That looks great Art.
For those who do not get what is being shown here :-
What Art is trying to show is that the tool shape is being taken into account when the profile of the part is roughed out, the unshaded parts are where the tool can not cut without gouging into the finished part.
If you look at the previous examples the tool could not have produced the shaded lines without the part being over cut in certain areas, this was before the collision detection was working.
Graham.