Do you dry the ribs, along with the board, prior to gluing ?

[Greg Newell]

Greg Newell
Greg's Piano Forté
www.gregspianoforte.com
216-226-3791 (office)
216-470-8634 (mobile)

-----Original Message-----
From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of John Delacour
Sent: Thursday, January 31, 2008 4:08 PM
To: Pianotech List
Subject: RE: Do you dry the ribs, along with the board, prior to gluing ?

At 21:53 -0500 30/1/08, Greg Newell wrote:

>... I myself am in the opposite camp wherein I believe that there is 
>cellular destruction of the old wood and therefore due for 
>replacement. My reasons follow that of which we've heard for years 
>now on this list. This of course is assuming a CC board assembly. 
>Your thoughts?

Why should anyone be interested in what you or I or anybody else 
_believes_?  

Well, I guess you shouldn't. Please stop reading here.

What scientific evidence can you point to to support 
this assumption?  

Well, assuming the compression crowned board, I think the cellular damage is
obvious given the ridges that develop, don't you? Admittedly these ridges
are not always present if the piano is kept in a nominal environment but
such is rarely the case on this side of the pond.

In what way are the "cells destroyed" and by what 
agent?

Um, compression ridges are clearly broken fibers are they not?

To be sure, it is quite demonstrable that when a spruce board is 
compressed beyond a certain point across the grain it will yield or 
shear at the weakest point, hence compression marks.  Does this mean 
that the remainder of the board is also irreversably damaged? 

Not necessarily but how will you reuse the parts that are not? Is it really
worth the effort to remove areas having experienced compression damage and
splice in new wood? Of course it's also necessary to remove (cleanly) all
the old ribs too isn't it? I don't see the point. Again, if you will hearken
back to my original question I wanted to know why the old board was better
not the same or still good. 

 I've 
never seen any evidence that it is.  And if the degree of compression 
to which the board is subjected is less than to cause it to shear, 
are you suggesting that the whole board is nevertheless damaged or 
inferior to a board made of new wood?  Where can I read the results 
of serious scientific research into the phenomena you believe in?



JD