Start with the material and tool
Cutting speed is not a universal constant. Workpiece material, tool material, coating, operation and coolant strategy all affect the appropriate starting value.
RPM follows diameter
For a given surface speed, smaller diameters require higher RPM. Check the machine speed range and never exceed tool, holder or machine limits.
Feed should create a real chip
In milling, feed rate combines spindle RPM, tooth count and chip load. Feeding too lightly can cause rubbing rather than cutting; feeding too aggressively can overload the tool or machine.
Treat calculated values as starting points and adjust using toolmaker data, machine rigidity, sound, chip formation and finish.
Use the related tools
Engineering guidance only. For safety-critical work, follow the applicable manufacturer data, drawings, standards and competent professional judgement.