70 Amp MOT Stick Welder

[scorch]

Home made Microwave Oven Transformer (MOT) stick welder. I based my design on the welder by Randy Gross (Homemade 70-Amp Arc Welder). It looks like Randy's web site is gone now but my welder lives on. This welder is made from two transformers from old microwave ovens. The transformer secondary coils were rewound, to achieve welding voltage, with 10 AWG solid copper wire. I included a fan from one of the microwaves for cooling.

(EDIT: here is a link to an archive of the original AAA Welder web page that I used as a guide to construct this welder.
https://web.archive.org/web/20100411...com/70amp.html )


Input: 120V, 20 Amp
Open circuit voltage: 40 Volts
Welding current: 73 Amps
Rewound transformer secondary coils with 10 AWG solid copper wire.
Welds best with 5/64 welding rod