CIM direct drive
 

Hi,

I was wondering how I would use a CIM motor in a direct drive application to directly drive a sprocket on the CIM. The CIM is keyed, but it looks a lot smaller than i thought it would be. What size key is on the CIM, and can I buy a sprocket that is already keyed? I don't have tools to key it.

Thanks

Re: CIM direct drive
 

it's a 2mm keyway, and the only place that would sell them would be AndyMark, but im pretty sure they only sell gears with 2mm keyways and not sprockets.

Re: CIM direct drive
 

The CIM motor shaft has a 2mm keyway.

What size/material sprocket are you looking at? Unless you are using a metric sprocket, you may be a little hard pressed to find a stock imperial sprocket with a metric broach.

Edit: Cory beat me by three minutes...

Re: CIM direct drive
 

Mcmaster has a 8mm sprocket (item 2302K1). also they have 2mm keyway (item 90457A100) though the sprocket is unfinished, so youd have to either cut your own keyway into it or send it somewhere to do so. also its a metric sprocket, and I dont know how ISO and ANSI chain play together.
though if you had the abilities to cut out a keyway and bore it, you could just go with a small ANSI sprocket, and custom bore it and key it.

why would you want to direct drive it though?

Re: CIM direct drive
 

Well, I am doing this apart from my team, and dont have large funds to spend. I wanted to go with a route that didnt require me to have to purchase a transmission, but I think i may have to now.

Re: CIM direct drive
 

NOTE: I am not completely sure this will work. We did something similar and didn't notice a problem, but you never know. Maybe somebody with more knowledge can help me.

In 2006, we took an ANSI sprocket and wrapped the CIM shaft with some tin to make it close enough to the same size as the ID of the sprocket so the sprocket would spin fairly true when mounted. We then used the setscrew to hold the sprocket on. The sprocket definitely wobbled when we turned the CIM on, but the number 25 chain never fell off. So it works, but is not a very elegant solution. Thinking back on it, another way would be to take a sprocket with a smaller hole, like a 5/16" bore sprocket, and then bore it out to the size of the CIM shaft. Then, run the set screw into the keyway of the CIM. I am pretty certain that the CIM doesn't produce enough torque to make the setscrew fail. Does someone else know if that is true?

Re: CIM direct drive
 

yeah i'm not sure about this i do not see the chain taking the speed of a cim well unless you have perfect tension and even than it still may not work so well

now a belt there would would work very well here they can take that speed very well

Re: CIM direct drive
 

we had a heck of a time keeping our pinions in place this year. Due to having 2 gears on one CIM shaft we had no room to use retaining clips like we usually do and we had to rely on a setscrew to keep the gear from moving. Even with 2 set screws 90* from each other the gears would slide out and eventually maul themselves on the adjacent gear. We had to resort to green loctiting them, which didn't work well either when we didn't let it set for 24 hours.

Furthermore the only way to release the loctite is heat. I melted a bit off one of our Delrin sideplates the other day trying to break a stubborn one free.

We hate setscrews and figured this was probably one application where they might be OK. Lesson learned-never again will we rely on them.

Re: CIM direct drive
 

I dont know what you plan on using it for but my guess is that you wouldnt be able to gear the CIM motor down to a reasonable speed simply with sprockets. You can get a Toughbox from AndyMark for cheap.

Re: CIM direct drive
 

i am not sure what you really want to spin at over 5000 rpm's but I believe we did this on our poof ball shooter from AIM HIGH. It wasn't all that perfectly successful but we used a three piece jaw coupling I think.
It was some type of flexible disc coupling.

It is hard, running the CIM directly like this, to get much acceleration (read torque) ... it took awhile for our shooter to come up to speed and one of its problems was that as we shot the balls it would decrease speed and we would have to wait to come back up for proper trajectory.

If you anticipate doing a direct drive of the CIM for a wheel drive system
That would not be a good idea... I don't think that is your application though.

thanks
R

Re: CIM direct drive
 

Your best solution is to get an ANSI sprocket with roughly the right diameter hole and put a pin through the sprocket and CIM axle. This is fairly easy to do, but drilling a hole through the CIM axle can be tricky.

I would not recomend attaching sprockets, gears, whatever to the CIM with just set-screws. The CIM produces far to much torque for those methods to work.

Re: CIM direct drive
 

Sounds like a Lovejoy coupling I've used these before and they're pretty nice if you can't keep your shafts perfectly aligned.

Re: CIM direct drive
 

I think you are right Cory,
We used the aluminum one I believe ... the AL..

It was an interesting mechanism. Originally it was geared down...
When we found out it didn't have enough speed we made the change to direct drive.... and forgot that we were using an IGUS bearing on the other end of the shooter drum.... it failed.... Just like they told us it would at intermittent speeds above 2000 rpm

The IGUS engineers are really good at helping you out when you have "alternative" uses for what their parts are designed.
They are invariably correct when they tell you not to use it for that.

that makes sense... its a German company....
good engineers the Germans....

Re: CIM direct drive
 

Keep in mind that 6.35mm pitch roller chain is the same as #25. You may have an easier time finding parts with a metric bore if you use the metric number for pitch.

Re: CIM direct drive
 

Did you grind flats on the motor shafts, for the set screws to seat against?