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

[Greg Newell]

Thump and others,
	Since we're all asking for proofs and hard facts here in the finer
points and minutia of soundboard technology would you please expound on why
you feel that the old wood of the existing soundboard is more resonant than
the new? It seems that if you're going to persist in this line of thinking
then you must have good reasons for it, or is it just speculation? 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?  

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 Prof. Euphonious Thump
Sent: Wednesday, January 30, 2008 12:33 PM
To: Pianotech List
Subject: Re: Do you dry the ribs, along with the board, prior to gluing ?



> jobs you can easily experiment with then I'd say
> renew the glue joint 
> between ribs and soundboard, f

What do you mean by that ?  Dribble thin CA along
them, and watch it soak in ??? 

     Figure how much new
> support you think you 
> need from rib extenders and make them to appropriate
> dimensions, 

And how do I figure that ? I was just thinking more in
terms of increased crown/ dowbearing, created by
laminating maybe a  3/16 strip to the back of the
current ribs. How can I be more scientifical about
determining its actual dimensions ?  

 jack up 
> the soundboard a bit and glue them on. 


Well, that's one of the fun parts about this system. A
hardwood board is screwed along the back of the piano,
with threaded inserts right above where the ribs cross
the cracks. Bolts are screwed through it to really
jack the board up, RIGHT UNDER the crack being worked
on, and then it's moved to the next crack. When gluing
laminations to the spine of the extant ribs, these
"board and bolt" jigs would work terrifically, to
REALLY jack the board up in a  bowed-out condition,
while the glue cures, and then when it's
removed-presto! - You've got a  board with lots of
bearing and crown ! ( And I still like the bamboo
skewer idea,  to make double extra sure nothing ever
"slides"  ! They're quite strong, only 1/8" diameter,
and already have "fluting ".  ) 

My only concern would be in putting TOO MUCH crown, or
stifness, into the board, thereby wrecking the tone in
some way ?  Is that a  reasonable fear ???  How do I
calculate "how much " ? I would imagine, with ribs
thus laminated, they'd keep a  lot of their arc, once
the jig was removed. ( As long as the glue cured fully
. ) And that they'd be more resitant to downweard
deflection. ( My 1899 Knabe has laminated ribs, and
plenty of crown, still ! )

 Since you no doubt have this thing strung
> down and the plate off 
> you should be able to get a very reasonable
> estimation of the 
> re-finished assembly strength. 

Yeah ? Like how ? I'm totally  "in the dark' as to
what you're talking about doing here. ( Sorry. )


Figure how much down
> bearing you are 
> going to end up with and make sure the thing can
> hold it. 

Sure.  And how much do I want ?  And How  do I figure
if it can "hold it ?"

 You can easily 
> enough work all this into your scaling spreadsheet.

Sorry. Don't  know how that relates, either ? Will you
please "clue me 
in " on this ? 

> All this said.... its probably easier and better to
> just knock out the 
> old panel and put in a new one.  

I dispute that. I'm still one of those "politically
incorrect " types who believes that old wood is more
resonant than new, and if you can get the desired
crown back into an old board, it's better !!!!!!!! 

Thump
> 
> 



 
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