thanx for the good ideas. But I think that all does not help. There IS aftertouch, but there is a minimal resistance that makes the player not to press the key deeper. In other words: there is a minimal resistance that hinders the jack to let off and it´s not due to aftertouch. The player could easily press the key deeper but he won´t because he feels that subtle resistance wich makes him think that the down pressing procedure is finished. If the keybed had become deeper due to dryness then there should have been lost motion, which is not the case. And there is enough aftertouch. Jack stop rail is not involved because the jack does not came to the let off point and therefore does not touch the stop rail. Needling the check felt is useless because the hammer butt dances on the jack top so that check does not touch the back check. The same is true for the check distance. I tried a smaller distance but that did not help. For a moment I thought that the damper spring is the cause. In that moment when I feel this resistance the damper lifts off further (with down pressed pedal). I.e. the pedal lifts the dampers and pressing the key deeper lifts the dampers more. I eased the damper spring and had the feeling that it helped. But it´s hard to say because it´s even hard to reproduce the bobbling. It happens only with a certain kind of playing and my trials were not allways by the same reliable power. Then I lifted the damper with pressed pedal by hand completely and the bobbling was still there. Furthermore, the bobbling is present in the treble area without dampers, too. Concerning the hammer butt spring: if this were (too) weak this would be good, or not? If it were strong it had forced the hammer butt back to the jack top where it had danced on. Or is this a thinking failure of me? Unfortunately the piano is in the client´s home and not in my shop. So I can´t test around again. I "fixed" it with greater let off but in the end this is not realy acceptable. I am suffering of self confidence now because I could not solve the problem and don´t even see its cause. I am in this business for 21 years and thought I know how to deal with bobbling hammers but obviously i don´t. That makes me feel bad :-( And I can´t see the relation to the dryness in the last weeks. It´s not sure that there is such a relation but I think it´s likely. Perhaps the hammer butt gets smaller due to dryness so that the jack travels too far under the butt? In this case a thicker hammer butt felt would help. Or the dryness makes the hammer butt buckskin dry and harsh so that the jack movement is hindered? I applied talkum powder but that did not help. Very strange Gregor From: luc.calande at versateladsl.be To: pianotech at ptg.org Date: Thu, 22 Jan 2009 09:15:16 +0100 Subject: [pianotech] Bobbling hammers and jack spring pressure? Perhaps you could have to look on the jack-stop rail (see here under from the list) that could be too close ? Luc ----- Original Message ----- From: <pianoguru at cox.net> To: "Pianotech List" <pianotech at ptg.org>; "Mark Wisner" <markwisner at earthlink.net> Sent: Friday, August 22, 2008 2:49 PM Subject: [Norton AntiSpam] Re: Yamaha U1 > The jack rail is effective in improving repetition.. Julia, you'll notice > that in other upright actions there may be felt on the back side of the > let-off rail to serve the same purpose, or a felt block on the jack near > the top, or a smaller felt block on the back of the catcher, all serving > the same purpose. The difference is that the rail is adjustable, to > achieve the absolute minimum of necessary movement away from the hammer > butt. The same screw that mounts the rail is the adjusting screw. If the > threads of the screw were the same along its length, turning it would > affect no change in the rail position, but the threads through the rail > are "faster" threads than at the tip where it enters the main rail, > allowing for the tiny bit of movement to finely control its adjustment. > > Frank Emerson > > > ---- Mark Wisner <markwisner at earthlink.net> wrote: >> It's a jack-stop rail, and supposed to keep the jack from whipping too >> far on back on a very hard blow. >> >> -----Original Message----- >> >From: KeyKat88 at aol.com >> >Sent: Aug 21, 2008 6:15 PM >> >To: pianotech at ptg.org >> >Subject: Yamaha U1 "extra" rail >> > >> >Greetings, >> > >> > What's with the extra rail in the front of the Yamaha U1 action? I >> > have >> >never seen this before. Its down in front near the letoff rail >> > >> > >> >Julia Gottshall >> >Reading, PA >> > >> > ----- Original Message ----- From: To: Sent: Wednesday, January 21, 2009 5:22 PM Subject: [pianotech] Bobbling hammers and jack spring pressure? List, is there a way to ease the jack spring? I have problems with a Yamaha P121N upright that has bobbling hammers. The hammer butt is dancing on the jack tip. All regulation measures are okay and there is enough aftertouch. I suspect the jack spring being too strong. Any thoughts how to get it right? There is no lost motion, check is about 15 mm, aftertouch is okay and I gave some talkum powder to the jack tip and the let off button. The only thing that helped was to set the let off to 10 mm, but that´s not a satisfying solution. The strange thing is that one could play without bobbling hammers but something makes the player stop pressing down the key before the let off point. A very subtile resistance gives the player a hint that the key is pressed down now, but that´s not right. The player could and should press further on. The strange thing is that this problem is new for a few days. I should mention that we had very dry air last weeks and the customer has a floor heating. Therefore I suspect a connection between this problem and the dry air. Any comments? Gregor What can you do with the new Windows Live? Find out _________________________________________________________________ News, entertainment and everything you care about at Live.com. Get it now! http://www.live.com/getstarted.aspx -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090122/d3a4b87e/attachment.html>
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