How to build a spot welder without burning your fingers off

Now With Pictures!


I wanted a spot welder. I nearly NEEDED one. While wandering around online I ran across the wholly wonderful website of Kurt Bjorn who, besides making spot welders, also makes rotary aircraft engines and miniature turbojet engines. (yow.) Anyway, he had a discussion of how HE made a spot welder. Go there, read that first. Then read my version.

My needs were somewhat different than his so my construction follows a different path. I will try and explain how I built what I built, while discussing what he did.

I have had no problems welding mild and stainless steel, and welding aluminum to steel. I have not yet managed to weld aluminum to itself, and can't weld silver at all. But steel to steel, I can weld all day long, and get beautiful welds very nearly as strong as the wire I'm welding in.

I found something interesting: if you want to reface your electrodes nicely after the faces have gotten chewed up from lots of welding, a really good way of doing it is to take a piece of 220 grit sandpaper and fold it so that it has the sandy faces on the outside, put this between the electrodes, close them gently, and pull the paper out. This has the nice advantage of keeping the electrode faces parallel to one another.

This page created 3/15/02, last modified 4/23/04

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