Face Gear Differential Swerve

My design for a compact, 3-d printed face gear based differential swerve module.

4.5" Tall (without controllers) x 5.4" x 5.4".
2.4" Diam Center-Spur Wheel.
1.5" floor clearance.

All gears are all 14dp 3d printed polymer (TBD for the moment, looking at PEEK)
Two speed model nearing finalization.

Thoughts and comments welcome.


Looks nice! could you possibly post section views and or multiple angles of the module? I can’t fully visualize what’s going on here.



I’m no expert… but I bet you would have some serious backlash problems using gears like that.

I can see why you might think that based on appearance only.
Face gear pairs are made up of a conventional straight spur involute pinion meshing at 90deg to a tooth form that is generated by the swept area of a cutter with effectively the same profile as the pinion and rotated at the desired ratio.
The resulting mesh does not require any special toleranceing to control backlash and as a bonus the face gear can be moved” along its axis allowing for zero backlash. Great tool and link here. https://spiralbevel.com/crown_face

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I had no idea about that. That’s pretty neat.

Could you post the CAD for this? i would love to take a more in depth view of it.

CAD will likely be ready for release once I get the assembly 3-d printed.
Lots of preliminary design actions that need to be addressed before I move to critical design. I will post some section views in the next couple of days.

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How did you model the tooth profile for that crown gear? Super neat.

Check out the link in previous reply

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How much does one module weigh?

Target is under 4 lb (no controllers) stretch goal is 3.5

Love the compactness.
What are the steering (azimuth) and end drive gear ratios?
The steering looks like it might be fast for good control?

Yes the steering ratio at 3.6:1 is agressive from a steering stability perspective. The drive wheel to motor ratio is also 3.6:1 with a 2.4” ish wheel yields a free speed of around 16fps . Given the relatively low amount of information available regarding stable azimuth control, I am thinking about using a rotary damper to passively limit rotary occilation amplitude this complementing software driven control. Our team, 2358, successfully used rotary dampers to reduce occilations of our shooter mechanism in Aerial Assist. Location for damper is directly between the stationary housing and the azimuth (swerve) axis with zero backlash. Also a zero backlash connection to an encoder just above the damper. The damper can also be integrated directly into the upper housing. That design is in the cue for me to incorporate.

Hope this helps clarify. More to follow.


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