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Music box drum

A cardboard tube, a comb and some pins, and you have built a machine that remembers a tune. Printable wrap included.

about 30 minutes an adult pushes the pins makes a working machine

What you need

A cardboard tube
A cheap comb
Dressmaking pins or map pins
The printed wrap
Sticky tape
An adult

How to build it

Wrap the template round the tubeTape it down. The lines across are time; the rows up and down are notes.
Mark your tuneA dot wherever you want a note. Copy something simple first, three or four notes long.
Push a pin in at every dotAn adult does this. Push them in far enough to hold, sticking out a few millimetres.
Hold the comb against the pinsLine the teeth up with your five rows. Rest it firmly, do not press hard.
Turn the tube slowlyEach pin plucks a tooth as it passes. Turn at a steady speed or the tune goes wrong.
Pins are sharp and small. An adult fits them, and count them in and out so none are lost on the floor.

The template

Print this at 100 per cent, not fit to page, or the sizes will be wrong. The ruler line below tells you whether it printed correctly.

10 cmGFEDCwrap this round the tube, mark a dot where each pin goesacross is when the note plays, up and down is which note
The bar above should measure exactly 10 centimetres. If it does not, your printer has shrunk the page.

Now send something

Put the same pin in twice, side by side, and listen to the difference. Then move one pin along and hear the tune change.

Where it comes from

Switzerland, the early 1800s
A machine that remembers a tune

Watchmakers who could already make tiny precise things put pins on a drum and teeth on a comb, and built a machine that plays music without a musician. The pins are the memory. Move one and the tune changes, which makes it the same kind of object as a punched card or a piano roll.

Why it works

Where the pin sits is when the note plays; which tooth it hits is which note. Time along one direction, pitch along the other. That is a graph you can hold, and it is exactly what sheet music is.

When it goes wrong

It usually does, the first time. Almost always one of these.

Some pins do not soundThey are not standing out far enough, or the comb is not resting against them. Push them a fraction further in and hold the comb firmly.
The tune is unrecognisableTurn it steadily. A code sent through time only works if the speed is right.
The comb buzzesIt is loose. Tape it down at one end so only the teeth are free.

Where to go next

Why position is a codeBack to Make