This is a rework of the Z-Axis drive system to reduce the infamous z wobble and to increase Z resolution.
The 1:2 gearing allows print layers that are a multiple of 0.02 - 0.04, 0.08, 0.10, 0.12 etc. whereas the factory system allows for layers that are a multiple of 0.04 - 0.08, 0.10, 0.12 etc.
I have successfully printed down to a layer height of 0.04 with no noticeable Z-axis wobble.
2x 20T 5mm bore GT2 pulley
2x 40T 8mm bore GT2 pulley
2x 150mm closed GT2 belt
4x 608zz bearings
2x 40mm M3 screws for top mount
Motor plate (left and right). This fixes to existing motor mounting plate.
Top bearing holder (left and right). Keeps the lead screw in position at the top.
Bottom plate (left and right). This fixes underneath the existing motor mount plate using the holes for the motor. The Z smooth rod is supported by the motor itself in the original, this plate replaces that support.
The top z screw holder is based on this thing: https://www.thingiverse.com/thing:1858435