Build a Microwave Transformer Homemade Stick/Arc Welder

Picture of Build a Microwave Transformer Homemade Stick/Arc Welder
I had no idea making a DIY welder would be so easy to do. And, it's pretty much FREE!

Additionally, the stick welder you get is definitely better than anycheap commercial welder you can buy.
Why is this homemade thing better than something you can buy? Because when you factor in shipping and labor and the little bit of retail markup - the companies that make typical cheap buzz boxes will skimp on copper as much as possible. Whereas you can use enough copper in this to make something really juicy, and still spend less, to nothing, compared to a store-bought arc welder.

So here's what you need to build a welder:
- Two beat up old microwaves
- Some 10 gauge wire
- Wire nuts

People throw out microwaves all the time, if you keep your eyes on the curbs.
Or, you can get microwaves at the local thrift store for $10 each.
Try the warehouse that processes donations - they have to pay to get rid of tons of broken ones.

Stuff you need for welding:
- Welding helmet ($16 and up)
- Welding rods ($6)
- Vice grip or purpose-built electrode holder ($6 for either)
- C clamp for grounding clamp
- Gloves
- Thick nonflammable (leather) clothing that will cover your arms

Disclaimer: High Voltage ELECTRICITY and lots of CURRENT! Heat, electrocution, and DANGER! You could die and you could go blind.

That said, try this at home!

See this for a lot of welding safety tips

Here are the really good how-tos that this project is informed by:
build a 70 amp welder
the tiny tim welder by tim williams
home made welding machine (via afrigadget)

Dan Hartman's how-to is good for reference, too.

And here's the quickest way to make a DC welder with a bunch of 12 volt batteries.
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Does anyone want MOT ? I just destroyed my new microwaveoven to take the transformer out and to build a welding machine ,but new i lost my interest in that and want to sell my MoT ,pls help me
OVERLOADED3 years ago
does wiring the sec in series also give you double the voltage ?
No. Wiring in series boosts current. Wiring in parallel boosts voltage.

I know it is an old post, but wiring in series raises voltage, not current. Wiring in parallel raises current.

Also be carefull with your transformers, make sure they are the same gauge thickness and windings, preferably exactly the same transformers. That can bring you trouble both in long term and short term use.

Great project, waiting for my microwave oven to go down so I will give it a go ;)

Sorry, but wiring in series boosts voltage, not current.. Two 6 volt batteries in series gives you 12 volts. In parallel, gives you 6 volts at twice he current.
Sorry, you're right. In series current stays the same, in parallel voltage stays the same. Long night.
correct,no need to be sorry for nature lol. it is what it is.
thx wasint too sure about trans or even why i asked that question so long ago?
sphawes2 years ago
Ive built mine using two transformers wired in series. I was only able to get about fifteen winds in my secondary coil for each of them. Being a new welder, i get the stick stuck to my piece quite often, causing my fuse to blow. Is there a way i could wire it up better so that this wont happen, or is it just a matter of not sucking so much at welding?
DanniM sphawes1 month ago

use a house breaker in place of the fuse. if know ur current then you should be able to find a safe rating.

can you plz tel me if safe totachit with my hands







squiddarling6 months ago

Hexavalent chromium (a.k.a chrome 6 mentioned below) is carcinogenic. Just a heads up, that you NEED a mask...

does anyone know what the standard output is on one of these transformers?

Its about 1.2kV


hhofkhan9 months ago

between 16 to 24 volts but not more than 24

dan7 years ago
referring to your 'one hand behind the back' electrical safety position - for high voltage work you can't just put either hand behind your back - it must be the LEFT hand behind your back. the reason is that if you are prodding at some high voltage gear with your right hand and get zapped - the primary current flow is the shortest path to ground: through your right arm, down your torso on the right side, down your legs and into the ground. now if you use your left hand instead - then unfortunately your heart is in your left side torso and is now part of the predominant current path. high voltage electrical work is unfortunately not a good career choice for lefties. now, as shown (with either hand behind back) it is usually ok for 120vac work, because if your shoes are dry and have decent rubber soles then 120vac isn't enough to go through that.
Your heart is in the CENTER of your chest and has only a small protrusion to the left. All your talk up about the dangers of putting one hand behind the back vs another are all hoo-nanny.

Back in the dark ages I worked a lot with some very dangerous equipment. We were taught to work with one hand in your pocket or behind your back. The problem was not current thru you shoes (electrical safety shoes were always used), but current from hand to hand with your heart in between. A couple times I had terrible bad enough to leave a bad burn on my hand. Good technique meant survival. Always remember things break...a safe place to touch today may really get your attention tomorrow.

tashammer dan7 years ago
The heart being on the left hand side is not always true speaking as one who's heart has been moved over to the middle right due to having a lung out.
There's always one! Lol
Ok but for the majority of people this applies correct?
esumon1 year ago

my microwaven primary side was burned . so i have difficult to make this . any body can tell me . how many turn need for primary( for input 220 (50\Hz)volt supply ) side and which gauge wire ?

Can I have three transformers on lower voltages?
subodh1011 year ago
Can somebody tell me the two transformers specifications if I want to buy those as new ones or if I can find a single one for this kind of diy.
Im also running like 14 gauge wire for the secondary.
So i got the transformers all wound up and ready, when i tested it, it came out to a 30.9v output and im ok with that, but i fogot to unplug it while it was on the multimeter. So over the course of 10-15 minutes the primary coil got hot. one transformer puts out 13v and the other 17v and the the 17v one got hotter but both primarys were pretty hot. should i be worried or is it because i had it on too long.
themudball1 year ago
i only had 600 volt wire for the secondary, i wrapped two coils in each transformer, ya think that's why i'm not getting good amps?
sirward771 year ago
I constantly emailed this site post page to all my friends, because if prefer to read it then my all friends will too.
metal fabrication
alahamm1 year ago
Hi star; I just got the secondary out and I see that the primary is separated from the filament winding by a few metal plates. SHOULD or SHOULDN´T I remove these?
Thanks; VERY useful ´ible.

First, I offer my condolences as well. I mean no offense what-so-ever in my following comments, as this is neither funny nor pleasing. With that said, I find it somewhat rude that you imply that this instructables author may be partially to blame for your sons horrific accident. Nobody forced him to pursue his endeavor into the field of high voltage experimentation. Despite the authors attempt at sarcasm (That said, try this at home!), there is warning about serious injury and possibly death.

There are many different projects that parts inside a microwave can be used for, all of which are quite dangerous. To assume that this article in specific is responsible for this tragedy, is not fair to the author or the instructables community. A more fitting comment would have been something to the effect of "We lost a loved one due to an accident caused by his curiosity of electronics and a high voltage project. Please, for the sake of your safety, be careful."

Again, I am sympathetic and sorry for your loss.
i am sorry
lol the link for welding rods actully goes to a drip irrigation kit maybe you should fix it
HeatUp2 years ago
plz answer me how much i need turns and how much wire plz answer thanks:)
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