Smart idea :whistling:

Quote Originally Posted by artmin View Post
I will have to wait (hopefully much) longer to see how it wears over time. But certainly there is no backlash & the recess in the aluminium housing due to the shorter nut maintains a resevoir of thin oil.
Plus when it does wear you can just remould it. (Edit: Clearly taking it too far but theoretically you could build in a coil inside the nut to surround the screw then pass high frequency AC through that to induction heat the screw every so often (not whilst running!) causing the nut to remould itself to remove any wear. Self healing nut.)

I'd me more surprised if there was any backlash. Gravity causes there to be a constant force pushing down on the Z-axis nut, effectively pre-loading. So as long as the force due to static friction does not exceed the weight of the Z-axis and the component of cutting force parallel to Z-does not either you will not get any backlash. For this reason the backlash on my ball-screw driven Z-axis is smaller than I can measure. Most likely with the previous set-up the static friction was too great so the Z-axis didn't naturally 'fall' into position.