Quote:
Originally Posted by artdutra04
Thanks! Elegantly simple is our design motto.
Originally the robot was designed to use foam between the polycord loops. This didn't work so well, as the foam from McMaster was a lot softer than we were expecting. So we replaced it with neoprene roughtop belting, with PVC pipe spacers on some of the rollers. The rollers were originally PET-G, but upgraded to aluminum as part of the 40lb allowance.
We had some minor issues with the polycord loops "jumping" from one track to another, but these only happened if for some reason there was a Orbit ball jam in the system, and were usually limited to one or two loops total moving over one or two spots throughout the entire match. Because the loops were close enough together, this usually didn't negatively impact operation. Had we installed sensors on the robot to detect jams, we could have easily averted most of these issues.
Other than popping one or two of the loops back into their tracks at the end of every match, nothing else on this robot ever required any sort of maintenance or repair. Our students even got into the habit of cleaning the fingerprints off the Lexan side panels in the pits just to have something to do. 
There was just a single part throughout the entire season (Connecticut, Championship, BattleCry@WPI, Where's Wolcott, Bash@theBeach) that required any kind of repair, and that was the 3/8" drive shaft on the ball intake bent slightly during a particularly nasty impact in autonomous at BattleCry@WPI. Even though it was bent and made angry noises, it still worked for the rest of the competition. We machined a replacement shortly thereafter, and it's been working great since.
Here's some photos of the spacers from our team's website:
(Hurray for the duct tape rule! We used small strips of it to prevent the #8-32 button head screws from backing out of the aluminum drive plugs, since even with Loctite we noticed them slowly backing out on the practice robot before our first Regional)
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I can't wait to show the team this tomorrow, at our last meeting before kickoff
, and watch everyone in the room kick themselves, because if we simply had PVC rings like those we could have rapped and riveted the wedgetop just like we did, but that extra 1/4 or so that the PVC has in it's wall thickness would have created deep enough channels to prevent the polycord from jumping if not 100% of the time 99.9% of the time. And as the driver who piloted the robots elevator conveyerbelt and shooter I have to say this would have saved me the trouble of finding the perfect sequence of running the motor forward and backward to jump back to the right loop, so we could still shoot (surprisingly that actually worked on occasion but it's not something I want to see have to happen). Once again thank you to you and the rest of 228 for showing us your robot, and like I said before you guys have the right motto because simplicity is the key to any successful design.
Also thank you to Jamie Kalb I think our mentors would be very interested in this approach to the design.