Crown without soundboards reply

[pianoman]

What model were these Steinways and what size and type were they?  This is
the first I have heard about this.
James Grebe
R.P.T. from St. Louis
pianoman@inlink.com
"A diamond is coal that stayed there", give me the paitence to stay.

----------
> From: Delwin D Fandrich <pianobuilders@olynet.com>
> To: pianotech@ptg.org
> Subject: Re: Crown without soundboards
> Date: Sunday, January 04, 1998 2:37 AM
> 
> 
> 
> Stephen Birkett wrote:
> 
> > .... Agreed again, but the panel simply forces the ribs to take on a
different
> > shape. The forces involved in differential wood movement are sufficient
> > to allow the technique to be used for stone-masonry, pyramid building
> > etc. so it is understandable they can deform the shape of the ribs.
This
> > doesn't mean the panel is "supporting" the crown though.
> >
> > A small line of pianos that Steinway produced in the 1940s illustrates
Jim
> > Snr's point to a tee. On these the boards were made with the individual
> > panels separated by a small distance, ca 2 mm, i.e. they were
pre-cracked
> > along every glue-line. The boards behaved as normal boards do.
> > Unfortunately the line was short-lived, since the pianos were
> > un-saleable...they were deemed to be broken coming from the factory.
> >
> > >... Perhaps we can
> > > gain a little more insight from the harpsichord builders who have to
> > > work with much fewer ribs and funny wavey things that go on with the
> > > soundboards.
> > >
> > What are funny wavy things?
> >
> > Stephen
> >
> > Stephen Birkett Fortepianos
> > Authentic Reproductions of 18th and 19th Century Pianos
> > 464 Winchester Drive
> > Waterloo, Ontario
> > Canada N2T 1K5
> > tel: 519-885-2228
> > email: birketts@wright.aps.uoguelph.ca
> 
> --------------------------------------------------------------
> 
> Stephen,
> 
> In a pure compression-crowned soundboard, the ribs actually resist
crowning. That is one of the reasons why ribs on these
> boards tend to be a bit wider than they are tall. Whatever their shape,
they would really prefer to remain flat. So, if the
> ribs are not supporting crown, what is? As Sherlock Holmes would say,
"Once you have eliminated the impossible, whatever
> remains, no matter how improbable, must be the solution."
> 
> About the "pre-cracked" soundboard: I worked on one of these a few years
ago, although it was not in a Steinway. In this
> particular case the crown was machined into the ribs. It wouldn't have to
be though. It would be quite possible to
> "compression-crown" an assembly even if the panel was not "solid." It
might put a bit of additional strain on the wood fiber
> and on the glue joints, but it would crown. Assuming that the wood strips
were dry enough when the ribs were glued on, that
> is.
> 
> Del
> 
>