Practical welding?

You take the A&P welding/sheetmetal/metalsmithing class at your ... local
.... community ... college.

For those of you who say it's cheap, come tell me about it when you pay your
house taxes or your state income tax.

And yes, I teach about 8 units a semester at my local community college and
it is the best education bang for the buck in this country.


Jim


"Michael Horowitz" wrote in message
...
wrote:


Not the point I'm trying to make. let's assume the student know how to
weld perfectly standing up comfortably at a welding bench. Now, how
much more (and how does he learn) how to repair a longeron that is
still attached to much of it's fabric, its engine and landing gear? -
MIke

I know a guy who took three semesters of welding... torch, TIG and MIG...
and one of the benefits was he had free use of the equipment, shop, tools,
etc.. for the duration of the class.


I know a guy that took a machining class for the same reason. The
instructor let him use the equipment for whatever little project he was
working on.

Practical welding can involve welding in all kinds of awkward positions,
like upside down, head first, under a pipe in a ditch and lots of other
strange positions depending on what you are doing. You can learn how to
weld in a class or at the bench. You learn how to be a welder by
applying that knowledge in the field. You learn how to tackle new
situations by asking knowledgeable folks, watching them, or using your
head, trying something and seeing how it works. As far as welding a
fabric covered airframe, you remove nearby flammable materials and/or
cover them with fire resistant material, and then have a firewatch
standing by with an extingiusher. Heck, plumbers sweat pipes in walls
with wood studs all the time. It is pretty much the same concept.

"Cy Galley" wrote in message
newsYmNe.45866$084.12269@attbi_s22...
You could attend one of the workshops at AirVenture or one of the welding
classes that the EAA has around the country.

Short of that, are there good book(s) that you could teach yourself?

I seem to recall practicing clusters with short sections, and putting a tire
valve in it, and see if your welds will hold pressure. I think I saw that
in BengalisIs (sp?) books. Is that a common practice to test the welds?

The second part, IIRC, is tearing it apart, to check penetration and
strength of the welds.

Another test is to put it in a vise and beat the crap out of it with a
hammer. If the tubes break before the welds, its a good weld.

John

"John T" wrote in message
...
Another test is to put it in a vise and beat the crap out of it with a
hammer. If the tubes break before the welds, its a good weld.

Right, that is the first part of step 2.

Step one is to see if the welds are airtight, because aircraft welds should
be, so corrosion (rust) does not eat away the tube, with no visible warning.
--
Jim in NC

On 19 Aug 2005 06:13:21 -0700, "mhorowit" wrote:

A friend lent me an OA rig so I could learn to weld. Lots of good
material in the library and on the NGs. But all that welding is done on
a welding bench, at a comfortable height. Apparently one does not have
to get near an airframe to get a certificate to weld 4130 with OA.

How does a welder learn how to weld on a built and covered fuselage
(say on fabric/steel)? How does he know how much fabric has to be
removed to insure his heating doesn't screw up glue adhesion? How does
he learn how to protect the nitrate from going up in flames from
sparks? How does he learn the tricks to weld all around a splice
without standing on his head or laying on his back?
-
Mike

Mike
I think you're approaching this the wrong way.
welding requires some practise, quite some practise, to develop the
fluency and quality of weld.
like you I was repairing a vintage fuselage.
I did all the preparation work myself and then enlisted the services
of a certified and experienced aircraft welder.
he did a truely stirling job of the welding ...but only after telling
me to **** off out of the hangar because my watching him was making
him nervous :-)

best decision I made actually was getting that welder in. he bought
with him 30 years of practical hands on experience, something that I
could have achieved myself of course, but in another 26 years.

focus on finishing a truely quality restoration, not on doing it all
yourself. use other peoples expertise as well.

ymmv
Stealth Pilot

Yup. Finch's "Welder's Handbook". Well written, easy read.
Also, just visit your library. Although after trying and if
unsatisfied, visit an EAA Chapter.
- Mike


"Morgans" wrote:


"Cy Galley" wrote in message
newsYmNe.45866$084.12269@attbi_s22...
You could attend one of the workshops at AirVenture or one of the welding
classes that the EAA has around the country.

Short of that, are there good book(s) that you could teach yourself?

I seem to recall practicing clusters with short sections, and putting a tire
valve in it, and see if your welds will hold pressure. I think I saw that
in BengalisIs (sp?) books. Is that a common practice to test the welds?

The second part, IIRC, is tearing it apart, to check penetration and
strength of the welds.

Part of the tube cluster test after welding involves sawing the tubes
cluster along its center line. This alows a visual inspection of the root
for each side of the entire joint.
From this half cluster you can cut out bend test coupons.
Depending on how the bend test fails you can determine if you have adaquate
fusion on both sides of the joint; and if preheat may be required.

One method used to extend the life of welded aircraft structures was to pour
in a gallon or so of boiled linseed oil after all welding had taken place
and the structure passed a leak test. It is a time consuming task involving
rolling the structure as it is being tilted to ensure full coverage of the
interior of the tubes.

There is a publication out there that goes into great detail of fabricating
weldments for the tubular weld test just don't remember the name off hand.
I do have one reference I was able to find but it is the tentative code for
welding aircraft structures dated 1944.

They proposed the use of a piece of 1/4" x 6" flat bar 6" long. Three tubes
would be notched and coped to slide over the flat bar and form a Y type
connection with the third tube center on the two tubes forming the Y.
After the weld is completed the weldment was cut across the the flat bar
around the 2 1/2" mark exposing the ends of the tubes; allowing inspection
of the interior .

I had posted a pdf file many years back to a web site I forget the name of
but it was titled welding tubular structures or something along those lines.
It may still be out there.


John Noon


"John T" wrote in message
...
Another test is to put it in a vise and beat the crap out of it with a
hammer. If the tubes break before the welds, its a good weld.

John

footy wrote:
Practical welding can involve welding in all kinds of awkward positions,
like upside down, head first, under a pipe in a ditch and lots of other
strange positions depending on what you are doing.

So there I was trying to finish up welding on the last engine mount
flange to my Delta's fuselage. By the time you get to the engine mount
flange, the Delta has grown to a considerable size and I had it up on
sawhorses. All the tubes coming back from the firewall to form a closed
box. The only way to get inside the box in through a lot of longerons
and diagonals.

Well, I had managed to get my head wedge up between a couple of the
bottom diagonals. My right hand snaked the torch around the longerons,
and my left hand wrapped around the front bottom crossbrace to bring in
the filler rod. The metal was hot and flowing and the bead was running
smooth. Then my filler rod got short. Not the whole rod, just the part
on the weld side of my hand. It had taken several minutes to get wedged
into this position, and I didn't want to kill the weld bead just to feed
more filler rod. Thinking quickly, I grabbed the back end of the rod in
my mouth, pulled my hand up further and continued the weld. "Smart", I
thought to myself, as the bead rolled on.

Most of you have already guessed what happened.

Melt. Fill. Melt. Fill. Advance. All in a steady staccato beat. More a
habit than thought. And then, as I reached the end of the filler rod,
for some indiscernable reason, I decided that I could slide my hand all
the way to the rear of the rod if I grabbed the other end in my mouth.

I'm not sure if the burn mark is still discernible across my tongue, but
I do know that there isn't much worse that having your head caught in
your airplane when you need to scream.

Later, I learned the proper way to advance your filler rod without the
aid of gravity is to dip it in the weld pool and let the pool cool just
slightly. It'll solidify just enough to allow you to slide your hand
back. Bring the heat right back in and keep going.



--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."