After removing the bulk of excess posting material on a purpose-built machine, I do some finish work on the spindle grinder.
The hindfoot and forefoot need to be in the same plane, with the low spots in the molded contour showing through the posting material.
This establishes the ‘neutral grind’; the state of the footbed prior to fine tuning with the client. This particular client has high arches, and his foot is mobile to the lateral side.