We have shielding gas for the welder now. It welds much more cleanly. Here are some knob positions that seem to work well. Be sure to open the gas valve on the top of the cylinder before use, and close it after. Leave the pressure-setting knob where it is. Run the exhaust fan when using gas.
I hooked up the leads wrong at first. See the welds in the middle below. The nicer welds on the sides are after we changed the leads.