mrmuddy76,
A DC only machine can weld aluminum, but...
Stick Welding: DC electrode negative, with flux coated stick welding rod for thicker aluminum above 3/16".
TIG: DC electrode Positive, you can do very thin aluminum if you use a very large diameter tungsten, most all the heat will be directed at the electrode, the aluminum will be a frosted etched surface because of the pure cleaning action.
I've seen other people DC TIG on aluminum. I've tried it, it's nothing I would recommend.
Good Luck,
John
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