Hi, I have built a microvawe transformer spotwelder, I have put a single turn of welder wire for in the secondary and I’m timing it with arduino. Worth mentioning it was/is a 230V transformer. Electrodes are sharpened copper rods. I believe the voltage is still high. The spotwelds it produces are slightly discolored and not as strong as you would expect. Is this design fundamentally borked? Is there anything else I can make to make it better? Photo from test stage before it was built into a project box, it is less “shocking” now.

  • roterabe@discuss.tchncs.deEnglish
    1·
    1 year ago

    Yeah, just gonna chime in here real quick.

    I went down this road just as you. I found out that most MOTs are rather weak for 18650 nickel strips.

    You need a transformer rated around 1500 watts. Most are 700-900 watts. I ended up wiring 2 transformers in parallel. Also, make sure to remove the transformer’s shunts. They are a form of current limiting and will impact your amps at the end.

    Finally, make sure to carefully regulate your pressure with the copper tips. High pressure does indeed equal a weaker weld.

    AC in general is also not the best for very short pulses of welds. I have found that 40-60ms work best for 0.2 with around 1000amps. Anything less didn’t weld tbh and the MOT couldn’t pull amps fast enough. I tried all sorts of windings and cable thicknesses. I finally chose 6AWG and I’m happy enough with 2 transformers.