Dennis Dohogne

Parametric Spur Gears - Internal, External, Inch, Metric

Discussion created by Dennis Dohogne on Jul 30, 2020

I have been asked many times for my parametric gear files and realized they are buried in other posts and can be hard to find so I am posting them here.


These gears use a Design Table where you input the number of teeth, pressure angle, and module (metric) or diametral pitch (inch).  They are very good for the involute profile. 


Several years ago I saw a nice SWX model using an involute equation, but I did not like certain aspects of it.  These models use the geometry definition of the involute curve where the arc lengths, A, equal their unwrapped lengths, B.  This capability (setting arc lengths equal to straight line lengths) became available in either SWX2015 or SWX2016 and really simplified the models.

Caveat emptor (Disclaimer):

These models DO NOT deal with undercuts that would occur when there are few teeth, and specifics of the root and tip radius are up to the user.  They are offered simply as a good starting point for someone, but the ultimate responsibility is yours in using these models.


If someone would like to make helical versions of these and share them here that would be great.  I have not done so simply because I have not yet had the need.


I invite you to also contribute more advanced parametric gear files, in particular bevel gears, spiral bevel gears, worm sets, and profile shifted gears.