Dynamic Tumbling Toy

This retro-inspired toy uses a bearing and a rotating case to demonstrate physics concepts in action. Watch as the toy tumbles down a track, with the bearing moving back and forth inside the case, while the case itself spins and shifts around two pivots.

It uses a multibody system, which means it’s made up of several parts (the case, the bearing, and the track) that all move together in a complex way. This motion is controlled by four important factors. They are:

• The horizontal and vertical movements of the case (the big part of the toy) as it shifts along the track.
• The amount the case is rotating as it tumbles.
• How the bearing moves inside the case, rolling from one side to the other.

Together, these four variables help explain how the toy tumbles, rolls, and spins, making it a fun tool for learning about motion, forces, and balance.

When you set the toy on the track, the bearing starts rolling inside the case, causing the case to shift and rotate. As the case moves along the track, the bearing rolls from one end to the other. This continuous back-and-forth motion makes the case spin around its pivots, showing how different forces work together to create complex, dynamic motion. You can experiment with different angles to see how it affects the motion of the tumbler.

This model was designed to be easily printed and assembled. The only part you will need is a standard 608 bearing. Print the parts, place the bearing in the case and use a small amount of glue to glue the parts together. Be careful not to get any glue on the bearing itself or it may prevent it from rolling back and forth smoothly. Press fit or glue the two rails together and add the eyes to the bearing to give the little guy some character as he makes his way down the track. 

The drawings included above come from a research paper by Leine, Campen, and Glocker. This paper was the inspiration for this design and if you're interested in learning more about how the authors used the Newton-Euler approach to solve this system, you can find their original work in the Other Files below.