Screwing down the board: was Re: soundboardinstal again

[David Love]

Del:

I notice a variations in approach to screwing down the board.  Some do not
(Steinway) some do (Mason Hamlin).  What is your general approach to the
use of screws to secure the board around the rim both for a dry fit and
with glue.

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Delwin D Fandrich <pianobuilders@olynet.com>
> To: Pianotech <pianotech@ptg.org>
> Cc: David Love <davidlovepianos@earthlink.net>
> Date: 7/22/2003 12:47:36 PM
> Subject: Re: soundboardinstal again
>
>
> ----- Original Message -----
[link redacted at request of site owner - Jul 25, 2015]
> To: <davidlovepianos@earthlink.net>; "Pianotech" <pianotech@ptg.org>
> Sent: July 22, 2003 11:59 AM
> Subject: Re: soundboardinstal again
>
>
> > I suppose if you
> > didn't use the wedges you may not notice this.
>
> I've pre-stressed many a board and still have not noticed this. We dry-fit
> our boards by screwing them down without glue around the parameter. We
then
> check string bearing, do our bridge work and establish a plate height.
When
> all is as we want it we glue the board in, finish it and set the plate
back
> to the same elevation established during the dry-fit. We generally end up
> with the expected string bearing with no further adjustment.
>
> I do agree, though, that a soundboard might well be moderately stiffer
with
> the parameter glued than it is while simply screwed down. A clamped-edge
> panel will always be somewhat stiffer than a semi-clamped, or
semi-floating
> panel. It would be some difficult to screw a board down tightly enough to
> qualify as a truly clamped-edge panel. Trying to predict just how much
> stiffer it will become brings in a number of variables, including how
> tightly it was screwed down, how thick the panel is, how thick the ribs
> are, the stiffness of the various materials, the crown radius, etc.
>
> A couple of things to keep in mind:
> -- This phenomena is noted whether the panel is crowned or not. In other
> words, with all other factors remaining the same, it will be similar with
> both a crowned panel and a flat panel.
> -- Soundboard panel stiffness and the ability of a given soundboard panel
> to retain crown over the years are two different things.
>
> Del
>
> Del
>