Yes, this post is 2 1/2 years old. But in the event someone is curious about carbon arc and does a Search, he likely will end up here. So le me offer this as a place to start. I posted it on Wiki Answers to help a few guys who were talking about building their own torches a few years ago: http://www.answers.com/Q/What_is_Carbon_arc_welding&isLookUp=1