/diy/ - Do It Yourself

>>1761751
Beefier spot welder for farm related things.

>>1321540
Here's another MOT spot welder using 2 MOTs to up the voltage to get through dirty work pieces.

>>1308420
Those are DIY Spot Welders made from MOTs.

>>1308434
I made a few, they work quite well. Mine are 400A to 1200A. I prefer the double MOT so the voltage is twice as much and it can burn through dirty work surfaces a little easier.

>>1308429
The voltage is probably 1.5V. I've never been able to get one below that with 110V-124V main. Most of mine are 1.8xV for a single MOT, using 1 turn of wire like in the OP's setups.

>>1207769
I take it you've never actually been in these threads before.

>>909759
With as many secondary windings as shown in that image the voltage on the secondary will be around 1.8 to 2 volts for a single MOT transformer. You can safely touch these with wet hands and not get shocked. You can volt meter them to be sure.

Wear safety goggles. These sparks can sometimes be bits of metal, not just a birthday sparkler. Catching an abnormally large spark in the eye is no joke.

The main problem from spot welders can be smoke. It really depends on what you are doing. There won't be smoke like from an arc welder, but there is usually some smoke. Don't breath it. Work in a ventilated place. Or, like me, use a ventilated helmet or flow hood. I love my flow hood for ring welding.

With all things electrical that can kill you, always keep one hand behind your back at all times.

To get an amp reading for the secondary side, just use a clamp meter on the primary side when the welder is being used. Get the voltage on the primary side. Then do some easy math for the watts. Then use the primary side watts and secondary side volts to math out the secondary side watts. Don't try to measure the secondary side amps or you'll fry out your meter or get a reading too high for the clamp meter. Depending on your setup, you can get anywhere from 1,800 watts to 3,600 watts (120v or 240v).

Here's pics of my latest one from a while ago (reposted). They are in series so the voltage on the secondary side is doubled. I did that to power through less than optimal surfaces and oxides. As you can see the sparks are quite something. Though it is welding zinc-coated rods together. (3.72V 491A 1826watts) I found that the shorter the secondary cables the better the results. 6 feet long cables sucked compared to 10 inch cables. Thicker cables are also better than thinner cables.

>>909783
It is no more dangerous than making a normal 120v lamp in shop class.