Re: Flux-core/MIG for frame welding?
It may take a little more practice, but I have been surprised what I can weld with a decent inverter stick welder, and use it for most of my welding these days.
The old PIG welder don't get used much anymore, I liked it when it was on gas and it got a bit of use in the old days welding up rusty old cars until I started to realize if your going to weld up rusty old cars you'll be patching the thing every year.
But cause I rarely use it and it's so wet/humid here, I find the wire goes rusty, and the old girl keeps jamming.
It took me a fair while after swapping to flux core, that I realized the reason the wire kept jamming was because of the bend in the hand piece nozzle, seems the flux core is quite a bit stiffer and does not like to take corners, I straightened the bend in the hand piece and it works better now but gives a weird twist to the wrist when using it.
I'm no expert with the stick welder, and it takes quite a bit more practice to master than a MIG but gives so much nicer welds once you get the hang of it.