Thursday, January 5, 2023

3D Printed Timing Belts for Prototypes

We experimented with 3d printing 5mm HTD timing belts. 

CAD files

OnShape link to the belt generator we are using to make our belt models:

We need to be able to tune the geometry of the belt to allow us to print it correctly and work well with our slicer settings (details below)


  • TPU 95A: This material was too elastic and stretched too much.

  • PCTPE: This is one of the most promising materials. It’s a nylon and TPU copolymer. It’s flexible but not very elastic. Belts made with this at the correct size could slip due to stretch, but we believe there may be a way to print belts slightly undersized that will stretch to the correct size.

  • TPU-CF: TPU with chopped carbon fiber this material also worked very well.

Slicer Settings

  • This was the important part of making timing belts that worked the way we wanted.

  • The main principle is getting each layer to only be complete loops of filament. In our case, this is 4 total perimeters of 0.6mm thick extrusions. You can adjust the model to help get the correct setup.

  • The top and bottom solid layers are turned off.

  • Avoid Crossing perimeters is turned on to limit stringing

  • The seam position is set to random to avoid a misshapen tooth where the seam may be.

  • This does leave a small hole in the belt, but that didn’t seem to cause a problem with our tests.

Results and Recommendations

  • We printed two belts for our 2022 launcher hood and were able to launch balls well with the printed belts. They do feel looser than the stock-reinforced belts.

  • At the current stage, we are confident we could print a belt for a prototype or test, but we wouldn’t want to use a printed belt on a competition robot in any critical area.

  • The next step is to alter the geometry so that we can easily print a belt with a slightly smaller diameter than a standard belt but with a similar tooth size so that we can account for the stretch built into the printed materials.

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