Ormerod Z Gears Modified Fit.

Amsterdam's Remix was nice, but didn't produce a tight enough fit for my Z stepper motor.

I've revised the OpenSCAD code borrowing lines from DC42's mix of Iamburney's extruder gears, to produce some that fit my printer.

The original Iamburney's Z stepper gear works as normal, but i've flipped the nut cavity over to the bearing side, and decreased the hole that the M5 rod goes through, to help it line up centrally.