Re: What motors do you use to drive your robot?
 

It doesn't matter what motor has more torque at 40 amps, its what motor has more power at 40 amps. You can change the torque by adjusting gear ratios, but you can't change the power.

Re: What motors do you use to drive your robot?
 

The Bosch and the Chiaphua are both excellent for driving. The versatility and relative ease of use of the Bosch drill motors for drive applications is unparalleled, and many teams use them for that very reason. They are a safe choice, and a strong choice as well. As Paul Copioli pointed out, we have found the CIMs to be very good in both directions and they are fine even after long use. They are actually usually colder on the exterior after a match than anthing else we've used in recent memory, including the drills and Fisher-Prices. For Fisher-Prices and drills (which clearly aren't meant to be used nonstop and stalling for two minutes), I highly recommend some kind of compressed air cooling spray to use between matches.

Many older teams with the means to build a gearbox do so in order to get CIMs and Bosch drills running together (i.e. four-motor drive). That way they can run at relatively high speeds while maintaining the power they need in order to hold their own. Or even have a transmission in addition to the four motors. Some teams (including 217 in 2002 and 188 for the past two years) mate three motors per gearbox for a whole lot of power. Or at least power drain; by the latter third of a match, these robots tend to be out of juice. Last year we built a simple gearbox that mated the Bosch drills, CIMs, and Fisher-Price motors so that we could run at high speeds and still outpush the vast majority of our opponents. We did have some trouble with our battery voltage dropping low enough to cut out our controller in two matches (one of which being the finals in the Canadian Regional :(), but those were very extreme circumstances.

While we have used Fisher-Price motors in our drivetrain before, we don't use them by themselves. Depending on the configuration of a robot, in some cases they won't be able to even turn it, and then you'll get the distinctive toasty Fisher smoke and smell.

Re: What motors do you use to drive your robot?
 

Team 25 used a combination of Drills and CIMs in the 2003 season, and will do so again in 2004.

Re: What motors do you use to drive your robot?
 

Team 356 used the drill motors only in years 2000, 2001, and 2002.

Team 356 used both the Chips and the Drills in our 2003 drive system. They are both excellent motors to use if you pay attention to all of the mounting and cooling quirks.

Since 2003's drill motors were so happy to have a friend (the Chips) we thought we'd add another friend for the drills and the chips this year, the Fisher Prices.

It didn't occur to me to use the Globe Motors in the drive system. Hmmm. Maybe in 2005.

Re: What motors do you use to drive your robot?
 

Team 116 has a 2-motor, 2-speed gearbox that has worked well in the past, and will hopefully continue to work well for us as we use it again this year. It combines the chipuas and drill motors and the plans are in the white pages on this site for anyone interested.

Re: What motors do you use to drive your robot?
 

Be sure to watch your current draw in designing this year then. We haven't had much trouble with six motors (I don't think we ever tripped a breaker last year for example), but that depends on many factors. A robot with too many motored devices (especially those that run constantly), too much friction in its gearboxes, or too high a gear ratio to push other robots can seriously gulp current and cause your battery to run out as well. I personally wouldn't consider using the Globes for driving; they aren't particularly powerful. The gearbox they come with is nice as it is, and increases torque to something useful for non-drive applications, but the Globes just aren't powerful or reliable enough to warrant driving with IMO. Good luck in getting six motors to work well. :)

Re: What motors do you use to drive your robot?
 

I was actually joking about using eight motors (counting the globes) in a drive system. Aside from the current draw thing, there would hardly be any motors left to do anything else or any weight allowance.

On the current draw thing, up to a point, as you add motors (especially in the drive system) there is a tendency to balance the load among the motors and run each motor at a lower current draw.

Re: What motors do you use to drive your robot?
 

Oh, I figured you meant Globes instead of F-Ps (i.e. still six-motor) actually, but eight motor has been done before, sort of.

Yeah this is supposedly the case, but I think the difference is pretty negligible.

Re: What motors do you use to drive your robot?
 

does anybody know what the max watts of a CIM motor is?

Re: What motors do you use to drive your robot?
 

~320 Watts I believe.

Re: What motors do you use to drive your robot?
 

Ok, I will let everyone in on our team secret. We use the globe motors for our drivetrain, and they work great, but you have to give them... ummmm..

special treatment!

before each match we soak them in liquid hydrogen to get their core temp down to 3°K, which is almost low enough to become superconductors

but once they start to spin, the airflow over the coils causes a windchill factor of -7°K so they superconduct - we get about 4HP out of each one, and once you apply a current to it, it keeps running (because of the supercondution) until you reverse it. Therefor they actaully consume almost no power at all.

:c)