A long time ago, I built a spot weldor using some 1 kw variac cores
and a single turn made of aluminum that pretty much filled the hole in
the center of the variac cores. It was plenty powerful enough. I
crossed two 3/8 th bolts and applied pressure and current. It welded
them into a cross with the bolts almost in the same plane. About four
microwave oven transformer cores ought to be roughly equivalent. You
will have to wire the primaries in series/parallel and use 240 volts
to avoid popping a 120 volt breaker.

Dan



Howard Eisenhauer wrote in message . ..
Anybody here ever built your own spot welder? I've got some major
re-assembly work coming up on my jeep tub & I've been thinking it
might be easier/faster to do real spot welds instead of the "drill
hole/mig weld plug/grind down" route. I've found a few references on
google to plans for units using re-wound microwave oven transformers,
intended for use on small projects such as model gas turbines, but
there isn't enough detail to convince me they'd work on heavier sheet
metal.

So, if you have any experience with something like this or know of any
on-line resources that google (Gasp!) doesn't know about I'd
appreaciate hearing from you.

Thanks,

Howard.