For the latest steam engine I am building, I needed a nice thick baseplate. I had a large peice of 3/4" copper left over from an automated welding cell, so decided to use it.---Now don't get me wrong---I had been warned by others on this board how nasty it was, before I even started. however, free is free, so I decided to go with it. Firstly, copper is much heavier than brass or aluminum, even slightly heavier than steel. It does cut okay on the bandsaw where I cut my aluminum. When you are machining it, it does not machine cleanly---rather it smears!!! If you are cleaning up the face with the end of a a rotary end mill, it will push a "bow wave" of uncut material ahead of the cutter, then grab, briefly try to stall the machine, then shear off, and keep repeating that action. cutting fluid helps a bit, but not a whole lot. Along machined edges, copper pulls up an incredible burr, that has to be filed off later. It seems to saw, drill, and tap okay, but is kind of a miserable pig to machine on a mill. This is the first time I have tried to machine copper, and I probably won't use it again, but I thought I would share my experience with you fellows.---Brian