Creality Ender 3 Z Axis Bearing Block

This is a modification for the ender 3 creality dual z axis drive kit or any other dual z axis drive kit meant for the ender 3.

This kit is meant to be used to lock the lead screw in place while being driven by a belt by an overhead motor driving a synchronization belt linking the two drive screws together.

Motivations

This design was instigated by the rampant z-banding present in most cheap bed slinger printers that use pom wheels for the z-axis. The cheap lead screw assembly and poor alignment often lead to heavy z-banding and gantry sag resulting in poor print quality and inconsistent z-hop.

The bearing block with an overhead belt drive system and Oldham couplers eliminates all problems plaguing these printer topologies. The overhead drive assembly ensures only two points of contact on the lead screw and complete stability of the drive position of the lead screw. No more coupler issues, no more coupler shifting, no more misalignment. All z-banding artifacts should be addressed with this drive system.

The design uses 608 bearings to eliminate axial movement and needle thrust bearing to eliminate z axis movement. The lead screw is locked in place providing a true bearing block for the z-axis drive.

This model has been FEM verified. I tested the model under pulley and vibration testing forces 2x those encountered in a printer running at 400mm/s @ 10k accelerations. It will deflect within tolerances below the print resolution of 0.2mm in the z-axis.

Modifications

As always, I have included the full CAD model done in solidworks. The design is parametric and part-dependent. Feel free to swap out my parts for parts you have on hand and it should automatically adjust itself. Pop into the equations tab for more modifications if you want.

I went a little overboard with the chamfers and it does look a little unprofessional, it was late when I designed this haha.

If you do not have Solidworks I recommend Onshape, it is great, free, and has a modern version management system akin to github. I recommend anyone give it a go.