Twist-to-tension transmission

[aamott]

Maybe my Ender 3 is an odd one, but the original Z shaft is too short and the pulley hangs off the end of the shaft, resulting in artifacts. In addition, #72 and #51 both point to complexity in the current design. I think it would be simple to redesign the motor mount to use a twist-to-tension design, simplifying the print and eliminating the need for a separate motor carriage and M5 bolt entirely. I used this in my own printer for the Z axis. I think this would solve the issue with short shafts, bolts, nuts, and remove one more piece of hardware.

Only one screw is anchored. The other 3 move in a path along arcs centered on the anchored screw.

It's not easy to tell, but the Voron Zero has a belted design that uses this: https://www.teamfdm.com/files/file/319-v01-belted-z-drive/