I stand corrected. By the way, it is part of the principle of the Steinway accelerated action design, right? Paul Mike and Jane Spalding wrote: > Paul, > > I believe you are mistaken regarding the inertia. (As a former machine > design engineer who recently jumped out of the frying pan and into piano > tuning, I have some experience with this). It does indeed vary with the > placement of the lead: Putting less lead further out will result in more > inertia than more lead closer in. Half the weight, twice as far out, same > static downweight, but twice the inertia. (For those of us old enough to > remember phonograph records, this is why the counterweight on the tone arm > is very large and very close to the pivot point.) Doesn't change your > conclusion: all other things being equal, keep the lead near the pivot > point. > > Mike Spalding > > ----- Original Message ----- > From: <larudee@pacbell.net> > To: <pianotech@ptg.org> > Sent: Thursday, March 29, 2001 10:15 AM > Subject: Re: Ideal leading pattern: > > > David, > > > > As a matter of simple physics, it makes no difference whether you put less > lead > > farther away from the balance rail or closer in, with one stipulation. > The > > stipulation is that the key is perfectly rigid and has no flexibility. > > Otherwise, both the momentum and inertia will be the same either way. > > > > Of course, we know that the key is not perfectly rigid, so placement of > more > > lead closer in is probably preferable, all else being equal. This reduces > the > > sense of inertia in the key because the part that takes the force of > depression > > has less mass in it than otherwise, and applies leverage to the part that > has > > the mass, closer to the balance rail, after some momentum has already been > > gained in the key. Along with the use of cylindrical key bearings, I > think this > > design is part of what Steinway calls its accelerated action, but I am > prepared > > to be corrected. > > > > Paul Larudee > > > > David Love wrote: > > > > > I run into this sort of situation frequently and I would like some > opinions. > > > Steinway model S ca 1936. I am replacing hammers and shanks only. I > use > > > Steinway hammers full taper, Abel shank 16.5 mm knuckle gives me the > best > > > combination of regulation/downweight from which to work. The strike > weight > > > is medium and consistent throughout. Key weight ratio is 5.0. When I > > > install the hammers, I will still want to take 2-5 grams off the > downweight > > > throughout much of the piano (though it is somewhat erratic) to get a > 52-48g > > > taper. Doing so does not compromise the upweight. The present front > > > weight of the keys allows me to add lead without exceeding the maximum > > > recommended front weight (according to Stanwood charts). But... the > keys > > > already have a fair amount of lead grouped mostly toward the balance > rail. > > > Though the front weight is not excessive, the keys themselves weigh a > lot > > > because of the amount of lead in them (e.g. C16 = 163g , C40 = 144g, C64 > = > > > 133g). I have the option of adding a small lead, or removing two or > more > > > large leads from near the balance rail and replacing them with one large > > > lead out toward the front of the key. The latter will produce a more > > > conventional leading pattern--and involves a lot more work. > > > > > > My questions are: > > > > > > 1. Which one will produce a better feel? > > > 2. Will the difference be significant? > > > 3. Do front weight parameters change with the overall length of the > key: > > > i.e., is the allowable front weight greater for a model D than for a > model > > > S, or there other factors. > > > 4. What additional information will be helpful in making a quantifiable > > > decision? > > > > > > David Love > > > _________________________________________________________________ > > > Get your FREE download of MSN Explorer at http://explorer.msn.com > > > >
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