Posted by BillS on September 06, 2012 at 17:02:33:
In Reply to: Worm gears posted by Dave moon on September 05, 2012 at 20:51:00:
There is a FAQ topic that tries to explain using Tangential hob shifting:
http://www.meshingwithgears.us/faq.htm#(h9)
This was based on a Fellows Pfauter 400 hobber. Your machine design might use the same formulation to apply tangential shifting.