This page contains a more readable version of the threading, feed, and worm gear cutting charts that are in the manual on page 13.
The Colchester's change gears are 16 diametral pitch, with a 14 1/2 degree pressure angle. The stock gears are 0.5" thick and have a octal keyed bore with a primary diameter of 0.8125". The eight keyways are 0.175" wide and 0.03125" deep.
The following table is a list of the standard change gears that were originally supplied with the Colchester Bantum Lathe. Also included are some of the calculations needed to cut these gears.
| Number of teeth | Quantity on hand | Outside diameter | Involute cutter number | Maximum Measurement over wires 0.108" wires | 0.003" Backlash adjustment | |
| 21 | 1 | 1.4375" | #4 | 1.4595" | 0.0084" | |
| 35 | 0 | 2.3125" | #3 | 2.3387" | 0.0092" | |
| 36 | 1 | 2.3750" | #3 | 2.4035" | 0.0092" | |
| 39 | 0 | 2.5625" | #3 | 2.5894" | 0.0093" | |
| 42 | 0 | 2.7500" | #3 | 2.7792" | 0.0093" | |
| 49 | 0 | 3.1875" | #3 | 3.2157" | 0.0096" | |
| 57 | 0 | 3.6875" | #2 | 3.7165" | 0.0096" | |
| 60 | 1 | 3.8750" | #2 | 3.9055" | 0.0096" | |
| 66 | 0 | 4.2500" | #2 | 4.2808" | 0.0097" | |
| 69 | 0 | 4.4375" | #2 | 4.4673" | 0.0097" | |
| 100 | 1 | 6.3750" | #2 | 6.4070" | 0.0105" | |
| 120 | 1 | 7.625" | #2 | 7.6574" | 0.0106" | |
| 127 | 0 | 8.0625" | #2 | 8.0944" | 0.0106" |
Gear | Feed Rate |
R5 | 0.001 |
R2 | 0.002 |
S3 | 0.003 |
S2 | 0.004 |
T5 | 0.005 |
T3 | 0.006 |
T2 | 0.008 |
Gear | Feed Rate |
R5 | 0.005 |
R4 | 0.006 |
R2 | 0.006 |
S6 | 0.010 |
S4 | 0.012 |
S2 | 0.016 |
T6 | 0.020 |
T4 | 0.025 |
T2 | 0.032 |
Gear | Threads |
R3 | 80 |
R4 | 72 |
R1 | 64 |
R2 | 56 |
S5 | 48 |
S6 | 44 |
S3 | 40 |
S4 | 36 |
S1 | 32 |
S2 | 28 |
T5 | 24 |
T6 | 22 |
T3 | 20 |
T4 | 18 |
T1 | 16 |
T2 | 14 |
Gear | Threads |
R5 | 24 |
R6 | 22 |
R3 | 20 |
R4 | 18 |
R1 | 16 |
R2 | 14 |
S5 | 12 |
S6 | 11 |
S2 | 10 |
S4 | 9 |
S1 | 8 |
S2 | 7 |
T5 | 6 |
T2 | 5 |
T4 | 4 1/2 |
T1 | 4 |
T2 | 3 1/2 |