OK...I went with the test method to determine the settings. I started out with the settings used for sheet steel and adjusted them in an attempt to improve the cut quality. The settings that I ended up using were 30 amps, 80 arc volts and 140 IPM. I would describe the cut quality as "just OK" since there was some dross on the bottom of the cut. Making streight line test cuts doesn't always give you an accurate sample of the final cut on a file that has many curves and direction changes. Some of my streight cuts ended up with a bit of a saw tooth contour. Perhaps I could have improved the cut by turning off the height control after the pierce was complete. For supporting the material I inserted all of the support slate that the table had slots for. This gave me support every 3 inches.This was not enough to prevent the torch from bending the copper down and changing the pierce height. A possable work around would be to a thin sheet of aluminum or steet under the copper to help support it.