laminated ribs -- a side question

[David Love]

First, I am not a wood technology expert.  I still don't understand what you
are asking exactly.  Are you asking what needs to happen to the panel to
support any kind of load?  One place you might look to for the answer is the
comments made by Ron Nossaman, Del Fandrich and Ron Overs on the list in
various discussions on the subject.  To illustrate and reiterate, RC&S
boards are calculated based on beam formulas for supporting a load.  The
calculations anticipate a certain amount of deflection of the panel and
these calculations are made, if I understand correctly, without the panel
even being considered as a factor.  After the whole thing is glued together,
the amount of deflection anticipated is almost exactly what the formulas
suggest they will be.  Any variations are due to the idiosyncratic nature of
the wood in the ribs and making the ribs from laminated materials reduces
that variability.  The addition of the panel adds no significant resistance
or change to the deflection initially calculated from the ribs alone and you
would have to conclude that the panel's contribution to load bearing is
minimal.  

Stiffness, or the resistance to the movement when the assembly receives some
input of energy, say, from hammer string impact, is a function of the
overall structure of the assembly and cannot be isolated to the panel alone.


But then, that's just my non-technological understanding.  I'm confident
someone will correct me if I am wrong.      

David Love
davidlovepianos at comcast.net 

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ric Brekne
Sent: Wednesday, March 29, 2006 2:13 AM
To: pianotech at ptg.org
Subject: laminated ribs -- a side question

Hi David..

Sorry to have confused things... I was just asking a side question that
probably should have had its own subect line.  I'll restate the question
here if you care to speculate on it.

Thanks
RicB


If you have soundboard grain alligned roughly perpendicular to the 
bridge... and assuming for the moment that you are able to create with 
this allignment enough load support for a low tension / low load 
scale....  what are the real demands for cross grain load support ?  And 
is this (can it be ?) independant from the need for cross grain stiffness?

Thanks
RicB