On 19 Aug 2005 04:58:37 -0700, "mhorowit" wrote:

I'm not sure I made myself clear. My A&P is concerned about 'stress
risers', but the articles I read about making joints involve a process
which scratches the surface of the tubing and appears to actually
produce those 'stress risers' - Mike

Has your A&P never welded a tube or marked one? You don't have to
scratch it with anything. You can use any number of writing
instruments to make a mark including a magic marker. Use your
imagination.

In the event, even if you do scratch the surface to mark the length,
you end up grinding right up to that mark, and then welding a large
bead right over it. It becomes one with the weld, so to speak.

There is no need to scratch a mark in the middle of the tube.

You will find that the act of welding tubing together is intuitive and
relatively simple, if you just start doing it. You can be very very
precise and use things like a lathe to mill the angle, or something
like the "Ole Joint jigger" that does basically the same thing,
although with a lot of noise and smoke. You can also just round off a
grinding stone and hold the tube against it until you approximate the
curve you need. You aren't gluing this thing remember, it doesn't
have to be accurate to within a fraction of an inch all around. The
filler wire can cover a lot.

Corky Scott