So, back to the main topic of this thread…
There have been some design iterations with regards to hand (the whole hand that is) movement and ergonomics. Historically those were documented around 180 years ago – the so called horizantal arc-shaped keyboards. There are modern vertical arc-shaped keyboards which are an abomination IMnsHO.
A designer company in USA built such arc-circular piano for some Lady GAGA show or something and they presented it on NAMM in Los Angelis about 12 years ago.
• these are the oldest ones (please, notice that they are two types):
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According to the book "The modern Piano" by L. Nalder from 1927 there are arc-pianos fith radial keys and one with key that are 'straight' but attached to a horizontal curve. I hope the difference is visible.
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I prefer the radial ones. Ergonomically it makes a lot of sence, especially if the piano has more than 70 keys and especially intended for pianos with 88+ keys.
• here is the one the guys at ArcPiano (USA) designed for Lady Gaga (the problems are self evident)
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They made it with an arc-shaped keybed, radial but messed up the widths big time (as with a typical piano)
Here is a similar one (but acoustic grand with all parallel strings, hence – exesivelly long body) built by Chris Maene (Netherlands); it alse has messed up widths despite the arc is more gentle
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Here is my solution. Only as a concept. I could not build a prototype because the price was extremely high to order such bespoke elements and parts.
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I am really fascinated by the idea of building it one day. But it will be with two manuals (each with 57 keys, where ~17 will be duplicates in the middle range, can be adjusted how many will be duplicates).
Notice those are "flat" keys. Of course I can design them as curved keys and from a design engineering point of view it is quite a intricate and very challenging task!
Oh, here are the abominations (I can not even…):
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