CIM motors

[Ether]

Originally Posted by Conor Ryan

The load that is on the shooter will likely be minimal by comparison.

I would think so.

Maybe you don't need a CIM on the shooter wheel, and you could use 2 on the climber. Has anyone tried one of the lesser motors on the shooter with successful results ?

[billbo911]

The Mini CIM looks to be close enough to the standard CIM with respect to it's specs. to be used for the shooter. Granted, you will loose some of the rotational inertia provided by the armature. But, a good control algorithm just might overcome that.

---------Free RPM---Stall Torque----Stall Cur---Free Cur-----PWR
Mini CIM---6200--------1.40Nm-------86.0A-----1.50A-----227.24W

We will be testing the Mini CIM in our shooter soon.

[Ether]

Originally Posted by billbo911

We will be testing the Min CIM in our shooter soon.

Smile.

Do you guys have a clamp-on ammeter? Could you measure the current draw for both the CIM and the mini CIM while at the desired wheel speed ?

[billbo911]

Originally Posted by Ether

Smile.

Do you guys have a clamp-on ammeter? Could you measure the current draw for both the CIM and the mini CIM while at the desired wheel speed ?

I know you've seen the video's we posted already. Did you see the server rack power supply we were using? Fortunately it has an integrated Vout meter and an Iout meter. I will see if I can get those values this evening. These will be free speed values only. I truly doubt the metering circuit can display the actual current drawn when the Frisbee passes through the shooter.
We have seen the current jump from 3A range to 10A+ and back down with the CIM and a 6in wheel, but I doubt it is accurate.

More data to follow.

[cgmv123]

Originally Posted by billbo911

The Mini CIM is looks to be close enough to the standard CIM with respect to it's specs. to be used for the shooter. Granted, you will loose some of the rotational inertia provided by the armature. But, a good control algorithm just might overcome that.

---------Free RPM---Stall Torque----Stall Cur---Free Cur-----PWR
Mini CIM---6200--------1.40Nm-------86.0A-----1.50A-----227.24W

We will be testing the Mini CIM in our shooter soon.

You have the Mini-CIM and the BAG motor confused. The BAG motor is last on the motor chart. The Mini-CIM is next to last. (The BAG Motor is the bigger of the two.) Don't fret, I mixed up the 2 at first as well.

That said, I like the BAG motor for shooting as well. You're allowed 4, so ganging 2 together comes close or even exceeds the specs of a CIM. Keep CIM's for driving and climbing.

Nevermind

[Domtech]

Originally Posted by cgmv123

You have the Mini-CIM and the BAG motor confused. The BAG motor is last on the motor chart. The Mini-CIM is next to last. (The BAG Motor is the bigger of the two.) Don't fret, I mixed up the 2 at first as well.

That said, I like the BAG motor for shooting as well. You're allowed 4, so ganging 2 together comes close or even exceeds the specs of a CIM. Keep CIM's for driving and climbing.

According to this page the BAG motor is the smaller one.

EDIT:
Also, the mini CIM is 2/3 power of a CIM at a slightly higher max rpm.
I feel they should work great for shooters.

[Jon Stratis]

Originally Posted by cgmv123

You have the Mini-CIM and the BAG motor confused. The BAG motor is last on the motor chart. The Mini-CIM is next to last. (The BAG Motor is the bigger of the two.) Don't fret, I mixed up the 2 at first as well.

That said, I like the BAG motor for shooting as well. You're allowed 4, so ganging 2 together comes close or even exceeds the specs of a CIM. Keep CIM's for driving and climbing.

Double check that...
Mini CIM: http://www.vexrobotics.com/vexpro/mo.../217-3371.html
P/N: 217-3371
Size: 2.5” [63.5 mm] diameter, 3.36” [86 mm] long
Specification

Free Speed: 6,200 rpm (+/- 10%)
Free Current: 1.5A
Maximum Power: 230 W
Stall Torque: 12.4 in-lbs [1.4 N-m]
Stall Current: 86A
Mounting Holes: (4) #10-32 tapped holes on a 2" bolt circle

BAG motor: http://www.vexrobotics.com/vexpro/mo.../217-3351.html
P/N: 217-3351
Size: 1.59” [40.4 mm] diameter, 2.72” [69 mm] long
Specification

Free Speed: 14,000 rpm (+/- 10%)
Free Current: 1.8A
Maximum Power: 147 W
Stall Torque: 3.5 in-lbs [0.4 N-m]
Stall Current: 41A
Mounting Holes: (2) M4 tapped holes on a 25mm bolt circle


The Mini-CIM is bigger and more powerful than the BAG motor, although that power comes at higher torque and less free speed.

[John]

Originally Posted by cgmv123

You have the Mini-CIM and the BAG motor confused. The BAG motor is last on the motor chart. The Mini-CIM is next to last. (The BAG Motor is the bigger of the two.) Don't fret, I mixed up the 2 at first as well.

Not according to the VEX website. BAG motor is 217-3351, miniCIM is 217-3371.

[nathan_hui]

Maybe we should just call them grandpa CIM, father CIM, and baby CIM.

[billbo911]

Originally Posted by nathan_hui

Maybe we should just call them grandpa CIM, father CIM, and baby CIM.

Ah, but don't forget the Great Grandpa "Mini bike motor" CIM from a few years back.

[Domtech]

Originally Posted by nathan_hui

Maybe we should just call them grandpa CIM, father CIM, and baby CIM.

Our team has been referring to the BAG motor as the micro-CIM

[billbo911]

As promised, here is some very raw data. This is a comparison between the CIM and Mini CIM driving the same system.

In a nut shell, the the Mini CIM draws more current at the same voltage.

[Ether]

Originally Posted by billbo911

As promised, here is some very raw data. This is a comparison between the CIM and Mini CIM driving the same system.

In a nut shell, the the Mini CIM draws more current at the same voltage.

Using the CIM's current draw (19.4 amps) at 10 volts, the CIM's speed can be estimated.

[billbo911]

Originally Posted by Ether

Using the CIM's current draw (19.4 amps) at 10 volts, the CIM's speed can be estimated.

3726 RPM at 10v. Excellent, that confirms that it is operating exactly in the range we expected it would, 2K-4K RPM. It also confirms the video was accurately representing these numbers.

[Mr V]

Based on our shooter for last season the motor power does not make a huge difference in shooting distance, it does however affect how quickly you can get the wheel back up to speed.

We initially designed our shooter for Rebound Rumble to be powered by two 775s. One night when we were at our practice location the shooter started making a funny clunking sound. We traced it down to one of the motors. Since we didn't have a spare with us and we were mainly working on our autonomous we removed the second motor. We still shot 95% or so of the distance as we could with two motors, so we stuck with the single motor.