Posted by John Cerra on April 05, 2007 at 15:54:08:

In Reply to: Barber Colman 6-10 feed gearing calculations posted by David Hollinger on April 05, 2007 at 13:09:57:

Hi.

The "12/K" term in Pn/(C*Sine of helix angle) * 12/K represents the feed constant of the machine. For example, our 6-10 12/N has a feed constant of .075" or 3/40. That means, with 1:1 feed gearing, we would feed .075"/rev of work. For feed in a helical job, I use Pn/(C*Sine of helix angle)*.075 . Perhaps if you put a 1:1 feed each of these machines, you can verify their feed constants. Then you can just use Pn/(C*Sine of

helix angle)*feed constant for helical feed calculations. Once index and feed constants are

known this math should work for the 6-10 as well as other hobbing machines.

Good Luck

John C.