Alan Forsyth wrote: >Gordon Stelter wrote; > > > >>>"P.S. I have 30 years' professional experience >>> >>> >repairing pianos. As the too wide let-off on this >piano ALSO exists on notes 1 and 88, which show no >sign of being played, I can only assume that this >"adjustment" was introduced in the factory in an >attempt to overcome the pre-existing problem as >described above." > > > >You hit the nail on the head there Thump! I have this problem with new >Yamahas and to tell you the truth, you either have to end up with zero >dithering hammers or an action with no power or dynamics. Compare the length >of the jack with that in the action of a piano a hundred years ago. You will >find that the modern actions have very short jacks. Now logic tells me that >the shorter the jack the less speed there will be at the tip of the jack on >let off; in other words the movement of the jack tip is much slower for the >same amount of leverage induced by the let off button. The hammer is >bouncing off the strings much faster than the tip of the jack is able to >escape from the clutches of the butt. I never seem to have such problems >with large actions. > > If the whippen itself has enough travel, and the jack is not angled too far foward, then any contact with the butt at all should simple push the jack out of the way. If the jack doesnt get pushed away.... then either its too stiff (for reasons mentioned previously) or its not high enough for the angle it has with the butt. It really cant be much else.... tho the causes of each of these can be many. Again... -- Regulate for proper letoff, keydip, blow, check, lost motion and confirm the jack is clear of the hammer butt leather when you depress and hold the key down. -- confirm that the angle of the jack is not too steep -- look for other impediments to key and/or jack travel... ie... friction between the jack and the hammer butt, spring strengths, stop rails... and the others that have been mentioned. This little algorithm will solve most any upright bobbling problem. >One other thing you might look at is the strength of the damper springs. >When they are new they are very strong >so much so that they may in fact be hindering the touch at the keystroke >i.e. slowing down the keystroke at the aftertouch stage. > > This is more along the lines of what I normally find. Something slowing down that last bit of key stroke and/or jack travel. >Just some ideas. > >AF > > > > >_______________________________________________ >pianotech list info: https://www.moypiano.com/resources/#archives > > >
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