#15 Stretchelator

Note number 15 is played by this invention from Abbey Junior School with support from the University of Cambridge. They have created and built this giant hand which extends using this pantograph mechanism, which works like an accordian.

Niamh’s design shows a beautifully decorated hand mounted on jack scissors. These are the set of connected levers that you sometimes see on cork-screws or on lifting platforms used by builders and decorators. We wanted the hand to move the whole distance from the player to the keyboard – because this will look so exciting – but as it’s over six metres, we need to use a lot of levers. To make them strong enough but not too heavy, they’re cut from aluminium and to make it easy to play, we’ve made all the joints with small bearings. However, the real challenge in building the Strechanator is to make sure the rails stay exactly the right distance apart. The two rails have to be mounted separately so the hand can move along, but all the bearings tend to push the rails apart.  While we were building them, we realised that we needed extra stiffening to keep the rails exactly where we wanted them.