Summary

A printable set of metric change gears to allow metric screw cutting on a CVA toolroom or Monarch 10EE lathe.

Instructions

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32DP 20 PA gear set,

starting with the 127 tooth, the first test print attached, expecting this will not be printable with my current setup, however one day it may just be possible.

Converting Diametral Pitch to Circular Pitch and then to Pitch Diameter.

Number of Teeth * 32/25.4 (32 teeth per diametral inch) measurements in mm

Further work into understanding Greg's parametric gear creation, I finally am closer to understanding a key issue. the module appears to be metric, whereas 32DP is an imperial designation (bring on the stormtroopers!)

32 teeth per inch of diameter of gear wheel. so to use Diametral Pitch in Greg's Gears, I need this to be a metric value, 32/25.4 (so we have teeth per mm of diameter of the gear)

a 127 tooth 32DP gear should be 127/32*25.4mm = 100.80625 mm pitch circle diameter.

the actual gear measures this plus addendum 2 ( to top of tooth )
the valleys of the teeth should measure this minus dedendum 2 across the diameter

previous output was not producing this.

By using

module testDPGear()
{
gear(number_of_teeth=127,
diametral_pitch=32/25.4,
pressure_angle=20);
}

the output gear is now a lot closer to the required size, with slight variation expected to be due to slicing configuration.

A full set appears to be
Assorted Stud Gears:
50T
55T
60T
65T
70T
75T
80T

127T/48T Composite
127T/72T Composite

Idler 154T (possibly 156T, but should be close enough to work)

48T (gearbox drive)

photographs of lathe changewheels located at http://www.practicalmachinist.com/vb/monarch-lathes/cva-metric-changewheels-192963/

I added a lid to the box.

CVA Lathe Metric Gear Change set