Servo Spline Maker

Note: you will need to use the customizer for this to be useful. (Or use the OpenSCAD model directly)

Think a 3D printer lacks the resolution to print splines to fit on an RC servo? Think again!

This customizer generates a test plate with splines of slightly different sizes. By fine-tuning the sizes, you can usually get a pretty good fit.

The behavior of the printer and the slicer will have a large influence on the final shape, so this must be kept in mind. Even the slicer layer height or printing speed could have a small effect on the shape, and could mean the difference between a good fit and a loose fit that slips.

Slice and print the test plate using a configuration as close as possible to the final print.

Here's how you can get a good fit on your servo:

1. Count the number of 'teeth' on the spline. It is very important that this number is exactly correct. I've found a close-up picture to be helpful.
2. Measure the diameter of the spline. This will serve as your initial guess.
3. Generally for the first attempt I recommend a step size of 0.2 mm, which is the difference in diameter between successive splines on the test plate.
4. Generate the test plate and print it.
5. See which spline fits best. The ideal diameter may be in between two splines of the test plate, where one is too tight and the next larger one is too large (slips).
6. Note that the test plate is labeled with the number of steps from nominal, which you can use to calculate the size of each spline on the test plate.
7. Estimate the ideal size and try again, possibly using a smaller step if you know you are close to the ideal size.
8. Once you are happy with the spline, you can download an STL file for the spline alone, which you can integrate into your model.

This design is partly for me to experiment with customizers. Let me know your thoughts!

Category: Robotics