Modern industrial spot welders actually monitor the welds as they occur, the really clever ones can adjust the parameters during the weld! - so once you have set the weld up and tested a few by pulling slugs the weld quality remains fairly constant.yeah, thats the thing with 'cheap' equipment. its not always fit for purpose, the end of the day.. even with a industrial spot welder i'm never fully confident in the nuggets. you can't beat a proper plug weld don't you think, a nice grind down and its sweet....