Bridge design

[Farrell]

Del wrote:
> Typically we undercut a new treble bridge along the leading edge. This
> undercut extends back as far as a perpendicular line drawn straight down
> from the leading rows of bridge pins.

And how far along the long bridge from C88?

Terry Farrell
  
----- Original Message ----- 
From: "Barbara J. Fandrich" <pianobuilders@olynet.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Wednesday, March 26, 2003 9:07 PM
Subject: Re: Bridge design


> 
> ----- Original Message -----
> From: "Ron Nossaman" <RNossaman@cox.net>
> To: <davidlovepianos@earthlink.net>; "Pianotech" <pianotech@ptg.org>
> Sent: Tuesday, March 25, 2003 8:56 PM
> Subject: Re: Bridge design
> 
> 
> >
> > >I notice on Steinway bridges (as well as some others) that the lower part
> > >of the bridge root narrows in the treble section of the piano.   What is
> > >the design purpose of that and does it serve its purpose?
> > >
> > >David Love
> >
> > It's to get the "footprint", or attach point of the bridge to the
> > soundboard panel away from the rim as far as is practically possible. Yes,
> > it's a good idea since a bridge sitting on the rim doesn't move the
> > soundboard all that well. It would be nice to be able to get it even
> > further from the rim, but there is a practical limit in a grand determined
> > by hammer clearance of the belly rail, and the upper limit of the speaking
> > length of C-8.
> >
> > Ron N
> > _______________________________________________
> 
> 
> David,
> 
> The idea was certainly to reduce the size of the footprint, but it was
> thought to be helpful along the entire length of the bridge. The theory was
> that the soundboard produced "tone" by "undulating" and anything that
> inhibited this undulating would interfere with the tone production
> capability of the soundboard. A positive side effect of this practice was to
> move the attachment point of the bridge some away from the soundboard liner
> through the treble region.
> 
> Taken to its illogical extreme it has the effect of reducing the stiffness
> of the bridge leaving it somewhat inefficient in its task as a coupler
> between the vibrating string and the soundboard panel. It can be a
> contributing factor to short-sustain problems.
> 
> Typically we undercut a new treble bridge along the leading edge. This
> undercut extends back as far as a perpendicular line drawn straight down
> from the leading rows of bridge pins. We do not undercut the back side of
> the bridge.
> 
> Del
> 
> 
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