Teaching machine design & mechanics by jacques maurel


First page: Screw cutting any lead on the lathe (from the standard gear box). 

Fully described in Moldel Engineer magazine issue 4270 (apr 2006).

Explanations: look at the drawing here under.
Using Thales theorema, the tool movement is the result of the B movement given by the carriage (standard lead) multiplied by the ratio AC/BC which can be adjusted by moving C.

Watch the video:

1 - The attachment is almost entirely contained in a toolholder (only a bench stop
     must be added).
2 - It works only for a short thread length from 50 to 90 mm Maxi according to the
     lead cut.
3 - The adjusting lever is graduated  (and charts are given for the usual leads) for
     a quick and easy set up. But almost any lead can be machined within the
     range of the gear box.
4 - No change gear is needed.

5 - The thread dial indicator can be used and the half nuts opened according to
     the standard lead used.

This attachment is not a new idea: look at this "short thread cutting machine" contrived and made by the French horologist Antoine Thiout (1750):

This machine can be seen in Paris in this museum:
" Conservatoire national des ars et métiers"