Re: Big CIM Impressions
 

Thanks for your concern; your words are good for all to hear.


By "getting close" I meant after kickoff.


I would also bet you a lot of money that Andy wouldn’t be making those fancy new wheels if he didn’t know some inside info.. :wink :wink

Re: Big CIM Impressions
 

I don't think any member of FIRST with inside information would use it to their, or anyone's advantage; Atleast I hope not.

Dave is on team 116, but I doubt he lets them know the game before kickoff.

Re: Big CIM Impressions
 

Wheels have been allowed from any source for quite some time now. While it's not a sure bet, it's a pretty good possibility that this rule will remain the same.

Re: Big CIM Impressions
 

I don't know the game. We are only supplying these wheels because the demand is there (teams are showing much interest).
AB

Re: Big CIM Impressions
 

As always, those are very wise words from Dave. Teams tend to forget that FIRST is a non-profit organization and has to rely heavily on donations from private industry. Most of the motors in the KoP are donated and thus subject to change from year to year. All those window motors, seat motors, van-door motors, and Globe motors are donations from our friends in Detroit. The FP motors are for those FP kids cars. All of these donations were probably because of production changes or overruns. I doubt very much that anyone in Detroit said let's make a few thousand extra motors for FIRST. AFAIK, the only motor made specifically for FIRST is the small CIM. Now this in no way guarantees it to stay the same from year to year since even it has changed some over the years. It may not even be in the kit at all. I would bet that the same is true with the big CIM motor and that some manufacturer ordered a bunch of those big CIM motors for a scooter product and then either canceled the order or changed the specs after CIM made a bunch of them so FIRST somehow got them. I wouldn't be surprised at all if they weren't in the KoP at all this year. One way (in addition to changing the rules) FIRST has of keeping us on our toes is to change the contents of the KoP each year. That IS THE challenge. Give us a pile of stuff, a task, and some rules and see what we can do with it in 6 weeks. Personally, I can't wait to see what new surprises they have in store for us on January 6th.

Re: Big CIM Impressions
 

I never intended to suggest that Andy would cheat or use any information to his advantage. It was just a poorly executed joke.

Andy is one of my FIRST heroes and it is always a pleasure to work with him and his company.


Dave I don’t know…….







See that was a bad joke too..

Re: Big CIM Impressions
 

Dave Lavery is on the game design committee. He DOES know the game and the rules. He also happens to be a mentor for team #116.

Re: Big CIM Impressions
 

I think my sense of humor is not working well in here today.

Re: Big CIM Impressions
 

I understand the importance of discussing COTS parts, vendors, and the like. However, please start a new thread and discuss it there.

Could we please get back to answering my initial question, and post your experiences with the Big CIM in a drivetrain application, using the kit gearbox in parallel with a small CIM.

Thank you,

BEN

Re: Big CIM Impressions
 

Thank you Ben. Getting back on topic my team 1251 used the big cims last year along with one small cim per side in a two speed custom mesh shifting setup. I can tell you they have some nice torque and we were able to push around most robots with two small cims. We did notice with them in this application that they like battery power and drain the 12 volt quite quickly especially in a shoving match. I can tell you that probablly 70 percent of the time during matches we were running them above there peak power that the motor curve shows for them not sure what that is right now but ya our robot was primarily defensive last year so we ran them pretty good. I definitely think there worth investing in the drivetrain considering the array of motors you still have left for everything else. We thought about 3 cims last year but didn't see the advantange in it considering last years game. Finally, I can say that our team came out with positive impressions of the big CIM, so much so that plans are to use them in our transmission again.

My two cents,
Drew

Re: Big CIM Impressions
 

I want someone to clarify something for me.

The specs that FIRST gave in 2006 were:

Stall Torque:

Small CIM 343.4 oz-in
Big CIM 570 oz-in

So how come most people are saying you get more torque using small CIMs? What am I missing? Please explain this to me as I have always used the stall torque to determine how much total torque the gearboxes have.

Re: Big CIM Impressions
 

The big CIM is about half the speed of the small CIM, when those numbers are calculated. If you gear the small CIM such that its running at the same speed as the big CIM, then you'll get a much higher torque than 343.4 (maybe 725 oz-in?). The big CIM has less power.

Re: Big CIM Impressions
 

We did use the big cim with the small cim motors together on the kit
gearbox, it worked good. We had very good power and speed.
our biggest problem was in justiyfing the extra weight at around 5 lbs each.
I belive we used the free speed for the gear ratio.

Tim

Re: Big CIM Impressions
 

From what I could tell from our roller application, and the general feel of the motor, it is well suited to a drive train application where there are many stops, starts, and near stall points of operation. It's high mass allows it to handle more heat caused by stall than any of our other motors, and as such, will provide a very good life.

However, it also has a lower mass-power ratio, which is typically very important, but this issue is something that must be weighed by teams. Generally speaking, FIRST robots have far more power available than they can actually apply to the floor, so the small power reduction is not all that important.

Though we have not used them for drive train applications, with the exception of their weight, I would feel very confident using them on the drive train. It also frees up a more standard motor for other applications!

Re: Big CIM Impressions
 

For what it is worth, we used the Big CIMs for our 2006 drive and we were very disappointed with the power. The lighter Fisher Price/Mabuchi motors with a well chosen gear down seem more than adequate for non drive applications. Given the same motors we would put 4 small CIMs in the drive.