----- Original Message ----- From: Farrell To: Pianotech List Sent: Thursday, July 20, 2006 10:15 AM Subject: Re: tuning pin torque There will certainly be some variation of opinion on what "acceptable" tuning pin torque might be, but maybe about 60 to 150 in.-lbs. (note: inch-pounds, not foot-pounds) will yield a reasonable-tuning piano. Terry Farrell Just to hijack this thread, I've always been curious about the exact units for torque. In rec.music.makers.piano, Don Gilmore (an engineer) wrote this reply. I wrote: > ...The force on a tuning pin is measured as torque, but just considering > string tension, I guess simple mass is the right unit, as though a weight > were hanging off the end of the piano (right?). Hi Cy: Yeah, tension is just in pounds. Properly it's force (or weight), not mass, but that's just being picky. One pound-mass on earth weighs one pound (exerts one pound of force downward) and since you probably won't be working on pianos on the moon, a pound is a pound. Torque is the tension multiplied by the distance from the center of rotation. If the string has a tension of 150 lbs and the center of the string is .125 in. from the center of the tuning pin then the torque is 150 lbs x .125 in. = 18.75 lb-in To get lb-ft we can divide by 12 and get 1.56 lb-ft. In the engineering world we call torque "pound-feet" instead of "foot-pounds" so that we don't confuse torque with energy. Sorry to interrupt the thread with my nit-picking. Don Kansas City ----------------------- Thus it seems the common unit we use is simply the string tension (150 lbs.), while the proper (?) equivalent in torque would be 18.75 "pound-inches". Yet the torque wrenches we use for tuning pins are calibrated in pounds... right? --Cy-- -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060720/d0cda624/attachment.html
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