Ron Nossaman wrote: > Hi Gang, > > Just getting back to this because my server's been down... Again. > > My point here is that strings don't hang up on bridge pins in the first > place, so seating them back down isn't curing anything. Sure, they move, > ping, and seem to have been up the pin before seating, but I think that's > just because we're not looking past a basic false assumption (yet again). > Here's the scenario according to the way I see it. > Hmm.... you make as usual a good case, one that makes a lot of sense, but I still remain a bit unconvinced about a couple points... so before we go along with agreeing on what are and are not false assumptions, let me make a couple points and see what you have to say .. > Incidentally, this does assume a reasonably well set up piano with positive > bearing at both the front and back notches and the notch edges remotely > centered on the pins - for simplicity's sake. Ok..... > During the wet cycle, as the swelling bridge is pushing the string up the > pin against down bearing, side bearing, and pin inclination, the wood > surface of the cap is crushed under the string. Since the most resistance > the string offers to being pushed up the pins happens AT the pins, rather > than in the center of the cap, the cap edges crush more than the center. This sounds great.. could even be exactly whats happening. Or it could be just a compounding factor. I would think that given our starting point, (reasonble front and back bearing) that even without bridge pins, for that matter even if the bridge itself never swelled as a result of a climate cycling, that we would see this same development. In fact if you take a peice of soft clay, form it into a rectangle with a nice flat top and press a string down evenly you will see what I mean. So whether or not the pins themselves actually play a significant role here... remains as far as I can see not demonstrated. > The string is no longer lying on a flat cap. This is important. In the dry > cycle, the soundboard crown is less, the bridge is shorter, so the > downbearing angle is less across the bridge. At some point, it's likely > that the string isn't touching the bridge surface at the edge of the notch > where the pin is, but it is touching a little further back on the bridge > because the edge is crushed down below where the pin inclination can force > the string under tension. The string hasn't climbed the pin. It's > horizontal termination support just no longer coincides with the notch > edge. Heres the other point that makes me scratch my head.... you see (again assuming we have this nice front and back positive bearing) if you remove those bridge pins... the string will bend really nicely over that somewhat "rounded" bridge top. Of course it wont be tight enough secured to the bridge to sound good... but thats not the point in this connection... the question this fact raises is why doesnt the string conform to the somewhat rounded profile of the bridge ? > If the pin is even a little loose at the bridge surface, it will > flagpole and produce false beats. I'll buy this... but this seems like a different issue ?? I dont seat strings on the bridge to solve any false beating myself. > Seating the string will knock it down on > the bridge, creating a slight negative front bearing angle between the > speaking length and the length of string that wasn't touching the bridge > prior to seating. Do we know this or is this speculation ? Can you demonstrate this to be true, and why then the same string under the same conditions "bend" nicely over the bridge if you simply remove the bridge pins ? I would think that you would have to have a point on the bridge near the edges that was below the level of the front temination point, or the bearing point behind the bridge in order to create what you describe above. > The false beat may go away temporarily, but it isn't > fixed, and will return as the piano is played and the string tries to go > back to it's natural straight line between termination points. That then, depends on whether you are right about this small area of negative bearing angle between the speaking length and the segment of the string right around the bridge pin. If the bridge wood right at the pin is higher then the termination point... then how can negative bearing come into being ? > The false beat is there in the first place because the bridge pin is loose, > the bearing angle is low, and the cap is deformed so the horizontal > termination point is behind the (-20°) vertical. I am with you on the first point... but I am not sure how false beats can be created by the second two. I wonder also if you could explain what you mean by "behind the (-20°) vertical. > The notch in the pin may > eventually be a factor, but these kind of beats will often show up very > early in a piano's life before any significant wear damage accumulates on > the pins. I dont see the notches themselves as being the problem here... Now that is not to say notches in bridge pins dont make nasty sounds from time to time... but the reason I seat strings is simply to insure solid contact between the string and the bridge. I dont solve much in the way of false beats by doing this... but I do get rid of some buzzing sounds...and I have a feeling it increases tuning stability...tho that second point is more speculation then it is anything else. > Seating strings won't cure any of these conditions, so why is it so > universally insisted upon? It's quick, easy, and gives the immediate > illusion that the tech is improving something. At least that's why I used > to do it before I decided it wasn't a long term fix. If anything, seating > strings hard across the center of the bridge to hammer the string track in > the cap flat again (if deeper) should do a lot more long term good than > lightly seating them at the pins. No, I haven't, and no, I don't, but yes, > I will probably eventually try it. Hmmmm.. perhaps it might help to point out that seating the strings means to me that one taps the area of the string inbetween the two bridge pins. I tap very lightly along this entire length. I never push on the string over the speaking lengths...I aggree that seating the strings is not particularilly effective as a false beat eliminator. Once in a while it may help somewhat, for a short time. But it does address other issues that seem to need to be addressed from time to time. I dont think banging the strings into the bridge has any positives to offer, but who knows ?... in anycase I recommend only the very light tapping inbetween bridge pins that is neccessary to insure contact with the bridge. If you do indeed have a situation where you have negative bearing coming out of this as Ron describes... it would seem to me that you have a bigger problem on your hands. > Ron N -- Richard Brekne RPT, N.P.T.F. Bergen, Norway mailto:rbrekne@broadpark.no
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