On Feb 17, 10:33*am, wright1902glider
wrote:

PS: Thanks VeeDub, Mike H., FighFlyer, and everyone else over the past
8 years.
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And Thank You, Harry... for sticking with it.

Now the fun begins. No smiley; this is some serious ****.

Got some fire bricks? Eight or a dozen. BAKE them first... low heat
(mebbe 170) four or five hours. Leave them in the oven over night.
They're you're foundation. If you'd bought a MIG'ger we'd be looking
at a slab of steel plate. But with O/A, firebricks will do ya.

There's a strange kind of magic in that golden puddle. It's like one
eye of the Dragon. Learn how to create it, then how to control it,
then weld some of your coupons together, flat edge-to-edge first,
then over-lapped, then standing ON edge, forcing you to dig your
puddle our of the CORNER between the two coupons. After that, you're
ready for tube.

Don't buy real tube. Start with EMT; even junked stuff, if you can
find it. Or pick up a couple of sticks at the Borg.

Same story with the acid. Cut your coupons first. Make a 'quickie'
holding block. gouge-out a vee, slather in some BONDO, press the OILED
tubing into the Bondo. Align it by eye, keeping your errors on the
'deep' side of perfection (why? Because you can always sand off a
little bit). Once you can HOLD a tubing coupon, you can create a fish-
mouth.

If you don't have a set of round files, use your angle-head grinder.
For practice your joins don't have to be perfect metal-to-metal fish-
mouths (save that for 4130 and real airplanes).

We use mild steel rod with O/A because the TYPICAL FILLET is 3x as
thick as the wall of the tubing, which means the joint is going to be
plenty strong enough. Using EMT for practice, with a sloppy fish-
mouth, your fillets are liable to be as much as 6x or even 8x the
tubing wall (it's about .047" for EMT)

EMT is no longer marked as such because starting with the year 2000
ALL tubing formbed by the ERW processing had to meet the SAME
standards, so once you've removed the galvanizing (and the epoxy
coating) you've got basic mild steel tube created from flat-stock
using the Electric Resistance Welding process, which is now done well
enough to allow the tubing to serve virtually all the functions of
mild steel tubing.

You start with an 'L' joint. Like, a perpendicular at the end of a
horizontal piece. The trick here is the fact that ALL metal SHRINKS
as it cools, which means if you want to end up with a perfect 90 'L'
you gotta start out with something 'WAY outta shape. Then watch it
slowly 'clock' over as the weld on the inner corner cools. a

After 'L' comes 'T'. After 'T' comes diagonals.

They are all a lot of fun. Each has it's own peculiarities. You'll
smile when you see what they try to do.

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Metal mass vs the Golden Eye. The more metal, the more heat, the more
difficult it is to create and BALANCE the puddle.

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Everything you learn will be needed to keep a structure to spec.
Start with some basic squares, about a foot on a side. Four 'L'
corners. Too produce four 90 degree corners. (Trick: Do to 'L'
shaped sides FIRST. Then heat & hammer until you've got a true 90.
Then put your two L-pieces togeter to form the Square. Use your fire
bricks. Tricky bit here is to TACK-weld the square; to make sure your
new corners are MORE than 90. (Remember, they're going to CLOSE as
they COOL.)

Square & rhomboids lead to diagonals. But start with several 12
squares to begin with. Then try to make a 12" cube by welding two of
your squares together. Then add diagonals. Then hire an elephant to
test it :-) (Seriously. Even EMT is strong enough for some serious
structures.)

Compared to squares, triangles are easy -- and smarter. But that's
where you have to know your onions when it comes to fish-mouths.

Basic triangular structure is a TOWER, which for practice is based on
a 12" 'cell' size.

When you find yourself thinking of airplanes, let us know. What you
want is a 'Headwind' as a school project. Lots of welding (and it
flys just fine with one of the larger VW engines).

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I'm envious. You're the guy having all the fun!

-R.S.Hoover