On Thu, Jun 4, 2009 at 12:18 AM , Gene Nelson wrote: > sharps travel more than naturals. Sounds like poor action/key geometry. I remember years ago, Pratt-Read engineers trying to argue that their "standard" dimension from natural-key balance-pin-line to sharp-key balance-pin-line is optimal, regardless of the key length. I didn't believe it then and don't now. For optimal results, once you have worked out a good geometry for the natural keys, you really need to do the same for the sharp keys, which means that the distance between the natural and sharp balance pin lines will vary with the lever arm lengths. It sounds like what has happened all to often in the piano industry, rather than fixing what's broke, finding a way to mask over it, more often than not, creating more problems that are resolved in the process. > The key length increases about 8mm from note #1 through #65. I had to re-read this a time or two before I realized that the capstans are probably in a straight line, parallel to the balance point, and the additional key length is only beyond the back check, to reach the tapered line of the damper underlevers, presumable maintaining the same key length from 66 to 88, because there were no dampers involved. Are my assumptions correct? > After I build the back action it is my sincere hope that this is > really a solution and the new damper timing will feel and look even. Sounds like you found the same "work-around" as the manufacturer did. My greater concern would be what does the significant difference in natural and sharp key ratios do to the action performance and regulation. Too much aftertouch in the sharps? More key leads in the sharps than naturals? Significant inertial differences that make the sharp keys feel heavier than they really are, relative to the naturals? Frank Emerson
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