Posted by BillS on January 21, 2016 at 18:43:36:
In Reply to: calculating helical gear dimensions posted by Rich S on January 15, 2016 at 23:02:07:
I can point you to this:
Even if your gears are not standard diameter for a helical with these specs, the span measurement would not change. This is because the contacts are made tangent to tooth profiles by skipping over a predetermined number of teeth (this is true for ideal involute tooth profiles but not when profiles are distorted).
This calculator is an alternate to over pin measurement for checking proper depth of cut when cutting a gear. It may not be as accurate as an over-pin measurement since it relies on a caliper measurement. The calculator determines the number of skipped teeth required to bridge from one profile contact to another profile contact.
Sorry, I don't know the tolerances...