Increasing Crown

[Fenton Murray]

All,
I'm watching this thread with interest because of egos not subject. Thump,
go for it! Let us know, I remember John Block, met him in Denver, with his
valve springs.
Trent, "tautology" come on! I think Terry's statement was informative of his
position on the subject, how else to express it?
Terry, Please stay on this list.
I'll shutup now.
Respectfully to All,
Fenton Murray, RPT
www.MurraysPianoTuning.com
----- Original Message ----- 
From: "gordon stelter" <lclgcnp@yahoo.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Tuesday, March 15, 2005 1:37 PM
Subject: RE: Increasing Crown


> Thanks Terry, I certainly don't mind your considering
> this idea  "beneath you", but if it could easily save
> some glorious old pianos ( like Knabe uprights ) from
> the dump because they would simply be economically
> unfeasible to put new boards into, isn't that a nice
> thought ?
>      I have put the whole procedure into a simple
> step-by step format, and will elaborate at length when
> I have more time, but, basically: a brace is attached
> to the piano back through which are threaded inserts
> which allow bolts ( 3/8") to impinge upon the rib
> spines at the point where the bridge crosses on the
> other side of the board. By adjusting the bolts any
> amount of pressure can be applied to bow the board out
> at the bridge line, up to popping it right out of the
> piano ( if not adequately secured at the margins. ) A
> thin laminate ( designed by someone else, I guess, as
> you seem not to be interested ) is glued to the ribs'
> spines, with a another layer of laminate temporarily
> on top as a caul. Then the whole shiboo is bent
> outward by turning in the bolts, bellying out the
> board, allowed to dry, and the brace and cauls
> removed.
>     Specifically: I wonder what laminate would be
> thin, strong and light enough ? It's kind of neat to
> think of an old, shot CC board suddenly becoming a
> rib-crowned board, IMHO.
>      I'll put up the whole procedure as it occured to
> me ASAP> I invite anyone with more time than me
> presently to put this idea to the test.
>      Thump
>
> P.S. I also thought that the elliptical rib laminate (
> as in Ron Overs' I beam type, which are wider across
> under the bridge line ) might be nifty, if he doesn't
> hold patent rights on them. Also: one simple brad
> could be placed through the added laminate at the
> bridge line point, to keep it from sliding all over
> once pressure is applied. And a 4 more hanging driven
> through the caul-laminate sides, to keep the glued-up
> laminate from sliding off sideways. The problem of
> gluing a flat laminate to a  curved rib spine might
> not be so bad, if the "squeeze-out" were trowelled
> along the glue-line, to add a  bit of filler. I
> imagine "West's" with some of the additive to give it
> "body".
>
> >
> > I didn't answer because I didn't know quite how to
> > respond without sounding
> > sarcastic.
> >
> > Sooooo, not meaning to sound sarcastic.........
> >
> > Yes, I suppose if you wedge up a flat board and glue
> > on some auxillary
> > laminations, you might be able to get the structure
> > to retain a bit of
> > crown - but will that do any good? You are
> > increasing the mass of the ribs.
> > What effect will that have? How much crown do you
> > want? Will it get you
> > enough crown?
> >
> > I guess I just don't have any real interest in
> > haphazardly applying
> > band-aids to a soundboard that is shot.
> >
> > Terry Farrell
> >
> > > I am currently fiddling with the idea of gluing
> > > auxilliary laminations to the spine of existing
> > ribs,
> > > while the two are flexed together, along with a
> > > backing caul, by a jig secured to the back of the
> > > piano.
> > >      I asked Terry Farrel to recommend a
> > > laminate--perhaps 3mm thick, 3 ply, but have not
> > heard
> > > back from him yet. Anyone else care to comment?
> > >      Thump
> >
> >
> >
> >
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