So I am still waiting on my mill to arrive so I have to entertain myself by trying to pick the brains of the many experienced pro's on this site. I have tried a search and not really come up with a great answer. I have been watching youtube videos of different milling operations. I have seen many machines produce a near mirror finish on aluminum straight from the machine. Of course these where VMC's and I have no idea of what RPM they where turning. I will be running a kneemill which currently can turn the spindle at 4200rpm max. My question is what spindle speeds do I need to produce these types of finishes right off the machine, assuming the set-up, tooling and coolant is all perfect?