Tig Welding with Power Mig 300

[LoneMopar]

I recently added a tig torch and foot control to my power mig 300. After lots of practice I have become fairly proficient tig welding steel. My question is can aluminum be tig welded with this machine? I can find nothing in the owners manual.

[JohnnyWeld]

only if it has an A/C setting

[BBchevy396]

I tried it today with my invertc 350, and didn't have much success. DC just doesn't have the cleaning action of AC's rapidly swihching polaritys. I hear it is possible, but I've only tried it a few times, Usually by accident 'cause I forgot to switch my squarewave from DC:rolleyes: . Anyone have any Alum DC tig tricks?

[ShieldArc]

you use reverse polarity with a big tungsten.

[chopper5]

i dont know about tricks i tig it just like any thing els

[BBchevy396]

With DC ?..... Huh, I know it's possible, But I guess I just dont need to do it anyways, just foolin' around.

[LoneMopar]

No A/C setting - DC only.
ShieldArc: Does reverse polarity means + or - ground? And what size tungsten should I use for .063 sheet aluminum?

[BBchevy396]

Dont think you'll get it on alum that thin, the guys were talking about heavy...1/2" & up material.
I have the same set-up for my PM300, and it tigs great, but no ac, I think your outa luck, to do alum well, get a real ac/dc high/freq tig machine, or use the mig pulser on that 300, it is AWESOME!!!!

[ShieldArc]

No A/C setting - DC only.
ShieldArc: Does reverse polarity means + or - ground? And what size tungsten should I use for .063 sheet aluminum?
Reverse polarity on dc is negetive ground. You can weld thin amum. With a 3/16 tungsten use 55 to 80 amps. With 1/4 tungsten use 80 to 125 amps. Hard to explain how to grind the tungsten, but u grind a hour glass shaped neck so there is a ball on the end. Also i think u should put a piece of copper on the alum so u can start your arc on so u dont contaminate the tungsten.