[artdutra04]

If you have Machinery's Handbook, you can sketch the profile of a single tooth on a sketch. Then you can use equations (for # of teeth, pitch, and pressure degree angle), and dynamically link those equations to key features in the tooth profile that would get modified by a change in teeth, pitch, or pressure degree angle. By simply changing the data in the equations and hitting Rebuild, you can have any spur gear in the world.