Anatomy of a Virginal: The Keyboard

The keyboard of a virginal or harpsichord is independent of the case. The two components are constructed separately and only brought together fairly late in the building process.

To make the keys, or key levers, planks of softwood (basswood is typically used for its lightness and strength, although the choice of wood apparently is not critical) are glued together into a single large board and planed flat. In a small workshop, a template showing all the keys is drawn onto this board and then each key is sawn out by hand or with a bandsaw. In a large production facility, such as a piano factory, specialized gang bandsaws are set up to saw all the keys in one go.

Did you ever look really closely at a keyboard? The geometry is not trivial. The tails of the keys are evenly spaced, twelve to each octave (since there are twelve half-steps in each octave). But in the front, there are seven evenly spaced naturals per octave, with the sharps recessed behind the natural key heads. So each natural key head must be 12/7 of a half-step wide, and everything has to come out even from one octave to the next.

Once fabricated, the keys are placed on a keyboard frame to hold them in position. Smooth iron balance pins are sunk into the balance rail, and provide a pivot for the keys to rock forward and backward on when depressed. The front rail limits how far down the keys can move (this measurement is called key dip), and the back rail supports the backs of the keys when they are at rest.



To obtain the smooth rocking motion of the keys, a small hole, just large enough to fit over the balance pins, is drilled though each key from top to bottom. On the bottom of the key, this hole is left at this size so the the entire key does not slip back and forth, but from the top of the key, the hole is enlarged to permit the balance pin to move freely from front to back as the key pivots. Once cut, it is necessary to use a spare balance pin to burnish the holes in order to achieve a smooth action.



At the back of the keyboard frame is the rack, also called the diapason. This rack consists of a thin hardwood veneer with narrow slots sawn into it, twelve to the octave. Small iron pins are inserted into the ends of each key, and the pins ride up and down in the rack, limiting the side-to-side movement of the keys so that they do not rub against each other when played.

To see some construction photos of a single-manual harpsichord keyboard, visit this site. Be sure to follow the links at the bottom of each post to see the complete process.