Ok so I changed the setting and now I can see backlash working correctly but the other behaviour is still the same. So then I started to think its a condition of velocity and or mechanical. So I looked closer at the dial while Im jogging in .01 single step mode. What I did was to move in .01 increments for a total of.1mm and low and behold the dial only moves .06mm that's why when I press goto the dial seems to move beyond the original value set on my dial gauge. The goto 0 is moving allot faster up and down and this engages the gear drive fully while my small incremental changes don't(at least thats what I think). Doing such movement on my x or y is fine, I can see the dial gauge move properly and setting soft 0 returns it to 0 the first time.
So now I guess I have to look at the mechanical aspects of my z and I'm a little disappointed that my machine is being a bit tricky, has any one had such behavior before mechanically? The machines motors are operated by steppers and a 2:1 belt driveand has ball screws all all 3 axis. I'm not sure the best place to start. I keep it well lubed and clean haven't had any crashes and only cut 2007 alu with it so I be surprised if bearings have allot of wear, but I'm still pretty new at this all.