Keyboard Consistency

Good morning everyone. I apologize for the delay in responding. Instinctively, for the Kawai KG 2, I had thought of a weight greater than 55 g, even though the ratio you refer to seems quite good to me. I only have one curiosity, which is what this value of 2.174 refers to in a practical sense.

Thank you all

Have a good day

As already stated, the value expresses the ratio between the downweight and the return weight of the key

Thank you all for the answers and sorry for the delay in returning to this topic. I believe the downweight (55/57) refers to the central area, so the low area should be around 60g and the treble area 53/55g? I don't think it is advisable to uniform the entire keyboard with the same weight. Thank you all and have a nice day

These values seem high to me regardless. However, some instruments are weighted uniformly and others are not. Even some Steinways (grand pianos) start at 51 and reach 47. All other models are weighted at about 47 grams. The Bösendorfer starts at 52g and reaches 47-48 in the treble. Now, these weightings are dictated by optimal return weights that must not fall below 20-22 gr. - 1 gr. and + any value.

Pianoaccordatore wrote:

Hello,

To ensure optimal mechanical operation (assuming that it is well regulated), the proportion ratio between the descent weight and the ascent weight of the key is expressed by the value 2.174, but, to satisfy the needs of modern schooling, this ratio can also take a value of 1.9.

For your Kawai model, the let-off distance must be 10.5 mm.

The let-off weight is 55/57 grams and the ascent weight is 20/21 grams.

Thanks a million! However, something escapes me because, if I am not mistaken, to calculate this exact proportion ratio between descent weight and ascent weight, one should perform a division between the first weight (descent) and the second (ascent), but dividing with the indicated weights (57/21) the result is not what was indicated. Could someone tell me where the error lies? I have never been a math genius.... Thanks to everyone

The indicated value is the optimal one. 2.1 is obtained, for example, with a down weight of 47 g and an up weight of 22.

I am joining this post to ask you a few things in preparation for the requests I will make to the technician during the restoration phase.

in my Petrof I found (using the coin trick) these ratios: 60 gr as down weight and 23.5 as return weight....(Petrof VI quartino)...I feel it is slow on the return...what can I do to improve it?? It seems to me that I have understood that the ratio isn't too bad. Being a Petrof, I imagine these are the original weights and that the keyboard hasn't been weighted down, but what does the slowness I perceive depend on? Maybe I am getting confused, but if the weights are fine, are the frictions also correct?

please do not laugh at my great ignorance...I am trying to make up for it thanks to Paolo's beautiful video tutorials, but I am not a good student in these matters...

...ah sorry maybe it's important....these are measurements taken in the V do...in the center I have a 65 /23,52...

To me the lowering weight seems a bit high, but I don't know the factory specifications. Have you ever changed the center pins?

Not me... I don't know what the previous owner did. ...before meeting you all, the mechanics of the pf were an absolute mystery to me... I wouldn't even dare to look inside. These pins are the ones that are under the key and provide more or less play to it, right?

No, they are the ones from the forcole.

....I'm getting lost... tonight I'm rewatching the videos and seeing how to get out of it.

as a keyboard, I don't feel it is heavy... maybe I'm used to it. Of course, if I compare it with others like Yamaha, the difference is huge. In those, I don't feel at home because I slip, I can't control them! But mine isn't as ready as I would like it to be.

anyway, I have to study quite a few things about mechanics...

