Sorry if this is in the wrong area. Maybe electrical?I'm building a spot welder using a microwave transformer. There are tons of videos on Youtube showing how it's done. I've followed them exactly. The metal gets glowing red hot on top and bottom but the pieces don't adhere at all. They just fall apart. I've tried 16 ga and 24 ga. My neighbor is an electrical engineer and he said I've wired it exactly right but he says he's not a welder so he doesn't know why they aren't adhering. I wondered about cleaning the surface prior to, but no one on YouTube does that and their versions work fine.I had it all neatly put together and was testing it before adding a switch, fan and cover. Then I had to tear it all apart to work with the problem which is how you see it now.Any ideas on what's wrong? It's a 700w transformer but putting out over 500 amps/1.5 volts the way it's set up. I took one coil out of the transformer and the volts went up a little but it still didn't join metal. You can see the welding spots in the metal photo. They were held together with pliers then fell apart when I took them out of the welder.
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Reply:If the metal is galvanized. that is the problem. Galvanized sheet metal does no spot weld easy. Strip off the galvanize coating at the weld points and try again.Or find some clean sheet metal or shipping band strap for another test.