Hi Friends ! I also have encountered that nasty repetition on Yamahas (even larger ones) To their defense I should say they work perfectly well for a year or so ! Indeed a bit more air to the action, little friction, the checking may be a tad farther. When out of trouble the hammer letoff shows a definite drop, a little like in a grand. that's a neat way to check it (and check the return springs at the same time). May be fussing with the angle of the letoff button rail can speed the jack a tad at the end of its travel (a little slant on the rail brackets) This problem is also noticed on pianos that have been played heavily (pounded) , or while out of regulation for a long time. Then the jack dig its place in the cushion and the leather, and then the letoff occur in fact too late, and the hammer bounce on the jack. It is fairly possible that on those problem verticals, the "magic line" between the balance pin bottom and the pin of the whippen is not well respected, then it produce a loss in the leverage at the end of the stroke, slowing too much the whippen and jack in regard of the hammer return. I never checked it (it is easy to correct bending the capstans on those) but will for sure next time. Best Isaac OLEG -----Message d'origine----- De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la part de antares Envoyé : mardi 13 avril 2004 22:36 À : Pianotech Objet : ( new Yamaha w/bobbling hammers) On 13-apr-04, at 21:50, Richard Brekne wrote: > Hey there Andre' Ricardo Mio, > > You illustrate one of the main points I was trying to make really well. This is again proof of a vibrant and razor sharp intelligence,......... ta da ta da!! (; >)) )) )) (by the by, yours or mine?, I forgot....duh) > Bobbling caused by hammer butt bouncing off the jack means really one > of three things is going on.. > > 1. The action is simply regulated wrong, > 2. There is a design flaw with the angle of the jack that makes is > borderline impossible to get it easily out from under the butt to > begin with. > 3. Something is impeding the jack travel at the bottom of the > keystroke. > > The first two are easy to address and rule out of the picture. If you > do that first then all that remains is the 3rd, so you look at things > that can slow down or resist jack travel at the bottom of the key > stroke. Friction can definantly be an issue here for sure. I like to > manually travel the jack with a capstan regulator to feel the contact > between the jack top and the hammer butt, and to check return spring > strength. I can also check to see how stiff the jack feels pulling > out in general this way... and how far it actually is allowed to > travel. I've never yet been totally stumped without the problem > being the second mentioned above. I agree Ric, There err.. ah.. is a problem here ah, and maybe the techs at Yamaha are not aware of it. However, I have noticed this problem a long time ago and that's how I came to my conclusions. All we can do is work on the friction points, (very err.. ah.. important here), make a sharp and uniform 2 mm let off, and if necessary, make the striking distance somewhat smaller to say 44 mm. Oh yes, and like you said... give the jacks some "Luft".. (The Luft Waffe) (; >)) André > > antares wrote: > >> Hi Gordon, >> >> I too have wrestled with this Yamaha upright problem. >> According to me, the angle and position of the jack is such that it >> is hard for the jack to away get from under the butt. >> I have tried several things myself in the past. >> 1. I used a thicker cushion, which immediately helped but the hammers >> lost power, so no good. >> 2. When encountered with this problem, I always take out all the >> keys, spray the balance and front rail pins with McLube, and make >> sure that the keys have very little friction. >> Any friction before the jack movement may add to the problem. A more >> or less friction free start helps the jack to get out from under the >> hammer butt. >> 3. I made the striking distance smaller by gluing some thick red felt >> on the hammer rail rest. Thus helped very much because the angle and >> position of the jack improves, but you lose some power because the >> striking distance gets smaller. A compromise may be the answer : >> raise the hammer rail just a bit and adjust the action. >> 4. I have noticed this problem also, and in particular, with Schimmel >> uprights. Lubing the jack heads with McLube helps immediately and is >> extremely effective, especially in combination with a sharp >> regulation. >> With plastic jacks however, you have to be very careful and not spray >> too long and too much, the plastic may turn into a candle. >> > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives > > friendly greetings from André Oorebeek Amsterdam - The Netherlands 0031-20-6237357 0645-492389 0031-75-6226878 www.concertpianoservice.nl www.grandpiano.nl "where music is, no harm can be" _______________________________________________ pianotech list info: https://www.moypiano.com/resources/#archives
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