Piano Action Adjustments and Voicing

Whereas tuning a piano adjusts the pitches of the piano strings, voicing a piano adjusts its tone. The piano can sound "bright" or "mellow", powerful or quiet.  Some degree of tone regulating  is usually desirable at each tuning session.  For a piano to sound good and play properly, the mechanical parts must be maintained to a high degree of fine adjustment.  Wear and tear on cloth bushings, leather pads and felt piano hammers, as well as changes in the moisture content of the wooden piano action parts, can alter the geometry and tightness tolerances away from the design specifications of your piano action.

The following three pictures are intended to illustrate why minute changes, multiplied by several action parts, can affect the overall performance, or "feel" of the keys of your piano.

 

How the Piano Action Works

This cutaway view of the piano action shows one key and its movement.  When the front of the key (1) is pressed down, the back comes up.  It raises the underlever (2) which lifts the damper (3) off the string (4).  At the same time, the capstan screw (5) pushes the whippen (6) up, which in turn flips the hammer (7) so it strikes the string. The unnumbered parts between (6) and (10) make up the escapement mechanism, virtually unchanged since the pianos invention over 300 years ago, that allows quick repetition and the ability to play loud and soft.

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