Dear Sirs:

We have installed a Gear Shaping machine (model: similar to Lorenz
LS400). We would like to operate at 20 mpm cutting speed while cutting
internal splines. The intruction manual says:
cutting speed = pi * stroke length * strokes per minute / (1000)

(note, here stroke length = spline length + approach + over travel)

I do not understand why greek pi (value = 3.1428) presents in this
formula
when the cutter does not follow a circular motion. Here the cutter
follows a reciprocatory movement and shifted for relief by about 0.5mm
away from cutting surface. To my understand, I think the formula must
have been
cutting speed = 2 * stroke length * strokes per minute / (1000)

Can anyone explain why "pi" is considered in the formula.

Awaiting your help

with best regards

N. Ayyavu