Homemade simple spot welder using MOT: Easy Steps
Homemade spot welder using MOT

Spot welding is both fun and fruitful. This handy device can weld thin sheets of metal. This device is a simple transformer that produces very high current with low voltage. My apparatus consists of a MOT (Microwave Oven Transformer) from 1050 W rated oven which is wound with thick copper wires of 3 round.

This causes less voltage and more current production (V=IR). We can use such high current to create high heat for spot welding. Using that heat we can melt metals and also join them. Just for warning, this is for educational purpose and we are not liable for any risks and damages that might occur.

So for start, We have a 220V 50 Hz transformer from an oven. We cut off its high voltage secondary made up of very thin wire. The secondary was about 2000 V which is very dangerous. There is usually a big powerful capacitor in coupling. Always discharge such big dangerous capacitors carefully because they store charge for long time.

Read More: Homemade Arc Welder using MOT


Be very careful while working with the primary coil. Carefully remove the secondary winding of the transformer. After removing the shunts and secondary the thick copper cable or Jumper cable is wound around about 2 turns. This gives us very low voltage but a very high current which is required for heating. H=I2rt .


We have all the details in our YouTube video. All you need is old powerful transformer and some thick copper wires. Simple remove the thin secondary winding and replace with thick copper wires. Many people make a good setup using holders, lugs and terminals. This is a fun simple weekend project. Just be careful before extracting the MOT from Oven because there is a lethal Capacitor that you should discharge at first.

You can also modify your setup and use carbon rods to create melter. There are lots of uses of this kind of project. It is fun and useful in times of need. If you have a home and repair things yourself then definitely try these kind of projects to improve your skills and collection

If you have any questions and feedback than share with us. Be very careful while working because it is related to high voltage electrical works. User safety gear, protective gloves and always have a tester for checking. Check voltages with good digital multi-meter and maintain good distance from any thing flammable.

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