Honey, Your jig's on fire!

For the past few days, I've been working on a project that is semi-
related to aviation. That is, its related by the fact that the skills
necessary to complete it may also be usefull in building an aircraft.
I like to think of it as a training project.

What I'm building is a kinetic-sculpture racing vehicle. By
definition, its a whacky-looking multi-wheeled craft powered only by
humans that will be capable of traversing roads, trails, sand, mud,
and small lakes. These crafts also have an artistic theme, but that's
not really important. The real issue is that my craft is being
constructed of welded steel tubing. In that respect, the skills
required are exactly the same as those needed to build a steel-tube
fusalage (sp?? never could spell)

So, following in the great tradition or Anthony Fokker, I spent the
past few days laying out a design on a sheet of particle board,
attaching pine blocking, and cutting tubes to fit. I've made good use
of the H-F tubing notcher. BTW, the arbor on mine likes Vermont
American and DeWalt hole-saws, but not Lennox. I've also descovered
that my notcher can't really cut an angle greater than about 25
degrees on 1 1/4" tubing. So I've been using Tubemiter and the tripple-
cut ******* file that my Dad to left me as well. Fitting tubing for
this type of project isn't critical, so its a good way to practice
without getting dead. The type of tubing isn't critical either. I've
been using EMT since its cheap and easy to obtain from the Borgs.
Since the stuff is always slathered in zinc, I've built an "acid tank"
which is nothing more than 4' of 1 1/2" PVC with one end capped off.
Fill 3/4 full with a 20% solution of muratic acid and water, insert
steel tube, no smoking for 20 minutes, rinse. (Remember, I'm making
art here. I'd never use EMT in an aircraft. I've seen what's under the
zinc.)

Then come the two fun parts. Fitting everything back together, and
keeping it aligned long enough to tack weld the joints. I'm using an H-
F torch, this time with the #2 tip. I fire up the torch, adjust, start
heating the tubes focusing intensely on the joint when I hear "Honey,
your jig's on fire!"

Yes dear, that happens to wood when you point a 6300 degree fire at
it. Yes, that's OK. Yes, I planned on it. YES, I DO have a big bucket
of water, and a hose, and a fire extinguisher.

I still suck at welding, but I am getting better. Next weekend's
lesson is in gymnastic welding and warpage. Should be fun.

Harry Frey