The parent comment makes a good point. If accurate positioning is an issue it seems like you would want a closed loop control system that measures and optimize

The parent comment makes a good point. If accurate positioning is an issue it seems like you would want a closed loop control system that measures and optimizes for that. The position measurement itself could be made using machine vision or perhaps more precisely using lidar or some other technique. I've even wondered if that might allow you to build a less rigid and hence less expensive CNC mill.