But 10,000 is as fast as my mill will spin, so that will probably always seem fast to me. I think I would have started at 5,000. 20 inches may be all those bits can take in aluminium. Almost all of my machining is doing exotic contours, so I have to take very small bites, but can usually up the feed rate once the first few passes are over.
How long are your "1/2" compression spiral carbide bits"? Do you have a part #? I need something better, now that I'm doing more wood molds.