Hi Susan & all, My whole point here is that I'm NOT assuming the string gets up there by= hopping, creeping, or anything having to do with being struck by a hammer.= I still haven't seen a clear argument in support of this. That's why I= proposed the argument that strings driven up the bridge pins by a blow= would go sharp as they were stretched through a wider stagger angle. I= asked if anyone had ever seen a piano driven SHARP by heavy play. In an= environment where the heat and humidity have been reasonably stabile, the= piano is tuned, beat through a recital, and tuned again for a later one, we= should see that ol' octave 5 1/2 - 6 debil going significantly sharp if= strings are being driven up the pins. I haven't seen this. If they are= creeping up over a period of time, there are too many variable conditions= to be able to separate this conjecture from that of the bridge swelling= from humidity increase and leaving the pins stranded high when it recedes.= There isn't any conclusive evidence for creeping. Unless someone can come= up with a logical scenario in support of impact induced pin climbing/creep,= I'll have to consider the humidity model the better answer pending an= impact logic model that covers more of the observable phenomena.=20 In further support of the humidity swing model, I'd like to offer this. I take humidity and temperature readings when I tune. It's dry the day of= the tuning, maybe 35%RH. I look at the recorded RH reading taken at the= last tuning. It's 36%. I tune the piano and find that the Tenor is pretty= close to pitch, but I have to LOWER the octave 5 1/2 - 6 area a bit. I've= seen this a lot of times, and always wondered how it happens. I know that= the humidity has, until about three weeks ago, been above 50%RH average. My= thinking is that the high humidity swelled the bridge and pushed the= strings up the pins. when the RH dropped back, the soundboard and bridge= went back to about where they were at the previous tuning. The strings,= being higher on the bridge than they were, and tighter via the resulting= increased stagger, remained a bit sharp. I don't habitually seat strings to= bridges with regular tuning, so (if this model is accurate) why did the= strings go sharp. Why weren't the strings still up the pins from the last= high RH period so the next one wouldn't have moved them? I think that, if= anything, strings creep DOWN toward the bridge with play. Otherwise, the= first high RH cycle would put them up the pin where they would stay forever= (unless tapped down) and the bridge surface would NOT BE GROOVED at all!= The string wouldn't have touched it for years! That's contrary to MY= observations. I think the observed pin indentations are the result of this= continual upping and downing with high RH pushing the string up, and low RH= letting it jiggle back down. The pin get's burnished flat through the= migration path. I don't think the flat spot has ta thing to do with holding= the string up, but rather, it is a wear track of where the string has been.= The vertical distance traveled is very short, making the wear track look= like a notch that catches the string and holds it up, but I think it is= ovoid, and the pin NEVER LEAVES this indentation. As I proposed earlier, if= pin climbing is impact related, why don't we see bigger gaps between the= string and bridge in extreme cases? And why aren't tunings knocked= sharp????? I think this stuff is basic to the puzzle. Has anyone got cause= & effect models on the impact theory?=20 Endtrans, you're all "it" Regards, Ron Nossaman PS: Sorry about the length of this (these) thing(s). This language is a= great thing to play with, but a miserably cumbersome communication meadium. =20 At 09:45 AM 4/18/97 -0700, you wrote: >If there's a groove in the pin, doesn't that imply that the string was up >there quite awhile, sawing away? We seem to have been assuming it hops up, >but wouldn't it just creep up, reach the limited height that tension and >downbearing allowed, and then proceed to vibrate and groove the pin?=20 > >If so, this would support (relatively) frequent seating as a procedure. If >the string wasn't up there long enough to groove the pin, it wouldn't have >the indentation to hang up on.=20 > >Susan Kline >skline@proaxis.com >P.O. Box 1651, >Philomath, OR 97370 > >Murphy's out there ... waiting ... > Ron Nossaman
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