Karateboy (or anyone else) - I may be the only one not in on the secret, but which welder is being used here, please?
what kind of welder is it
Does look like a bit too much heat.
Thin metal is tricky. I tried lowering the power, but that was difficult when joining two pieces together that did not fit perfectly. The arc would find one edge and burn back especially on inside corners. Gets real bad on <1mm steel.
I found upping the power and moving faster was easier for me. I'd keep the power settings the same and moving the torch faster. You welds look good and would be acceptable, you are just making more work if you need to grind them flat.
You can try lowering the power/wire speed and it will work. but I find going real slow a pain to keep a steady line.
Yes, the 140 is a good machine. Wish i could have afforded one when I started.