Unless you use a very large diameter cutter you will only "chew" most timber at 4000 rpm.This is where the horses for courses bit comes in. Milling machines are generally very rigid and are designed to cut metals and harder materials, but do not usually have high speed spindles. Routers on the other hand do usually have high speed spindles and are used predominately for softer materials. If you really want to cut timber (I seem to think that your first post referred mainly to cutting metal) I think you will need to become a "dab hand" at using abrasive paper!! Good luck. G.