Bridge pin spacing (was Baldwin SD-10)

[Tom Servinsky]

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