Change gears (imperial) for EMCO compact 5 lathe

3D-printed change gears for EMCO Compact 5 lathe

EMCO compact 5 feed mechanism comes with 6 change gears
(for common metric threads): 20, 25, 50 and 3x 60 teeth

For uncommon threads or imperial threads additional change gears are needed:
26, 30, 34, 35, 36, 72 and 40 teeth

While you can buy them from EMCO in Austria and they are beautifully
cut from steel blanks, I wanted to print them on my 3d printer.

The gears are 5.4mm thick and have a bore 14H7mm with a keyway (approx 4x1mm)

I undersized them for the printing and reamed them to 14H7 using a hand reamer. As you can see in the foto, they fit perfectly.

In the second and third picture you can see a 7/8"-14 UNF thread being cut, this uses only the 60 gear from EMCO and the other 3 gears are printed (72, 34, 35). Despite being a quite a large thread with heavy cuts, the printed gears work well. (hand-cranked, though).
Cutting a 7/8-14 thread was the primary objective as that is the thread for my single stage reloading press and I am building a couple of custom dies.

The scad file is fully parametric and can be changed as required. You need the parametric involute gears (see credits below) in the same directory.

I printed at 0.4mm with 30% infill and 3 perimeter in PLA.

Credits:

openscad code written from scratch by me, stemer114
using the example code from parametric involute spur gears library (see below)

Credits:

Parametric Involute Bevel and Spur Gears by GregFrost
It is licensed under the Creative Commons - GNU LGPL 2.1 license.
(c) 2010 by GregFrost
http://www.thingiverse.com/thing:3575

This module makes use of the polyhole library function by nophead (MCAD library)
MCAD Library - Polyholes Copyright 2011 Nophead (of RepRap fame)
It is licensed under the terms of Creative Commons Attribution 3.0 Unported.
https://github.com/SolidCode/MCAD/blob/master/polyholes.scad