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The upper part of the white key of the piano is extruded (I don't know if anyone will get my point so I'll put a picture here)? Is it just for ornamental use or does it actually have a practical utility?The part in the red circle is what I mean by extruded.

  • Ha, interesting question; welcome to Music.SE! – Richard Sep 20 '17 at 23:59
  • Note that the Hammond B3 organ and many imitators specifically do not have this overhang. But that was invented in the 20th with far more modern manufacturing practices and materials available. – Todd Wilcox Sep 21 '17 at 2:23
  • Welcome! With an interesting debutante question! – Tim Sep 21 '17 at 9:37
  • @Tim "debutante" :-) an interesting malaproprism there. – Carl Witthoft Sep 21 '17 at 11:21
  • @CarlWitthoft - it's the French in me coming out! – Tim Sep 21 '17 at 11:30
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This style of key dates back to the earliest keyboards. My guess at the reason is because they were easier to make that way.

In fact making the keyboard itself was one of the most skilled operations in hand-building early instruments. Originally, all the keys in a keyboard were cut from a single plank of wood. The reason was that any warping caused by changes in humidity would affect adjacent keys in the same way, and therefore avoid the keys binding against each other. Of course with modern kiln-dried wood and moisture-proof treatments (not to mention replacing wood with stable materials like plastic) this is no longer such a big issue.

On some instruments (particularly clavichords) the main part of the key is often dog-leg shaped rather than straight, because the spacing of the strings is different from the spacing of the playing part of the keys.

Marking out and cutting all this accurately with hand tools is not easy, and a single mistake could ruin the entire keyboard!

The tops of the playing part of the keys were often made from different material (e.g. two different colours of wood, wood and ivory, etc) and the slight "overhang" conveniently disguises any minor errors in perfectly aligning the top and the body of the keys.

If you messed up when shaping the end of a key top by hand when creating a smooth playing surface, you only have to scrap that one key-top. If you messed up shaping the end of the complete key (for example by removing too much material) you might have to scrap the entire keyboard and start again because of the warping issue described earlier.

In early instruments, the key tops for the "white" keys were often made in two parts with different widths - a narrow part fitting between the "black" keys, and a wider part for the unobstructed ends of the keys. In this case it would be easier to finish the ends of the keys to a consistent shape (avoiding any sharp edges which the player would dislike) and then adjust the "joint" between the two parts of the key top to fit together perfectly for each individual key.

See the photo "detail of boxwood and ebony keys" here, for example.

On early instruments the end of the key body was often decorated by engraving, or cutting an "arch" on the underside. On instruments with more than one keyboard, the front of the keys was often beveled at about 45 degrees so that the upper keyboard protruded over the lower one, allowing more finger-room for the player.

While there doesn't seem to be any real reason to preserve this design with modern manufacturing techniques, there is no particular reason to get rid of it either - so like the human appendix, the tradition continues in piano keyboards even if it doesn't have much functionality! The "45 degree bevel" style is reproduced in some plastic keys for one-manual synthesizers - the only obvious reason would seem to be to use a bit less plastic, cutting the cost by a few cents.

  • Excellent and informative answer. I'd add that appart from hiding any possible irregularities in the cut of the key, hiding the "join" or "seam" (I lack the proper word in English) itself, however perfect, would be according to the aesthetical principles of fine crafts (much like fine pieces of furniture). The only way to to this with an ivory "veneer" is to protude the upper surface, as a join between ivory and wood, or even two pieces of ivory, would be very hard, probably impossible to disguise. With the little extension you get the illusion of a single solid block of ivory. – José David Sep 21 '17 at 9:59
  • ▲ For lovely link – and an otherwise good answer. – PJTraill Sep 22 '17 at 13:14
  • I can think of if not a ‘reason to get rid of’ the design at least a disadvantage of it: they are more likely to be unstuck by brushing against the key from below; I’m not sure if there are any situations in playing when that may happen. I have the impression that the glue on our upright Liebmann is not very strong, but I am wary of using something stronger. – PJTraill Sep 22 '17 at 13:19

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