Any data on how the durability compares with these wheels? We were able to get away with only having to change the Black Nitrile tread on our Mk4i’s about once per competition this year, should these be comparable?
Out test rig showed that V40 had a coefficient of friction on FIRST carpet of 1.6 while the standard black nitrile from SDS had a CoF of 0.9 on the same rig. This was a static rig with 35lbs on one wheel. We saw some differences between our static rig and the actual SDS Mk4i’s on a real robot. HOWEVER, we put them on virtually identical robots (this year’s competition robot, Scorpion, and our practice robot, Slither) and it wasn’t even close. V40 TPU90A easily pushed its twin around the field (and left less noticeable marks on the carpet FWIW)
I have played with designs like this for 3D printed RC cars and figured out an additional trick you can make use of for further tuning of stiffness and damping. The void space in the “spoke” region can be filled with a very low durometer pourable polyurethane or silicone. When the ratio of TPU spokes to soft fill is correct it seems to have a more damped behavior, but I haven’t done enough testing to see if that is really true or simply a lucky combo that worked well.
Actually, the whole tread even reminds me of a high density version of the old Tamiya pin spike tires
We’ve thought about selling them. Not sure if there is a market for them. Also, Team 88 has a Fuse1, which can’t print TPU90A (yet?) but even it if could, it isn’t super easy to convert between powders and we wouldn’t want to give up printing in Nylon12 (the parts as SO good).
As a Formlabs employee I have access “infinite prints” (best perk EVAR) but generally speaking that doesn’t include making parts to sell. Who can say? Perhaps I can convince them to make an exception for FIRST related parts.
As to Rev Max Swerve tire, there has been a ton requests from people stopping by our pits this year. I guess the stock tires are, let’s just say, less than ideal. I don’t see any reason not to make versions for other swerve modules. Our initial work was with a 3.5" tire we were planning to sell with our Diff Swerve Module (that we’ve pulled back from not enough bandwidth to do all the things we want to do in life.)
It was a lot of fun checking out what 88 was up to in Houston this year. The intermixing of yellow and tie-dye in our two pits was cool to see. Props to the awesome students and mentors for putting up with a lot of our questions and repeated visits - every time we were checking out the robot a new nifty thing caught our attention. The world needs more innovation (and more DoFs).
Joe - we would have loved to track you down and talk Fuse and the awesome parts and printer workflow. Hopefully next year!