Oops... Re: Unusual rib structure?

[gordon stelter]

Hi Del,
    A real cutoff bar excludes a "dead" area of the
soundboard from absorbing vibrations, converting them
to heat, right? Or, more specifically, the flexion
area between the resonant portion, and the restrained
portion, as per stiffness caused by the case design. 
And it supports the more vibratory portions a bit,
too, so they maintain crown longer.
     And you know a whole lot more about pianos than I
do.
     But, from the photos, this does not look like the
builders' intent in this case, to me.  Looks to me
more like they were just trying to get more vibration
spread around into the dead corner. Not define it from
the vibratory portion with a vibratory stop.
     Sort of a different idea, it seems to me.
     Respectfully,
     Thump


--- Sarah Fox <sarah@gendernet.org> wrote:
> Hi Del et al.,
> 
> So these rib ties were somewhat of a "missing link"
> between the old
> no-cutoff-bar design and the more modern cutoff bar
> construction???  Just
> curious -- What was the evolutionary history, in a
> few sentences or less?
> 
> Thanks!
> 
> Peace,
> Sarah
> 
> ----- Original Message -----
> From: "Delwin D Fandrich" <pianobuilders@olynet.com>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Wednesday, May 07, 2003 3:16 PM
> Subject: Re: Oops... Re: Unusual rib structure?
> 
> 
> >
> > ----- Original Message -----
> > From: "Sarah Fox" <sarah@gendernet.org>
> > To: "Pianotech" <pianotech@ptg.org>
> > Sent: May 07, 2003 10:32 AM
> > Subject: Re: Oops... Re: Unusual rib structure?
> >
> >
> > > Hi Thump,
> > >
> > > >      As you know, vibrations pass more rapidly
> along
> > > > wood grain, than across it. I believe that the
> intent
> > > > here was to allow the vibrations, passing into
> the
> > > > ribs from the bridge crossover point, to have
> another
> > > > means of surface distribution. One which helps
> them
> > > > overcome the "cross grain slow-down". And I
> suspect
> > > > that Mr.Wissner tried it for this reason,
> liked the
> > > > effect, and let it stay.
> > >
> > > Dunno...  These ties are at the ends of the
> ribs, not the middle.  I was
> > > thinking they might be under light tension to
> help maintain the crown.
> > >
> >
> > They are there to simulate a real soundboard
> cutoff bar. They evolved from
> > a time when the largest possible vibrating area of
> soundboard was
> > considered to be some sacred. Indeed, it still is
> by some piano makers,
> > evidence to the contrary notwithstanding. In any
> case, these straps did
> > improve the sustain slightly through the mid-tenor
> and lower treble. Not
> as
> > much as a real cutoff bar would have, but they
> were/are better than
> > nothing.
> >
> > Del
> >
> > _______________________________________________
> > pianotech list info:
> https://www.moypiano.com/resources/#archives
> 
> _______________________________________________
> pianotech list info:
https://www.moypiano.com/resources/#archives


__________________________________
Do you Yahoo!?
The New Yahoo! Search - Faster. Easier. Bingo.
http://search.yahoo.com