I'm building a 4WD robot, I've buy this encoders on ebay :
I'm asking if any member of this forum have used this enconder? I dont able to found any resource using this encoder, with the small dc motors I'm using :
I suppose the first thing is to see if the encoder wheel slips onto the axle. If not, maybe you can file it a bit and get it to fit? Or make much bigger holes and glue it to the axle?
For the reader part, well you'll have to try fashion a bracket of some kind. I see the reader has holes, so perhaps you could attach it to the end of a metal strip, with the other end mounted on the robot chassis. Then bend the strip until the "legs" of the "U" are in the right position across the encoder wheel?
All in all it's going to need a bit of imagination and experimenting....