That’s a pretty good explanation. The linear rails and ballscrew on the HDZ deal with the backlash with a similar preload mechanism, the bearings rolling in the tracks are slightly over size and therefore don’t wobble up to a certain load, nothing is truly zero backlash.
Just in case anyone is interested, I stuck a 0.01mm dial gauge on my HDZ and heaved it around with “large cutting force” i.e. about 5kg force up, down, left and right by the spindle and the backlash I measured between the spindle mount bracket and the fixed Z plate on this sample was;
- X backlash - sod all, squat, couldn’t even see the needle move
- Y backlash - as above, below my measurement capability
- Z backlash - < 0.005mm
I think that exceeds any performance we would require of it on a Shapeoko, nice one Luke