[pianotech] FW: laminated ribs again

[David Love]

I think it's not so much an issue of stability but rather of tossing a salad
of different lots so that there is a greater likelihood of blended
uniformity from rib to rib.  If you just cut all the plies from one piece of
wood and then glue them back together that would defeat the purpose of
lamination.  One needs to cut the plies from a number of different planks,
shuffle the deck and them glue them up.  That insures greater uniformity and
thus predictability (the real goal) between ribs.  

 

I do wonder, however, since added mass in the treble seems to be a goal, why
one wouldn't use a heavier wood or better yet a graduated blend of different
woods to make up the laminations so that you could gradually increase the
mass coefficient as you ascended through the treble.  Rather than just
switching the type of wood, as has been done in the past, you could simply
gradually add one, two, three plies of a heavier would in each consecutive
rib as you moved into the treble.  

 

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of erwinspiano at aol.com
Sent: Wednesday, January 28, 2009 2:39 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] FW: laminated ribs again

 

Hi Marco
  I have used laminated ribs infrequently. Although I agree with the big
boss as to a more stable Modulus of elasticity they can still vary a great
deal depending on the grain density/wood density you laminate with.
Laminating two sets of identical Stwy B ribs using wider grain wood on one &
very tight grain on the other, indicated a definite and marked difference in
the strength of those two sets. The denser grain was a stiffer set of ribs.
I believe it important to make note of this difference & make an informed
decision about stiffness parameters. Ie. how deep/wide/crowned the rib
should be...cutouts. 
 The next best thing to Laminated ribs is good set of stiff Sitka ribs cut
from the same cant of wood, which, will yield a more even M.E. than ribs
selected willy nilly as the to grain count. Wood density/stiffness will be
more uniform.
  I know it's always something.

 I'm open to hear more comment on this.
  Dale

 

 

 

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