I use solid carbide SKI-CARB End Mills from Fullerton Tool for Aluminum milling and an A-Symmetric Solid Carbide End Mill from Hanita for steel. A high shear positive rake carbide insert cutter will also work and with any tool the right depth of cut, corner radius, feed & speed needs to be considered.
You stated you were digging into the work piece on entry and exit. try a shallower depth of cut and leave .010 to .020 for a finish pass to improve the finish. Make sure your work piece is solidly held and that your work head and table are both locked in place.
I am not much of a manual machinist so I do not know the workings of a knee mill to give you better operating advice. I run a 5-Axis Okuma MC60H CNC Horizontal Mill with a 100 tool capacity. 5000 max rpm.
Milling is milling. The tool does not care or know what machine it is being used in. Hope this helps some.