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Compressed air can also be an issue with carbon arc gouging. "You want to keep compressed air blowing away the metal to get a good result," says Snyder. "Generally, you want to have about 80 psi or more of compressed air."

Generator quality issues
When performing repairs, a grinder is most always used in conjunction with the welder, with the generator end powering the tool. "Practically any welder/generator can operate grinders," says Leisner.

But to ensure optimal performance and prevent tool damage, the quality of the power is important. "Some light-duty generators don't hold the voltage up where it needs to be when they are under heavier loads," says Leisner.

Although the label may list the amp rating (i.e., 13 amps), power tools actually operate in watts. Wattage equals amperage multiplied by voltage. "As the volts go down on the generator, the amount of amps the tool needs to keep operating goes up. As you turn up the amps, you are generating a lot more heat in your tool," Leisner explains. "If the generator goes down to 110 or 105 volts, the amperage is 15 or 18 amps, rather than 13. So you are really putting more heat into that tool than what it was designed for."

The amount of power you need from the generator really depends on what you plan to do with the welding unit. "Generally, machines with 3,000 watts are plenty for a grinder," says Snyder. "Now, if you start getting into things like plasma cutting, you are going to want an engine-driven welder with more generating power than 3,000 [single-phase] watts. You definitely want a machine that is going to handle 10,000 watts or more."