6 CIMs and 4 MiniCIMs - Will they stay?

[cgmv123]

I only see the extra motors staying if the available power increases (bigger battery/main breaker).

[EricH]

Originally Posted by ttldomination

I'm not sure about this, but there was a discussion and quite a few teams came out in support of this. I think the argument was along the lines of, "they end up doing more work than stalling so it's fine." I don't quite remember.

I know of a couple of very, very good teams that did FP+2 CIMs in the drive for one year and then swore never to do it again. Something about having to replace the FPs--I know one of those teams had to do it on Thursday at a regional and it was a long job, or something like that.

[theawesome1730]

We used all 6 CIMs and all 4 Minis and absolutely loved it. I really hope they continue the use of all 4 Minis even if they drop back to 4 CIMs

[coalhot]

I like the idea of 6 CIMS and 4 MiniCims. However, if FIRST does decide to stay with them, I'd like to see them ramp up the battery size and PDB.

Maybe they'll do that with the new control system. Who knows?

[MichaelBick]

Originally Posted by EricH

I know of a couple of very, very good teams that did FP+2 CIMs in the drive for one year and then swore never to do it again. Something about having to replace the FPs--I know one of those teams had to do it on Thursday at a regional and it was a long job, or something like that.

I know 254 and 968 did it 2008 and had problems. We used 550s this year and ran into no problems whatsoever.

Also anyone doing a 6 motor drive needs to make sure they have a traction limited gear

[Zebra_Fact_Man]

I sure hope so.

[cbale2000]

Originally Posted by DampRobot

...6-CIM drivetrains can break the main 120 amp breaker if they are stalled...

Does anyone know of an instance where this has EVER happened on a FIRST robot?

[AlexH]

Originally Posted by DampRobot

Let me just say this: 6-CIM drivetrains can break the main 120 amp breaker if they are stalled. With a 6-CIM drive, you're essentially giving good defenders a way literally shut your robot down.

you just gear to break traction before you trip the breaker.

[DampRobot]

Originally Posted by cbale2000

Does anyone know of an instance where this has EVER happened on a FIRST robot?

Yes. 766 shut down 971 in this way at a match at SVR, and we won the match because of it. I have also heard anecdotal evidence of 254 having similar problems.

Originally Posted by DampRobot

Yes. 766 shut down 971 in this way at a match at SVR, and we won the match because of it. I have also heard anecdotal evidence of 254 having similar problems.

Maybe someone from 971 can answer this, but what gear were they in (and what speed)? Do you have video of the match?

[DampRobot]

Originally Posted by Andrew Lawrence

Maybe someone from 971 can answer this, but what gear were they in (and what speed)? Do you have video of the match?

I believe its on TBA. It might have been match 50.

[MichaelBick]

Remember 971 also has 2" wide wheels which give them a ton more traction. I have a hard time believing that they are not traction limited in low gear, but is it possible that in high gear they blow faster because of this?

[Mark Sheridan]

Originally Posted by DampRobot

Yes. 766 shut down 971 in this way at a match at SVR, and we won the match because of it. I have also heard anecdotal evidence of 254 having similar problems.

I should know 766 drivetrain since 3309 is running their drivetrain. We are running pretty much the same gear reduction as 254 except with just 4 motors. however we would be more likely to trip the breakers. A big difference was we chose not to groove the colson wheels knowing our gear ratios in both gears were too high to permit that. If we ran 254's wheels, we would have breaker issues big time. We managed our traction and were safe to prevent breaker trips. 3309 tested this ourselves by doing a simulate push test, the wheels always spun in low gear, we could never trip the breaker.

We gotta credit 766's old mentor Scott Baron for teaching us this back in 2005.

[Mark Sheridan]

Originally Posted by cbale2000

Does anyone know of an instance where this has EVER happened on a FIRST robot?

Yeah i did this in 2003. Long wheel base 4 wheel drive with 2 inch wide wheels w/ conveyor tread on them. It was two CIMs and 2 drill motors. Couldn't turn and would pop the breaker from the stall. Would up changing to low traction wheels.

[Cory]

Originally Posted by MICHAELABICK

I know 254 and 968 did it 2008 and had problems. We used 550s this year and ran into no problems whatsoever.

Also anyone doing a 6 motor drive needs to make sure they have a traction limited gear

We ran 2 CIM's and 2 FP's in 2006. These were the super awesome 300W FP's that were only rated for 6V, IIRC.

It was a nightmare. We smoked too many motors to count and our drive was unreliable at the worst possible times as a result. We did indeed swear we would never use only 2 CIM's in a drive again (Lunacy notwithstanding).