I've been thinking of buying one of those cheap (~$100) 120 VAC "stick" arc welders for a particular project: Welding an angle-iron frame to hold a larger version of my experimental electric kiln.
(No, I don't need or want a big 240V model, and the low duty cycle of a cheapie is no problem at all for my purposes.)
But then I had a "duh!" moment: The monster 120 VAC transformer (easily over 100 lbs) for the kiln is far more capable than that of any cheap welder, or anything I could rig from microwave oven transformers (MOTs). It has massive switches for coarse and fine output voltage control from 33 to over 100 V and can put out a solid 25A continuously for hours. (Originally, this was an industrial furnace for melting test specimens, etc. Uses silicon carbide heating elements.)
The secondary windings (at least the leads coming from it) are better than 8 gage... maybe 7 or even
- (The overall leads are 0.250 with insulation, and I'm only peeking at the stranded conductors where they connect to the switches.)
So I'm quite sure this could handle the larger currents needed for welding, with some duty cycle constraints. The problem is, it doesn't have the current-limiting due to puny primary windings that a commerical cheapie welder (or MOT homebrew) would have. I imagine that I'd pop the mains breaker a lot, meaning a trip to the basement each time.
Anyone have any suggestions for a simple current regulator / limiter? I found one MOT design that used a choke in series with the primary to "soften" things. I have a MOT, and plenty of old junk box chokes and transformers, that I could use for the choke. Any selection advice?
Is that the best way to go? I don't think I need anything fancy, since this is pretty much a one-off job, with maybe further "improvements" to the kiln design at a later date.
Thanks, and best regards,
Bob Masta DAQARTA v5.00 Data AcQuisition And Real-Time Analysis