Ron, Thanks. Tom Servinsky,RPT ----- Original Message ----- From: "Ron Nossaman" <RNossaman@KSCABLE.com> To: <pianotech@ptg.org> Sent: Saturday, September 08, 2001 3:43 PM Subject: Re: Bridge pin spacing (was Baldwin SD-10) > >Newton, Del, Ron O, Ron N and other scholars out there, > >This might seem like an over-simplified question, but what factors in > >scaling determines the optimum width of a bridge and the facing in the first > >place? I have always pondered the reasoning behind the broad width bridges > >vs. some of the extremely narrow bridges found in all types of pianos. > > Having rebuilt oodles of instruments, the good, bad, and the ugly, I have > >yet come to a conclusion as the "why's" vs. the "how effectives" are each > >design. > >Tom Servinsky,RPT > > There really isn't a simple answer either. Stiffer and heavier are > determined by width and height, like with any beam. The impedance of the > soundboard assembly at any point in the scale is determined by the mass and > stiffness of the assembly, as seen by the strings at that point. Scale > tensions, soundboard panel thickness and grain direction, rib dimensions > and placement, rim stiffness and proximity to the bridge will all have some > effect. Like everything else in a piano, everything affects everything else > in some way. Too flexible an assembly, and you get one big killer octave. > Too stiff and heavy an assembly, and you get a very quiet piano that > sustains for days. Something in the middle, and a considerable range of > something at that, is what you want. I've found that I can get enough > control of the process to produce the kind of sound I'm looking for with > panel and rib design without having to worry too much about bridge cross > sections. A couple of years ago, I replaced a 40mm wide bridge with a 30mm > wide bridge with a new soundboard and rib scale, and was very pleased with > the result. Since I haven't replaced a bridge with one of different > dimensions on the original soundboard, I can't say exactly what would happen. > > Ron N
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