Mini-Lathe Change Gear Calculator

This tool can calculate possibly alternative gears that can be used to cut a particular thread on a 7x12 mini-lathe like my Sieg SC2. It works with either a 1.5 mm pitch leadscrew (the default) or a 16 TPI one. It is heavily based on the work of Al Harral; I just thought it would be nice to have a web-based alternative for those (like me) who don't use Windows very much.

The code is based on Al Harral's GEARS.BAS so I certainly can't claim any credit for the intelligence behind this code: I simply ported it to javascript (via a python version as I find python a bit easier than javascript).

Leadscrew: Metric (1.5 mm pitch)
Imperial (16 tpi)
Extra Gears: 21 tooth gear
Extra 50 tooth gear
63 tooth gear
Options: Always show four-gear options
Target Type: Metric Pitch
Imperial TPI
Target Pitch:
Target TPI: