170 Amp MOT Stick Welder

**scorch** · Jun 14, 2015, 09:15 PM

Home made Microwave Oven Transformer (MOT) stick welder. I based my design on the welder by Daniel B. Hartman (Dan's Workshop). This welder is made from four transformers from old microwave ovens. The transformer secondary coils were rewound, to achieve welding voltage, with 6 AWG solid copper wire. I included two fans from one of the microwaves for cooling. The power adjustable so it can be used with various sized of welding rod. The SCR module used to adjust the power is mounded to a homemade heat sink made from two old aluminum frying pans.

Input: 240V, ~25 Amp
Open circuit voltage: 47 Volts
Welding current: 170 Amps
Rewound transformer secondary coils with 6 AWG stranded copper wire.
Variable power provided via SCR module

Welder installed on the shelf of a cart that I use for welding.

170 Amp MOT Stick Welder-170amp_welder_640.jpg

Welder removed from the cart with the top cover removed.

170 Amp MOT Stick Welder-170amp_welder_indide_640.jpg

The SCR for the power control mounted to a homemade heat sink made from two aluminum frying pans.

170 Amp MOT Stick Welder-170amp_welder_scr.jpg

**Hotz** · Jun 15, 2015, 11:16 AM

wow great job, congratulations.

**kbalch** · Jun 15, 2015, 04:47 PM

Thanks scorch! I've added your Stick Welder to our Electrical category, as well as to your builder page: scorch's Homemade Tools. Your receipt:

Stick Welder by scorch

tags: stick welder, electrical

**kbalch** · Jun 18, 2015, 11:38 AM

This thread has been moved to the Must Read subforum. Congrats (and thanks) to scorch for making such a valuable contribution!

**LESTER MARTIN JR.** · Sep 26, 2017, 11:46 PM

Great job on the stick welder . Anyone happen to have plans for a small T.I.G. welder for small and hobby welding ?

**esaenzrn** · Mar 19, 2018, 09:08 AM

Nice configuration! I've been wondering if more transformers would result in a better device. Seems like you nailed it.

**rickmcolorado** · Jul 12, 2018, 06:03 PM

I would like to plans as well for a small hobby welding if someone has one. Thanks in advance.

**Warthog** · Jul 12, 2018, 07:56 PM

has anyone come with plans for a DIY 170 amp tig welder. I’m looking to make such a beast. Thanks😉

**Jon** · Jul 13, 2018, 02:24 PM

Try this link for homemade TIG welders: Homemade Tools Search: tig welder - HomemadeTools.net

**nova_robotics** · Aug 19, 2020, 08:15 PM

Awesome work. The wooden box on a welder is no bueno. 1/8" aluminum is nice to work with if your experience and tooling is working with wood. You can even cut it with a circular saw. And the aluminum will help dissipate a lot of heat.