Just for reference in this thread, I did some weld testing a few semesters back.
It was all normal aws plate qualification setup and procedures. Two pieces 3/8 plate, 60 degree total bevel, 1/4” gap at the root, 1/4” backing plate. Did two tests for each one, one vertical, one horizontal.
I was mainly concerned with amperages and settings. Did three sets. .035” solid wire, 75/25. Vertical is done with 3 passes, root, hot, and cap. Horizontal was done with 5 passes, 1 root, 1 hot, and 3 cap stringers. The root and hot are weaved, while the horizontal cap was three overlapping passes, more like doing circles with the gun.
1st set 17.5 volts, 175 ipm on the wire. Right around 95-97 amps while welding. Everyone except one really smart guy I have a ton of respect for said it would break instantly.
Flawless, no runs drips, or errors.
2nd set is my go to settings, 18.0v, 200 on the wire. 105-110 amps. Again flawless. No single discontinuity anywhere in the root or face bend.
3rd set, felt hot, and while welding I felt rushed. I felt like I didn’t have completely control of my technique as I had to move so fast. 18.5v 250 ipm on the wire. Memory is fuzzy on the amperage, but IIRC, was 135 amps.
Several discontinuities in the face bend of the vertical, one small spot in the root. Nothing that would fail it according to aws, but not perfect.
The horizontal had several discontinuities in the face and an obvious defect in the root that would have failed by aws guidelines.
My point to all that, is regardless of that the machine papers, settings, and specs say, proper technique trumps all.
Moving too slow for any mig weld will cause it to fail under stress. This is especially true when you are forced to work faster that normal losing the precision of your technique.
This allows the weld pool to build outward from the base metal as the bottom of the puddle cools and reduces penetration. This is extremely bad, and the weld can still look great.
Testing your welds and being confident in you technique and settings matters more than any machine choice.
Drag the wire, pull the puddle, keep the wire stickout short, and trace the front edge of the puddle, regardless of weave style. It needs to sound smooth and consistent while welding and while weaving for a quality bead.
This post pertains to most things encountered in fabrication related to Offroad and vehicle fab and welding. This means it’s for normal short circuit mig with solid wire.