Here’s an easy way to control the cutter’s plunge location so that its outside of the part perimeter and you don’t end up with a “dwell groove” on the edge of the part. Rather than letting Carbide Create determine the toolpath based on the part outline, I simply drew the toolpath by offsetting the parts edges to a distance equal to the cutter’s radius. I then extended the start and end points of the toolpath so that the cutter will plunge and retract outside of the part’s finished perimeter.
This is a part that I programmed in Carbide Create this morning. I was using a .250" cutter, so I offset the part perimeter by .125" and extended the intersecting lines of the part’s lower-left corner in order to create the start and end of the toolpath. When programming in CC, the offset direction is set to “No Offset” so that it follows the drawn path:
If you’re programming a circle, offset the outline, draw a couple of tangent lines, and then trim the circle to the lines (then circle geometry will actually become greater than 360°). This way, the cutter drifts into the part at a tangent, circles the part around its entire perimeter and then drifts off at a tangent.