---------------------- multipart/alternative attachment 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 = 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/0b/ed/1d/aa/attachment.htm ---------------------- multipart/alternative attachment--
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