Two of the shop lathes are fitted with both Transposing gears for metric pitch cutting, and VFD's so the spindle can be slowed, brake to a stop and reversed from the apron control lever.
The third lath, a Wade 94, has no feed mechanism. Strictly a precision bench lathe.
In the reference, the heading starts with how it is possible to cut "near enough to metric" threads by using the closest imperial pitch (example 26 tpi is useful for 1.0 mm pitch, and this does work just fine for short threads!)
If that is what you want to do, the threading dial works just fine! You are still cutting imperial pitches, which is a match to the lead screw.
I should be noted, that even if you had a "metric lathe" with a metric lead screw, the threading dial would need to be a complicated piece requiring gear changes to properly indicate any range of metric screw threads. Even the metric guys keep the lead screw engaged until the thread is complete, reversing the spindle up after every pass.
Such is life!
|This message has been edited by CalG on Apr 2, 2012 10:49 AM|