Sprocket on large CIM

[s_forbes]

Can anyone tell me how we could mount a sprocket directly to the large CIM motor? It's a weird sized output shaft, and I can't find any sprockets that would work. I'm thinking we may have to make some bushings and buy larger sprockets, but I thought I'd see if anyone knew of a distributer anywhere that we could get sprockets that already fit.

Thanks in advance

[Jason Kixmiller]

There will be many people that will probably strongly discourage you from running a sprocket directly off the CIM output shaft...if the large motors are like the smaller version, they do not respond well to any type of side load. Basically, the motor will perform much better (if at all) if it either has a support at the end of the shaft or is run through a simple transmission. Posted by Al Skierkiewicz in a post referring to running a sprocket from the output shaft of a smaller CIM: "I agree with Chris but must remind you that the side load on the Chalupa shaft must be minimum. The bearing at that point is very small. If you just add a sprocket to the output shaft you are asking for problems, failure is guaranteed." I don't know if this is in fact the case with these motors, so I am hoping that someone with more mechanical knowledge of these motors will respond.

With that being said, there is a pretty easy way to fit any sprocket - just buy one with a smaller hole and drill the hole out to the size that you need. You can either put the sprocket in a lathe and turn out the hole or buy a drill bit that is as close to your size as possible.

In either case, good luck and be safe.

[s_forbes]

Thanks for the warning. We have plenty of room to move the motor back and put more support on the axle, so we will probably do that now. This also solves my problem of not finding suitable sprockets, I can just attach an axle to the motor shaft and support it on either side of the sprocket.

Whew, problem solved. Thanks again!

[Rick TYler]

Originally Posted by Jason Kixmiller

There will be many people that will probably strongly discourage you from running a sprocket directly off the CIM output shaft...if the large motors are like the smaller version, they do not respond well to any type of side load.

Interesting. Based on the sprocket mounted on the motor shaft F-P clearly uses this motor with a belt directly on the motor. I wonder if this might indicate that the large CIM handles side loads better than the small one? I'm not saying that it does, just asking the question.

[Kevin Sevcik]

Originally Posted by Rick TYler

Interesting. Based on the sprocket mounted on the motor shaft F-P clearly uses this motor with a belt directly on the motor. I wonder if this might indicate that the large CIM handles side loads better than the small one? I'm not saying that it does, just asking the question.

My reasoning is with you. It has a pulley and beefy tensioner right on there. It's meant for mini bikes. I'm pretty sure it has to handle side loads better.

[Andrew Blair]

I would agree. Side loads on that shaft with such a large spring tensioner would be very large, easily comparable to running a sprocket on it. But I'm wondering about how well all of the CIM motor's handle side loads. I know of teams that have done a sprocket drive directly off of the small CIM; with no failures, that I know of. Maybe someone from 357 can enlighten us on how their drive performed?

[Sachiel7]

Yes, for two years we ran a 4WD system with sprockets directly off the CIMs, and had No trouble at all.
In fact, in was probably one of our smoothest and most powerful drive systems over the past few years.
The way we did it - Take a 1"x5/8" shaft, lathe a 8mm hole through the core, add in some setscrew spots, and we used industrial epoxy to assist holding them onto the CIM shafts.
Most #35 sprockets run with a 5/8" shaft + keyway.
The systems we've built have worked fine. I'm not entirely sure what the fuss is all about...

[Tristan Lall]

I don't have one in front of me, but doesn't the large CIM have a roller bearing where the small CIM has only a bushing? That would significantly improve its resistance to side loading.

[s_forbes]

Originally Posted by Sachiel7

Yes, for two years we ran a 4WD system with sprockets directly off the CIMs, and had No trouble at all.
In fact, in was probably one of our smoothest and most powerful drive systems over the past few years.
The way we did it - Take a 1"x5/8" shaft, lathe a 8mm hole through the core, add in some setscrew spots, and we used industrial epoxy to assist holding them onto the CIM shafts.
Most #35 sprockets run with a 5/8" shaft + keyway.
The systems we've built have worked fine. I'm not entirely sure what the fuss is all about...

That's what I was considering doing for the large CIMs, but I didn't know if it had been done before. After hearing that it has worked for other people, maybe we should try to mount the sprocket right on the motor. It would keep things a bit more simple.

What size sprockets did you use on your motors? I am thinking I need about 15 teeth, should I use a smaller one?

[Sachiel7]

We used to use a 10 tooth #35 sprocket on the output of the CIMS going to a 45 tooth "Jack Shaft" (Reduction) which was keyed to two 10 tooth sprockets, which carried chain to the wheel sprockets.
For reference, check out my Whitepaper on our "Standard Drive" here:

http://www.chiefdelphi.com/forums/pa...le&paperid=247

edit::
I realized that these were made in the pre-Inventor days! Ah!
(well, my pre-Inventor days)
so, please bear with them, they were hand-drafted in Anim8or, but should give you an idea of how the system worked.
We used this system (With the CIMS mounted higher) in 2004, and had a really fluid drive system.
Only thing you have to keep an eye on is weight....