On 9/4/97 1:48 AM, Richard Moody <remoody@easnetsd.com> wrote: >miniscual "miniscule" (adjust your Spelch-Ecker according <g>.) On 09/04 6:16 PM, Delwin D Fandrich, pianobuilders@olynet.com ,wrote: >Most of what I have to say on this subject I've already said. See >"Action Power" Part 1 (August, 1996) and Part 2 (December, 1996) >published in the Piano Technicians Journal. May I respectfully refer the >reader to those articles? Hats off to Del for this and many other wonderful articles. On 9/4/97 1:48 AM, Richard Moody <remoody@easnetsd.com> wrote: > On the other hand, a bent hammer shank may possess potential energy >just as a bent bow ready to shoot the arrow. So perhaps after let >off, the bent shank tends to spring back and actually accelerates the >hammer onto the string. Yes this is what is happening. However this temporary ricocheting of the action's energy into the springiness of the shank is worth considering only if it is complicating our measurement of the hammer's final velocity as it meets the string. The shank's whip is a complication only in that it modulates a direct correlation between the key and hammer velocity. If the shank has restored itself (ie. straightened out) before let-off, then it is not complicating the reading of the ham,,hammer's final velocity. More importantly, how the springiness of the shank may affect the acceleration curve of the hammer head is moot if the shank has restored itself by let-off. What I mean is that if you have two keys with identical parts in their lever trains, excepting that one has a shank which will bend under the rabbit-punch at the knuckle and the other which won't, AND if the flexible one has restored itself by the time let-off occurs, AND if both keys are both driven by the same striking force, both hammers will have taken the same time interval to travel to let-off. Never mind that they'll have different acceleration curves to arrive there, they'll both arrive with the same velocity. Now while acceleration is in the "moot bin", velocity is the salient factor, as it combines with the hammers mass will determine the hammer head's deceleration when up against the opposing force of the steel wire's springiness. All of which is to say that if the flexible shank has restored itself by the time the hammer reaches let-off (minus of course energy lost as frictional heat during the mechanical flexing), the flexing will have no effect on the hammer's momentum. If the shank hasn't finished its restoration by let-off, then the flexing will have a significant effect on our knowing what the hammer's momentum is, going into the interaction with the string. Hey, I've only got a HS diploma (and barely that). Corrections, please. Bill Ballard, RPT New Hampshire Chapter, PTG "No one builds the *perfect* piano, you can only remove the obstacles to that perfection during the building." ...........LaRoy Edwards
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