Rib overkill

[Mike Bratcher]

Ya' know...I had this same idea years ago.  The idea was based on the
violin.  The panels are made of different woods to cater to different
characteristics.  Maple for stiffness and good high end tones, and spruce
for bass tones.  I thought about this in relation to the piano.  Maple is a
tougher wood than spruce.  The top panel made of maple could hold crown
better (maybe), and give better high end sustain.  While the lower panel,
made of spruce and crowned downward,  could be thinner and give better bass
response.  Connect these with a tone pole and you have a pianolin.

Would it work?  Who knows...?

Just a crazy idea I had to use up more wood and drive rebuilders crazy, not
that they need any help.

Mike Bratcher
----- Original Message -----
From: "Joe And Penny Goss" <imatunr@srvinet.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Sunday, July 27, 2003 8:48 PM
Subject: Re: Rib overkill


> ??
> Has anyone ever made a piano with two boards. Parallel to eachother with
> different stiffness factors?
> Joe Goss
> imatunr@srvinet.com
> www.mothergoosetools.com
> ----- Original Message -----
> From: "Ron Nossaman" <RNossaman@cox.net>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Sunday, July 27, 2003 7:28 PM
> Subject: Re: Rib overkill
>
>
>
> > It can. A more flexible board will tend to be generally louder, with
> > shorter sustain. A stiffer board will tend to be not as loud, with
longer
> > sustain.
> Will the bass suffer?
> >
> > Yes. If there is to be any hope of getting a fundamental out of the low
> > bass, the board needs to be flexible down there, and the back scale
needs
> > to be long, and the core wire needs to not be the diameter of an 8d
nail.
> > At the same time, the treble needs to be stiff or you will get the
> > percussive attack and short sustain of the "killer octave" through the
> last
> > two octaves or so. Stiffness requirements are widely different from one
> end
> > of the scale to the other.
> >
> >
> > >I think I also remember Del mentioning something about a board giving
too
> > >much of a percussive sound and not as much string sound.  Is this with
a
> > >board that is too stiff?
> >
> > Probably too flexible.
> >
> >
> > >How does the thickness of the board relate to how much load it can
> support?
> >
> > It depends on the crowning method. A compression crowned board will be
> > stiffer with a thicker panel, and support comparatively more load than a
> > compression crowned board with a thinner panel. With a rib crowned
board,
> > assuming it is really rib supported and not just a compression crowned
> > board with machine crowned ribs, the panel thickness makes much less
> > difference. With a rib crowned, rib supported board, there is no need
for
> a
> > thick panel if the rim is solid.
> >
> >
> > >And in relation to the rib thickness?
> >
> > Again, it depends on the crowning method. Compression crowned boards
tend
> > to have ribs wider than they are deep, because they start out flat and
the
>
> > panel expansion has to bend them to form crown. Rib crowned and
supported
> > boards will have ribs less wide, and deeper, regardless of panel
> thickness.
> > Ribs get stiffer in proportion to their width, and to the cube of their
> > height (and inversely to the cube of their length), so a little bit of
rib
> > height makes them a lot stiffer.
> >
> >
> > >I'm sure all these things are interrelated.  What are the trade-offs?
> >
> > Those are some of them.
> >
> >
> > >Next, I'm sure the size of the board is a factor.  A smaller piano will
> > >have more support from the rim, because the there is more rim per area
of
> > >board.  Yet another factor to consider, aye?
> >
> > Absolutely. Soundboards, contrary to manufacturers' marketing literature
> > bragging about how their soundboards have more area than their
> > competitors', are for the most part already too big. Redesigns I do
> > typically lose something around 20% of the existing active soundboard
> area,
> > depending on what I started with.
> >
> >
> > >How does one judge or weigh the trade-offs?  There are so many
variables.
> >
> > A bunch of variables, the most critical of them not the ones we have
> always
> > been taught were all important. One can either put in a couple of
hundred
> > soundboards, making incremental-to-major changes in virtually everything
> > until he works out a set of priorities and effects of design features,
or
> > he can do what I did and start rethinking what I thought I knew against
> the
> > good fundamental science and physics based advice and guidelines of
> someone
> > who did do the basic R&D from scratch. That would be Del.
> >
> >
> > >There's no real point here to my questions.  I am always trying to
learn
> > >more about my trade.  And who else do I learn from other than the folks
> > >who do this every day?
> > >
> > >Mike Bratcher
> >
> > Every day's a new day for all of us isn't it? There's always something
to
> > learn - and heal up from.
> >
> > Ron N
> >
> > _______________________________________________
> > pianotech list info: https://www.moypiano.com/resources/#archives
>
> _______________________________________________
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