Hi Ron, Hey this is starting to get fun! Here's one idea off the top of my head as to why the string can create false beats when rising up the pin: One side of the string terminates very nicely on the pin, but the other side, not being seated, is free to vibrate. The result is a very confused string with two pretty significantly differant lengths. A *very gentle* tap seats the string, and (assuming the bridge has been notched correctly) terminates the string in one specific location on both pin and bridge. No more confusion. No more false beat. What do you think? John Mckone, RPT St. Louis Park, MN (612) 280-8375 P.S. Thanks for returning the apology - I'm sure I'll need it in the future! : ) ---------------------------------------------------------------------------- -------------------------------------------- Ron Writes >Lastly, how would a string stuck up on a bridge pin cause a false beat in >the first place? If it's hanging in there good enough to withstand all the >above mentioned forces to the contrary, the string termination is as solid >as one could hope for! If it's because the bridge pin is loose, we are >back to my original premise that most of the false beats found in pianos >are the result of loose bridge pins and aren't curable by seating strings >to bridges. I don't mean this to look like I'm trying to lead the >discussion with a bull whip, but this is where the logic process brought >me. All enlightenment, clarification, pertinent random musings, empirical >observations and universal truths cheerfully entertained. > > >Expectantly, > Ron Nossaman > > > > > ><******* History beyond this point *********> > > > >At 09:17 PM 4/11/97 -0600, you wrote: >>Hi Ron, >> >>My apologies for misinterpreting your question. I understand now what >>your asking, and I have tried a very un-scientific, but possibly >>enlightening experiment this evening. >> >>I am currently doing some work on my personal piano in my shop. I rebuilt >>this piano (a Bradbury 5'6" reproducer grand) about six years ago, and it >>happened to be my first bridge recapping job. Because of this some of the >>bridge pin placement is, well, pretty embarasingly wacky. A few pins are >>placed in such a way that there is very little, if any side bearing. The >>rest of the job is fine: good downbearing, nice tight well angled bridge >>pins etc. I took some strings off and checked bridge pins and found no >>*visible* notching in them. >> >>I got to thinking that this would be a great situation to test if side >>bearing played a major role keeping the strings off the bridge. >> >>Here's what I did: With the piano up to pitch, I simply pulled up on the >>speaking lenght side of a couple of strings until they lifted off the >>bridge, then let go and watched what happened. The strings that had no >>side bearing went right back down to the bridge. The strings that had >>decent side bearing stayed up! I did several in the sixth octave of the >>piano (this is where the misplaced pins are) and the strings rode up >>above the bridge anywhere from 10 to 15 thousandths according to my >>feeler gauge. >> >>This little test, while not very controlled, would seem to point to side >>bearing, and its attendant friction as one of the major contributing >>factors in keeping those suckers up in the air. >> >>Comments anyone? >> >>John McKone, RPT >>St. Louis Park, Minnesota >>(612) 280-8375 >> >>----------------------------------------------- >>>From : Ron Nossaman <nossaman@southwind.net> >>Sent : 04/11/97 >>To : pianotech@byu.edu >>Subject: Re: bridges/seating >> >>At 08:58 PM 4/10/97 -0600, you wrote: >>>Ron, >>> >>>If you're asking why the string can creep up against the pressure of >>>downbearing and friction, you need look no further than the impact of >>>the hammer (on a grand anyway) Especially on a hard use piano. >>> >>>John McKone, RPT >>>St. Louis Park, Minnesota >>>(612) 280-8375 >>> >> >> >>Nope, nope, not at all. It's quite obvious that a string can be knocked >>up hill against tension, friction, or anything else you care to name. You >>can here it happening if you work at it. It's quite clear to me how a >>string GETS up a bridge pin. I'm saying that it's not possible for it to >>STAY up off the bridge, AT REST, against tension and side/down bearing >>and pin angle, unless there is something physically wrong with the bridge >>pin. What else would hold it up there magically???? David Copperfield >>plating? There has to be a real reason for an observable physical >>phenomenon. I get enough mysticism and "have faith, trust me" metaphysics >>from Government. Demonstrations can illustrate that it's possible (I'm >>still working on that one), but I don't think anyone can realistically >>champion a fix without a clear understanding of what's broke. Let's talk >>"mechanism". I'm willing to accept the notion that this happens only in >>the context of a rational explanation as to WHY it is possible. Wouldn't >>you like to know too? >> >> >> Ron Nossaman >> >> >> Ron Nossaman John McKone, RPT St. louis Park, Minnesota (612) 280-8375 mckonejw@skypoint.com
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