Quote Originally Posted by 1gary View Post
Hammer and dolly on the weld??.
Gary, when you weld on sheet metal it shrinks,you hammer and dolly on the weld to put a little stretch back in it and to planish it (smooth it), before you grind the weld down. Do not create too much heat with the grinding or you shrink it again. Example take two pieces of say 20 gauge, fit the edges together and make a couple tacks on one end,this creates a shrink @ the welds and you'll notice the other end opens up the gap. Simply planish the spot welds (stretch) and the gaps will close back up on the other end. Metalmeet.com plus Youtube has a wealth of information