So for the case that I can't get it to work, here is another usecase for the machine, to be not completly wasted effort - Automatic Spot Welding.

The machine could be used as automatic spot welder, so that you can set the parameters like power, duration, number of pulses and pressure in the GCODE.

For that I could add another welding tip in the middle of the builtplate for using it as lower electrode.

You have then just to put your two workpieces between the two electrodes and start the right file from an SD card.

After a short countdown the workpieces will be clamped between the electrodes and will be welded together with the selected settings.

The clamping pressure can be set with the Z axis parameter which moves the spring loaded buildplate more or less close to the printhead.