#53 Punch Tube

Abbey Junior School invented this brilliant mechanism called 'punch tube - which does exactly what it says on the tin!

Angelica’s design shows the player, Greg, sending a marble along a tube to release a plastic doll (a boxer) which lands on the right key.  When we went back to Abbey Junior to discuss this design, the pupils noticed that the marble would have to roll uphill to get to the doll. They thought of a range of solutions: we could blow the marble up the tube with a hair-dryer, or a leaf-blower, or perhaps a passing stork could pick up the marble in its beak and fly to the doll… Several of the pupils thought of a different idea, that the marble should run along a track on a see-saw. This was the solution we’ve used. To play the note, the player lifts the see-saw, so the marble runs down towards the piano and triggers a latch to release the doll. Then the player lowers the see-saw, so the marble runs back, and two metal jaws lift the doll back to the top of the latch. One important choice we had to make was about how to transport the mechanism from our lab to the performance in Birmingham. To fit into a normal van, no piece can be longer than three metres, even though the mechanism must work over a distance of about seven metres. We decided to make the see-saw in three sections, held together by nuts and bolts so it would fit.