Laminated Soundboard Ribs

[Delwin D Fandrich]

----- Original Message -----
From: "Phillip L Ford" <fordpiano@lycos.com>
To: <pianotech@ptg.org>
Sent: February 13, 2002 3:56 AM
Subject: Re: Laminated Soundboard Ribs


>
> OK.  The chosen stiffness and mass (and perhaps other parameters that
> I'm not aware of - like speed of sound through the material, damping,
etc.) will
> affect the way the board vibrates.  So, the same board built up in two
different
> ways with ribs of two different materials, those different ribs having the
same
> bending stiffness but other parameters being different would not vibrate
in the
> same way and so would sound different. This gives the designer some
choices,
> although it does make things more complicated.
>


I've been using laminated ribs since the early to mid 70s. Initially, they
were simple substitutes for solid spruce. The idea was to gain consistency
and use lumber that was otherwise not viable. Besides, I've always been a
sucker for a new idea. Much like Terry, I figured if laminated ribs were
good for small wooden boats they should be good enough for pianos.

That grew over the years to bending the crown into the rib stock as it was
being glued up. We now use five different presses with five different radii
for use in various parts of the piano.

While I've not done any testing specifically designed to either prove or
disprove the point, as near as I could tell the acoustic performance results
were the same for both solid and laminated ribs as long as their physical
characteristics were similar. That is, both rib sets having the same height,
width, crown radii and feathering. Initially our upright used solid ribs,
the conversion to laminated ribs coming sometime in about the middle of the
production run. Again, there was no change in acoustic performance that we
could credit to the laminated rib specifically.

Initially they were feathered and sized just like the solid ribs I was
replacing. This is no longer the case--feathering design is considerably
different nowadays. I've shown and/or demonstrated our current practice in
various classes over the years and will be doing so again this year in
Chicago.

Phil is certainly correct in his observation that laminating the ribs does
give the designer more choices. And, I suppose it does make things more
complicated--though in this case the complication is most welcome. Having
worked with laminated ribs for nearly 30 years now, I would never willingly
go back to using solid ribs.

Del