So, our team is using 4" 60a neoprene fairlane wheels for our shooter, and we’ve had two wheels fail via the same failure mode, and we’re unsure why. They appear to develop a small radial crack, and part of the wheel appears to delaminate from the hub(we can pull it off slightly). The first one had an issue due to our camera mount coming loose (causing it to dig in and wear it excessively), and we thought that was the culprit, but the replacement wheel had no such issue or wear but failed similarly, so we don’t know what’s up. Any ideas? (Initially running at 7500 rpm, dropped it to around 6000 for the replacement wheel). One of the wheels is a slip fit and wiggles a bit on the shaft, so could that be causing issues? Our shooter also vibrates a fair bit, which is probably related? Idk
6000-7500 rpm is pretty fast. I believe we are using the 60A solid roller wheels from WCP, which are very similar though they have more solid hubs than what is pictured here. But we don’t run them above 5000RPM, typically sticking around 3000-4750RPM for all of our shots this year.
That being said, this post by R.C from wcp suggests the WCP 60A’s should hold up up to 9k RPM. But I’d read the rest of the thread to figure out how to wrap a safety wire around it to try and prevent some of that delamination.
The WCP 60A wheels are urethane, they are closer to the blue/green urethane McMaster wheels than the black neoprene ones. We’ve ben running our WCP 60A wheels above 6000RPM most of the time with our 2020 robot and never had issues.
The black neoprene wheels from McMaster have been known to delaminate from the hub above 4000-5000 rpm due to the rubber expansion (See this post from Devin on 1678). 1678 counteracted this in 2016 by wrapping safety wire around them to prevent expansion. Devin has a demo video of how to do this later down.
You are correct, I should have been more specific - McMaster sells the Fairlane brand wheels to my knowledge (the ones we’ve gotten from McMaster before have the brand embossed in the rubber).
I’ve found that seems to be hit or miss - of the 4 fairlanes I have on a bot 3 of them have nothing embossed and the other one does. (These are all the neoprene ones and boy do they smell) but my source was not McMaster.
These are also the 2" OD 1.125" ID in a couple of durometers. I think the next set I order might switch materials.
While, based on images Im guessing they are the Neoprene rubber that is common in FRC, I wanted to point out they do sell other materials as well. It’s likely not pertinent to this discussion as I think Urethane, Nitrile, or Neoprene would all exhibit very similar behaviors at those RPMs.
The highest rating I was able to find was 1000rpm on precision bearings but this was a lifetime rating for the wheels with a bearing pressed in already so hardly applicable here. But it does confirm at least to 1000rpm that all wheels function the same.
Thanks for all of the great responses in here! We got our issues sorted by lowering the rpms, and are likely going to be switching shooter material/durometer soon. We’re not sure whether to go with 60a urethane, 80a urethane, 80a neoprene, or 80a nitrile, and were wondering if there were any destructive tests done on the latter 3 to see whether they’d hold up at high shooter RPMs (can’t find any on CD). Does anyone have any insights or relevant experience?
For future reference, I would recommend using the WCP 60a solid wheels when pushing RPMs. Many teams have had success with it, but something about wrapping a steel wire around a wheel spinning at +5k rpm with a history of delaminating from the hub makes me very uncomfortable. if it’s really necessary, I’d probably use something like a synthetic string that won’t turn into a needle flying at 71.4 mph (114.9 kph for those of you who don’t live in Myanmar) inevitably towards our safety captain knowing our luck.
Yeah, that’s also why we don’t want to have to run safety wire. Wcp’s wheels have been backordered since last February (2020) when we ordered them though, so fairlanes are our only real option, tho they should be functionally equivalent
