We used a pretty run-off-the-mill type of welder (albeit running on industrial current) when I worked as a welder/fabricator years ago. It had all the usual amperage/voltage control knobs as well as the AC/DC toggles. Nothing over complicated.
We predominantly welded thin gauge Alu; min 1.2mm to a max of 3mm. For the really thin stuff, instant control was necessary and for that we had "accelerator" pedals.
Argon at 100% is the gas to use. It's much cheaper than Helium. Helium is more efficient and protects the smelt pool better, but has a tendency to be a little 'flighty' and therefore you need a much greater flow which makes it even more expensive.
For the thin Ally we used 0.8 to 1.00 mm rods. Buy a couple of packets of these 'cos you'll be going thru them like hot potatoes when you're starting off.
Yeah, we had an Ally MIG machine as well. But we spent a long time extricating the ally wire each time it jammed up. What used to happen was that the last blob of ally in your previous weld would glue itself to the welding gun tip, so unless you regularly sprayed the tip with a spray-on lubricator, you'd be there forever disconnecting, extricating, cutting, reconnecting.
It made it even worse if someone had folded the welder cabling etc. This would kink the plastic conduit for the weld wire with obvious consequences.
Hope that helps.
