I guess I don't understand why a 120 volt mig won't do a good job on tubing
We commonly use in aircraft? And as far as worrying about hardness caused
by rapid cooling. Just preheat the area too hot to touch 160/200degrees,
before welding and let it cool slow. Cover if necessary.
I have very good 120 and 220 mig welders and a very nice tig setup,
I think pre and post welding prep has more to do with success than the type
Of welder.?? Just my 2cents