The piano may be the best known and loved of all musical instruments. It also has the broadest range of any instrument, so music for all other instruments can be composed on it. It can be played solo, but most other instruments, including the voice, use the piano for accompaniment. Technically, the piano may also be the most complicated musical instrument with over 2,500 parts.

The piano is a stringed instrument. Its many parts are organized into five general structural and mechanical areas of either grand or vertical pianos. These are: the case of the wing-shaped grand piano (or the cabinet of the vertical or upright piano); the soundboard and the ribs and bridges that are its components; the cast iron plate; the strings; and, collectively, the keys, hammers, and piano action or mechanism. The case has many structural parts for attaching legs and tuning pins, but perhaps the rim and the keybed or shelf where the keys and piano action will be installed are most important. The soundboard amplifies the vibrations of the strings, which are transmitted through bridges.

The cast iron plate is installed over the soundboard and pinblock (part of the case), and it provides the strength to anchor the strings under tension. Nose bolts and perimeter bolts anchor the plate to the braces and inner rim of the case. The 220 to 240 strings of the piano are attached to hitch pins along the curved edge of the cast iron plate and to tuning pins across the front of the piano, roughly parallel to the keyboard. The piano action is still more complicated and includes the keys, hammers, and mechanism or action.

Names for pianos usually indicate their sizes. Grand (wing-shaped) pianos range in length from 4 ft 7 in-9 ft 6 in (1.4-2.9 m) from the front of the keyboard to end of the bend. The "baby" grand is 5 ft-S ft 2 in (1.52-1.57 m) in length; smaller grand pianos are called "apartment size." The larger sizes are the medium grand and concert grand. Modern vertical piano design has changed little since 1935. Verticals range in height from 36-52 in (91-132 cm) with small variations in width and depth. The five standard sizes from smallest to tallest are the spinet, consolette, console, studio, and professional pianos. Pianos are frequently chosen for appearance, and cabinets are available in most furniture styles and finishes.


The piano's ancestors are the first stringed instruments. Plucking, striking, and bowing of strings was known among all ancient civilizations; the harp is mentioned in the Book of Genesis in the Bible. The psaltery was an ancient box-type instrument with strings that were plucked with a pick. Keys were added to stringed instruments to make the family of instruments led by the harpsichord, but keys are used to pluck strings in the harpsichord, the most popular instrument of the seventeenth century. A parallel development was the dulcimer, another stringed box with strings that are struck. Keys and strings were paired in a striking instrument in the clavichord, which led directly to the invention of the pianoforte or fortepiano.

Bartolomeo de Francesco Cristofori made harpsichords in Padua, Italy. He is credited with having invented the piano in 1700. Cristofori's piano had hammers that struck the strings by falling by momentum, after having been moved by the action parts linking the hammers to the keys. The hammers were caught by back checks or hammer checks to keep them from bouncing up and down on the strings after the initial strike. This method allowed the strings to continue to vibrate and make sound and for them to be struck loudly or softly, unlike the harpsichord. Johann Andreas Silbermann of Strasbourg, France, continued Cristofori's interest in the pianoforte, and the instrument became popular in Germany after Frederick the Great purchased several. Johann Sebastian Bach approved of it in 1747.

The piano had replaced the harpsichord in importance by the end of the eighteenth century. Cabinetmakers built beautiful cases for them. The square piano was built mid-century, and more musicians began writing music specific to the piano, rather than borrowing harpsichord tunes. Piano building began in America in 1775, and changes to the design of the hammers and to the playing mechanism or action improved the sound and responsiveness of the instrument. Jean Henri Pape of Paris patented 137 improvements for the piano during his life (1789-1875). In England, John Broadwood developed machines to manufacture pianos and reduce their cost.

Improvements continued from 1825 to 1851 with over 1,000 patents in Europe and the United States for stronger, more deft pianos with greater control and repetitive motion. By the mid-nineteenth century, the modern piano had emerged based on the development of the cast iron plate for structural strength and cross-stringing by fanning bass strings over trebles. By 1870, Steinway & Sons had developed this fanning method called the over-strung scale, so that the strings crossed most closely in the center of the soundboard where the best sound is produced.

Advertisement for a Beckwith player piano from the 1915 Sears Roebuck catalog. (From the Collections of Henry Ford Museum & Greenfield Village.)
Advertisement for a Beckwith player piano from the 1915 Sears Roebuck catalog.
(From the Collections of Henry Ford Museum & Greenfield Village.)

In the early twentieth century, the player piano achieved great popularity, allowing people to feel artistic and produce music in their homes without having to invest endless hours in practice. The pianos, equipped with a built-in player mechanism, were activated by foot pedals or electricity and used perforated paper rolls to play a variety of music.

Manufacturers advertised their player pianos as good family entertainment and a source of cultural enrichment. An eager public responded with enthusiasm, purchasing over two million pianos by the end of the 1920s. Parents hoped that the pianos would interest their children in attaining musical skills—although they often had the opposite effect, since player pianos offered, as one manufacturer described it, "perfection without practice."

