What you’ll need
- A cardboard box (the size of a shoe box)
- 50 cm of sturdy wire (approx. 2 mm thick)
- 1 wooden skewer (approx. 20 to 25 cm)
- 1 cork stopper
- Colored paper, colored pens and other decorations
- A ruler
- An awl
- Quick-drying glue
- A sharp knife
- A cutting board
- End-cutting pliers and flat-nose pliers for cutting and bending the wire
- Topsy figure: download here to print and cut out
Note: Let an adult help you with all the steps that require a sharp or pointed tool!
How to do it
Via the wire the rotation of the crank makes the wooden skewer go up and down.
What's the secret?
A crank drive is not just a bit of fun. Before the invention of motors, water wheels were used to drive machines, for example. Of course the mechanisms they needed were more complicated than this one, but they used the same principle of rotation. You can imagine how the rotation of a water wheel would have been able to move a saw up and down, for example.
In the case of an internal combustion engine, it is the other way around – the recurring small “explosions” during fuel combustion cause a piston to move up and down. This movement is transformed via a crank drive into a rotation that drives the wheels.