How to Make the Metal Melter





Introduction: How to Make the Metal Melter

In this project you'll learn step by step how to modify a microwave oven transformer into a high-current device that can pump out 800 amps of electrical current.

If you liked the Metal Melter you saw in a previous project, here's how you can make your own!

Step 1: Find an Old Microwave

Start by finding an old microwave for free. The bigger, the better.  

You can find them in various places, like on free classified adds, or in your neighbors garbage can, like where I found this one.

Step 2: Harvest the Transformer

The transformer is the piece that you'll need, and it looks like this.

CAUTION: Make sure you're familiar with the dangers of opening a microwave, because there are components inside that may still carry a charge and could hurt, or even kill you. Even if the microwave isn't plugged in.

The transformer core is only held together by 2 very thin welds, as seen on the side of this one.

A hacksaw, or angle grinder can be used to cut the weld, then a hammer and chisel used to break it open, giving you access to the primary and secondary coils.

Be very careful taking the primary coil out because you'll need it again. Make sure not to bend, break or scratch it in any way.

NOTE: The secondary coil is harder to get out, and may be damaged by the time you do, but that's ok because we don't need it for this project. However, if you can salvage it intact, it may be a source of thin gauge enameled copper wire for future projects.

Step 3: Re-wind the Coils

Ok, your transformer core should now be bare. These are the "E" and "I" sections of the core, and have been scraped with a chisel to remove glue and paper stuck to the insides.

The next step is to carefully replace the primary coil, an ensure it's snug at the bottom of the core. Then add a 5' length of 2 AWG insulated copper cable. This thicker cable will extend the amount of time a massive electrical current can flow before the cable overheats.

The secondary cable is only wrapped 1-3/4 times around the center.

Step 4: Glue It Back Together

If you don't have a way to weld the base back on, you can use some 2-part epoxy-glue and apply to all the surfaces that will be in contact.

Then clamp it together to let the glue set. I used my bench vise as a clamp and it worked perfectly!

When the glue is dry, your Metal Melter should look similar to this. None of the wires are actually touching each other, but what it can do is very impressive.

Step 5: Melt Some Metal

The output voltage on this is just barely over 2 volts. But the Amps are closer to 800!!

That's enough current to melt iron nails and steel bolts on contact!

Step 6: Spot Welder

I found a practical use for The Metal Melter, in making a Spot Welder like this one. The electrical current can be concentrated to a single point, to fuse thin sheets of metal together. This is known as a "spot weld".

You can see how I made this in a different project.

Step 7: Now You Know!

Know you know how to make The Metal Melter!

If you liked this project, perhaps you'll like some of my others. Check them out at

3 People Made This Project!


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2 Questions

Can you please tell me what power supply i would i use on this unit? i am in australia and run 240V 50hz. i have a few other power supplies 12v 120v 22v 32v. so please tell me which would be the best one and how it conects to the coil? Thanks Dave Ware

You go from step 4 to step 5, and poof, you have hot ends... you don't mention a thing on power imput type or voltage, actually nothing on this... though it appears some are figuring out ways...would one more step explanation hurt?


I made one and it hums quite a bit and it throws loud sparks instead of turning red hot and melting. Did i do sonething wrong?

I made this project and am trying to use it to heat up a heating element but when I clamp my electrodes to my element the electrodes get hot but my element does not. But when I barely touch the electrodes to the element, then it gets hot. What am I doing wrong

My 600 volt cord says it has max 30amp take 30 amps isn't this going to be an 800 amp project so it's not big enough can you please help I'm standing right here trying to finish and I have different 600 volt wires to work with don't know which one to put on so I can finish this. Please help



Sir / Madam

I am a Chinese who do not understand English, should not understand English, I rely on translation software, see your article! But there are still a lot of places do not understand! I'd like to see the video! It's a pity that I don't know where to look at the language!

This tool is good, can melt much of the metal?

"I was using the translation software to write, it may make you feel tired! I'm really sorry.


Can if the 2 AWG wire at the top?...

does it have to be a microwave transformer?

Question: Why wouldn't you use a cable with a higher ampacity?

2 AWG is only capable of handling 130amps max ( Yet even just using 2/0 AWG bumps your ampacity up to 195amps. Would a cable with a higher ampacity heat up slower during use than one with a lower rating? I'm just trying to learn as much as I can before making one of these. I'm also trying to make it usable for longer periods and possibly larger items, or sections of larger items. I'm a hobbyist blacksmith and this would be awesome to use if it could be modified somehow for forging.

wait i thought that amps or current were what killed and not the volts because from what I've heard even 2 amps is enough to kill a person..... or was the information wrong? And it doesnt need to be plugged in or anything?