It'd be a problem if the primaries aren't phased, and worser if the
secondaries aren't.

Just thought I would add another note here. Since resistance welders are used
very intermittantly, I wouldn't hesitate to try just one and overload it for
your welding operation. Similar to the Lincoln buzz box welder, it is rated for
a certain duty cycle depending on the output current.

A microwave transformer rated at 1000 watts can probably put out twice that
power if used at no more than a 10 to 20% duty cycle. Just a guess, but an
educated one. :)

Earle Rich
Mont Vernon, NH