The Cost Of A Radius

Is a 1.5 mm design choice worth a $$$ price hike?

In CNC machining, the “hidden tax” of a tight radius is very real.

Look at the left side of image blow.  An internal radius of 1.5 mm forces the shop to use a 3 mm end mill. To a machine, that means:
- Lower material removal rates
- Higher risk of tool deflection and breakage
- Significantly longer finishing cycles
- Higher cost

Small cutters simply cannot remove material as aggressively as larger ones. That often means more toolpath passes and longer cycle times. The Optimized Choice by simply increasing that radius to 3.0 mm, you unlock the ability to use a ~6 mm end mill. The result:
- Higher tool rigidity
- More aggressive material removal
- 25–35% faster finishing
- Lower cost

Don’t just match the cutter size. The most expensive parts usually aren’t bad designs. They’re designs that are unintentionally optimized for the wrong variable. If a corner radius isn’t functionally critical, make it friendly for the machine.