R2D2 no-slip tire for droid builders

My friend asked me to help design a tire for his Lucas certified R2D2 astromech droid build that would not slip off in the middle of performances.   

You can see his droid here: https://www.facebook.com/profile.php?id=100067737259025

An E-bike motor powers the droid, the model currently favored has rounded everyting, and is difficult to anchor to.  This no-slip solution involves a rubber spacing ring, a rigid clamp, screws to hold the clamp in place, a tire that dovetails with the clamp, a lock ring to hold the tire in place, and a custom tool to tighten the lock ring.

*New locking ring and rigid base designed August 2026 address a flaw involving thread depths causing weakness.

Print the spacing ring and the tire out of TPU.  I printed the rubber parts at 98% size, and found this fit to perform well with just a little stretching.  The rest of the parts I printed at 100%

All of the other parts should be printed with PETG as it withstands a little more abuse than PLA.  Vinyl or more durable plastics would be even better.

Assembly instructions:

1. Stretch the spacer ring over the motor.

2. gently spread the clamp over the motor that has the rubber spacer on it.

3. Use 18-8 Stainless steel socket head screws and 18-8 Corrosion resistant narrow profile hex nuts to tighten the clamp onto the motor housing with the TPU rubber spacer.  Do not use excessive force, finger snug is enough. The screws do not provide friction to directly prevent the clamp from sliding laterally, there are shoulders on the motor, and a corresponding shoulders on the clamp that keep the clamp from sliding off, the screws just hold the clamp together.  I purchased two different length screws from McMaster Carr 5/8 and 3/4 I think I ended up using the 3/4 to get the threads started, and then once the clamp was closer together I may have switched them out for 5/8"   https://www.mcmaster.com/products/92196a131/  and https://www.mcmaster.com/products/92196a130/ I used these nuts: https://www.mcmaster.com/products/90730a006/

4. Test the lock ring to make sure the screw tension holding the clamp together isn't too tight pulling the threads past sync, or too lose where sync hasn't been reached.  Place the lock ring on the custom wrench and make sure you can thread it all the way down without excessive force required.  Take the lock ring back off.

5. Slide the tire into the dovetails of the clamp, the tire is universal, and can go either direction, the V in the tractor style tire typically points in the forward direction.

6. Now install the threaded lock ring onto the clamp using the tool, locking the tire in place, and make it snug, but don't crack it. The 3d printed threads tend to stay put. 

7. My friend had to remove some of the metal of the wheel housing with a dremmel because this tire solution is a couple mm larger than his original unit. 

Best of luck to the very few in droid building community who would ever need these files!