How to Design For CNC Milling · For example if the tool being used is a 10mm diameter end mill 5mm radius make the part corner fillet a bit bigger say 6mm Dog Bone Corners If a square corner is a must for a mating part then use a dog bone corner Keep the diameter of circular corner cut as large as possible Feature Height Keep the height of machined features less than 4x their width Tall and skinny features will