This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment 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 -----=20 From: alan and carolyn barnard=20 To: Pianotech=20 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.=20 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. =20 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/99/98/73/0f/attachment.htm ---------------------- multipart/alternative attachment--
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