Soundboard grain angle

[Delwin D Fandrich]

----- Original Message -----
From: "John Delacour" <JD@Pianomaker.co.uk>
To: <pianotech@ptg.org>
Sent: December 04, 2001 2:50 PM
Subject: Re: Soundboard grain angle


> At 11:26 AM -0800 12/4/01, Delwin D Fandrich wrote:
>
> >  we
> >might as well forget the function of the arch in the real world piano.
Even
> >a highly crowned board has so little once it's loaded by string down
force
> >any effect the arch might contribute is lost in the compliance of the
wood.
>
> I've re-read this a few times to try and make sense of it.  I can see
> that the wood of a new board is bound to have multiple places or
> "high points" in its internal structure where the first use of the
> arch is going to result in a crushing of the material, but once this
> has happened and the board has to that extent "complied" and settled
> I see no further compliance in the wood and the board will return to
> the settled unloaded height time and time again.

Sorry. What is in my head is the concept of the Roman arch. I've gone into
this repeatedly in the past, complete with drawings in my Journal articles
(which, of course, it is unlikely you've had access to). Soundboard does not
gain any support by being 'squeezed' by the rim. Whether there is a
Centripital Tension Resonator there or not. There is simply too much
complience in the wood and the amount of arch is too slight.

Actually, wood continues to change as long as it is under load. The process
is called a variety of things; 'creep,' stress relaxation, compression set,
etc. A good text explaining this phenoma is "Understanding Wood" by R. Bruce
Hoadly.


>
> Two weeks ago I made some strings for a 6'0" Collard and Collard that
> a local man was restoring and asked him to let me know when they were
> on because I wanted to hear the results in such a short s/s grand.
> The piano had a few interesting features that made the trip worth
> while.  Not only did my strings sound well right to the bottom but
> the tenor and mid range were also extremely sweet and long-lasting.
> The board was at 90° to the straight side.  I was not able to judge
> the treble owing to poor tuning, but it was certainly not bad.  C&C
> is a make I avoid because of its really lousy actions with shocking
> geometry, but the sound of them gave them a good share of the
> international market at one time.

There are just a whole lot of ways to do this stuff.


>
> >I have been refining the radial-dispersion rib configuration over
> >the years and am now fairly comfortable with it as well.
>
> You would be interested to see how Brinsmead did this and to hear the
> effect, which is almost unique.  The soundboard is so responsive that
> the load pedal has the effect of opening the swell on an organ.  This
> is very rare and gives the player a whole ne vista of expressive
> possibilities.

I thought I had come up with something really new with this idea. I first
tried it in the mid- 70s. I was real proud of myself until I walked into a
dealers dead piano room a few years later and found an almost identical
looking soundboard/rib system on an old upright built in the 1880s. Ah,
well....

Del