SNIP
You did well, Eric. The SP125+ is a very sweet little machine for
light work -- up to .125" or so. I still use mine in preference to
my larger 220-volt MIG for work on 1/16" (16 gage) and under. It
is also capable of doing up to 3/16" with fluxcore, handy when it's
easier to bring the welder to a job where there's no 220 handy.
I was talking to a customer today and he was wondering what the
machine would do since he had a similar one. I told him he could use
it up to 1/4 but if I had to weld anything that heavy it would be tig
or stick. I know that the rusty wire would cause problems. But I
figured if I could get it to make a good weld even with the rusty wire
then the machine would work. And I not only got a good looking bead,
it passed the big hammer test.

It can do 3/8" or thicker in the hands of a skilled weldor. I know
a guy who stuck 1/2" hinges on a truck with one, though it took him
quite a while, doing multi-pass welds with good fusion each pass.
I'd ride anything he welded and pronounced good.

I think for the average Joe 3/16" should be regarded as tops. Even
there it's slow and duty cycle is a significant issue.
I am a good TIG and Stick weldor. I went to night school for a few
years learning how from an excellent teacher. I have done some
aluminum MIG and steel MIG. With steel I've also run Innershield and
Dual shield. But I don't have a lot of experience running wire feed
welders. I'm confident that I could weld 1/2" plate with this little
welder, especially if the plate is pre heated. But that would be with
the proper gas and proper filler. The rusty wire that came with this
machine is only rusty in places. After unwinding quite a bit to remove
most of the rusty wire there is still rusty wire on one side. When
welding the beads will be good and then there will be a few inches of
porosity and uneven wire speed. I can actually see rust dust coming
out of the gun when the trigger is pulled. Since the wire is still
rusty in places I'm gonna use it up making a bunch of practice beads.
When it's all gone I'll clean out the wire guide and put in a roll of
good wire.
ERS