Frankly, I think that some extrudeed, lightweight aluminum key, basically a shell buttressed with reinforcement along stress lines to stiffen it, would be FAR better than the 16th Century technology we are dealing with! And it should be hinged on a lateral pin ( at the bottom, on a pivotable plate ) to eliminate all "wobble". And weights ( not poisonous leads, either! ) could be affixed to the inside with bolts and lock washers along an adjustable track for exact balance. Thump --- Phillip Ford <fordpiano@earthlink.net> wrote: > > > At 12:11 PM 5/1/03 , you wrote: > >>The direct quote from the second link is > >>"The well-known Steinway "accelerated action" > works because it adds > >>acceleration to the hammer motion by use of a > rounded support under the > >>center key bushing. This causes the pivot point to > move forward with > >>keydrop thus shortening the front side of the key > and lengthening the > >>back side and thereby causing the capstan to > accelerate for a constant > >>keydrop. This illustrates the importance piano > designers place on > >>accelerating the keydrop, and the arm weight > method ensures that we take > > >>full advantage of gravitational acceleration to > control the tone. The > >>effectiveness of the "accelerated action" is > controversial because there > > >>are excellent pianos without this feature. > Obviously, it is more > >>important for the pianist to control this > acceleration." > >> > >>Now this is a new one to me. And Phil Ford who > just last week wrote such > > >>a nice nearly error free essay on the reasoning > for the accellerated > action :) > > > Does this mean that I don't get my Ph.D.? I guess > they meant it when they > > said my degree was BS. > > Essay? That little thing. Just wait for my 30 page > article in the > Journal > on this subject. > > I've heard this idea (about change of ratio as the > key is depressed on the > > half round supports) before. Why don't we take some > real numbers. Assume > > the radius of the half round dowel (with felt) is > 10mm. Assume the > distance from the balance pin to the point of > contact between the back of > the key and the rest felt is 200 mm. Do the > trigonometry and you get that > > the change in tangent point of the bottom of the key > and the dowel > for > the depression of the key is about 0.5 mm. How does > that affect the key > ratio? Let's say before key depression it's 200mm > from the balance point > to the measuring point, and 100 mm back to the > capstan. Ratio = 0.500. > So > after key is depressed the numbers are 200.5mm and > 99.5mm. Ratio = > 0.496. A change of 0.8 %. Is that significant? > You tell me. I would > guess that most factories are not controlling the > distance from balance > pin > to capstan within a half a millimeter, so this > effect is in the noise. > > >>The idea of a significantly changing key ratio > tho.... is intriguing ! > >> > >>Thanks Cy > >> > >>Cheers > >> > >>RicB > > Also, since we're having some conjecture on the > purpose of the accelerated > > action, here's what Steinway thought it was supposed > to do: > > According to Steinway patent 1,826,848, the half > rounds 'reduce to a > minimum the frictional resistance offered to the > rocking action of the > keys, and consequently they make provisions for easy > depression of the > keys > with a corresponding rapid and forceful > re-positioning thereof'. > > And from patent 2,031,748 the weighing off scheme is > 'to reduce the weight > > toward the outer end of the keys and reduce the > motion of the weight in > the > movement of the key'. And 'the main objects of the > invention are to > reduce > the distance the weights or leads have to travel in > the depression and > rise > of the keys and the inertia which has to be overcome > in the movements of > the keys, and to weigh off the keys proportionately > to the quickness in > action of their respective hammers so that the > playing of the piano may be > > accomplished with less fatigue and muscular effort > and greater ease and > facility be had in the playing'. An interesting (to > me) aside is that > this > patent states that they are shooting for a 50g DW > and 20g UW at the bass > end, and a 45g DW and 27g UW at the treble end, > tapering in between. > > Inertially, > > Phil F > > > > Phillip Ford > Piano Service & Restoration > 1777 Yosemite Ave - 130 > San Francisco, CA 94124 > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com
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