I have another sprocket question here:
I’ve been looking around, and I need a sprocket I can mount directly onto the CIM motor. The CIM has a shaft diameter of .31 inches (8 mm) and I’m not sure where I can get a sprocket to fit that that has one of those spots to screw in a hex screw or whatever to hold the motor shaft.
Please tell me you’re not trying to direct drive your drive train… :eek: I shudder at the thought of it. I’m not sure if those kinds of sprockets are available. You may need to get an attachment to the CIM shaft to make it thicker.
well I guess I could get a larger bore sprocket and insert my own cylinder to fill the gap while keeping the threading from the COTS sprocket, but I’de rather not 
I’m not sprocket expert (as you can see from my various sprocket posts), so don’t take my word as law, that;s just my thoughts on the subject.
No way lol, That would be sweet though if you used the sprockets to gear down the motor 4:1 and run on super RPM with a light as hell bot 
But in reality, this is powering our centripetal arm, and it would be nice to use the sprockets to gear down the motor instead of a gearbox to equal sized sprockets. I already have the second gear made (60 tooth with machined holes to mount on the arm spot done by our machine shop)
I do like the shaft diameter option though!! I’ll look into that tomorrow!
Nice. You can try Andymark, if you haven’t already, or McMaster Carr. They both have great hardware, and just about anything you’ll need can be found at McMaster.
Andymark has a hub for the 8mm shaft that you can attach a sprocket to.
http://www.andymark.com/product-p/am-0320.htm
Yeah I’ve been surfing McMaster all day, and basically have a bot in the cart lol But they are just missing the sprocket size needed for direct connect to the CIM motor. I’m surfing andymark right now too
YES THIS IS EXACTLY WHAT I NEEDED THANK YOU!
Glad I could help.
Enjoy.
You can purchase some sprockets from AndyMark, but try bearing supply stores. Around here (Toronto Ontario Canada) I use “Canadian Bearing” “Toronto Bearing” “Oshawa Bearing” “BMI” etc. Also McMaster Carr. All these sources should be able to sell you sprockets with the correct bore or they will likely sell you a stock bore sprocket. In this case, you to chuck it in a lathe (a drill press can also be used in a pinch) and drill the center out of it to the right size of your shaft. Then you drill and tap a hole in the side of the sprocket to install an allen key. You can also buy cheap keyway broaches which with the help of an arbor press (or something really heavy, a car jack and some creativity) are used to cut internal keyways:
If you start with a sprocket with a 5/16" bore you can ream to 8mm and key to 2mm. I do this with 12 and 14 tooth gears for my gearboxes every year.
This hub is meant to be mounted onto a wheel with the typical 1.875" bolt pattern. Not saying that you couldn’t also mount a sprocket to it (it would work perfectly fine), but you may want to mount a smaller one than the ones with that bolt pattern. Andymark has a few sprockets that are meant to be mounted on gearbox output shafts or motor shafts. See Home - Mechanical - Motion - Sprockets - AndyMark, Inc. Specifically for the CIM there are two 25 chain sprockets with the appropriate bore, as well as few more with a smaller (.25") bore that could be reamed out.
Otherwise, check out Mcmaster-Carr. They have a very large catalog that is relatively easy to work with and they are bound to have hub mount sprockets for the chain you want to use (#35, 25, 40, whatever) with the bore you are looking for.
I think this is what I’ll do, thanks for all the input guys! FIRST is amazing!