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He explains, "Every engine-driven welder will do arc gouging. The difference is how big a carbon electrode it can support. Gouging is an extremely demanding process. It is both high amps and high volts."

There are several different sizes of carbon electrodes available. "It is really a productivity issue," says Snyder. "The bigger the carbon electrode, the faster and deeper you can go. This is a repetitive process."

As a general guideline, you can gouge down approximately as deep as the diameter of the carbon rod with each pass. So if you have a 3/8-in. carbon rod, you will be able to gouge to approximately 3/8 in. per pass. But a 3/8-in. carbon requires a big machine. "If you are going to run that carbon, you need to have a machine that has 450 to 600 amps of welding output," says Snyder.

You can get away with a smaller welder if you use a smaller carbon rod. However, your production rate will correspondingly decrease. "If you have a 3/16-in. carbon rod, which is half the diameter, you are probably going to need a 250-amp machine," Snyder advises. "If you have a machine that is smaller than 250 amps, you would probably not have enough output to run that carbon rod at full capacity. It is going to take you a lot longer to get the same thing accomplished."

Leisner adds, "For carbon arc gouging, engine drives with a 300-amp output work best... They can run 1/4-in. carbons, which is the most common diameter of carbon arc sold. If you need to remove a lot of metal, an engine drive with 500 amps of output power will allow you to run 3/8-in.-diameter carbons for increased speed and metal removal."