Gunnie - Funny you ressurected this thread just as I've been getting back into smithing! It's been 4 years since that experiment, wow. And yes, arc welders do have a duty cycle. I never used this long enough to trip mine, so I can't really say much more than that. If you give it a shot, don't be fooled into thinking my contraption was safe. I doubt it was safe at all. It mostly just seemed like a neat idea at the time. A good rule of thumb is that if something seems neat, it's probably dangerous.
Thomas - The gases were what ended the experiment. I realized after a few tests that there was a funny smell lingering afterwards -- oh, right ozone. darn it! And put the project on the backburner.
I'm now out in the country, and have a nicely ventilated shed under construction. I might ressurect the idea someday, but for now I've finally been getting comfortable using coal, have a very cheap supply, and am better adapted to heat than I used to be, so then again, maybe I won't.
HWooldridge - I'd definitely prefer induction, too, but this was easier to slap together with materials I had around. I didn't, and still don't, forsee having 3 or 4 grand around for an induction machine any time in the near future.