Dimensions of a micro servo output gear
 

Hi! For a project of mine, it would be nice to be able to 3d-print a custom servo horn, instead of having to rely on ones included with the servo.

It's a Turnigy TG9z micro servo. 21 teeth with an outer diameter of 4.9 mm, as far as I can measure with my caliper. The teeth are too small for most printers/materials, but I know an option that might work.

I struggle with measuring the diameter in the valleys, to not even speak of the exact spline shape. Searches so far has not brought up any specifications. Do you happen to know the required geometry, or where to find out about it, or do you have an idea on how to make the required measurements (without spending money)?

Answers along those lines for standard size servo are welcome, too.