... In G97 spindle mode with a feed of 1 unit per minute (G94) and a spindle speed of 1000 the feed rate is 1/1000 = .001/rev if you then drop the spindle speed to 500 rpm then the feed is still 1 unit per minute but the feed rate is .002/rev...

Graham

Graham,

Bill Wulkan asked me to review your post reply.

On line three, I believe you have mixed apples and oranges. FPM and IPR

In G97, G94:

.001 IPR @ 1000 RPM => 1 IPM

.001 IPR @ 500 RPM => 0.5 IPM - Slower not faster.

In G97, G95:

.001 IPR @ 1000 RPM => Feed rate = .001

,001 IPR @ 500 RPM => Feed rate = .001 The same, because the feed rate is locked to the RPM of the spindle. As it should be with threading on a ANY lathe!

Wayne

Wayne