Most acoustic pianos have a flat wooden section immediately to the left of the lowest key, and a matching one at the right-hand end. It is a noticeable piece of the instrument and I have never seen it explained.
It looks like an obvious place to rest a cup, which I assume is exactly what it is not for.
What is it called and what does it actually do?
There is a playing reason as well, which is easy to appreciate once you have needed it.
The key block sets the space around the outermost keys. Without it — with the case wall coming straight down beside the lowest key — your hand hits the side of the instrument when you play the bottom of the keyboard with any force or with the hand angled. On a piece that lives down there, that matters.
The height of the blocks is also part of the geometry. They are typically level with or slightly above the white keys, so they do not obstruct the hand travelling along the keyboard, and on many instruments the upper surface is where the fallboard rests when closed.
So: structural first, ergonomic second, and it is doing both jobs at once.
On the cup of tea: please do not, and the reason is worse than sticky keys.
The key block is directly above the key frame and the action. A spill there does not sit on the surface — it runs down into the mechanism, into felt and cloth and wooden parts that swell. Technicians will tell you that liquid in the action is one of the more expensive accidents an instrument can suffer.
A piano is one of the few pieces of furniture where the flat surface is genuinely not a surface.
One historical note that explains why they are as prominent as they are on grands: they relate to how the strings are laid out.
Modern pianos use overstringing, where the bass strings cross diagonally over the others to get more length into the case. That arrangement puts the frame and the plate in particular positions, and the key blocks sit in the space that arrangement leaves at each end of the keyboard.
On older instruments with straight stringing the proportions are noticeably different. If you look at a square piano or an early upright the blocks are there and much narrower, which is a nice illustration of a part whose size is set by something happening entirely elsewhere in the instrument.
@tuner_tessa · 3d ago
It is called the key block, and its primary job is structural: it holds the key frame in position.
The keys sit on a frame that has to stay precisely located relative to the action and the strings. A shift of a millimetre or two puts keys out of alignment with the hammers. The blocks at each end clamp the frame laterally and are usually screwed down through to the key bed. On most instruments they can be removed, which is the first step in getting the action out for servicing — so if you have ever watched a technician start work, that is the piece they take off first.
The reason the case side cannot simply do that job is that the frame needs to be removable and adjustable. A fixed case wall would mean dismantling the instrument to service the action.
Reply
Report