Dear Nancy, the values, if properly measured, are excessive. When the mechanical friction is excessive, increase the let-off weight and decrease the repetition weight. Not all pianos have the same values. It depends on the length of the key lever. It is evident that a long action (grand piano) is easier to play; the let-off weight is low and the repetition weight is high. Aside from the values, it is important how lively the key moves, that is, what "inertia" the action has. To give an example I believe understandable to everyone, if we have a balance scale with opposing pans, let's try to put one gram on both pans. The balanced scale will oscillate with a certain ease. If we put 5 kg per side... the scale will achieve the same equilibrium, but... the oscillation will be less easy. It is said that the two weighings have different inertia. It is therefore evident that one tries not to make the keyboard too "heavy" (lead-like) precisely so as not to alter the inertia too much. In baby grands, the keys are shorter than in a grand piano and their oscillation is less easy. Forgive me for an explanation that is certainly not scientifically exhaustive, but I hope it is intuitive. Now, sometimes, the manufacturer chooses a higher let-off weight to have a good repetition weight and to avoid making the keys too heavy. The important thing is that there is proportion between the two values, as we have already stated. If the let-off weight results in being high and the repetition low... then the friction of the pins is excessive and the keyboard feels "muddy". (see my tutorials on mechanical friction and regulation)

Ok, here I am.... I understood everything. Infinite thanks to both of you for the patience... I don't feel the keyboard is muddy, but rather slightly imprecise and a little sluggish in its return, especially during fast passages. But at the moment, perhaps all these sensations are not clear because the disturbance caused by the excessively ruined timbre is too strong... anyway, I will have the weights and pins checked as well.... and it seems to me that if the technician confirms these anomalies in addition to the hammer mechanism, I will also have to review these pins and the felts... I can't wait to fix it

Today I finally found a technician who inspires confidence in me.... (after seeing three!!!)...he checked absolutely everything and you were right, it is a problem with the pins and excessive friction...the action needs to be regulated and the repetitions also need to be fixed. Regarding the hammers, contrary to what the other two had said, he said they are brand new and that pre-regulation and regulation will suffice so as not to have to replace them, thus avoiding the risk of not being able to reproduce the originals and upsetting all the balances....

Thanks to you, I understood everything he said and I was able to choose the technician with greater awareness...I hope he doesn't let me down!

Fine. Let us know.

Hello,

Regarding keyboard action, I would like to pose this question to you, even though it seems partially related to this discussion.

So, I own an old Roland digital piano (an HP1300, a bit dated) that is still working (it reproduces notes quite well), of which I have preserved the fundamental parts for generating sound, namely all the electronics, some boards necessary for essential functions, the speakers, and the keys.

Being an engineer and having a background in physics and construction, I had the brilliant idea to attempt the emulation of acoustic mechanics, in the sense of wanting to implement the escapement mechanism, respecting weights and forces similar to those found in an acoustic piano.

In my opinion, the system should essentially involve a series of simple levers that emulate the mechanism, appropriately dimensioned. The reduction is due to the lack of the string, the damper, and the hammer.
Do you think it is possible to succeed in this endeavor, or would it be better for me to set aside a budget and buy a high-quality digital piano instead?

I am fully aware that the second alternative would be the most obvious, practical, and rapid solution.

The fact is that I was given this piano, and I wanted to make use of something I already own. Therefore, the goal is a great challenge, but also a small satisfaction.

It seems like a small investment of money, even if large in terms of time.

Curious to know your opinions, best regards

There are digital pianos with grand piano action, not a simulation of levers and weights, but properly the wooden mechanics, pins, and felt.... obviously the strings are missing and the hammer strike on the string is missing, which is a fundamental aspect in the mechanical response and in the sensation the pianist feels when playing... A relationship between mechanics and sound that goes beyond simple weights and levers, which depends on the acoustics of the environment, the dwell time of the hammer on the string, how it rebounds, etc. etc... All things that a numerical system cannot manage to simulate because the (mathematical) model is truly, truly complex....

Of course you can try, but you won't invent anything new

Thank you,

well, I'm not claiming to reinvent anything; in fact, I took a look at the grand piano mechanics, trying to understand how it is made and how it works. It is already quite complex. What I want to do is reproduce that mechanism, doing without the parts that aren't needed. It won't be easy, I don't know what will come of it. We shall see. It's possible I'll rethink it and do some math, and just buy a digital piano directly