Spot Welder




Introduction: Spot Welder

This is very basic homemade spot welder. Tested! Works ok! :)

Notice the way electrodes are fixed to the wire. It is most basic way and takes some filing (sharpening electrode tips) - can burn your fingers during operation- gloves needed!! Next time ill try to make a armature for proper electrodes alignment.

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    6 Discussions


    3 years ago

    Lately, I have been having a lot of fun with these spot welders. I plan on making an instructable soon. For now, I am just posting my pictures on my google page. But I have found a simple way to use the 2 small relays in the microwave to control the pulse. I'll also put up a schematic on how to use it(don't laugh, I still use rules paper and pen..LOL). If you have a soldering iron and know how to de-solder. Then you pull the 2 small relays from the control panel(normally one main relay and a few smaller ones). One is rated for the mains voltage and the other rated to work on DC voltage for safety reasons. Then combined with a small capacitor you can control the pulse pretty easy. I have found 100-220 uf caps to be the sweet spot. This might help smooth the pulse. Its pretty simple and available if you still have the Microwave you took apart to get the MOT. I have found that all the parts needed to make a controlled pulse spot welder, is with the Microwave. I have even seen other DIYers use the metal casing from the inside to make a nice looking case, with some bending and a few screws. I plan on making another one soon with all I have learned, only using the parts of the Microwave. But that is another project for another time. I also plan on posting Videos on my future projects. I am new to DIYing and wanted to brush up on my soldering and wiring skills

    Great Instructable! Simple is the way to go!


    Reply 3 years ago

    I just realized I gave the schematics to the simple switch only. No Cap. Here is the one I later made using a capacitor and timed. Hope you find it helpful.

    mot schematics.png

    Are you making contact then applying power or applying power then making contact ? I think the former would serve you better and you would avoid arcing.


    Reply 8 years ago on Introduction

    First I put one of electrodes on the top of the battery and then I turn the power on. Finally i put the other electrode on and I press on. Takes some practise and I didnt have much time to play with it for long but I will let you know as soon as I will figure out easiest way. I am sure it cn do the job - I did a sample on batterry.


    8 years ago on Introduction

    This project should be a step by step Instructables. That way you can explain each step in details so we can replicate your project.