Dealers offered music rolls for a broad range of age groups, musical tastes, and interests. Young adults sang along with the latest tunes, while musical versions of nursery rhymes enchanted toddlers. Classical music enthusiasts listened to sonatas or operatic melodies. Many Greek, Italian, and Polish-Americans purchased song rolls with words printed in their native language.

Coin-operated player pianos were popular among hotel, dance hall, and restaurant owners, who purchased them to serenade customers and increase profits. Fitted with rolls that played several tunes, these pianos poured forth music at the drop of a coin. Customers glided across dance floors to waltzes and fox trots, dined in restaurants to popular melodies, or drank in speakeasies to uptempo tunes.

The enthusiasm for player pianos began to wane in the late 1920s, however, as phonographs and radio provided keen competition for leisure time and entertainment dollars.

Jeanine Head Miller

C. F. Theodore Steinway also developed the continuous bent rim for the case, which enhanced sound transmission by using the acoustic properties of long wood fibers. These improvements were adapted to all styles of pianos including grand, upright, and square pianos. By 1911, there were 301 piano builders in the United States. Production peaked in the 1920s and declined greatly because of the Great Depression in the 1930s. Today, there are approximately 15 piano manufacturers in the United States, and Japan is the world's largest producer of pianos.

The design of the piano has not changed appreciably since the late 1800s, although manufacturers may use different materials or approaches to the manufacturing process. The manufacturing process for the grand piano is described below; there are some differences in manufacturing the vertical or upright piano and in operation methods, particularly the angle at which the hammers strike the strings.

Raw Materials

Pianos are made of the finest materials, not only for appearances but for excellent sound production. The long fibers of maple wood are strong and supple for construction of the rim, but long fibers of spruce are needed for the strength of the braces. Wood is also needed for making patterns of other parts. Metal is used for a variety of parts, including the cast iron plate. Sand is needed for casting molds. The character of the sand is modified by using additives and binders such as bentonite (a type of clay) and coal dust. Molten iron for the casting is made of pig iron with some steel and scrap iron to add strength. Strings are made of high tensile steel wire that is manufactured at specialized piano string mills.


Pianos are designed by specially trained and educated engineers called scale engineers. Scale engineers choose the materials, create the designs and specifications, and develop the interactions of the parts of the piano. Perhaps the most important aspect of design relates to the structural strength of the piano. About 160-200 lb per sq in (11.2-14 kg per sq cm) of tension is exerted on each of the 220 or more strings in the piano. The piano must perform well, but it also must remain stable over time as changing conditions affect the many materials in the piano differently.

The cast iron plate must support the tension of the stringing scale, covering the sound-board very little; it must have maximum mass for strength, but minimum mass for sound quality. Its shape is unique to the design of the piano because it conforms to the string layout, the placement of the bridges on the soundboard, and the paths of the strings. Because the material is brittle, it must be supported in places where the strings apply tension. Holes are designed in the curved side to prevent the plate from cracking due to thermal stress after it is poured and cooled, and this design allows sound to rise from the soundboard too. The scale engineer first sketches a proposed plate, draws it to scale, and makes a wood pattern; this design is later used for manufacture.

The Manufacturing

Bending the rim of the case

Making the structural components

Creating the soundboard

Stringing and tuning

Constructing the keyboard and action

Quality Control

Pianos would not exist without quality control in all aspects of production because the instruments are too sensitive and dependent on the interaction of many parts and materials. For example, quality begins with the scale engineer's design. Metallurgists check the metal content of the iron plate; chemical analyses are made of the other contents, including carbon, sulfur, phosphorus, and manganese. Temperature is also critical; the molten iron is 2,750°F (1,510°C), and founding or hardening temperatures are also carefully monitored. String is similarly controlled and tested during manufacture for elasticity, resiliency, and tensile strength.

The Future

The process of piano manufacturing has remained essentially the same for a century, but scale engineers are always seeking new methods. Vacuum casting has recently been used to produce cast iron plates with smooth finishes requiring no grinding.

Where to Learn More


Ardley, Neil. Music: An Illustrated Encyclopedia. Facts On File., Inc., 1986.

Bielefeldt, Catherine C.; Weil, Alfred R., ed. The Wonders of the Piano: The Anatomy of the Instrument. Belwin-Mills Publishing Corp., 1984.

Dolge, Alfred. Pianos and their Makers: A Comprehensive History of the Development of the Piano. Dover Publications, Inc., 1972.

Ehrlich, Cyril. The Piano: A History. Clarendon Press, 1990.

Ford, Charles, ed. Making Musical Instruments: Strings and Keyboard. Pantheon Books, 1979.

Gillian S. Holmes

Also read article about Piano from Wikipedia

User Contributions:

John Bartlett
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Jul 23, 2015 @ 9:09 am
Should I have any concerns:
Does any piano cast iron plates to your knowledge have any lead in them?
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Jul 26, 2015 @ 4:16 pm
To my calculation, a No, 19 wire (1,075mm dia), with a (high) stress of 900 Newton, needs a length of only 6,5 meters for 27.5 Hz, not nine.
And I would say SOLIDIFICATION temperature instead of hardening. Hardening is something completely else, namely making a material harder.

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