Quote Originally Posted by John S View Post
Every chance.

One other detail required on gears is to know the pressure angle, PA, the involute [ shape of gear tooth ] is generated at.

Modern gears are cut at 20 degrees, older gears at 14.5.

Bad news is it's really hard to measure a PA in the home shop without specialist equipment.

Good news is most machine tool maker use 14.5 and stick to it because of legacy issues.

Early Colchesters also had 16DP gears at 14.5 PA.

.
Both DP16, but his are 3/8 wide and mine 5/8. Also I have 55 and 65 while his set includes 56 and 64 so maybe intended for a different pitch leadscrew (mines 8tpi)