Internal sharp corners are to be avoided when designing for the CNC process. If you want to engineer like a boss, you will never produce a part design with sharp internal corners.

The way to accommodate corners in CNC machining is by adding reliefs. There are 4 methods of managing internal sharp corners. Follow the picture above, the callouts and the list below.

1. Hole centered in each corner; cheapest solution.
2. Half-Moon; slightly more expensive than the hole.
3. Internal Radii; equivalent to half-moon in costs.
4. Sharp Corner via broaching or Wire/Sinker EDM; most expensive.

Please ensure that you don’t have any internal sharp corners in your designs, as it allows us to provide the lowest prices and shortest lead times possible.