Quote:
Originally Posted by jblay
We want to get the power that a CIM provides us, the other motors won't do the job at the speeds we need if at all with our current ratio and a ratio change would mean major mounting adjustments in something that has holes setup at the base of our robot which is pretty impossible at this stage in the game.
It was working really well for a while before the problem so we are pretty confidant that if we can connect the collar to the CIM better it will hold up through competition. We just need the clever engineers of the CD world to give us a better idea than mine of, just put a pin through both.
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It sounds like pinning the CIM motor could be your best option at this point.
Without knowing the exact details on your setup, it's hard to give specific (and relevant) advice, but here are some ideas worth thinking about and/or questions worth asking:
Which CIM motor are you using? One of the newer ones, or one of the older ones? I'm not entirely sure when - but at one point or another (I think somewhere around 2007/2008, maybe earlier) CIM motors went from having a 'full'(ish) keyway on the output shaft, to the current milled slot sort of setup. I don't have a motor in front of me at the moment, but I'd imagine that if you cut the CIM output down to 1/2" long, then you're only getting a 1/4" key there - if you're lucky. If this is the case, finding an "older" cim motor with the full (More full) keyway might be worthwhile. Or, on the same train of thought, if you've got a halfway decent mill, you could always extend the keyway another .125-.25" towards the CIM's mounting boss, but that could get a bit tricky (Need to fixture the CIM just right). The longer keyway would allow you to run a longer key, which should be able to take a bit more abuse - assuming that the versaplanet's input isn't the limiting factor in key length. **see edit below
Otherwise, since your failure seems to be rooted in the CIM to VersaPlanet interface, you're only real option seems to be to make the interface stronger via some other mechanical method. Pinning the CIM to the input doesn't seem like a half bad idea to be quite honest - I'd imagine you can get a reasonably large pin through both shafts without issue. At that point assembly/dis-assembly might become problematic/annoying/etc, but if you've got the money/resources to have multiple motor/gearbox assemblies on hand, then it could be a non-issue.
Edit: Did some digging on older CIM motors, and came up with this drawing from ~2002. It appears that back then, CIM motors had a keyway that was ~.125" (3mm) longer than the current ones, at least when looking at where the keyway stops relative to the CIM mounting boss.
Old CIM:
http://www.team1322.org/chip.jpg
Current CIM:
http://files.andymark.com/CIM-motor-curve.pdf
Also, there's part of me that thinks that the 2007/2008ish BaneBot's Supplied CIM motors may also have a longer keyway too. Can't find a drawing to get conclusive proof, but it might be worth looking through old CIM motors, just in case - there are a bunch of legal part numbers that are legal, so you may get lucky and find the 'right one.'