A simple approach with AC Motor Worm Gearbox

Using a Wuma AC Motor Worm Gearbox
When cutting a worm on a lathe fitted with a gearbox the comments made  regarding metric threads with a gear box still apply. This, as you can set the box to 8TPI and set up the change wheels as though the gear box was not fitted as its input and output rotation are identical.
The mechanical variable speed gearbox is though a relatively simple method for achieving the majority of common DP values. This entails fitting just a 55 tooth driver and a 35 tooth driven and using the gearbox to establish the values required. The table shows just a few of the possibilities but other values are easily determined. Typically, as 32 DP uses the 16TPI setting then 18TPI would result in 36 DP.