CIM Motor Sacrifice

I was wondering how many people are thinking of sacrificing their CIM motors to use on their ball shooter or something else and just have 2 CIM’s on the drivetrain.

Thinking about it? Definitely. Cims would be really helpful for a powerful shooting mechanism. We are of course wondering if we can run the robot over the barrier and the ramps fast enough with only two CIMS powering the wheels.

You can add an FP motors as the 3rd/4th drive motors.

Though for a shooter, is the CIM really that much better then a FP motor?

Stall Torque: 2.42 N-m, or 343.4 oz-in


Max torque (stall): 450 mNm (63.4 oz-in)

I believe quite a difference

Apples and Oranges. It’s all about power not just torque.

FP motors actually seem to be a bit better than CIMs.

In any case, using only 2 CIMs for drive will halve the power of your robot. Replacing 2 with FP motors will help, but you’ll get weird, unequal forces that are really only good for a basic 4wd robot. Using 2 FP motors for a shooter and 4 CIMs for the drive keeps the drive consistent in terms of power and allows you to use different types of drive, especially omni/mecanum, which are practically impossible if you’re using motors with different torque and speeds.

Not to be rude, but there’s some faulty logic and a heck of a false-statement if I’ve ever seen one.

Would you guys mind clarifying your choices? My team has been looking into motors to serve a pitching machine styled launch system and I was originally thinking that we would start with the motor with the highest rpm… and hadn’t even considered using Cims here. What should we be looking for in relative motor torque vs rpm? Thanks!

I’m coming from a team that has only ever used mecanum while I’ve been on it, so I’m probably exaggerating by a lot. But my omni/mecanum statement still stands.

Fair enough. I see your point now.

Back to OP, this year we are placing a BB 775 with a CIMulator gearbox in places where a CIM would be normally used.
You could do this on your drivetrain or anywhere else really. If you are going to build a ball pitcher, I would use the 775s and keep the more powerful CIMs for drive.

This is EXACTLY what I would do.:slight_smile:

If we go with the shooter, probably what we would do.
Use the FP/775 and leave the CIMS in drive.

In general I think you will see a lot of 775 based shooters. This years motor allowance gives a lot of variability of what you can and cannot do, you can go 775 cimulators for the drive or the shooter/ vice versa.

We have faaaaaaaaaaaaaar more motor power than we ever had available in the past this year. If you you can’t figure out how to use the 22 available motor to make all you mechanisms and drive work then I would love to know what you’re planning. We may not have the mini-bike motors we had during 2006 but we have far more power available with the replacements.

We might try the cimulator for launch, and then change over to an FP set once BaneBots breaks my heart all over again.

I gave my bot to you, BaneBots, and then you just short it all away? tears

Assuming the shooter in a given robot is higher than the drive train motors (likely) I think that using the 775s to shoot is a good choice because they weigh about 2lbs less than a CIM. Keeping weight low in the robot will be very important for balancing and going over the barrier.

We’re planning on having our shooter at the top of the robot, so keeping 4lbs at the bottom will help make the robot more stable while only sacrificing a little bit of shooting power.

Wait, when was it decided that 775’s are better than FP’s?

Our plan is to put 4 CIMs in the drive-train. With single motor drive and trying to balance, especially attempting to push other robots on the ramp (single person controlling the balance instead of 2 or even 3. This is accomplished by a low level of stall by the other balancing robot against your robot, and then back-driving or sliding the other robot to control the balance.) would be all but impossible without either 2 speed gearboxes or a 4 CIM drive. I would recommend the CIM SIM from andymark as an alternative power method for flywheels, belts, conveyors, and other high power systems. A pair of 500 series motors will actually perform better than a single CIM in most cases, and with the gearbox is comparable on weight. I try to avoid the RS-775, because they don’t offer the same benefit/weight as the other motors, designed properly, the fragility of some of the 500 series motors wont be a problem, and there are more gearbox options which allows for the possibility of keeping it lighter with more power.

I’ll be honest. I’m more worried about battery power droop than our motors. I believe you will see a lot of robots resetting 1.2 way through the match because they are running so many motors.

Just my 2 cents