Build a Microwave Transformer Homemade Stick/Arc Welder

Step 6 Wire your two transformers together

Why do we use two transformers?
Just one of these isn't big enough to make a really juicy welder.
If you happen to find a big enough transformer somewhere, feel free to use that.

Here's how to hook up two transformers.
First we wire both primary windings in parallel to the wall cord.
Then we wire the thick secondaries in series so they both"Push and pull" in the same direction.

Comments

[OVERLOADED]

does wiring the sec in series also give you double the voltage ?

[archer1232]

Do you even hook up the green ground wire to anything on the transformer? I dont get it. :/

[TimAnderson]

green goes to the cabinet. It's not supposed to carry any current. It's just there so a a loose wire that touches the enclosure will blow a fuse instead of giving you shocks.

[microedit]

About the three prongs...one is ac electricity always on, the next is used only if there is a short to it... i.e. bad wiring....the third the government added for the housings of appliances, so a short would not get to a person touching the appliance. But ...a double short would still get you (very rare!). Also, the second wire is necessary to complete the AC circuit but never has juice...its just a conductor (unless a short).

[HSPrzepa]

should the green be hooked up to both cabinets? and a cabinet is the transformer right? lol

[DirttrackinRedneck]

It wouldnt be a bad idea to hook the green wire up to both the transformers so no madder what you do or wat happens they stay grounded.   

[archer1232]

So basically you are just hooking up two wires to each tranformer(positive+negative)

[fishnfreak18]

would the transformer out of a golfcart charger be enough to use by itself for a welder? and how would u wire it?

[fast400ex]

First of all, I would like to say PROPS TO YOU for this awesome project; I really want to try it. But I have a couple questions. If 10 gauge wire like, what is in an extension cord? (Bare with me, kind of a newbie) so this welder requires one outlet plugs, correct? Would it be possible to add more transformers for higher amperage? Do you strip the ten gauge down to bare solid copper? And you wrap it where the original smaller wire was right? Also, in the schematic, how are the existing primaries connected to the new 10 gauge windings? Okay, so I think I’m figuring this out a little better, connect the original windings together and connect the new windings together so it is two long lengths of wire? And connect the negative of the one outlet plug to the smaller wire guage winding and the positive to the larger? Or what? Sorry I am just slightly confused by the wiring. sorry if I sound like an idiot here, but I would appreciate a response because this is an awesome project I want to try.

[fast400ex]

also, whats the final output? and would there be a way to change it? like a large potentiometer or something?

[fast400ex]

a finished product schematic would be great

[kekeiffer]

not to prove my ignorance here... but what would happen if you tried to beef up this design by adding two extra transformers.. 4 insted of 2? ive seen plans for an ark welder with 10 but thats too out there again there is probably a logical reason just wondering why not four

[Grimarr]

If you use 4 in series do about 10 turns per transformer instead of 20. The plan using 10 transformers uses about 4-6 turns of wire per transformer.

[eric m]

Hey Grim. Do you increase the gauge size of wire when you use 4 instead?

I have 8 mots? 5 turns = gauge?

[Grimarr]

You don't have to increase the wire gauge, since the amperage should be the same, but if you want to you certainly can. With fewer turns per transformer you should be able to get heavier wire in there.

[stayputnik]

Um... I'm pretty sure that using half the turns will give you half the voltage and DOUBLE the amperage. I would definitely use heavier gauge to account for that change. Someone please correct me if there are any experts around.

[Grimarr]

Yeah, you're right actually. I was being lazy and didn't do the basic math. You will get double the amperage so definitely use heavier wire. My thought on that though, is that with double the amperage the arc will wind up just blowing holes in most material you can reasonably weld with this rig.

[vernors]

then wouldnt that be pointless. 4 transfomers with 10 turns each would do the same as 2 transformers with 20 turns each and you would be just carrying extra wight around. now 4 transformers with 20 turns each would produce double the voltage then 2 trnasformers with 20 turns each wich would allow you to weld thicker metal. but id put switches on each trnas former to control the voltage

[Grimarr]

Not pointless, just heavier. I'm not really sure if using 4 transformers with 10 would be better than 2 with 20 from an electrical standpoint because I just woke up and really don't feel like working the math, but trying to get 20 turns of 10 ga. wire onto a microwave transformer can be tricky.

