I would usually touch my corner rounding tool off z-zero on the flat above the radius. That way I just program it as an end mill with diameter equal to diameter of hub. Then program tool to top depth of corner you want to round. Just watch out for clearance when you have to rapid over the part. Mastercam will just program it to a Z-depth equal to your radius, if I'm not mistaken. We all know different brand corner rounders have different depths from tip to flat. So this takes care of that. Hope this helps.