The Rear Castor

View a close-up photo of the castor

 

Since our MicroMouse is designed in a wheelchair configuration, it needs something in the rear of the chassis to act as a balance point. Throughout our prototyping, we tried several versions of skid pads but none of these would glide well on the plywood maze As a result the mouse had a tough time making consistent 90 degree turns.

When we switched over to the castor, the difference was incredible. The mouse did not miss a single turn. Finding castor wheels this small is a challenge so ours was actually created from a pinch roller from an audio cassette mechanism (purchased through All Electronics for $3, see our links page). The castor is based on an idea presented by Peter Harrison in his web site.

 

The Rear Castor - Exploded View

1. Nut
2. Brass strip, bent into a "U" shape
3. Nylon PCB standoff, glued in place
4. Spring (also from the cassette mechanism)
5. Bolt, coated with epoxy and sanded smooth so that it doesn't hang up when sliding through the nylon standoff
6. Pinch roller from surplus cassette mechanism