Quote Originally Posted by jakeru View Post
Copper seems to weld nicely together autogenously, which lets you really pick up the travel speed and not get the overall workpiece as hot or oxidized. You've got to have enough current to do it. Thinner materials being welded also helps, and pulsing does too (if you have enough peak current to spare).

http://www.everlastgenerators.com/fo...copper-welding
If Gwaltnak used non-pulsed amps of 220, pulsing peak amps would definitely need to be high to localize the heat.