Richard Brekne wrote: > So... I ask you... why we are supposed to measure down to the balance > rail, and up to the capstan and at the same time not take into > consideration the horizontal deflection of their angles before figuring > their ratio ? There are a number of different ways to measure key ratio. Which one you pick depends on the what you are trying to find out. For static weight measurements measuring along the key perpendicular to the force of gravity is best. If you are working on how the action moves angularly you need to measure the key differently. To get true measurements of the lever lengths of action parts you need to have the action assembled. There are only two measurements that can be gotten directly from the parts - the front length of the key and the back length of the shank. All the other lever arms are out somewhere in space and change throughout the key stroke. The link below from my web site is a drawing of the pitch point of the upper half of the action. The action is at half stroke. If you draw these out for other positions of the stroke you will see that the ratios change. [link redacted at request of site owner - Jul 25, 2015] John Hartman RPT John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] Rebuilding Steinway and Mason & Hamlin Grand Pianos Since 1979 Piano Technicians Journal Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015]
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