> 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
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