Posted by Ron V on July 23, 2014 at 18:55:15:
In Reply to: Re: tracing a helical gear on hobber posted by steve green on July 23, 2014 at 17:09:57:
It's the equation you use when calculating the gear train of the differential mechanism when cutting a helical gear. The result is a decimal ratio that is then used to calculate the gear train required.
It's usually shown in the operating manual and sometimes in the change gear compartment of the machine.