Scrap Microwave Spot Welder

This project involves AC power, high amperage, and high temperatures. Although this project is simple in principle replicating it on your own offers a lot of opportunities to hurt yourself. Proceed with caution.

Microwaves are treasure troves of useful electronic components. They’ve usually got some nice microswitches, a big transformer, a magnetron, and some smaller transformers and rectifiers to drive the display. I found a decent sized microwave hanging out on the street and transformed it into a shop tool I’d been wanting for a while – a spot welder.

Why Spot Welders are Useful

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Spot welders are handy to have around the shop. They can tack together wire for quick brazing, and permanently weld sheet metal for durable enclosures. If you want a thorough guide on what you can do with a spot welder, Dan Gelbart has all the answers. I’ve been looking to up my prototyping game and have more freedom to build custom components when off the shelf parts won’t suit. Unfortunately my workshop is in Brooklyn and space is at a premium. I spent a lot of time fabricating structures out of steel wire in school and have found that it’s a good replacement for bent sheet metal and structural framing if you play your cards right. Wire is easy to store in a small shop, doesn’t take much equipment to manipulate, and can hold good tolerances in various dimensions as its behavior is very predictable. You can still find the manual I follow for a lot of my techniques on Amazon. Continue reading