Microwave Oven Transformer Welder / Metal Melter
This is a super simple project that used a bunch of stuff I found for free in the garbage. A microwave transformer, an AC power cord and a short piece of 2 gauge (2AWG) wire--the kind used for welders, very similar to what's used in car battery connections.
As you can see in the video: within seconds the metal rod I used as a connection between the two cables glows orange hot (at only half power). This is probably putting out only 2 volts, but somewhere around 400 amps!
I used a variac to control the input electricity. I only turned the knob to about 60 volts AC. If I plugged this directly into the wall outlet the input would be 110V AC, but the metal rod would melt almost instantly. That would be cool, but I wanted to ease into running this device.
Here's the very small pile of "junk" I used. I actually didn't put on the nice battery cable connection end pieces, plus I added an AC power cord from some old device to plug this thing in with.
A lot of people hacksaw these transformers for some weird reason. They cut along the weld on both sides of the bottom and then take the two pieces of the core apart, remove the coils, throw away the thinner wire coil and replace the thicker wired coil, then add in the huge 2AWG cable and weld or epoxy the core back together. That's way too much work!
On the right is the thin wire coil (along with some pink wires) that I removed. On the left is the coil made from the thicker wires. Note the two input tabs on the left coil: that's where I hooked up the black and white wires from the old AC power cable that plugs into the wall outlet.
I dremel tool cut the thinner coil wire on both sides. It was really easy. I couldn't get a hacksaw in there without damaging the thicker coil at this point. I suppose I could have used wire cutters and just kep nibbling away at the thin wire core on both sides.
Once I cut through one side with the dremel I actually did hacksaw some of the spread out bits from the top of the coil.
After cutting both sides I pulled the cut wires through and out with a pair of pliers. It was tedious and painful, but simple. In this photo you can see the cut wires on top (along with the thicker pink wires that also get ripped out) and the thicker red coil wires on the bottom. In between are blocks of metal. This is a "shunt" made up of a half-dozen plates. You can carefully tap both of these out (save them) and it'll give you more room to rip out wires. I took care not to pry against the thicker wire coil-it has to stay right where it is...and stay safe.
Here's is the core with the thinner coil removed. I popped the metal shunts back in on top of the thicker coil--but then I removed them to make putting the huge 2AWG cable in.
Here is the huge 2AWG threaded into the core. Make sure that the way you put the 1.5 coils of it in: you have end out with the cut ends on the opposite side of the little metal tabs on the (now) input coil. That way the AC power cable plugs into the "back" of this beast, far away from the scary bare wire ends.
I folded the big cable in half, a "U" shape and shoved it into the holes. Then I bent each end and fed them back into a hole-just once! Shove one end under the cable on one side a nd one end over on the other. I had to add soapy water to get them to slide nicely (which is why my hands look filthy). I usually end up mixing water and high voltage (in this case low voltage but high amperage).
Then I remembered I had put the metal shunts back in: I tapped them back out and that gave me more room to thread the massive 2 gauge cable.
One shunt tapped back in easily. The other one was stuck, so I broke it open and tapped in the layers piece by piece with a little hammer. I had to be careful to do this into the little paper sleeve so the metal shunt wasn't touching the metal coil, or cutting into the rubber of the huge 2 gauge cable. Basically the top and bottom plates have to be insulated from the coil, I didn't have to add any electrical tape for insulation.
I used a hammer to tap in two plates, than kept adding plates in between the top and bottom so I wouldn't scratch up the enamel on the coil.
I've only given this thing 60 volts input and it melts steel! My variac outputs only 5 amps--a regular wall outlet can handle 15 amps, so when I plug this thing in directly to a wall outlet it will have an input of 110 volts AC and up to 15 amps (30 amps if I use the laundry room outlets).
I originally used a piece of copper wire strung across the two ends, but it was from the thinner core--and thus enameled: meaning it's coated in red paint and won't conduct electricity unless it's fed into the ends. Once I grabbed a metal rod (or a common carpentry nail) the connection was made.
I would be scared to put something thn across the ends when using full wall outlet power: thin wires or whatever will heat instantly and melt: kind of like when a photographic "hot light" burns out: a small pop, and then molten bits of metal zinging around.
I used an old screwdriver to pry and chisel with, a hacksaw, dremel tool for a few seconds, pliers to rip out wires, an old AC power cable, an old microwave transformer and a thick 2 gauage cable. If I had ripped up the little paper sleeves that the metal shunts fit inside I would have had to just electrical tape them.
This is a metal rod (actually with a square cross-section). It's from the hingle of a computer LCD display mount. My hands are grimy from working with the soapy, wet old cable.
Here is what 3 seconds of heating did to it!! Only 3 seconds at half input power!! If I had plugged the power cord directly into the wall outlet it would have melted and broke in half in less than a second.
I'm hiding over here until he's done!
