Soundboards

[pianoman]

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> From: Delwin D Fandrich <pianobuilders@olynet1.olynet.com>
> To: pianotech@ptg.org
> Subject: Re: Soundboards
> Date: Saturday, August 16, 1997 9:39 AM
> 
> Richard Moody wrote:
> > 
> > To Delwin and List
> >         Some where along the line I heard that some makers used wedges
> > between the sound board and rim ( in stratigic places) to help "shore
> > up" the crown.  Is this true? Or was I dreaming?
> > Richard Dreamon
> > 
> > ----------
> 
> 
> It's quite possible. A lot of things like this were tried that didn't
> work. 
> 
> The only technique that I'm aware of that did at least partially work
> was the arrangement developed by J. Bauer in which the soundboard was
> mounted on a separate rim that was attached only to the plate. The outer
> rim was a totally separate structure. 
Dear Del,
Do I remember that Julius Bauer had a plate above and below the soundboard.
 I worked on at least one of these pianos years ago and recall that they
would have been a very decent instument.
James Grebe
pianoman@inlink.com
> 
> In this case we have to say that the inner rim was attached to the plate
> and not the other way around. The plate was the main structural member.
> An by itself, it was about as heavy as most pianos of the same size.
> Anyway, it was fastened to the plate in a more-or-less conventional
> manner by using closely spaced screws coming down through the plate, a
> spacer mechanism—I’ve forgotten now whether dowels, spacer blocks or a
> top liner was used—and into the inner rim. The plate was a
> "full-parameter" plate in that the inner rim was mechanically fastened
> to the plate all the way from the upper bass corner to the treble
> corner. The “belly rail” was integral to the inner rim and was not
> attached to either the outer rim or the keybed. The plate extended down
> between the two rims and adjustment bolts were installed in the plate
> the heads of which bore against the inner rim. These bolts could be
> tightened against the inner rim and to some limited extent made the
> crown to the soundboard assembly variable. 
> 
> The only reason that this scheme worked at all was because Bauer also
> used what I would call a "half-rib" on each side of the soundboard. In
> other words the rib was made of two pieces one on top of the soundboard
> and one on the bottom.
> 
> In “modern” piano construction nothing done to the parameter of the
> soundboard is going to “shore up” soundboard crown—including the Mason &
> Hamlin centripetal tension resonator. Crown is lost because wood fiber
> crushes and creeps over time. No amount of strategically placed wedges
> is going to change that.
>