Gear reduction for small line follower

[Conscripted]

I'm working on a small line follower. My goal for the overall size is aproximately 2x3 inches or there abouts. It's a personal project so the final details won't matter that much. Anyway I've gotten most of the parts worked out. I have a pair of THESE. I need to gear them down but I'm not sure how.

I'm looking for ideas on how to gear them down without building a custom gear box.

Conscripted

[MikeK]

Do away with gear reduction and drive the wheels by contact, like this:

http://elm-chan.org/works/ltc/ltc02.jpeg
Pager motors are mounted with the shaft in contact with the rubber robot wheels.

EDIT: Image got deleted (?) so am posting the link and description.

[Conscripted]

I considered that but was a little worried about getting the pressure correct. Do you have any experience mounting tires this way? Any advice to give. Once I get this one working I'll build a smaller one using two of THESE.

Conscripted

[MikeK]

Those second motors have a much lower operating speed.  The first ones absolutely need a large ratio reduction to be usable in a line follower.  They're not going to be swapable.

The only trick to getting that technique to work is having wheels that are a little soft, about like a pencil eraser.  Put them in and give it a try!  They still might be too fast, 10,000-31,000RPM is quite high.  See what 10% duty cycle will do.

[Conscripted]

I'll play around with it for a bit and see what I come up with. I know the second set of motors are a LOT slower. They are a tiny gear motor. For that project it will be all surface mount and a tiny battery. Thanks for the help.

Conscripted

[waltr]

I've built some small Bots and used the motor shaft in contact with the wheel. You do need to adjust the contact tension but it isn't take hard to do. This method does work very well.