First I tried to produce a constant stitch weld bead, with enough burn through. I ended up setting the voltage and wire speed a bit higher. A more consistent spot weld was the result.
Good lighting is essential I found out, I used my engine hoist and attached a fluorescent light.
I still have some difficulties with shrinkage adjacent to the weld. I guess I should just treat that as a low spot and file the weld a bit more.
My spots have a hole in the middle, maybe the wirespeed is too low.
--GJ