I'm trying to come up with a design for a 4X4 router to use for making model airplane/glider parts in my shop. My current question is how to deal with backlash. I understand how anti-backlash nuts work on ACME lead screws, but how do you control these backlash issues with rack and pinion drives, or ball-screw systems? I imagine these other drives would be having these same types of issues. What am I missing, particularly with R&P drives. I'm trying to chose between ACME leadscrews and some R&P system.