Low Inertia

[erwinspiano at aol.com]

? David
? This?is a fascinating development! I'm curious. How high was the hammer flange center pin from the keybed before it you moved it up??The blow was the same ?
? By the way what vintage of D? Do we ever know enough...rhetorical question
? Thanks
?? Dale
?

Dear all,?
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Before these related threads scatter into oblivion I want to restate what I've already mentioned in the Journal past: it is my observation that distance ratio divided by weight ratio yields something I call the efficiency ratio which is a ratio of ratios....?
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As an example I was recently working in John Foys shop to help install a Precision Touch Design in a Steinway D. We found that with a 5.5 ratio the distance ratio was 5.0. The efficiency ratio was .9 and the action required a .430" dip with a 1.75" blow.... We checked the action center elevations and the whole stack was low by almost 1/4". Rechecking the ratios the weight ratio was 5.3 and the distance ratio up to 5.7 which was kind of astonishing. The efficiency ratio was now 1.1 and the action regulated with .400 dip...?
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This is just one example and I'm collecting much more data to formally publish but I can say at this stage that it is my conclusion that the efficiency ratio should be above 1.0 for good results...?
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To me distance ratio comes under the heading of geometry and is related to arcs and their angular interaction whereas the strike weight ratio is a result of vertical gravitational vectors.?
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I like what Fenton said.... it's about Hammer Weight, Action Ratio, Geometry and Friction....?
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Onward and upward....?
?
David Stanwood?
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