I've been continuing to practice since my last post. I also bought a 20 lb tank of CO2 last week, so I was able to change from flux core, to MIG. That's been a big help so far
It was a bit of an adjustment at fist, but I'm getting more used to MIG. The arc seems easier to control, the weld beads are smoother, there is *very* little spatter, and there's no appreciable smoke or mess, vs flux core. It's not as hot, so I'm using C or D voltage for things that used A or B, with flux core. That reduces my max thickness, but I get better results on the thinner materials. And I can go back to flux core for thicker stuff, if needed. I'm also getting less burn-through with MIG.
I tried making a little enclosed box. I had made one or two smaller ones with flux wire, using steel that already had a bend, for the side walls. So on those, I had kind of a head start. I did fill those half with water, and weld them shut, though, so that was kind of cool
You can hear the water when you shake them.
This one is made just from flat rectangles. The steel is 0.091" thick, I'm using 0.023" wire, pushing the gun. I set the machine to 3.5 wire, B voltage. Lower settings than it recommended, but I was lining up the "inside" corners at the joints, so the weld could have more easily burned through, which I wanted to avoid. I like how it came out. Some of the welds are better than others. Unfortunately, some of the less-bad welds are on the back side, in the first picture. I wanted to do each weld in just 1 pass, but I had trouble in a few areas, and had to go back and add little "touch up" beads. I deliberately did not grind anything down, to leave it the way I made it. I sealed a 5/16 nut inside, for fun. The box is about 1.2 x 1.2 x 2.7".