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Build a Microwave Transformer Homemade Stick/Arc Welder

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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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hhofkhan2 months ago

between 16 to 24 volts but not more than 24

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

Its about 1.2kV

dan6 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.
constablebrew dan8 months ago
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 shocks...one 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 dan6 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?
esumon6 months 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?
subodh1017 months 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.
themudball12 months 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.
Sandra,

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
sphawes1 year 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?
HeatUp1 year ago
plz answer me how much i need turns and how much wire plz answer thanks:)
HeatUp HeatUp1 year ago
oh and i live in 220 zone
I love the 1980's electronic baseball game in the back of the one pic. I remember having one of those and burned many of hours playing that game.
Nice build also, love all the idea's.
HeatUp1 year ago
how much i need wire if i live in 220 zone?plz answer
Tempted1 year ago
The steps here are very vague and difficult to read. Are there any more user friendly plans laying around?
I've a question about the power source(s) for this welder; could it be wired to work with a 220v AC (U.S.) service as opposed to plugging it in to two separate 110v AC circuits?

I'm not an electrician but it seems like it would be possible to tie the neutral leads from the transformers to the 220v neutral, connect the hot lead from one transformer to one of the 220v hot wires and the other transformer hot lead to the other 220v hot wire.
mykiscool1 year ago
Just want to let you know that the welding rod links to an irrigation kit.
billbillt1 year ago
Great!!...
PheonixZip1 year ago

Now I have my transformers prepped and I'm not trying to spend money here, and I've used up my 10ga wire on new lighting and outlets in my garage. So I have 3 sets of 8ga jumper cables (stranded) or 12/14ga (solid) idr but about a good 50' left. Reccomendations on what I should do and how many wraps? Thank you.

Also one or two AC inputs, US 110VAC
whos the gurl?
lloydrmc1 year ago
Great 'able. The Harbor Freight electrode holder you list has since been discontinued, and the SKU reused. This costs a little more, and it should do the trick: http://www.harborfreight.com/200-amp-electrode-holder-97892.html
stasterisk (author)  lloydrmc1 year ago
updated the link — thanks!
Thanks for the instructable! My first time welding and it works like a charm!
stasterisk (author)  DrDontDoDis1 year ago
That's what I love to hear! Post pics?
theloyz2 years ago
I don't know if this just sounds dumb, but since i'm Kind if new at this kind of thing I'll ask anyway. if you wanted the most output amps, couldn't you just have like two turns of super thick wire on the secondary coil?
A few months ago my nephew asked me why dogs noses are cold, so there are no dumb questions. The reason that would not work is that the amps and volts are inversely proportional to each other given the input. The inputs overall work capacity force must necessarily equal the outputs, because that's the total energy available. I, too, thought that amps was the chief factor to a powerful weld, and it still is. However, without enough volts [pressure] into the output, the weld will not begin or maintain, for these purposes. For a spot welder, per se, you would be correct, as they evidently go higher on the amps, way lower on the volts, but will only minimally "weld" thin metal. Here is a project of your exact description: #4 gauge thick output wire, only a few turns, huge amps, only a couple volts: http://hackaday.com/2009/06/23/how-to-build-your-own-spot-welder/
fidgety22 years ago
I have a couple of questions
1. How many power cords are actually plugged into the wall 1 or 2
2. Should the secondary cords be linked together between the two MOTs
3. Could someone please take detailed well lit pictures of how their welder is wired and post them

Thank you
Fidgety2
I would love to see a reply to this comment-- these are the same questions I have!!!!
OK, I'll try:
1) It's confusing [although they did a phenomenal job on this] because in the circuit drawing there are two wall receptacle cords supplying the x-formers, yet in the real life animated pic they have evidently supplied both x-formers with only one, which is probably wired in parallel. If both x-formers were inputted in series, instead of parallel, from one cord, it shouldn't work because of a division of the overall input voltage. Here in my region newer houses seem to have two separate cables in the wall, each supplying one of the two outlets in each individual receptacle. Therefore, i submit that there are good reasons to have two cords supplying your unit, and good reasons NOT to have just one, regardless of how hefty that one may be. 2 cords into any two outlets will take advantage of more power [and safe, third prong grounding] than any one under normal circumstances. With just one cord you are more likely to make your home wiring the limiting factor.
2) Yes, they should. Connect one of the wires you wound from one x-former, to one of the ones you wound from the other. You then need to follow their testing instructions. Remaining 2 of 4 wire leads that you wound go to the weld...doesn't matter which because this is AC not DC.
1) Will post pics ASAP. Meantime follow the "schematic" AKA wiring diagram/drawing that is obviously hand drawn...the one with pictures of two wall plugs and squiggly lines. I suggest you either put this project in wood, connect the third [green] wire from the wall to your chassis if using metal, or seek further advice on how to safely ground your project.
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