Subject: Time: 9:12 AM OFFICE MEMO Re Re Re Friction Date: 8/8/95 >Ken Sloane wrote: >The laws of nature do not change from one system to another. However, our >methods of analysis with pianos sometimes introduce conditions into that >analysis that do not exist when the piano is being played as a musical >instrument. For example, when we use touch weights to measure friction in an >action, the key moves slowly and the knuckle stays, more or less, continuously >in contact with the jack and repetition lever. This is also true with the >wippen/capstan bearing. I believe that it is generally considered that this >does not occur when the piano is played. After initial compression of the >knuckle against the jack/rep lever and the capstan against the wip bearing, >the hammer assembly gets moving. The inertia of the moving hammer assembly >then helps to carry the assembly to the string. So, is there more friction >during that "period of compression" (as opposed to when we use touch weights) >and less when the inertia "takes over"? Even more confusing is how the hell we >would begin to measure these "varying" friction levels when playing. > -------------------------- Dan Squire replied: No problem. First get information on the acceleration. Then do a combined static- and inertia-force analysis. Ken's Reply: Do we need the Oak Ridge Laboratory to do this?
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