Greetings, I wrote: > In regards to the jack's position, I would posit that the most >important thing is that it be no further under the knuckle than is required for dependable actuation. Richard writes: >>Gotta dissagree. Too far out and the key will miss and you loose power. >> Losing power is not dependable actuation! If it misses, it is too far proximal. There is a point where the jack delivers full power, dependably. Any position that is farther distal is wasted friction. Kjell writes: << I think Ed Foote meant the jacks position under the lever (not forwards or backwards). 20 years ago I learned at the Schimmel factory that the top of the jack should be positioned just a little bit under the lever arm (or more correct: the lever arm just a little higher than the top of the jack, "the thickness of a hair"). Some years later I learned the same at the Bösendorfer factory. And this weekend Sauter told us the same at the Nordic Convention in Denmark. << The problem with static dimensions like this is that they do not account for wear in the knuckles. I think the factory advice is somewhat compromised to allow the greatest number of techs to get dependable repetition. However, I think there is a finer refinement possible; to wit, (or to half or quarter wits, whoever gets involved like me in such obtuse obsession with such abstruse concepts.....) I set the balancier height so that the jack can be felt to scrape the knuckle as it is softly triggered by a finger on the tender, and will return under simple spring pressure. This assures me that there is no lost motion. Having the balancier carry as much weight as possible, with the jack still in contact, assures the most transparent escapement at ppp levels. Since I set let-off as close to the string excursion zone as possible, this combination(along with drop set at the same distance as let-off) gives the greatest sensitivity possible without compromising power or repetiton. I also favor springs that cannot be felt in the key when the hammer is released from check. Regards, Ed Foote RPT http://www.uk-piano.org/edfoote/index.html www.uk-piano.org/edfoote/well_tempered_piano.html
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