William: You'll get many different answers depending on who you ask. I find that this method syncs up with the other formulas I use (weight based) the best. A picture makes it easier to describe but I don't have one, so I measure as follows: EA = Effort Arm RA = Resistance Arm Key Ea measured from front of key (or touch point if you prefer-the farther in you go the higher the ratio) to center of balance pin hole along the bottom of the key. Key Ra measured from center of balance pin hole to a line drawn perpendicular from the center of the capstan to the bottom of the key. (Key measurements are all taken along the bottom of the key.) Wippen Ea (first draw a line between the wippen center pin and the jack center pin) Ea is measured from the wip center pin to a line perpendicular to the contact point of the wippen heel/capstan contact point along the line you've drawn Whip Ra is measured from the wippen center pin to the jack center pin. Shank Ea is measured from the hammer flange center pin to the center of the knuckle core (measured along the shank) . Shank Ra is measured from the hammer flange center pin to the center of the hammer molding (measured along the shank). Example below for this action. Multiply the three independent ratios (.5*1.6*7.35) to get your overall action ratio. Ea Ra Ratio Key 220 110 0.50 Wippen 62 99 1.60 Action Ratio Shank 17 125 7.35 5.87 David Love www.davidlovepianos.com What is the lever arm formula you use? William R. Monroe -------------- next part -------------- An HTML attachment was scrubbed... URL: <https://www.moypiano.com/ptg/pianotech.php/attachments/20130116/d650ada2/attachment.htm>
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