Its not necessary to break the bit, its more relatively speaking, though it could happen. Normally the bits are much more stronger than they look. What i am talking is when the feed is raised there is a moment where the cut quality starts to suffer and definitely it starts to seem like the bit will break. Usually it will not break. then back off a bit. The idea is for the bit to cut as its meant to cut, not just burn, like Dean said above.

The speeds i am referring will work on any machine , weak or not. At least on anything that could hold 6mm bit.

Manufacturers guides usually refer to industrial machines, so care should be taken making conclusions reading them. Not that they are wrong, we just have to start with much smaller depth of cut.

Basically that's the main trick. The speeds i was referring are perfect finish speeds. i will just change depth of cut depending on which machine i am working. people oftem mistake speeding with bettering the cut