Using some 6ga silicone wire from my combat robotic days, and some nice electrical connectors from Home Depot, these probes came out great. This set is 23.5″ long. I have enough wire to make another set at 40″ long.

I finally decided on taping the 1/4″ copper probes with an 8-32 thread and screwing the connector to it with a brass screw. This makes the probes universal so I can change them out for a different configuration of probes. The connector is plated, solid copper. So these connections should not be a bottleneck for the high amperage current flow.

Here are some practice spot welds. The first couple blew holes in the .010″ thick nickel strip. I dialed down the power and time. With more practice I could make strong welds what took pliers to tear apart, and only then the material would fail, not the weld. Then I started to see a vertical trail of smoke so fine, I thought it was my vision was messing with me. It was real smoke coming from the fet driver. It and the voltage regulator were blazing hot. I grabbed my IR temperature probe and the driver read over 400F. The input to the fet driver was at 3.4vdc. It should be at zero. The processor output was working, but not putting out any voltage. My DVM confirmed that the fet driver was shorted internally. So I ordered more drivers from Newark. Probably won’t get here until Monday. There is a fellow here in San Jose that made one of these welders too. Maybe I can borrow a driver from him.