Hi everyone, I recently purchased an upright piano in decent condition. The brand is Balthur and I believe it's from the 80s, unlike what I wrote in the introductions section where I was leaning towards something else. Logically there is something to be revised, but at least nothing is broken. First of all, I noticed that keys that are barely pressed have a slight play, so I unscrewed the pilot screws (on average by one full turn) in order to eliminate the play between the escapement upright and the capstan while still avoiding friction between them. The play disappeared, but as a consequence, the hammer escaped about 1 cm from the strings, so I loosened the escapement button screws a bit and now the hammers escape a few mm from the strings. Am I proceeding correctly, or should this have been resolved using shims under the center pins?
In the meantime, I have ordered paper washers to optimize the keyboard leveling.
Regarding the key dip and the hammer-to-string distance, they measure approximately 10mm and 4.7 cm respectively. Speaking of this latter measurement, I noticed that the hammer rest felt is quite indented at the position of each shank... does this mean that the original M-S distance has changed?
Furthermore, there are two noisy keys. One is due to friction at the center pin and I should replace the cashmere, but where can I find it? In the other key, instead, the noise is like a metallic vibration and is felt when the string is struck (I hope it disappears once it is tuned).
Sorry for all these questions and please, if you feel like answering, keep in mind that I am just now learning all the technical terms... basically, explain it to me "with a spoon" [in simple terms].
Dear Giuseppe, nomenclature is indispensable, otherwise it cannot be understood, but one can intuit what the intervention is. First of all, one must not move "an escapement button," but rather act on the regulators that must ensure the wippens do not have play under the cap, but also are not without return. To achieve this, a little experience is necessary. The escapement button must be moved to make the hammer escape at an adequate distance from the string. Every piano has its own specifics, but you have correctly identified that there is a close relationship between the hammer-string distance and the key dip. If you see that the hammer escapes without rebound in pianissimo, then the proportion is correct; otherwise, I would bring the first measurement to 45mm.
What does it mean to replace with cashmere on the center pin? Perhaps you mean the keyboard bushings? That too is not a job that can be done for the first time and requires special equipment. The felt is 1mm, 1.2mm, 1.3mm, etc.. Therefore, one must establish the thickness as well as the thickness of the caul that must be inserted into the bushing to glue the cashmere. Furthermore, the glue must be appropriate and applied in a certain way, otherwise it will not allow the key to slide.
The metallic vibration can depend on many elements: from the string, from an improperly voiced hammer, from a slight detachment of the hammer head, and from any other obstacle that the action encounters during its travel.
The final result—I will make a video about this—depends on an interdependence of adjustments, which must not be viewed separately.
Thank you very much for the punctual and exhaustive response. However, I would like to take advantage of your availability for a few additional doubts:
Can you confirm then that I am proceeding in the right way to eliminate the play under the nut by acting on the pilot pin instead of using shims?
Regarding the bounce you mentioned, I felt it on some keys, but after optimizing the escapement regulation, it has disappeared.
If I wanted to perform a test anyway, how do I proceed to reduce the hammer-string distance? The thing that comes to mind is putting a shim behind the hammer rest felt, but I doubt that is the correct procedure. Logically, by reducing this stroke, play under the nut will be created again and I would have to unscrew both the pilot pins and those of the escapement buttons further, right?
