I had just purchased an older Miller syncrowave 180 sd and Iam wondering what settings (neg or pos) I知 using neg. pol. I知 using a greenelectrode. I know amps depend on material thickness for aluminum. Every time Itry and weld the aluminum, it doesn稚 penetrate leaving a black mark or meltsthe aluminum. Any help at all would be very helpful to me. I had never tigwelded before, only stick and mig Thanks