<p>While calibrating recently I noticed about 0.1mm of backlash on the Z-axis - in other words the exact setting for paper drag changed by 0.1mm depending on whether I was moving up or down to that position. Is this to be expected, or should I be tightening the z-axis drive belt?</p>
check the drive belt of the z-axis. Maybe the z-axis clamping part is sliding too hard. It is the plastic part which is mounted to the z-motor shaft.
@donepearce I was experiencing the same issue, so I measured the powered move of the z-axis towards the print-bed when using the 9-point calibration procedure with and without the one-way bearing engaged enough to stop the free-fall. Using a .0005in Mitutoyo indicator I found the z-axis moving towards the print-bed was NOT moving a full .10mm as reported in the calibration software. Without the one-way bearing engaged, it moved the full .10mm with every single click within the calibration procedure.
I have since removed the one-way bearing assembly mentioned by @kirkdis33 and enjoy much more accurate leveling procedures and print-jobs.
@techsalad, I’ve always wondered if that (clamping force) has an effect, so thank you for sharing your findings.
@Arnold , you’re very welcome! I’m happy you took the time to read my post and helped at least one other owner/user.
yes, most people tighten the screw but the correct procedure is to tighten the screw only so much that the z-Axis is holding in the last position. I never had isses with positioning on mine and the axis stays where it was parked last time.
The one-way bearing works as intended for most users. @kirkdis33 , your correct procedure of its use was important to include here, tks for chiming-in.
I’m using an optical mirror on top of the stock build-plate, and sandwiched between are many brass shims of differing thicknesses to get my build-plate to within .05mm at all 9 points. It was important for me to do this so when designing mods everything is parallel and square and the 9 point calibration movement of 0.1mm is also accurate.
For layer-heights thicker than the +/- .03mm variance I found when moving the z-axis in the 9-point calibration, the accuracy may not be such a big deal. But when using layer-heights thinner than the 0.1mm movement of the z-axis when calibrating, the z-axis movement precision when calibrating becomes a huge issue for those demanding high-precision printing.
When I test a mod-prototype with multiple precision indicators simultaneously, +/- .03mm actually means the nozzle-height could be anywhere between a .06mm distance and when printing using a layer-height of .05mm …at an overhang on the model …print-quality starts getting messy. And it gets even messier if the starting-height of the overhang’s first-layer is not divisible by the layer-height you are using, either because the model was not designed to use that layer-height you are using or the slicing procedure did not account for the overhang.