Hacking a cheap MIG welder

One of the main drawbacks of this welder was the inability to use shielding gas, which ment it could only be used with flux core wire. I have added support for shielding gas. Welding with gas is much nicer than flux core, because the weld puddle can be seen clearly and there is almost no smoke. It also makes it possible to weld aluminum, but I'v not tried that yet.

Parts used:

• Solenoid valve (a cheap normally closed pneumatic valve)
• 6mm ID reinforced PVC hose: Connects the regulator on the gas bottle to the welder (in port on the solenoid).
• 4mm OD nylon tube: Connects the welder (out port on the solenoid) to the mig gun.
• Short piece of thin wall 4mm copper tubing bent at 90 degrees. (Used to connect the gas tube to the mig gun)
• Electronics: Turns on power for the solenoid when the switch on the mig gun is pressed and keeps it on for an adjustable amount of time after the switch is released.
• Various pipe fittings and such.

I tried the DC upgrade today. No explosion, no fires, nothing melted and no magic smoke released.

Using DCEN (DC Electrode Negative) at the 95A setting I'm geting less spatter than before and it appares to work fine. My added parts did not even get warm.

However at the 35A setting (still DCEN) I got a lot of spatter (more than with AC) and I had problems avoiding burning holes in 0.9mm steel. I also tried 35A with DCEP (DC Electrode positive) and it appared to work better with the thin steel, less burn troughs and less spatter.