Welder Damaged?

[micromike]

My son borrowed my Century 145 amp mig welder which has gas or fluxcore wire capacity to install a spiral staircase for a guy he works for. It typically runs from a 40 amp breaker. They for some reason tired to wire it directly into 200amp breaker with an extension cord made of heavy welding cable. The welder wouldn't work. They then wired it to a 30 amp breaker and the welder worked but wouldn't weld correctly...bubbles in the weld, won't penetrate well. They are using 030 wire and gas.

Could they have damaged the welder by hooking it up to the 200 amp breaker?

Also, I just used the welder this past weekend with flux core wire and reverse polarity and it worked fine. Does he need to use straight polarity with gas and wire? Or reverse polarity? Thanks in advance for any help.

Micromike

[chip hayden]

i can't think of how they could have damaged the machine but pinholing is caused by outgassing which usually means the molten weld pool wasn't shielded from the atmosphere. check for gas leaks if running dual shield wire[o-rings, fittings and hoses with soap].
solid wire run reverse polarity. some small diameter flux cored run straight. reverse polarity =electrode positive, straight polarity=electode negative. chip.

[micromike]

Thanks Chip

Glad to hear they didn't damage the welder. I'll have him check the hoses and the polarity tomorrow.

Mike

[75]

Couple of other things to check: Flow rate of the shielding gas (try 20 - 30 CFH as a starting point) and if there are any drafts in the work area - any open doors for example.