Tuesday, July 7, 2009

Homemade Spot Welder

Here is a homemade spot welder I made. It just connects to a car battery and welds thin steel and tin pretty well. The far right side is where the welding occurs. Just hook one side of the battery to the left side on the longer copper pipe. And hook the other side of the battery to the shorter pipe where there is a gap in the electrical tape. If you make this one, make the pipes shorter, about half the length. There is too much play in mine and that is one thing that I would change.

Take a look at this video. It talks about resistance spot welding and how it works.

Here are some videos of people using microwave transformers to make spot welders.

Just be careful when working on microwave ovens. The main thing is make sure it is unplugged and then short the capacitor out using a screwdriver. Those capacitors are very dangerous.



  1. Hey Richard thanks in advance I'm still gathering the parts I've got the 800watt microwave transformer now
    and sawed off the secondary coil they used aluminum wires !the single turn measured 1 Volt
    2 turns measured 2.3 Volts A.C...I'm still hunting
    wires for the secondary they must be thick AWG.

  2. Remember, you can take two wires and run them together as one in parallel. For example, using two 8 AWG wires is the same as a 5 AWG. That is probably enough as long as you let it cool down after every weld.


  3. Hey, really great design and nice job....

  4. Hi Richard, you have made nice spot welder using microwave transformer. I will wait for more creative updates like this!

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