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        Welcome to the Gary's Farm & Shop Projects
  Spot Welder from a Scrap Microwave Oven

Occasionally I want to repair a broken spot weld, but it's not really worth spending hundreds of dollars on a commercial spot welder. This one cost me a mere $10.00 for the 4 offset grounding lugs. All the reaming parts came out of the trash or my shop scrap pile. I saw this project on King of Random. It works great, I just wanted to make a few additional comments that are not in the video. My transformer was considerably larger than Grant's so the first thing I had to do was modify the case. You will also notice I did not paint mine as pretty as The King, at least not yet, maybe later.

Aside from the side of the transformer my first big issue was how to get the secondary coil out of the core without damaging the primary coil. It turns out that copper wire is so soft that an old wood chisel worked great. I cut it up into cubes and pulled it out. I happened to have an old welding lead of #1 copper which is very flexible it worked great. The ends are connected using 2 offset grounding lugs instead of the crimp-on ends Grant used

The biggest issue I had was the welding tips. I used 1/4" copper rod for the tips and could not get a good weld. The issue is the tips need to be rounded or ground to a dull point to make good contact and localize the electrical charge. Once the tips were ground down it worked like a charm. This is a great little Saturday project, I hope to get some good use out of it

spot welder transformer spot welder fuse
spot welder electrodes spot welder tips

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