[HoosierDaddy1]

Imagine simple round boss sticking straight up out of a flat plate (or a cylinder sticking out of a plate) . Its pretty easy to contour around this boss and finish the outer surface of the cylinder. How do I do this exact same thing, when the surface at the bottom (that the cylinder is sticking out of) is not flat, but irregular, fluctuating up and down in Z? I have a fairly complex part that I have already performed a number of Surface Rough, Finish and Surface Highspeed Scallop tool pathes on. I am happy with everything except the finish on the outside of this boss. I want cut 2d contour type finishing passes around out, while having the ball mill move up and down to avoid hitting the complex bottom surface. Ive included a few pics so you can maybe understand what I am talking about. I am really just looking for some guidance as to what tool path to use in order to accomplish this.

If you zoom in on the second or third picture you can see where the tool pathes constantly move in, touch the boss, then lift up and over it. As far as the surface finish on the rest of the part is concerned, this is exactly what I am looking for. However, I want to leave a smooth contoured finish around the boss. Does anyone know if there is a way that I can program a finishing contour that forces the end mill to follow the contour I drew in the last picture?

Id love to hear your thoughts!