This calendar hangs on the wall of our office for as long as I can remember. The months, weekdays and the digits of the day of the month are printed on belt which are operated by small knobs on the side. On the other side there is a pulley or roller which is mounted to a belt tensioner. One of these rollers broke its axle and I designed a new one.

Design

There are 2 versions. one is just like the original and the other one is slightly thicker in the middle to keep the belt centered.

Mechanical principle

It is counterintuitive but ir works.

Printing

A brim is mandatory with these small parts. To increase durability and printability I made the axle to be a seperate part which is glued into the pulley.