[Andy A.]

I'll echo the comments already made.

For your application, you want a motor that is powerful, rugged, light and inexpensive. For those traits, you can't do much better then a cordless drill. A drill motor has to be strong enough to drill through metals, rugged enough to survive drops, light enough to be used by a normal human all day and cheap enough for a normal human to afford. It's a pretty good match for robots in harsh places.

Not only will the motors be powerful for the size, they come with a bullet proof gearbox attached that should put speed and torque right around where you want it. One more reduction after the gearbox should be all you need. I can't stress the importance of having a built in reduction- no motor this size is going to have a free speed under 10000 rpm, so they'll be pretty useless with out some serious reduction. Trying to build your own gearbox may be more then you want to attempt, it will certainly weigh quite a bit.

Also, consider keeping the drill casing intact and using it as a motor mount. It's been designed to perfectly hold and protect the motor and gearbox, you're unlikely to find something better.

If you think a drill motor might be to much, or otherwise no good, perhaps you could use what we in FIRST refer to as a FP motor. The Fisher Price motor is used in the little electric buggys kids can ride around in. They are actually made by a few different companies and can have slightly different specs. Most however are 12 volt motors that produce a peak of around 100 watts. Most also mate to plastic gearboxes, which provide a easy, if not terribly reliable reduction.

Any of this helping?

-Andy A.