While recording the mechanics of my antique piano, I noticed that if I try to bring the escapement point very close to the string, some hammers bounce a little too much after touching the string and generate an annoying double sound. Since this behavior is limited to only a few hammers, I tried to understand the cause by observing the hammer and also the capstans, but I was unable to see any substantial differences from the others that are working well. For the moment, I have moved the escapement point a little further away (to 3 millimeters from the string instead of 1).
If they bounce, the key dip is certainly insufficient relative to the hammer-string distance. The escapement point, if a mute is present, must occur at approximately 2-2.5 mm from the string. Let us know
Thanks pianoexpert. I should specify, however, that it is a grand piano. How far should the hammer be from the string, considering it is a historical piano?
actually I checked the depth. at that point it is at 11. in the other points at 12. so even if it triggers the escapement at 11, do we have to set it to 12? thanks
No, No, No.... so there is something else that isn't right. Depths 11 and 12 are excessive. Check if the hammers are seating properly, and also check the spring tension. The hammer drop after the escapement is also important. Of course, I would hire a good technician who knows how to evaluate all the interdependent adjustments. Just speaking generally, excluding certain "obvious" interventions, one would need to see the instrument.
thanks again. at what distance from the string should the escapement rails stop the hammer? is there a video of yours that speaks well about how to adjust the escapement rails? Even though I have followed your examples with extreme interest and much gratitude, I don't remember seeing anything regarding the adjustment of the escapement rails. It would be wonderful to have a video explaining this aspect as well.
That being said, I tried setting the let-off to 10 mm and the jack escapes. I spaced the escapement point at 2.5 mm from the string and now the problem seems to have disappeared. Perhaps 1 mm from the string was too little? Anyway, I will post a video/audio soon to better illustrate everything.
Here is everything explained; since a technician had guaranteed me that he had fixed the keyboard, I did not doubt the fact that the let-off was wrong. I adjusted the escapement according to your precious advice, M. Ferrarelli, and I realized (and he was right) that the let-offs were at 11.5. Now I have set the distance of the escapement point to 10 and 2 mm, and there are no problems with the hammer rebound. It's a whole different tune now... although I imagine, obviously, that it will improve even further with the final fine-tuning by a good technician.
In both grand and upright pianos, all adjustments are interdependent. They may vary slightly depending on the pianist's expectations, but they must maintain a proportion to one another. The technician must be well-versed in these adjustments and, above all, the effect they produce. Therefore, "fixing the keyboard" is equivalent not only to changing the cashmere felts of the front and center keybed bushings (which must have a perfect minimum amount of play) and/or the front oval sliding pins and center round sliding pins (in case there is slight rusting or roughness!), but also to re-evaluating the entire keyboard regulation (general leveling - let-off and the proportion of let-off between white and black keys). Subsequently, one must check the geometry of the action and the perfect regulation of the escapement, the repetition (in grands), and the check. The tension of the springs also contributes to altering or aiding the regulation. Naturally, as I often maintain, one must previously check the friction of the repetition lever pins, the age of the hammer repetitions or the leather of the hammer heads, the felts of the jack heels; that is, all those sliding or rolling frictions that could certainly alter the regulation and hide the instrument's performance, leaving the pianist with a negative sensation.
When the pianist can "rely" calmly on the piano without "challenging" its performance, then we can say we have achieved a good result. (a concept often expressed in the past by Stefan Vertes of Steinway & Sons)
Maestro, is it correct that by bringing the hammers closer to the strings (respecting the 45 mm distance from the string) the sound is noticeably lower?
It will take more force to bring out the previous volume.
Aside from the fact that one must check the condition of the hammers (age, excessive shaving, etc.), it is precisely the alteration of the geometry that modifies the hammer's thrust toward the string. It is equivalent to pressing the piano's una corda pedal slightly, which deliberately decreases the hammer stroke to reduce its force. Therefore, when you play loudly, there isn't much energy left. The escapement lever is in a position that "slips" on the hammer head. In slightly more technical terms, the resultant of the thrust force applied by the escapement lever shifts in a direction less suited to what is necessary to achieve good energy. If this is the case, it means that the hammer rail has been shaved a bit too much and/or incorrectly.
A part from the fact that one must check the condition of the hammers (age, excessive shaving, etc.), it is precisely the alteration of the geometry that modifies the hammer's thrust toward the string. It is equivalent to slightly engaging the piano's soft pedal, which deliberately decreases the hammer stroke to reduce its force. Therefore, when you play loudly, there isn't much energy left. The escapement lever is in a position that "escapes" from the hammer head. In slightly more difficult terms, the resultant of the thrust force applied by the escapement lever shifts in a direction less suitable for achieving good energy. If this is the case, it means that the hammer rail has been shaved a bit too much and/or incorrectly.
Maestro, it is always an honor to read you.
Indeed, the force applied to the lever is designed to have maximum thrust or output in that position.
Conversely, a more advanced position, used to compensate for shaving, causes the lever to act as if it were escaping from the hammer head, resulting in less thrust.
You were very clear, superb, as always.
Let's just say that when one intervenes with shaving, damage is always created; it should never be done, even though you told me that designers always leave a margin for the possibility (shaving) being contemplated.
Let's say that one must find the right compromise.
Straying too far from 45mm (the first hammer), but getting too close, makes the mechanism underperform...
Theoretically, a solution could be to move the entire action closer to the strings without making modifications and therefore without varying the force applied to the lever.
But would it make sense, assuming you could succeed technically (though I believe everything is possible), if even with an over-shaved hammer rail, it is still valid?
Moving the action is an absolute no. The "geometry" is precisely determined by an alignment of the key center point - repetition lever - center pin of the capstan... in a specific phase of the dynamics. The manufacturer takes these geometries into account and establishes measurements, including the drilling of the hammers and their position relative to the strings.
You must always take these distances into account and verify if modifying them is decisive. 45mm is not mandatory. Many instruments reach 47 (see Steinway), others might require different measurements. Everything depends on the key dip, its length, the position of the repetition lever, etc.
On the vertical axis, then, the sensations become a bit more "artificial." All the components of the action move and return aided by small springs that favor performance.
Friction, however, acts as the "master" and must be checked beforehand to ensure there are no impediments to the delicate vertical movement.
In the grand piano too, friction coefficients are fundamental, but in dynamics, the return of the parts to their resting position by gravity helps the resolution of the movement. Keyboard stiffness and sensations of "muddiness," as well as jamming during rapid passages or repeated notes, are more natural and evident.
I hope I have been clear... even by using more intuitive rather than technical concepts.
I just wanted to confirm what I remember hearing in one of your tutorials regarding the escapement lever... It must be adjusted so that it remains suspended, detached from the hammer knob. Is that correct?
In effect, it is not the lever that should support the knob, but the hammer with its stem must rest on the rest felt, and even a sheet of newspaper should be left between the lever and the knob.
