pic: Low Profile Gearbox Front View

[mman1506]

Originally Posted by JesseK

Under what conditions would one "lose a CIM"? In 10 seasons I have yet to experience a bad CIM or see one in person.

We managed to damage all 6 CIMs in our drivetrain at Waterloo last year. We were having issues with popping breakers, inconsistent performance and the CIMs getting very hot very quickly. When we removed each CIM from the gearbox we found their no load current was 7-10 amps versus 2-3 amps a stock CIM would have. Replacing all our CIMs fixed our issues.

[Lil' Lavery]

Originally Posted by Chris is me

Are you using an odd size of retaining ring? I've never had this problem before with the ring catching on other gears, but maybe I've just been lucky.

It always happens to us. We can usually get it far enough out to wiggle it around the other gear, though.

[asid61]

Originally Posted by JesseK

Under what conditions would one "lose a CIM"? In 10 seasons I have yet to experience a bad CIM or see one in person.

I have right now no less than four cims sitting my garage. I took them home because they were burning up and were no longer used on the team.
Some grease on the insides brought them back to life, but it is possible if they heat up too much.

[JorgeReyes]

Originally Posted by Lil' Lavery

It always happens to us. We can usually get it far enough out to wiggle it around the other gear, though.

Even though it is a lot harder to switch out cims, I'm still think I'm going to keep the cims where they are because chances are we won't burn a motor. As far as the cim pinions go, its doesn't require the gearbox take apart because I could just take it out and change it.

One thing that does concern me though is the ease of changing belts if they snap.

[asid61]

Originally Posted by JorgeReyes

Even though it is a lot harder to switch out cims, I'm still think I'm going to keep the cims where they are because chances are we won't burn a motor.

You have essentially guaranteed that you will now lose all of your cims during elims due to Murphy's Law.
But seriously, is it that hard to just add one more non-cim standoff? Two standoffs can hold your box together when swapping cims. In that situation, having through bolts to your cims is wise because it becomes easy to remove and add cims.

What precautions are you going to take to ensure that your 6 CIM drive doesn't completely die when it goes under 7 volts of battery during a pushing match or high acceleration and the PWMs cut out due to the new control system?

[Arpan]

Originally Posted by Andrew Lawrence

What precautions are you going to take to ensure that your 6 CIM drive doesn't completely die when it goes under 7 volts of battery during a pushing match or high acceleration and the PWMs cut out due to the new control system?

I'd guess that implementing low-voltage protection in code by either auto-downshifting at low speeds or decreasing pwm power as voltage approaches 7 would keep this from happening.

Still waiting on 234's full report to make a call on it.

[JorgeReyes]

Yeah I think we are going to make an automatic downshifting program but we will do more testing to see what works and what doesn't. Possibly a shift light on the driver station to know when to shift.

[JesseK]

Originally Posted by asid61

You have essentially guaranteed that you will now lose all of your cims during elims due to Murphy's Law.
But seriously, is it that hard to just add one more non-cim standoff? Two standoffs can hold your box together when swapping cims. In that situation, having through bolts to your cims is wise because it becomes easy to remove and add cims.

Sure, it isn't "hard". But why add any extra complexity to deal with a very rare case? Sure, you have a box of dead CIMs - but would the average 6-CIM team also have as many? Why not deal with it by ensuring less stress on the CIMs to begin with, which reduces complexity and increases reliability?

[JorgeReyes]

Does anyone know if its possible to use this with the WCP gearbox bearing block ( which is currently shown on this gearbox) and using Versablocks on the sides. In the versa blocks, the 1/8" drop is created by flipping the block around.

http://content.vexrobotics.com/vexpr...40122-Rev2.PDF

Based of the drawing, I am thinking I could make the center of the gearbox bearing block .940" from the bottom of the 2in tube and then use versablocks on the sides. Would this work?

[Thad House]

Originally Posted by JorgeReyes

Does anyone know if its possible to use this with the WCP gearbox bearing block ( which is currently shown on this gearbox) and using Versablocks on the sides. In the versa blocks, the 1/8" drop is created by flipping the block around.

http://content.vexrobotics.com/vexpr...40122-Rev2.PDF

Based of the drawing, I am thinking I could make the center of the gearbox bearing block .940" from the bottom of the 2in tube and then use versablocks on the sides. Would this work?

Yeah that would work I'm sure.

[Oblarg]

Originally Posted by Lil' Lavery

It always happens to us. We can usually get it far enough out to wiggle it around the other gear, though.

Same here. It always catches, but I've never not been able to remove a CIM because of it.

[asid61]

Originally Posted by JesseK

Sure, it isn't "hard". But why add any extra complexity to deal with a very rare case? Sure, you have a box of dead CIMs - but would the average 6-CIM team also have as many? Why not deal with it by ensuring less stress on the CIMs to begin with, which reduces complexity and increases reliability?

Well, it isn't hard to add another standoff. You only need one more. It's a total of 0.05lbs on the robot extra. "Why not" is the question here.
It's good to ensure the safety of the cims OC, I'm just saying that's it's good to plan for the worst case. You can still plan for reliability and add a standoff to the gearbox too. Do both.