Unusual rib structure?

[Greg Newell]

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Del,
         Do I take this to mean that there is no sudden taper 4-6" from the=
=20
end of each rib? How thin is the gradual taper you speak of by the time it=
=20
reaches the end? Do you bring the rib all the way into the rim or does it=20
stop before the rim? Or do you still use the cutouts but leave a gap for=20
free movement?

Greg Newell


At 04:01 PM 5/8/2003, you wrote:


>----- Original Message -----
>From: "Ron Nossaman" <RNossaman@cox.net>
>To: "Pianotech" <pianotech@ptg.org>
>Sent: May 08, 2003 9:22 AM
>Subject: Re: Unusual rib structure?
>
>
> > As many concave crowned soundboards as I find with no measurable string
> > bearing in the killer octaves of pianos with "rib crowned" boards, I
> > suspect that these are indeed compression supported boards with crowned
> > ribs. Doing load analyses on these ribs, with string scale and bearing
> > schedules taken from the piano (allowing for what was probably in the
> > killer octave before it went flat), and considering the feathering of
>these
> > ribs, I see no way those ribs are holding up even half of the string=
 load
> > placed on the soundboard assembly. They may be rib crowned, but they're
>not
> > rib supported.  And as long as the ribs are feathered that way, they
>won't
> > be.
> >
> > Ron N
>
>
>Which is why we don't feather ribs that way. Basically, the rib is divided
>into thirds. Feathering starts about one-third of the way in from each end
>(depending on the location of the bridge) and is flat, not concave.
>
>Del
>
>_______________________________________________
>pianotech list info: https://www.moypiano.com/resources/#archives

Greg Newell
Greg's piano Fort=E9
mailto:gnewell@ameritech.net=20

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