Hello, this is my first time writing and I would first like to congratulate you on your beautiful and useful initiative.
I would like to ask if it is possible to calculate the key return weight with the classic "key weight" (the 60 gr. one) and what the ratio between down weight and return weight should be.
we have already covered this topic in the "friction" video tutorial, if memory serves me correctly.
While the downward weight is checked by placing weights on the key at rest and increasing them until the key begins to depress, for the return weight, the key is pressed and weights are placed on it, scaling them down until the key tends to return to its resting position.
It is all explained by Paolo in the video tutorial at this address in lesson 3.
The key return weight is very important. It makes us feel secure and guarantees the "mechanical repetition". As Casella says, the fingers adhere to the keys like car tires on a highway, and when the return weight is poor, this "grip" is lost. In almost all pianos, we should be around 20 grams. When the return weight is low and the let-off weight is high, we are dealing with excessive friction (See lesson 3). If the let-off weight is low and the return weight is low... perhaps we are dealing with incorrect keyboard "weighting". Inertia is important. The masses or rather the weights, even if well balanced, must not be excessive.
the downweight of the key is measured starting from the key at rest (as TheSimon says) i.e., raised, not depressed, and weights are added. The escapement shouldn't escape eheh!! :D ;)
The return weight is measured starting from the depressed key all the way to the bottom, passing through the escapement. I hope I said that correctly.
fermo restando i progetti originari delle case costruttrici e dei relativi modelli, cosa ne pensate di questa regoletta che ho trovato (è in inglese ma si comprende piuttosto bene):
"The ideal down weight is between 50 and 55 (usually 53 or 54) grams.
Place a 53-grams weight on the front end of the key, centered over the balance rail pin and bump the action with your hand. The key should slowly descend to the point of letoff, at which point the added resistance of the jack will stop the key. With the key in this position, if you remove the 53-grams weight and place a 20-grams weight on the front of the key, the key ideally should return to the rest position by itself":
We cannot say what the "ideal" let-down weight is. It depends on the dynamics of the action. Consider that Steinway manages to achieve a let-down weight of 47 grams with a considerable return weight. The "smoothness" of the action and its "responsiveness" are felt thanks to a good return weight. The ratio between the two weights (let-down and return) should be about 2.5... but be careful that the key weighting does not increase inertia too much. In fact, we would notice that, although returning to the resting position, the key reaches it too slowly, and this is not good. So yes, a proportion between let-down weight and return weight, but with a correct normal mass of the keys. (this is why one should not replace a hammer rail with a much heavier one to try to counterbalance with weights on the keys!!!!)
I would like to give a practical example: if we consider a ratio of about 2.5 between the downweight and the return weight, I believe I have understood that at a downweight of 55 grams, there should correspond about 22 grams for the return.
However, if, keeping the 55 grams of downweight constant, having also 30-35 grams of return would be better? I mean, would the best solution be to find a point on the key lever that increases the return weight as much as possible without increasing the downweight of about 55 grams? If that were the case, shouldn't we also consider the length of the key lever?
Perhaps it's nonsense, but these are just curiosities. Thanks a million!
I believe, however, that the two weights are inevitably interconnected. I don't think it's possible to keep the descent weight steady and increase the return weight.
Of course. Well done. Naturally, the length of the lever has an effect, as do other design measurements. Manufacturers subtly determine which let-off and repetition weights should be achieved to ensure good mechanical smoothness. This also takes into account the key dip measurement.
''When the return weight is low and the downweight is high, we are dealing with excessive friction (See lesson 3). If the downweight is low and the return weight is low... perhaps we are dealing with incorrect keyboard "weighting". Inertia is important. The masses or rather the weights, even if well-balanced, must not be excessive.''
I performed this coin test on an old Blüthner brand grand piano—what a sound, if one could play it at a university:
the downweight results in being high but constant across the entire keyboard (low octaves 16, moving to 15 and finally 13 at A) however, the return weight remains always constant but high, from 10 coins to a minimum of 8 on the highest octaves... given that the piano has likely received minimal maintenance and has probably been used quite a bit (I often meet students who enjoy playing), what do these constant but high return weight values tell us, when it should be at 6 coins??
F
Fra
Member
Reply 19 by Fra
Posts
266
The return weight and the strike weight are both high; it is likely that a lead weight has been added to the bottom of the key (in the rear part, corresponding to the hammers) to increase the overall resistance of the keyboard, as it was considered 'light' for practice.
Many pianists used to request this type of intervention on instruments from the beginning of the century.... perhaps with an ultra-smooth hammer action....
Today, since the fashion is to weight the keyboards of uprights or verticals at around 60 grams, such interventions are generally not required.
great, it seems like a truthful hypothesis to me; if I remember correctly, next time I'll note down the piano's serial number, anyway if it's not from the beginning of the century, it will certainly have 50 years