Try filing the top of the jack . Sent from my iPhone On Jan 22, 2009, at 4:11 AM, Gregor _ <karlkaputt at hotmail.com> wrote: > 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 t > hat 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 beca > use 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 bobbli > ng 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 conf > idence 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 las > t 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 tha > t the jack travels too far under the butt? In this case a thicker ha > mmer butt felt would help. Or the dryness makes the hammer butt buck > skin 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 playe > r stop pressing down the key before the let off point. A very subtil > e resistance gives the player a hint that the key is pressed down no > w, but that´s not right. The player could and should press further o > n. The strange thing is that this problem is new for a few days. I s > hould mention that we had very dry air last weeks and the customer h > as 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 > > Get news, entertainment and everything you care about at Live.com. > Check it out! -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090122/f8c942b0/attachment-0001.html>
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