Scratch start AC tig.

NO!!!!

AC TIG requires constant high frequency to maintain the arc.

Thanks for the quick reply Ernie. If I were to get my hands on a hi frequency device of some sort, would you have any idea how to wire it a welder?

"Mandelbrot"

There won't be a TIG welding machine for Al which does not have HF.

SMA/"stick" AC is simpler than DC SMA/"stick"

"AC" TIG for Al is much more complicated and expensive than DC TIG.

Apparently - the oxide on Al has electrical effects which mean that a simple transformer cannot be used for AC Al TIG - it's not as if you can put a TIG torch on an AC "stick" welding transformer to get Al welding capability.

What I do know is that when TIG'ing Al on AC, you can see the electrical effect of the reverse current flow blowing off the Al oxide

- which is serious stuff.

Rich Smith

I think the sort of thing you are looking for is this type of unit

I've got a hi freq unit on an old Wards Powercraft buzzbox. It's a separate unit that sits on top of the welder. Runs off of 110VAC. Couple of cables on the box plug into the welder sockets, welding leads plug into the hi-freq unit.