What method of crowning boards do the current piano factories use?

[Calin Tantareanu]

Hello,

I was wondering what method of crowning the soundboards is currently used by
today's piano factories? Let's say Steinway, Bechstein, Bosendorfer, Yamaha
or whoever else?
I couldn't find such info on their websites and it would be really
interesting to know which way they choose and why (if possible).

Thanks!


Calin Tantareanu
----------------------------------------------------
http://calintantareanu.tripod.com
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----- Original Message -----
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Tuesday, December 17, 2002 8:40 PM
Subject: Re: Soundboardcrown


>
> ----- Original Message -----
> From: "Farrell" <mfarrel2@tampabay.rr.com>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: December 17, 2002 10:17 AM
> Subject: Re: Soundboardcrown
>
>
> > Ron. I think what Peter is doing here is inducing a small amount of
crown
> by gluing a flat rib to a flat panel in a curved caul at ambient RH. And
of
> course, this will produce a small amount of crown. He then dries the board
> down and glues in into the piano. It would appear that he is relying on
the
> rigid-rim-supporting-the-crown theory to keep the board crowned after it
> expands a bit with the increased RH. Obviously, there are a few of us that
> do not feel that theory holds much water, let alone crown.
> --------------------------------------------
>
>
> No, Terry, the rim doesn't really enter into it. If you take a
> compression-crowned soundboard assembly back to its condition at the point
> of ribbing the compression stress that holds crown disappears. In other
> words, if you belly a board at 4% MC using flat ribs and a flat press it
> crowns up in a normal room atmosphere. If you then take it back to 4% MC
the
> crown disappears and the whole thing is more-or-less flat again.
> "More-or-less" because there has probably been enough compression set
within
> the panel that, back at 4%, it would end up under some tension and go into
> reverse crown.
>
> What Peter is doing is simply taking the compression out of the panel
> temporarily, letting the assembly flatten out, and then gluing it to the
> rim. As moisture goes back into the panel it once again becomes a
> compression-crowned soundboard assembly.
>
> Del
>
>
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