> This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ---------------------- multipart/alternative attachment My interpretation of the whole issue of bending of the pin is this: The tuning the pin flexes upwards while one raises the pitch whether one realizes it or not. This is due to the many forces acting on the pin during the raising of the pitch. At rest there is the string tension pulling downwards on the pin, not only a rotational tension but a vertical tension. The rotational force (torque) is balanced by the static friction between the pin block and the pin. The downward force is balanced by the strength of the elasticity of the steel in the tuning pin. The pin IS flexed down while there is string tension on it. The tricky part is understanding how the tuning lever is acting on the pin. When the string moves during the raising of pitch the forces are no longer in balance. At the very least (if the force of the tuning hammer is imagined as a person pulling on another string wrapped around the pin the other direction) , the rotational friction between block and pin and the tension of the string have been overcome. If the string is moving (raising pitch) has the vertical tension also been overcome? The solution is complicated by the fact that the force from the tuning lever is off center because it has one handle. Which direction is it being pulled from? Usually the from right but the variations in lever and arm position could cause upwards or downwards forces to act on the pin. The technicians arm position may also not be in line with the rotation of the pin (though it should be as close as possible) which is probably why this is more of a vertical piano problem than with a grand. Ever try to break a lug nut free with a tire iron and have it come flying off into the ground? That's because (like the tuning lever) the forces are not applied purely as torque or tangentially to the pin. The school of thought of "tweaking " the pin back down into its resting position believes that the pin has been relaxed from its flexed position during the tuning. A third hand to play the note and a T handled tuning wrench with the other two hands on it is what we need. Or a physics (mechanics) major. Sorry for the lengthy diatribe. Jon Rhee Weymouth, MA ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/0e/ab/a5/4c/attachment.htm ---------------------- multipart/alternative attachment--
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