[Espeefan]

Lou, I agree that you can better feel what the cutter is doing with an all manual mill. I honestly don't know much about calculating the feeds, speeds, and depth of cut. I just do what feels, sounds, and looks right. I am sure it's much more difficult to figure out all of that with a CNC machine.

I wonder if the quality of your aluminum is to blame. The stuff that gums up much faster and seems to act less forgiving is probably a cheaper grade. I've only ever purchased T-6061, and I'm sure it helps to develop a feel for one grade and type of material.

I've had really good results using Rigid Nuclear thread cutting oil on aluminum. I'll run a bead of oil ahead of the end mill, from a squeeze bottle, every two or three passes. I also do my best to remove the chips so that they don't get dragged back into the end mill on a second pass. Harder to do with a CNC mill, unless you can have a constant supply of pressurized air to blow the chips away. For my small operation, I've been using a blast of air from the compressed 'duster' air cans. Alternatively, I could use a portable air tank, with a blow off nozzle, filled from the compressor in the garage, which would probably be cheaper in the long run. Anything is better then nothing though. I should buy a small airbrush compressor someday.