Let's Make Robots!

coupling

Shaft coupling from 0.125 D to 0.25 square

Hi, hoping someone can help me with what I think is a pretty basic question:

I have 2 motors with a 0.125inch keyed (or D) shaft.  I need to connect it to a 0.25" square socket (vex tank tread driver).  I assume there's some sort of coupler or adaptor that could help with this?  I've been looking for most of the afternoon and haven't found any good solutions but I imagine it's largely due to me not knowing where to look...this is my first robot so I'm a bit new to the whole connnecting a shaft thing...  many thanks for any suggestions or thoughts.

Couplings or wheel hubs for cordless drill motors

I posted some design info and pictures of a robot I'm working on to the main LMR robots listing. You can check it out here

As I indicated in the post, however, I'm having trouble coupling or interfacing some cordless drill motors (the Harbor Freight 17v kind which I have read many people use in their bots) to some 1/4" screws, which are the axels of the wheels on my robot.

tractor-trailer coupling with power transfer

This is an idea for two (or more) cooperative robots. One passive bot (with wheels, but without motors) and one active bot (with motors). The motor-bot (the tractor) would pull the lame bot (the trailer). The trailer has a power source on board. The tractor wants to recharge its battery from that source.

The big idea is so big, I won't even mention it here. Yet.