This is a multipart message in MIME format ---------------------- multipart/alternative attachment I'm with you...a 100 cent change hardly moves the pin at all... David Ilvedson Original message From: Farrell To: Pianotech Received: Wed, 11 May 2005 21:18:17 -0400 Subject: Re: Grist for the Mill A 30 degree turn of a tuning pin every year on a stable piano? No= way! Calculate the pitch increase with a 30 degree rotation on a 2/0= pin - even the 7.5 degree rotation - I suspect you will very= quickly realize your numbers are grossly excessive. Unless, of course, I am wrong. But I don't think so. Terry Farrell ----- Original Message ----- From: alan and carolyn barnard To: Pianotech Sent: Wednesday, May 11, 2005 8:50 PM Subject: Grist for the Mill We recently had a long dialog on here about the actual changes in= a piano that has gone flat. There was much poo-pooing (can we= say that on TV?) from some folks of the notion that tuning pins= turned counter-clockwise when pianos go flat. Their arguments= were logical and some folks even produced mathematics to= demonstrated that pin reversal is unlikely. BUT ... I was thinking about this on my way home from PTG chapter meeting= (2.5 hr drive) and came up with a little point of logic which= suggests that the pins MUST move. See what you think ... Virtually all pianos go flat over longish time periods and= certainly are found flat more often than sharp if you go through= a whole cycle of season changes, i.e., an annual tuning. When we= bring a flat string up to pitch, it tends to increase the width= of the coil slightly every time we turn the pin. If the pin is= turned one full revolution--360 degrees--over years of tuning,= this would add the thickness dimension of the wire to the= overall coil width and one full wire wrap to the number of= coils. You with me? So let's take a hypothetical piano string--say a very stable 1905= Howard upright A4 middle string--that has averaged (let's be= conservative...) falling flat enough that a 7.5 degree turn of= the pin was required each year to bring it up to pitch. Now 7.5= degrees is a fairly small annual adjustment, just a little= tweak, actually. Ce n'est pas? It's only 1/6 if a quarter turn. So, between 1905 and 2005, we have turned that string's pin 100 X= 7.5 =3D 750 degrees, more than two full turns. How many old pianos do we run into that have five or more coils= on the pin? I never noticed any. In fact, most seem to have the= original 3 coils standing about as far from the plate as the day= it was strung--unless someone has hammered them in, in which= case it's still only about 3 coils! Pause ... thinkin on that? Now strings must become ever so slightly thinner as they stretch,= especially in the earlier years. So, for the string to produce= the same pitch, the string tension required would be ever so= slightly less over time. This would have a very slight= mitigating effect on the thought puzzle proposed above. But= nowhere near enough to explain 100 years of flatness, methinks.= And ven if the string is stretching, you would still be adding= linear length to the coil every time. I believe, in fact, that about a 30 annual correction, or more,= would be very common. Think about your own real-world,= real-piano experience. Visualize pulling your tuning hammer= through a 30 degree arc, i.e., 1/3 of a quarter turn. That's= still a pretty darned small once-a-year adjustment. So, I think= my estimates here have been very, very conservative. Anyway, at 30 degrees the piano would have to have a total of 8+= full coils on every pin if the pin never turned backward. Your turn or, as we used to say in Viet Nam .... I n c o m i n g= ! ! ! Alan Barnard Hunkered in the Bunker in Salem, MO ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/0e/ff/de/25/attachment.htm ---------------------- multipart/alternative attachment--
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