Well, I picked up a 12mm allen headed socket today and pulled the head. The bolt was only around 20 to 30 ft lbs. Not totally loose, but not tight by any means. Pulled the bolt and applied some red locktite and took it as much as I could which was right at 190 ft lbs. Really needed to be standing on the bed for better leverage, but never moved the head completely out of the way. My torque wrench goes to 250 ft lbs, but I guess I don't!!

I really wanted to get it back together tonight to see if that solved the problem. Not quite. I still got .003" to .0035" jogging from up to down. Continuos up or continuos down give me exactly what I'm jogging. So, starting loosening the gib some more. Now when I shut the motors off, the head comes down a slight bit, but then stops. No real slop in the head measured with the spindle all the way extended.

I'm wondering if there should be a anti backlash ballnut on the Z axis like is on X and Y. Or if further improvement to the attachment on the Z slide is needed. I think I'll pop the head back off tomorrow and get it out of the way so I can get real physical with it. Maybe should get a grade 8 cap screw and replace it as well. That is if I can find one around these parts.

Bob