#19 Press The Button / Sea Snake

Finger number 19 is a collaboration between Bourneville Primary School in Birmingham and Hillcrest Primary School in Norfolk with support from engineers at thr University of Cambridge.

Darcy’s design clearly shows how pressing a button causes a wheel to rotate and a lever to lift and play the piano. She’s explained this very well and even shown what materials we should use – but she forgot to show how the player actually touches the button.  So we decided to combine her design with Conor’s Sea Snake (“if you pat the head, it will move”). In fact, when the player pats the head of the sea snake, a hidden rod will move and press the button.  In turn, this makes a large gear wheel rotate by one tooth, and a “cam-follower” (a small wheel) on the other side of the wheel, then lifts the lever and pushes the piano key.  We had to think very carefully about the shape of the teeth on the gear wheel: their length was limited by how far the button can press in, while their height sets the distance the lever would move.