[Hubiewan]

Hubiewan asks, have you tried three transformers for use with thicker rods?

[Garik_axper]

In the schematics you have 2 electric cords that plug in the wall outlets,but here you are running the primaries parallel to one wall outlet . Am I missing something ? BTW thanks for this Instructable, you guys are geniuses :)

[xBrainstormerx]

what if the wire isn't insulated is it okay if wired it up anyways just respond somewhere above or msg me at [e-mail]

[rndmnmbr]

For the next one, you might instead try making it run from 240v instead of regular 120v wall voltage. 120v breakers are usually 15 amp, and wired like this you're pretty close to throwing the breaker every time you weld. 240v has two hot lines and one neutral, each hot carrying 120v (if you look in your breaker box, you'll notice that you're getting 240v off the pole, which is split into two 120v circuits by simply splitting the wire). Just run one hot to one transformer and the second to the other, and combine them back on the neutral. 240v breakers are generally rated from anywhere between 20 and 30 amps, which is plenty, plus the cross phases of the 240v will make for a better, easier weld. For reference, the best weld with standard 1/8" 6011 welding rod is done around 90 amps, or for the slightly less standard 1/8" 7018 rod is 130 amps. Most 120v welders, even set up like this, welds 6011 moderately to poorly and can't weld 7018 at all.

[MrV]

You mean that he should seriewirering the transformers togheter and run them on 240v?

[Derin]

try using 2 24 kV phase system. ding ding BUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

[Deskdiva]

Hi, I know a 15 year old boy that blew most of his hand off and set his room on fire last year building a welder from microwave parts. Use some sense with this.

[stasterisk]

Wow, that's surprising. Can you give me a better idea of how he made that happen? I wouldn't know where to start if I were going to try to reproduce that effect, and therefore I have no idea, based on your scary comment, how to avoid doing what he did.

[andrew_29]

maybe he had it plugged in and it shorted out big time and something just blew

[Coffee bean]

that or he made it work and began welding next to propane tanks

[twenglish1]

i accidentally ignited a container of black powder with my welder, it didn't explode or anything but it burned alot of stuff, and it scared the sh*t out of me

[Arcticpheonix]

I'm not trying to be mean here or anything but THIS IS NOT A TOY! Treat it the same way you would any other piece of dangerous equipment. Don't weld next to something explosive or flammable, wear eye protection cause this stuff is bright, and THINK BEFORE YOU ACT. This isn't directed at anyone in particular, just at the reader in general. Use some common sense when you're welding.

[Coffee bean]

seconded common sense is a required skill.

[brandon borick]

(removed by author or community request)

[welder guy]

-electition- why would you hook up 50 amp breakers?!? unless you have wiring rated at 50amps you could set the walls on fire from the inside!

[capn]

That isn't a good idea, just because the wires in the house (or where ever) are not rated over a certain amperage. If you put a higher amp breaker in you risk setting the wires on fire and eventually the house.

[Derin]

i saw 200amp welders where i live and the 3 phase wire is THIICK

[micojoy]

how am i going to know the number of turns in the primary? that's the only way i can solve the number of turns needed in the secondary winding because we can assigne the volts in our own need.

[stasterisk]

You're in luck! Microwave oven transformers are magic and have special properties!

The primaries are designed to be 1 turn per volt, and are built to turn voltage up by a factor of 10.

200 volts in, 2kV out!

The primaries in this instructable are designed for 120 volts, so we say without counting that they're about 100 turns, so whatever number of turns you put on the other side is the voltage you get out. 20 turns = 20 volts! Magic!

[MrV]

If I going to use this welder on 240v, as you recommended,serie wiring it. but is it important to follow the the step above? must the transformers be wired right, or dosent it matter?

[TimAnderson]

if your microwaves were made for 240, put them in parallel. if they were made for 110 but you're using them on 220/240/something, then put them in series.