Question on the microwave oven welder

admin

After reading Llamafur's praying mantis post my son and I decided to build one of the micowave welders. But we only have one transformer. We rewound the secondary with 10guage wire. It measures 24 volts at the secondary which I figure should be about right and good enough to run a bead. Anyway, we are using 1/16th 6013 rods and can't get an arc started. Good blue spark, but then the electrode just sticks to the workpiece. If it's not removed fast enough the entire rod glows cherry red. It almost seems as if the thing is running too hot but I don't see how that could be with only one transformer. I'd appreciate any thoughts on this. ( I can't just go buy a stick welder, I'm too poor right now and so far we've had fun doing this.) Thanks for any thoughts.
Reply:one transformer won't provide enough juice.two is ok, it works.three... four is the zone, decent beads. but building this beast requires lots of time, and knowlege of electricity, and how it works.head on over to Instructables Home Made Welder they explain it much better than I ever could. make sure to register so you can see all the steps.don't use 10 awg wire, use 6 or 8. when I used 10, the insulation melted.
Reply:I built one 6 or 7 years ago. It worked pretty darned well too, not much arc difference from any AC stick welder.Like llamafur said, you need 4 transformers. You also need a way to control the amperage. There are a few ways to do it. I went with pulse width modulation, which required building a simple circuit board. Primarily a 555 timer and some big transistors. It IS alot of work, but it's possible to build a fairly decent welding machine. It can be cheaper to just buy a used tombstone though. I probably spent $150 or so building mine, but it was a fun project.Miller EconotigCutmaster 38Yes ma'am, that IS a screwdriver in my pocket!
Reply:Yeah, not enough juice makes more sense than too much with just one transformer. I'm going to try to find at least one or two more microwaves. We're mainly doing it because it's kind of cool, good father and son project. If I find four transformers and wire it for 220 what thickness metal can I expect to weld?
Reply:probably 3/8 steel, the 6013 works the best on mine. make sure to clean the area to be welded, and chip off all the slag for multiple passes.
Reply:See what you started, Llamafur?  Now everybody's forgetting about building stuff by welding and just building the welding machines .....If y'all are going to be talking about these great machines ya built, there best be some pictures attached ....
Reply:Heres a old one i built in a 50 cal ammo can, it got fried when i used it too much, two microwave transformers. had relays for the on/off switch.
Reply:Hi my first post, i'm into microwave transformers i'm building a very high current supply for test HHO cellsHere is a picGary
Reply:Originally Posted by HHO BLASTERHi my first post, i'm into microwave transformers i'm building a very high current supply for test HHO cells...
Reply:Originally Posted by denrepWelcome HHO BLASTER, Keep posting! This is a very  interesting thread. I wouldn't want to take it off topic, but you know what I'd like to see built out of these same components?. . . A real battery charger! Heavy duty, for trucks and equipment.I haven't seen a decent store-bought battery charger in ages.Make it industrial quality, with a real transformer, real diodes and a real timer.May as well throw in a serious cord, leads, and clamps.Good Luck
Reply:I have done one welder with two transformers some time ago... as far I remeber the MOT was picket up in the street , free ... you may use two microwaves tranformers. The 2 magnetic core was easy opened with a small touche of hand saw  resulting a " I " and "E" cores, removed the secondary coil and some small sheet s of the  magnetic shunt.  The "I" iron were assembled togheter making a primary reactor, with core cross section 2200mm2Later I used the original magnetic shunts to reduce the current. The two "E" cores had a cross section of 2200mm2 or 0.0022m2 each, assembled in mirror,  giving a long closed core of 0.0022m2 cross section.Primary coil data, using the same original primary coil (120 turns, 115V). The 2 primary coils connected in series e (total of 240 turns size # 14Awg) and  proper phasing suitable for  230V. Secondary voltage shall be more tham 25V to avoid the electrode stick in the work> My case 55V. I wond 60 turns size 8AWG, copper wire for mottor winding, 180C. The MOT core was working with elevate induction, +- 1.7 tesla, magnetizing current high than normal. Two fans provide coil cooling. It works for more thal 20 years.  I remember also that the admissible current in the coils were 11 or 12 A/mm2, for copper w/ fans.Regards