Instructables

How to Make the Metal Melter

Featured
Picture of 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!
 
Remove these adsRemove these ads by Signing Up

Step 1: Find an Old Microwave

Picture of 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

Picture of Harvest The Transformer
4.jpg
5.jpg
6.jpg
7.jpg
8.jpg
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.
I_StarkGuy2 months ago

I just finished mine!!!!! Moving on to the spot welder!!

Benjamick2 months ago

Oh your Majesty, King of the Random, i have a question: i need a 6V DC transformer that puts out at least 1360mA. I didn't feel like looking all over for it, so i looked around what I had, and found a 300mA 6V DC transformer. Is there any way to modify it and make it put out 1.36A or more ?

ccrome6 months ago
Heh, my microwave pooped out, so I just built the metal melter. Awesome! I used #4 welding wire from a welding supply store. That stuff is super supple and flexible. Very nice cable.

Also, the #4 wire allows me to wind anywhere from 1 to 2.5 coils on the secondary WITHOUT disassembly! It nicely just scoots through the slots. If I have something a little higher resistance, I just increase the output voltage by winding another loop!

I love your videos! I think I'm gonna have to go get a projection TV now too...



connorACIII8 months ago
I found some 2 awg cable at Lowes but it's not pliable at all. are you sure thats the right stuff?
pwnag31 year ago
Don't weld it even if you can, transformer iron (silicon iron) spits like crazy when welded
(i speak from experience), also it may melt the insulation.
The King of Random (author)  pwnag31 year ago
Thanks for the tip! How do you suppose they weld it in the first place? It would be good to have a solid connection to help reduce noise from vibration in some cases.
Looking at the weld, I would say TIG or PLASMA at 100-150 amps, 30" per minute travel, argon gas shield, in an automated machine, although you could do it by hand with these parameters.
Thanks for your reply! It's impressive you can tell that by looking at the weld .. must come from experience? What do you do? I don't suppose you could do it with a stick welder could you?
You could but it makes a mess...you need intense pinpoint heat with a good inert gas shield...notice the weld is about 1/8" wide and 1/8" deep with little heat mark beyond the edge of the weld, that indicates high travel rate. You might also use a CO2 laser in an inert atmosphere.
25 years ago I designed servo controlled welding systems for defence contractors.
Spot on! Especially the part about high traverse rate. If you try it with TIG I would suggest submerging it to the top of the winding to heat sink the unit. Ya gotta be a little creative for this...
wire feed (MIG) welder; grind the area to be welded to free it of silicone. MIG is fast enough to prevent heat buildup
you could try a large stainless steel hose clamp around the out side to stop vibration. i have an old microwave, and need of a spot welder. i think i'll try that when i see if i can make one. thanks for the idea.
Excellent suggestion. Thank you for the idea as well, and best of luck!
I tried welding one together with FCAW. the laminations popped, everywhere, and my wire insulation caught fire
pwnag3 pwnag31 year ago
Although you COULD do some tack welds without much worry just set up some sort of shielding so sparks don't hit the wires
"submit" does not appear under the challenge
zacker1 year ago
how is it, you can touch both ends of your cables and not get zapped but when you touch them to a nail, it melts it? is it because the current flows through the metal faster than a human? or is it something to do with resistance?
The King of Random (author)  zacker1 year ago
It's Ohm's law. V=I*R. In this case 2 volts = (unknown current)*(resistance of my body).

The resistance of the body changes constantly, and depends on moisture and many other things, however I usually measure in the multi mega-ohm range, which puts the current (if any) in the less than 1 micro-amp range. It would take 100 Milli-amps to stop my heart .. and that's about a hundred thousand times more current than what would be flowing through me.

However, metal is millions times more conductive than me so can allow the full potential of the current to flow .. so in that case we can have around 800 amps flowing through the metal.

Does that make sense?

yep...lol
It's not about the current, it's about the voltage. Everything conducts electricity, even things that are used as insulators, you just have to get the voltage high enough. Dry skin doesn't conduct electricity until you have upwards of 1000's of volts. Once you reach the threshold for conductance, current will flow and you will have a shock. This is why stun guns and tasers are such a high voltage.

You are correct though in that it's the resistance of the human body that keeps us from getting the shock. It is what requires the voltage to be so high.
I see what you're saying, but it is about both voltage and current, because they work together.
The thing is, if the voltage isn't high enough, there will be no current flow. While current is what will hurt you, it's flow won't exist unless the voltage is high enough to overcome the resistance of your skin.
Yep, exactly. Wasn't that the reply I gave to sacker?
Well, kind of, except you never stated that it was the low voltage that made it safe. This had to be inferred from what you said, which is why I clarified with my post.
You're right in all of the above! Thank you for your clarification :)
yeah... its sorta what i thought... i just had it backwards, I thought it was because the metal had more resistance than the body so more amps would be sorta backed up instead of going right in and out..lol well, that explains it. thanks!

BTW, Im the one on you tube this AM with the bottle cap shooter...lol
The King of Random (author)  zacker1 year ago
Oh yeah, sweet. Thanks for all your comments!
no prob, thanks for all the cool posts... gonna possibly mess with my 55" fresnel this weekend.. see how that goes.
The King of Random (author)  zacker1 year ago
Sweet!
Just don't try this with your tongue - unless you need a flaming pierced one.
The King of Random (author)  ToolboxGuy1 year ago
Haha I agree!!
anoop vanguru10 months ago
Your youtube channel is amazing, full of awesome vids of things which I cant do often at home
I finished making mine and you can literally play with it all day! The only thing I still need is some thick hauge wire because I'm currently using taped-together strands of thinner wire just to test it.
Good 'ible, Clear enough for me to have a go myself... I have been given a 240v (I'm in the UK) m/wave transformer but I don't know which are the primary and secondary windings - how can I tell? - or are they always primary on top, although I have seen some side by side designs.
A few ways to tell are:
the secondary is very thin wire whereas the primary is thicker
The secondary has one wire output and the other end is grounded to the transformer
The primary coil has two spad connectors
The secondary is mostly wrapped in paper and the primary is mostly bare
Thanks, I seem to have got it right then.
manutea1 year ago
hé hé hé; very interesting; thank you for posting this idea.
nate711731 year ago
I will never, ever understand how meters can take readings off such colossal amperage without exploding. Any insight? (Obviously u don't want to go over max rating)
The King of Random (author)  nate711731 year ago
In this case I was testing for voltage. If I set the meter to measure current, it would blow the fuse easily as the fuse is only rated for 10 amps :)

Isn't it strange how the test leads don't melt? They must not close the circuit....
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!