1951 Vintage Spot Welder, Safe??

[MWT Inc]

Have the chance to pickup a 75Kw spot welder cheap. It's an old Federal built in 51. The control system is junk, tubes and old rotted wiring. Question is, does anyone have experience with older spot welders? The welder will be powered with 480v. I wonder if the old windings etc will handle the high voltage. Insulation was not as good back then. Don't need a fireball! What are your thoughts?

[gimpyrobb]

I picked up a K.O.Lee stick welder. When I emailed the company, they said it went out of production in 1949. I replaced the leads and some minor issues and it really runs nice. If its old you should get it cheap and have a unique piece of gear. If it doesn't work, scrap copper is 1.80lb!

[denrep]

"Insulation was not as good back then. Don't need a fireball! What are your thoughts?"


Fireball is right with 480.
It’s probably okay though. Look inside, blow it clean. If the insulation isn’t petrified and the shellac looks clean and heavy, power it up! Don’t rely on the last electrician, confirm your lead and ground connections.

[awright]

True, insulation was not as good in those days. But engineers on those days weren't dummies. They designed the equipment for the insulation they had at the time and for the rated currents and duty cycle. Just be sure to use it well within it's duty cycle. Since you probably won't know the duty cycle, put a temperature sensor as deeply in the windings as you can get (which would probably just be on the back side of the wire skein) without contacting the steel that would wick away heat. And don't use the welder beyond some very conservative temperature indication. Ask your local motor rebuilding shop what temperature to limit it to. You could set it up with a thermostat that automatically cuts power at the preset temperature or hook it up to a cheap temperature sensor. The motor shop or Grainger would have a thermostat that you can tie and thermally bond to the wire skein.

Unless there are some signes of deterioration, and provided you use it within it's ratings, I would go for it. Age alone in the absence of any signs of deterioration or misuse is no reason to pass it up. If possible, power it up and check it out before buying. But you probably won't be able to do that.

Smell it closely. If the insulation was burned it will stink. You can't miss the smell of burned insulation. If it does stink, or if any insulation is crisp and black, or if you can see any copper where you shouldn't, pass it up unless it is cheap enough that throwing it away won't hurt.

Enjoy it!

awright

[alanaker]

I'm scared!!

[awright]

There, there, alanaker. Everything's going to be OK. Just take a few deep breaths.

awright