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Comment by jacquesm | Hacker News Reader

Piano keys are weighted, this is to standardize as much as possible the downward force required to produce a sound. The lower keys are typically weighted heavier. You can have light grands and heavy uprights, it all depends on regulation and construction details but typically not all that much on the hammers, though the big factor is that the gravity assist allows for faster repetitation (as well as the double escapement, but that is because it can catch the key closer to the string so the next (and further) stroke requires far less movement and time).

https://www.youtube.com/watch?v=mq2pb1u0HIE

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I don't understand what you mean by the possibility of making a 'light grand'. Surely no amount of weighting can get around the fact that it is harder to lift a object up against gravity than it is to move it sideways, all else being equal. As such, I would expect a grand to require more force than an upright of comparable quality and leverage. Please could you elaborate on this?

The latter half of your comment I would agree with entirely; I would enumerate the factors like this:

1. The hammer falls down to its resting position with grands. This allows it to return to its resting position faster, at the expense of greater force required to move the hammer.

2. The double-escapement action of grands allows the hammers to strike again without the key having been fully released. This increases the maximum rate at which the same note can be played in succession, but again at the expense of greater force required because of the lack of leverage when not using the whole distance of the action.

3. Double-escapement mechanisms can be found on uprights, but these are different from the traditional grand action and are exceedingly rare. (From a cursory search online, the only such upright I can find currently for sale is the Bechstein Concert 8.)

At the back of the keys in a piano (and in a grand) there are lead weights that determine how much will be added to the weight of the hammer.

These are usually recessed in a hole in the side of the key.

Typically you'll be around 50 grams, no matter whether upright or grand. But the action is substantially different in construction and that can have all kinds of effects on key response once it is moving. You can test this for yourself with some reference weights.

A '60' would be on the heavy side, a 40 or even lower would feel very light.

Black keys tend to be a bit lighter (and are differently positioned on the cantilever) due to their shorter length of travel so it all works out roughly the same in the end. Treble keys tend to be weighted slightly lighter than bass keys.

I don't have an action in pieces right now so I can't make a picture of what the side of a key looks like, but I'll see if I can't find one online.

Thank you for explaining. So what I think you are saying is that you can make a grand feel as light as a typical upright because the weights typically added to pianos outweigh the inherent weight of the hammers that the grand would add to the action, giving plenty of leeway to adjust the action.

Exactly. The weights (different for each key) plus the total mass of the action (also different for each key) then shows up as inertia as you try to move the key (and you will need some force to overcome any friction) and I think that is where you will find your real difference.

Edit: so, I've found an image:

https://creativemarket.com/product/15418366-White-wooden-key....

If you look at the sides of the key you see two gray circles, those are lead weights, and they, more than anything determine the balance and weight of the key. Note that there also is a weight on the near side of the key! The weights on bass keys will be a bit larger at the back than for the treble side, and the hammers are also a bit heavier. You can still tune a lot in the action, but another major factor is simply friction. If there is lots of play in the pin that the key rides on it can make the action feel 'loose' all the way to unplayable (because the key will rub the keys next to it), and if it rides too tight (or has been twisted out of true) it will work so hard against the felt that you need a lot of force to overcome the friction. This all shows up as perceived weight, but it really isn't. It's just friction.

Piano actions are fascinating, apparently simple but they are really small works of art for each and every key. All the parts have to work 'just so' and they then still have to be regulated to get a really even action. One really nasty little thing that can happen is that the pins in the various action bits are corroded, this can cause lots of friction in ways that can be hard to track down to any specific linkage.

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