I am using a PCNC 770. I use it for light engraving of small pockets. My Z backlash is .0009, up and down. This tells me that the gib is tight enough to hold the weight of the headstock. I am suspecting that I am experiencing some creep during the dozens of up and downs of engraving and am getting poor depth results. I am wondering if I were to loosen the gib to the point that the weight of the headstock allowed the z axis to always run on the bottom race of the ballscrew, would this leave the headstock way floppy loose and cause problems not obvious to me? I am thinking that the super light cuts I make would not have much of a lateral effect on the spindle. But I wanted to throw it out here in case someone has done this and has any pointers or warnings.