Quote Originally Posted by russell View Post
Doesn't it also depend on the width of the cut or am I missing something?

Russell.
It does... I made a mistake and forgot to change the width of the cut when I calculated those. If it is full width of the cutter, then for steel it is about 105W and aluminium 160W assuming cutting full width of cutter.

The conclusion for a fly cutter is still the same, however a face mill will require the power above multiplied by the number of inserts... so too much. The thing is does it really matter ... with the machine being CNC you can generally just increase the depth of cut untill you hit the power limit and leave it to take as many cuts as required.