overmilling is where you defer control of the quality of a surface to the CNC instead of constricting it to mill what it is capable of milling.
this mostly just applies to milling an intaglio surface; enabling overmill for this area will let the cnc decide (based on its cutter geometry) to purposefully cut the surface deeper than the design permits, as to guarantee fit.
this is dangerous for 2 reasons: 1. any time you have designed an area at minimum thickness you will be assured that the part will be under minimum thickness once milled. 2. with steep prep walls the cutters will not be able to overmill (on a simple 3 axis machine) without compromising the margin (because on a 3 axis machine the part is unable to pitch-yaw-roll movement)
how t is safely applied is by ignoring die spacer settings completely in lieu of a 0 space gap, because this way the cnc will be able to generate its own fit.
