[timothale]

a copper backup helps with thin metal, it absorbs some of the heat, Harbor freight now sells them, I've use copper water pipe flattened, copper bus bar !/4 in thick reshaped ...back 50 years ago they used to sell what was called arc fender rod, i think it was 6013. metal about the size of a pencil lead. arc welding thin stuff is difficult, usually I weld down hill, the rod pointing up. It's hard to get your car in the right position for a good weld.