Machine insides.
Machine outside leaving material for cleanup pass....01-.02 or so all around.

Make a fixture using your layout from CAM program. Keep it simple, small piece of alum, hog out face leaving bosses that the I'd of your part fits snug on...drill n tap someplace inside to secure part to fixture.
Now put your part on fixture, secure and run your profile.
Parts secure, chips have someplace to go and a good finish should follow...also try 3 flute...single flute is great to pull chips out...not great for finish.