Good evening everyone, I am asking for your help once again after you helped me redo the strings of my Yamaha SU118C; now I have a noise on one key, more precisely the 39th "B" of the middle octave. When I press it, I hear a noise, almost a vibration in the key mechanism; this distracts me from practicing and makes me nervous. I cannot attach the audio file. It almost seems like the plastic pivot that pushes the hammer and then releases; at the moment of release, it makes an annoying noise. Some kind of friction or something similar.
It is very difficult to determine what it depends on. Some hypotheses: disconnections of the hammer and other mechanical parts. Hammer shank hitting some stop screw of the rail - limiter - escapement levers. Damper.
I advise you to separate the movements of the hammer, the key, and the capstan block. Finally, the damper.
Thanks for the answer, so to do something about this I have to take down the entire mechanical block and completely disassemble the part of key 39, right? By detachment, you mean the wooden parts, right? I didn't quite understand what you mean by separation of the movements of the hammer, the jig block, and the damper. Thanks again
p.s. Were you able to hear the audio file I attached then?
I mean separation: lift the rail with one hand, move the key and listen. Unhook the hammer, bring it closer to the string, move the rail with the other hand and listen. Then just the hammer.
Make sure the hammer head is glued firmly to the shank. Even a tiny failure of the glue, with the strike towards the string, produces a small noise.
Lastly, it could be a noise caused specifically by the bridge. Try striking the string at the bridge location (open the bottom panel first).
Also make sure the instrument rests well on the floor on all four casters. I always recommend putting four isolators under the wheels.
Check also the back of the instrument and the adhesion of the soundboard reinforcements (braces). If there are screws, make sure they are tightened. Then push on the reinforcements while someone plays the note loudly for you and see if the noise disappears. You should also do this by pressing on the bridge.
Sometimes, when tuning the piano, with the change in tensions, everything settles into place.
Thank you very much as always, so I disassembled the entire action and put it on the bench; after various tests I found that the problem (sorry if the terms are not correct) is not on the Harp but almost 95% even more so between the escapement finger and the cap, right where there is the coating that looks like leather; practically, the finger escaping from the cap creates that noise by rubbing. I disassembled both parts and noticed that the hammer seems healthy and not detached (through manual movement it doesn't seem to creak), also the finger which seems coated in graphite would seem fine; the cap part, however, has the "leather" crushed/worn, resulting in being black due to the transfer of the "graphite," and it is very stiff. At this point I cleaned the cap with a dry microfiber by rubbing vigorously; I managed to change its appearance making the leather less "plasticized," which greatly reduced the noise and for the first bars it disappeared, but it reappears, albeit lighter, after a few bars.
Alright. If you still hear a "squeak" when pressing the keys slowly, then you can lightly rub a graphite stick on the felt of the hammers or apply Teflon micro-powder. These noises may depend on the hammer felt being synthetic and/or dry. Naturally, use a little graphite rubbed with a stick, which you can buy in art supply stores (like a graphite pencil....4B 5B 6B...). If the stick stains your hands upon contact, it is the right one (very soft).
Naturally, to do a good job you must (carefully, otherwise they will break) unhook the straps and reach the hammer felts without having to disassemble and realign all the hammers. If instead you plan to disassemble the hammers, then take the opportunity to run some 400-500 grit sandpaper over the hammer felts to remove the old graphite. The hammer felts will appear clean and you can, sparingly, lightly pass the stick (the soft ones are cylindrical).
Good luck with the work
P.S. Very, very little graphite! Just enough to avoid the noise
Impeccable explanation, thank you! For now it works; the small straps will be part of some work I'll have to do—they are sound, but the red part of the attachment is dry. It is quite an old piano, at least 50 years old, but according to the tuner, it sounds very well.
