A piano’s action assembly is composed of over 5,000 moving parts that are made of wood, wool, leather, felt, and cloth – all degradable materials. This complex machine was first dreamed up 300 years ago, but at about 120 years ago, the current action style was perfected and the parts have remained fairly constant since, with small deviations in geometry.
These parts will wear with age and use. When a piano is rebuilt, the action assembly is replaced with new, matching parts that will allow the pianist to express themselves freely. The major parts of the action are the Hammer, the Hammer Shank, the Flange, and the Whippen. All of these parts can be replaced with great success.
The original action cage is cleaned and buffed. New felts and sandpaper are installed and the original keys are rebushed. The original ivories may be cleaned or simply replaced with a new acrylic top depending on preference. The leather back-checks are replaced and the hammers are hung and traveled as the entire assembly is prepared for its thorough regulation process. Special attention is placed on the geometrical design of the manufacturers original intent when choosing the new parts. Part supply houses such as Steinway in New York and Renner in Stuttgart, Germany are extremely important in filling this very specific need.
When completed, the piano will play like it did when new.
New Bass & Treble strings are installed while properly tuning the duplex ranges and muting the unvoiced sections with premium felts. The difference between a good and a great stringing of a piano is extremely significant. The overtones should be brilliant and false beats should be eradicated. The termination point of each speaking length should be precise in order for the strings to vibrate cleanly. The sustain should bloom.
To a piano technician, stringing a piano is a skill that takes many years to perfect. It only comes with continual repetition and is a talent that some technicians base their whole career on.