Gary Coffman wrote:

On Wed, 16 Jul 2003 13:40:02 -0500, Jon Elson wrote:


If the leadscrew is metric, only, then it gets more difficult. Some
lathes have
transposing gear sets that can be inserted in the gear train to make an
approximate
conversion between metric and imperial threads.



If the transpose gears are 127 tooth and 100 tooth, it isn't an approximation.
It is *exact*. 127x2 is 254 which is the *exact* number of millimeters in an
inch by definition.

Gary



The thread will come out exact, assuming the QC box has the right
selection, since
the metric way is thread pitch, while us imperial types do threads/unit
of measure.
But, you STILL have to back up without disengaging the half-nuts,
because the
leadscrew pitch doesn't repeat every inch.

Jon