Aviation Sheetmetal Work

To All:

Guy calls, wants to buy my metal brake & sheet metal tools. Left
unsaid is WHY someone you don't even know would call you up out of the
blue and want to buy some tools which, in a couple of cases belonged
to my grandfather, my dad, and my brother.

The WHY? Because I've been diagnosed with cancer. With multiple
myeloma.

But I can't sell my tools, firstly because they're already promised to
my son. But more importantly because I'd just have to buy all new
stuff WHEN I LICK THIS DAMNED CANCER!

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Okay, so it really isn't something that's worth the trouble to tell
all you guys about it. But I did mention it to a couple of friends.
One of them said he could understand the guy's point of view. Not
about the cancer but about buying the tools. Way back when, one
reason he bought a set of plans for the Fly Baby was because he didn't
have any metal-working experience at all, whereas the Fly Baby was
advertised as an ALL WOOD design.

You already know the punch-line, right? :-)
(There's no such thing as an 'All Wood' design. EVERY homebuilt, be it
wood, composite or metal, requires some skill in those other areas as
well.)

Buying a book on BASIC aviation metal-smithing isn't a lot of help
because they start-out pretty far along the learning curve. And if
you're out there by yourself -- no local Chapter to rely on -- you may
have a hell of a time learning how to bend tin.

So don't. Bend tin. Or roof flashing... or whatever else you're
using as your basic How-To material. Bend CARDBOARD instead. No, not
corrugated cardboard; something like a cereal box. You can draw the
part on the cardboard then bend it in your vise. Once you've mastered
the basic idea you can drop by the Borg and pick up some galvanized
sheet metal, roof flashing or what-have-you and TRANSFER your skills
to real metal. (The biggest difference is in the CUTTING and how you
DRESS the edges.)

You probably won't believe it but a good bench vise, one with
auxiliary jaws (ie, smooth metal jaws that fit over the regular jaws)
can handle about 90% of the bending chores in the typical "all wood"
design.

Need to make a LONGER bend? Then go back to the Borg and pick up a
piece of ANGLE IRON (or even TWO pieces if one isn't long enough).
Drill some counter-sunk holes in the angle iron and fasten it to the
edge of your work bench. Use... something.. another piece of angle
iron or just a piece of flat steel... to CLAMP the metal you want to
bend, to the angle iron you've bolted to the work bench. Now BEND the
metal by GENTLY tapping on it with a mallet. Thin metal, you need to
go over it a dozen times or more; thicker metal, you'll need to go
over it a LOT more times... mebbe a hundred. The idea here is to
DISTRIBUTE the energy of the hammer's blow so as not to WRINKLE the
metal. To do that you have to learn how to overlap your blows,
working your way over the metal again and again, SLOWLY folding it
over the angle iron 'edge' you've fastened to your workbench.

You won't believe it but you can produce a flanged wing-spar in forty-
thou 2024-T3 that is JUST AS GOOD as anything made with a metal
brake. What's the secret? Practice.

In the same vein, buying a lot of metal-working tools doesn't mean
you'll be turning out usable parts. Before that can happen you'll
have to learn how to USE those tools. A work bench with a metal edge
IS a 'metal brake' ('Brake' is an archaic term for vise or clamp.) So
instead of day-dreaming about a 48" metal brake from Harbor Freight
that you'll probably never buy anyway, why not pick up a piece of
angle iron and start LEARNING how to do metal-work. Seriously; it
doesn't cost very much and once you learn to 'hammer-fold' a piece of
metal, you'll never forget it -- You will have acquired a LIFE-TIME
skill. Which is better than coming down with a dose of cancer any
day :-)

-R.S.Hoover

PS -- I haven't mentioned spring-back or a lot of other stuff you'll
have to learn before you can can bend your Fly Baby hinges in your
vise. When you get that far along, ask. There's lots of good tin-
benders in this Newsgroup who'll be more than happy to help you.