Grand Piano Action (3D)
About this app
A concert grand to cut open: 88 simulated actions, the key throws the hammer, the jack escapes, the hammer flies free and rebounds. Slow motion, key by hand, repetition, pedals, partials of stiff strings and stretched tuning.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
How a grand piano action works
A grand piano action is a throwing machine. Through the capstan and wippen the key raises the jack, which pushes the hammer up at the knuckle. About two millimetres before the string the jack foot meets the let-off button, the jack tips away and the hammer flies the last stretch freely. It strikes the string and rebounds at once, otherwise it would choke the vibration. The backcheck catches it, and the repetition by Sébastien Érard (patent 1821) readies it again before the key is fully up.
What the app shows
A concert grand in 3D with cast-iron frame, soundboard, overstrung strings and 88 actions, each simulated individually. “Look inside” cuts the piano open at the selected key. In slow motion, a list of stages shows what is happening, the working part lights up and a graph records key and hammer travel. Further panels show length, tension and partials of each string as well as the stretch across the whole keyboard.
Things to try
Press the key very slowly with the slider: the action escapes but the hammer does not reach the string, and there is silence. Strike the same key in slow motion and watch the hammer fly freely. Turn the repetition off and notice how far the key must now return. Move the striking point: at one eighth of the string, partial eight is missing. Listen to an octave purely calculated and stretched, and pay attention to the beats.
Frequently asked questions
- What is escapement in a piano?
- Escapement, or let-off, is the moment the jack tips out from under the knuckle, typically 1.5 to 3 millimetres before the string. From then on the hammer flies freely. Without it the hammer would stay on the string and damp it.
- Why can I not change a piano note after striking it?
- The loudness depends on the speed at which the hammer leaves the jack. After that there is no connection between key and hammer. The finger can only decide when the damper falls back.
- What does stretched tuning mean?
- Piano strings are stiff, so their partials lie slightly above whole-number multiples. To keep octaves from beating, tuners set the treble a little higher and the bass a little lower than calculated, by about 20 to 35 cents at the ends of the keyboard.
- What can I try in the Grand Piano Action app?
- You play all 88 keys, watch the strike in slow motion, press a key by hand, switch repetition and pedals, move the striking point and compare tunings. The values are typical of a concert grand.
Subject: Music (Gymnasium)
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