Posted by Tom Ramsey on November 29, 2011 at 14:29:20:
In Reply to: Re: lead angle correction - worm gear hobbing posted by Bob M on November 29, 2011 at 14:07:15:
Thanks a good question. Your contact should be in the center. Usually the customer specifies a center line from a point on the registering face of the part. This is something that needs to be checked after the perpendicularity is established. We typically cut the first one .010 oversized. You can check all but the diameter of the worm gear first and recut to bring in the center distance with less worry of scrapping it. This way you can cut several pieces oversize and be sure of good parts.
The tooth flanks should have equal bearing. If not it may be the cutter has runout. You should have at least two lead teeth, more for large diameters.