Belly rail crown - Why???

[Erwinspiano@aol.com]

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In a message dated 11/24/2002 12:23:50 AM Pacific Standard Time,=20
pianobuilders@olynet.com writes:

         Del Writes
> Come on, Dale, you know better than that. Sure, gluing the board to the ri=
m=20
> makes it act like a clamped-edge diaphragm, but wood is still awfully thin=
=20
> wood and it still bends under load. Especially so when the load is=20
> essentially across-grain and most of it is along the bent side or at=20
> roughly a 45=BA angle as most of it is along the bellyrail and the straigh=
t=20
> side. And along the bass curve, well, who cares?
>       >> Also the board is often thinned down to as little as .250 at the=20
>> edges so undue stress once again not desired. The 1 and 1/2 degerees=20
>> typically found in the rim joint could as practicallity or compromise be=20
>> reduced to half that and this angle would more likely conform to the=20
>> residual crown angle after stringing

                And, that's pretty much my point. =20
 =20
          Del-=20
           My point though (lame is) that there is a cohesive stiffening=20
factor when the whole things glued up to the rim though. I have no major=20
investment in the idea of the spruce panel itself being glued down as being=20
more than a small factor in the whole stiffness equation. =20
         I'm completely lucid about the idea of the majority of the stiffnes=
s=20
coming from the ribs stiffness via materials & design but the whole unit is=20
stiffer when the rib ends can't move any more being glued to the rim that is=
=20
it not?
     Well then another perhaps faulty thought comes to mind and it doesn't=20
necessarily support my previous statement.  Why not just adopt the Charles=20
Fredrick Stein concept of leaving the rib ends thick and just glue them to=20
the a notched liner.  Heck forget the notch and glue them right on top of th=
e=20
rim? Anyway this leaves the thin soundboard edge unclamped/unglued around a=20
majority of the board except at the belly rail and around the first part of=20
the treble curve. He probably didn't thin the edge either come to think on=20
it.
   The one I heard ,a six footer, produced a very beautiful musical sound.=20
Though different I enjoyed it immensely.  Viva la difference ,what do we kno=
w=20
,so many things work, or not.
        Regards -- Dale Erwin
>=20
> =20
>=20
> >>   =20


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