Building a Free-Reed Accordion — Bellows, Reeds and Buttons

An accordion is a bellows with metal reeds. Squeeze or pull the bellows and air is forced past thin metal tongues, each of which flutters and sings. Buttons open the path to different reeds so you choose the notes — and the instrument carries its own wind, so it never needs a breath.

For each note, cut a matching slot in a small metal plate and rivet a thin springy tongue over it, sized so the tongue swings freely DOWN THROUGH the slot with only a hair's gap. This 'free reed' — a tongue that passes through its frame — is the whole secret. Longer tongues sound lower.

Tune each tongue by filing: scrape the TIP thinner to raise its pitch, or scrape near the RIVETED base to lower it — exactly how an mbira key is tuned. Make one reed for pushing air and one for pulling on each note if you want it to sound both ways.

Mount the reed plates over air channels in a wooden block. Glue a small leather flap (a valve) over the idle reed of each pair, so air only ever drives the reed meant to sound and does not waste out through its partner.

Build a small box at each end. Over each reed sits a hole kept shut by a leather-faced pad; a button on a lever lifts the pad to let air reach that reed. Fit a row of buttons on one end, the bass end on the other.

Between the two ends build a pleated bellows — stiff card folded into a concertina zig-zag, its corners sealed with leather so it is airtight. Screw and glue the bellows to both end boxes. This is the lung that supplies the wind.

Hold an end in each hand, press buttons, and pump the bellows in and out. Every push and pull drives air past the open reeds and they sing. Keep the bellows moving — steady air gives a steady tone; pumping harder makes it louder.

The accordion runs on the FREE reed: a thin metal tongue fixed at one end and free at the other, mounted over a slot it can swing right through. Push air at it and the tongue is bent into the slot, springs back past it, is pushed in again — flapping back and forth many times a second and chopping the airflow into a buzzing note. Its pitch is set purely by the tongue itself — its length, thickness and stiffness — NOT by any pipe or air column, which is why an accordion needs no long tubes and can pack a whole orchestra of notes into a small box, and why you tune it by filing the tongue (tip thinner = higher, base thinner = lower) just like an mbira key. This is the exact same free reed as the Chinese sheng and the Lao khaen — and that is no coincidence: the free reed reached Europe from China around 1800, and within a couple of decades makers in Berlin and Vienna had wrapped it in a bellows to create the accordion, concertina and harmonica. The accordion's own invention is the BELLOWS as a built-in, tireless wind supply: where the sheng and khaen need the player's lungs and the pipe organ needs a pump, the accordion's pleated bellows lets the player push OR pull air at will, so (with a reed for each direction) the sound never stops for a breath. Add leather valves so air only drives the intended reed, and pad-and-button levers to choose notes, and you have a portable, self-powered reed organ — the instrument that carried folk and dance music across nineteenth-century Europe and the Americas.