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  • In a previous video I used a modified Microwave Oven Transformer as an electrical metal melter.

  • In this video you'll learn step by step how it was made, and what I'm using it for now.

  • In a previous project, I found an old microwave in a dumpster and hacked it open to see what

  • components I could salvage. This power transformer was one of my favorites, and got used in many

  • other projects, like high voltage electrical arcs, making a homemade stick welder, and

  • melting metal. In it's current condition, the transformer produces a deadly high voltage

  • that's enough to kill a person on contact. But it won't melt metal. To do that, we have

  • to modify the transformer by rewinding the coils. Looking at the sides of this transformer,

  • you can see that these shallow welds are the only thing holding this together. I'm gonna

  • use my bench vice to secure this in place with one end of the welded sides facing up,

  • and try using a hacksaw to cut it open. This is a fairly weak weld, and a hacksaw will

  • work, but a quick buzz with an angle grinder works a lot better. Now that that's ground

  • off, a hammer and chisel can be used to crack the gap and pry the pieces apart. The rest

  • can be removed by hand. With the bottom off, I've got access to the 3 coils of wire wrapped

  • around the core. The top coil is the primary winding and I want to take very good care

  • of that, so I've wrapped a cloth over my chisel to protect it as I pry up on the winding.

  • It's in there pretty snug, but prying it slowly and gently from both sides gets it to the

  • point where I can put the chisels down and pull it off by hand. These metal shunts can

  • get knocked out now, and amazingly, this is the only form of current limiting this transformer

  • has. The middle coil is junk, and it all comes out. Then to get the secondary coil off, I'm

  • setting it with the coil resting on the jaws of my vise, and then hitting the middle of

  • the core with a rubber hammer until the winding is free. This got pretty beat up, but that's

  • ok because luckily I don't need it. A chisel works great for scraping off any excess paper

  • and glue stuck on the sides, and now we've got ourselves a naked transformer core. You're

  • looking at the "E" and "I" sections of the core, and at this point we're ready to reinstall

  • our primary coil. This coil has about 100 turns of insulated copper wire, and needs

  • to be replaced gently to avoid damaging it, or scraping the wires. That's why I'm using

  • a rubber hammer so I can still get it in nice and tight. OK, it's looking like it's supposed

  • to, so now we can add a secondary winding made from this thick 2 gauge copper cable.

  • I was lucky and got this from a scrap pile my brother had at work. Looking inside, you

  • can see it's made of stranded copper wire, insulated by a thick rubber coating. My brother

  • got me a heavy duty copper lug, and crimped it in place on the end of the cable. Next,

  • he added a little shrink-wrap to protect the connection, and hit it with a heat gun to

  • shrink it down and finish it off. Alright, so with the cable bent in half, I can move

  • it up next to the transformer and tuck it down into the gaps. The wire's so thick it's

  • a pretty tight fit and probably couldn't be any bigger. I'm pulling one end of the cable

  • back around the transformer, and I decided to switch the positions of these two so that

  • it forms more of an ascending coil. Now I can press the other side into place, and the

  • secondary coil is wrapped, as easy as that. The last step is to put this back together.

  • I don't have anything to re-weld the seems I broke apart, so I'm going to try using this

  • 2 part epoxy glue to see if I can make it work. Both the components get mixed equally,

  • then I'll add the glue to all the exposed surfaces at the top here, and find a way to

  • clamp this down. It turns out my bench vise has a gap wide enough to fit the entire assembly,

  • and after double checking the alignment on the connection, I'll synch it up tight. I'm

  • adding the leftover glue to the gaps on the edges and everything is looking as expected,

  • so that can be left to set. Ok, it's 2 hours later, and our modification is complete! There's

  • actually no physical connection between the two coils, yet this will pump out around 800

  • amps! To bench-test the device, I'm carefully hooking clips to both leads of the primary

  • winding, and then adding power. Using my multimeter I'm showing just over 2 volts now, which is

  • a lot lower than the 1000 volts this used to throw out. But instead of putting out 1

  • amp, now I'm getting closer 800!! What can you do with that many amps? I thought it would

  • be fun to try melting some metal, which you can see this does easily. The metal melts

  • because its not as conductive as copper wire. It acts like a resistor, and heats up from

  • the electrical friction until it reaches its melting point. Or until the insulation on

  • the lead wires melt and the system shorts out. Well not only was this a fun modification,

  • but I found a practical application for it in making a spot welder like this one. The

  • high current can be directed to fuse sheets of metal together at one precise location.

  • Look for how to make that in another project. Well now you know how to build the metal melter.

  • If you liked this video perhaps you'll like some of my others. Check them out at www.thekingofrandom.com

In a previous video I used a modified Microwave Oven Transformer as an electrical metal melter.

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