Making an ARC Welder - Part 1 of 2

How to convert scavenged microwave parts into a useful arc welding machine. This is part 1 of 2, and focuses on the modification of the transformers.

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Step 1: Watch the Video!

WARNING: Stick welding, and/or the modification of a Microwave Oven Transformer (M.O.T), can be very dangerous and presents risks of UV radiation, shock hazards, burns, fires, fumes and a multitude of other risks. This project should not be attempted without a thorough understanding of electricity, adult supervision and adequate training. Misuse, or careless use, of tools or projects may result in serious injury and/or death. Use of this content is at your own risk.

Step 2: MOT (Microwave Oven Transformer)

Picture of MOT (Microwave Oven Transformer)

In a previous project, I melted the lead wires on my first metal melter. But the transformer core was still in great condition, so I re-used it to make an AC stick welder!

The arc welder made sparks fly, but in the end, it wasn't enough power to make the metal stick, and the pieces of work would break apart with very little effort.

If I tried pumping more power into the welder, the wires would overheat and melt.

So to address this challenge, we'll be using 2 MOTs (Microwave Oven Transformers), because more transformers means more power!

Step 3: Transformers Transform

Preparing the MOTs for a new secondary is exactly the same as the first few steps we took in the Metal Melter project. As it's a little redundant, I won't spend much time on the step-by-step instructions for that, but if you haven't seen it yet, you can check out the Video, or reference the Instructable.

gennagonna11 months ago

I have been saving bottle caps

timififilger1 year ago

Great Videos ! I'm going to build my own. One last thing : With two MOTs, how to calculate the width, the lenght and the turns to obtain a 30V and 0 120 Amps welder? you say 8 gauge with 18 turns, but if i have a different first coil, would it be the same? Best regards from France

sibi.20091 year ago

Sir how much is the output current from this transformer ?

crazy-blender1 year ago

Grant have you posted part 2 ?

walkerbk1 year ago

Have you posted part two? and this runs on 240 volts??? nice build

iungerich11 year ago

hay grant already made your spot welder and i love it!
when part 2 comes out i will make this but i am getting all of the stuff now
i have 2 wire choices picked out witch one (if any) do your think will be best?

http://www.amazon.com/Cadence-4G150MP-B-50-Amplifier-Guaranteed/dp/B00BIU49VW/ref=sr_1_17?ie=UTF8&qid=1365698408&sr=8-17&keywords=50+ft+8+gauge+wire

http://www.amazon.com/gp/product/B00785ULO0/ref=s9_simh_gw_p422_d0_i1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=0RT7QW2870WFSFN463EY&pf_rd_t=101&pf_rd_p=1389517282&pf_rd_i=507846

thanks hope you can answer my question

MrPyr0fiRe1 year ago

I am from Germany and I will build this ARC WELDER too.
is this the right cabel

http://www.ebay.de/itm/Audiotechnik-Dietz-10-mm-mm2-QMM-Powerkabel-73-Meter-auf-Rolle-/330903831891?pt=Kabel_Stecker&hash=item4d0b67c553

crazy-blender2 years ago

are you going to make a video of the dual MOT stack i saw in your video?

The King of Random (author) crazy-blender2 years ago

Thanks for asking. I wasn't planning on it. It was just unballasted on 240 volts and I'm guessing it was pulling around 20-30 amps, but not enough to pop the breaker .. even after running for 10+ seconds at a time.

crazy-blender The King of Random1 year ago

You should make a video. I made I dual stack with a half-resonant circuit (2 microwave capacitors in series) and it gave me arcs about a foot long!!!

wolfgang641 year ago

Grant, great work! I have built your spot welder and have been very impressed.
I have two questions with this one. 1 how small can you take this and can you use this on other metals? You are an impressive tinkerer.

I_StarkGuy2 years ago

You are so awesome!!! And your videos are clear and professional. I will follow you to see your recent videos. I'm planning of repeating some of your projects myself.