Curve on Bridge Bottom

[Erwinspiano@AOL.COM]

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In a message dated 5/2/2002 9:07:11 AM Pacific Standard Time, 
RNossaman@KSCABLE.com writes:


> Subj:Re: Curve on Bridge Bottom 
> Date:5/2/2002 9:07:11 AM Pacific Standard Time
> From:<A HREF="mailto:RNossaman@KSCABLE.com">RNossaman@KSCABLE.com</A>
> Reply-to:<A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> To:<A HREF="mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> Sent from the Internet 
> 
> 
> 
> 
> >
> > >>>>>>>>>>>At this point I'm not convinced thats all there is to it. In a
> free
> > state the board is straight along the grain and in the example above I 
> stated
> > that. I have glued boards  into rims with no bevel in the rasten and no 
> curve
> > in bridge bottom (Hardman & Weber) or in the rim and these did not form 
> but a
> > smidge of this crown along the bridge line. How do I explain this?
> 
> 
> Where's the rest of the information? Stiffness of the ribs, stiffness of 
> the
> panel, crown heights, etc. There are still a whole lot of possibilities 
> here
> other than bevel and bridge crown, all of which would affect the long 
> crown. If
> the rim was indeed on a plane (same height all around), and you had  nearly 
> no
> crown along the grain after installation, then you had nearly no crown 
> along
> the ribs either. How do you explain that? 
> 
> 
> >
> > >>>>Don't foget though that the treble and bass ends usually need some
> > coaxing down at the ends which is also allowing the longer ribs to have 
> more
> > of the  effect you stated above.
> 
> 
> I didn't forget it. This is what I'm talking about. I said up front that
> forcing the board down on the rim forces the long crown to form. 
> 
> 
> >
> >  In this case it seemed even more so. If the rim were to be simply cut
> > slightly different, asending a bit so to match boards perimeter at that 
> tail
> > then this effect would not occur and there would be no or nomminal crown
> > along the bridge line.
> 
> 
> It would take a little more than slightly different, but yes. Why would you
> want to, and do you know of any piano where this was done? What has this to 
> do
> with crowned bridges?
> 
> 
> >
> > >>>>>>>> What I think would be of interest would be to attempt to measure 
> any
> > residual crown along the grain after the bearing goes on as Terry 
> suggested.
> > I think a thread could be pulled across the top of the board under the
> > strings and then make some allowance for the top being thinned. Perhaps a
> > comparison of that dimension with the rib compression too would be of
> > interest.  
> 
> 
> Since the rim plane and rib crown define this long crown, how can there be
> anything but a direct correlation? 
> 
> 
> >
> > What would that tells us? Hey I don't know I'm not the expert just a 
> casual
> > observer.
> 
> 
> Me too. I don't like the term "expert". To me it means someone who quit
> learning many years ago when they had their shirt stuffed. Let's avoid 
> experts
> as much as possible and work this stuff out with our own brain cell(s).
> 
> 
> >
> >                                  Back to the salt mines
> >>
> >> >>>>>>>>>>>>>>>>>Dale>>>>>>>>>>>>>>>>>>>>>>>>>>
> >
> 
> 
> Me too two.
> 
> Ron 


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