be
screened or it'll drive you nuts. Even then, keep a piece of
1/16 welding rod handy to jam up the nozzle to clean it out.

I used to use stuff called Black Beauty (I think) which was a
black, perfectly uniform specialized sand that produced zero
dust and gave a great finish. However, since part of my present
backyard is sand to begin with, I can use the other stuff and it
won't show. I just have to watch that i don't rearrange the
rocks by blasting them too hard accidentally.

bd

+++ #7610
Date: Thu, 6 Sep 2001 17:40:53 -0700
From: "Kent White" kent@
Subject: RE: sandblaster

Black Beauty, I believe, is a carbide-based sand.  We have it
here, sort of heavy stuff.

Kent White

+++ #7611
Date: Thu, 6 Sep 2001 22:23:04 -0400
From: "W. Shalm" shalm@
Subject: Re: sandblaster

Budd's right on both accounts Mike. A little bit won't hurt
you. It takes between 10 and 20 years of regular exposure to do
serious damage but certainly a mask would make sense even for
comfort's sake. On the other hand those that do get long-term
exposure are in big trouble.

In lay terms the scavenger cells in the body designed to kill
foreign bacteria matter can't handle the silica particles and
die forming fibrous tissue/masses that can affect lungs, heart,
lymph nodes and of course your generally "congenial disposition
toward your mother-in-law".

Warren

+++ 

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