It depends ; I'm an old farm mechanic so I take a piece of broken off leaf spring from a Japanese car (they're thinner and better metal to boot) , grind one end to a chisel point and the other end square for hitting with a hammer , and use this thin chisel to work the seam apart , splitting the spot weld and not ruining the steet metals pinchweld . Eastwood sells a nifty drill bit specially made for spot welds , I've not used it but my buddy the Kustom body guy has and he says it works . -Nate
