I had metal shop in 8-9th grade . We did stick arc , gas , spot machine , solder , riveting , forming , and sand casting .
Heli arc was as above very expensive and only found in a hand full of shops in our area . One of them was Yull Brothers Racing .
Hardest part of the older Tig units was you needed 3-phase to make it work. Now with the inverters being cheaper to make they are built into the units and are affordable.
I didn't know that they were 3 phase. That IS a PITA for most private homes. Usually only one phase in the
neighborhood, and they only run three phase to industrial park type areas.
That is why they have a phase converter in them so you can run off 110/220 now. Originally they were 3-phase. That was the reason for lots of people not getting them.
If you are not in a hurry, I can check with my welder friend. He has a big old heliarc in his home, worked
as a welder for decades, and has welded things for me, and always perfect. Brad could bring it down,
or you could mail it. I will be out of town for a while, though, so if you are in a hurry, no good.