Any grand piano, and subsequently its restoration, can be
broken down into three major areas of construction: the case,
the belly, and the action.
The rim is the curving fortress into which most of the pianos
components fit. The rim consists of the outer shell, the heavy
beams beneath, and the keybed on which the keyboard rests.
Above the rim rest the toplid and music desk; below, the legs
and pedal lyre.
In addition to providing a massive, rigid superstructure,
the case and its related furniture parts constitute the cosmetic
beauty of an instrument. Though the rim is bent of rather
drab looking hard rock maple, it is skinned with beautiful
veneer (mahogany, for instance) which receives either a transparent
natural finish or opaque black lacquer, a process referred
to as ebonization.
The belly is the vibrating system of the piano. It consists
of the spruce soundboard and maple bridges, plate (massive
gold-colored cast iron frame), strings, tuning pins and pinblock.
With the exception of the pinblock, all these components are
visible when the lid is raised. The concealed pinblock lies
beneath the plate at the front end of the piano, into which
some 230 tuning pins are anchored.
The belly maintains a critical, delicate balance between strength
and power and flexibility and freedom. The plate, rim and
pinblock manage the twenty tons of string tension, while the
bridges and soundboard transform the energy imparted to the
strings via the pianos hammers into what we appreciate
as beautiful music.
The action mechanism is a fascinating Rube Goldberg affair.
A rocking lever (the key) lifts a series of levers (collectively,
a whippen), which propels a felt-covered hammer (pivoted on
a hammer shank) towards the intended strings above. There
are 88 such mechanisms side-by-side in a piano action. In
addition, the key also lifts a felted damper head (via a damper
underlever) off its related strings so the note may sustain
at the pianists will.
Further, the pedal assembly (the lyre) houses three controls:
the left pedal for soft play (the una corda), the center pedal
for selective sustain (sostenuto), and the right pedal for
global sustain. The trapwork, situated on the underside of
the keybed, connects the motion of the three pedals to the
action mechanism above.
If a restored instrument is to perform as it did the day it
left the factory, or better, each of these elements, along
with all its numerous subassemblies and subtleties, needs
to be fully addressed in the rebuilding environment. Please
continue on to Restorations
for an outline of how each of these restoration phases is
performed in my shop.