Okay, just a thought... the metal that I purchased had a thin layer of something grey on it to prevent rust from forming. I didn't use my angle grinder to clean up a spot on the metal for the ground, because the area I was welding was within inches of where the ground was. Should I have cleaned the spot down where the ground was attached? Could this also have been my problem? I just figured, it's metal ,with no crap on it (rust, dirt, paint) so, why should I clean it, right? I placed the ground on the metal, wiggled it back and forth to make sure it's seated nice, and went on to weld. Should I have done differently?