Posted by Ron V on December 14, 2015 at 15:22:01:
In Reply to: Re: Fly Hobbing - Substitute Hob Shift for Tangential Feed? posted by gearhead1 on December 14, 2015 at 11:30:43:
In the same way a differential is used to add or subtract motion to the table relative to the movement of the tool when cutting a helical gear; the same happens when hobbing by using the tangential method.
As an example; for every 1mm that the tool moves tangentially, the table movement is circumferentially corrected by the same amount. This is the job of the differential.
Without a differential, unless you had a CNC machine, you couldn't fly or tapered-hob cut.