Lately Ive been getting some copper plates that need details welded to them(not brazed per engineer). Ive been tig welding them after pre heat to 875 degrees. My question is- Does any body know if you need to preheat base to mig weld with copper wire? This is all deoxidized by the way! and yes I do have the equipment a phoenix 456, xra push pull gun and an optima pulser.