I have begun the process of building a finger piano, which will consist of eight or more bamboo or spring-steel keys laid across a bridge and extending over a resonating chamber. The finger piano (or Mbira) has two origins: The wood-keyed piano was first used 3000 years ago in West Africa, and the metal-keyed version was developed in the Zambezi River area of Southern Africa around 1,300 years ago. The finger piano is a part of the Lamellophone family, which create sound by vibrating a series of thin plates with one attached and one free end.
The finger piano seemed to be the instrument that would require a good amount of engineering without running the risk of sounding awful.
The finger piano is a percussion instrument in that it produces sound by being struck. Within the realm of percussion instruments, the finger piano is an Idiophone, which produce sound by striking metal bars or chimes. More specifically, it is a plucked Lamellophone, which produces sound by plucking a series of keys or tines.
The initial medium for the sound waves in this type of instrument are the metal keys. The vibration originates at the free end of the key and travels through the key and into the base on which the keys are mounted.
The nodes of the finger piano (the point at which the medium is least displaced from equilibrium) is the point at which the keys meet the bridge of the piano. The vibration passes through the key as a transverse wave, and the displacement from the equilibrium decreases as the wave moves towards the bridge. Therefore, the node is at the point at which the key can move the least — the point at which the key meets the bridge, where it is held in place. The antinode (the point at which the medium is most displaced from equilibrium) is at the free end of the key, the movement of which is least restricted by the force of the bridge. In any harmonic, a node exists at the fixed end and an antinode exists at the free end.
The materials necessary for the construction of a finger piano are:
|2||Putty Knife||3.99 (each)|
|1||Wood Box/Cigar Box||1.50|
|6||Small wood screws||0.06|
|1||30 cm. of Copper Wire||0.30|
An alternative to the putty knives: 1 meter of Bamboo (Free).
A few sources that could give some direction on the project:
I am still unsure how I can build a bridge that does not damp the vibration of the keys. I also cannot clearly visualize the vibration of the keys — this is largely because I do not understand pliability. I am operating under the assumption that the maximum amplitude of the vibration occurs at the free end of the key, though I cannot explain the reasoning behind my assumption.