Restoring crown in old soundboards

[Isaac OLEG]

Hi Del,

ANd what about gluing back (partly) the soundboard and the ribs wedged
a little apart of the belly. Was aid it can produce a little crown
from treble to the killer zone - but it for sure seems a lot of
uneasy work to me (unglue, push toward center, glue back ...

Forcing the ribs may well give them a tad of resistance is not it ?

Curious of what you think about .

Best

Isaac OLEG

Entretien et réparation de pianos.

PianoTech
17 rue de Choisy
94400 VITRY sur SEINE
FRANCE
tel : 033 01 47 18 06 98
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> -----Message d'origine-----
> De : pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org]De la
> part de Delwin D. Fandrich
> Envoyé : mercredi 16 avril 2003 19:32
> À : Pianotech
> Objet : Re: Restoring crown in old soundboards
>
>
>
> ----- Original Message -----
> From: "Farrell" <mfarrel2@tampabay.rr.com>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: Wednesday, April 16, 2003 4:13 AM
> Subject: Re: Restoring crown in old soundboards
>
>
> > There are old PTG Journal articles on this process. I did
> this on my first
> restringing job - little Estey microgrand. I dried the heck
> out of the
> board - cracks opened up all over the place. I wedged in
> blocks between ribs
> and framing until I heard c-r-a-c-k-i-n-g (and in some
> cases, until I heard
> C-R-A-C-K-I-N-G!). I did the Spurlock shim method.
> Installed at least 20
> shims - maybe more. Man, that thing bellied up like nothing
> you've ever seen
> before. Give that rascal a sharp fist in the middle and you
> got this massive
> (relatively speaking) B-O-O-M out of the piece of trash
> soundboard. Strung
> that puppy up (with carefully measured downbearing),
> measured crown - and
> found that the board was at best F-L-A-T.
> -----------------------------
>
> Alan,
>
> As Terry found in the above illustration, soundboard
> shimming is a cosmetic
> repair only. Yes, you can make the soundboard look really
> nice. And you can
> create some illusion of crown before the piano is restrung.
> And, as often as
> not, the piano will sound better once the rebuilding is
> complete. But any
> acoustical problems related to a flat soundboard will remain.
>
> I've been preaching away on this subject for something over
> thirty years
> now. But we seem to find it necessary to rediscover this
> truth over and over
> and over. There is no way to "restore" crown in a flat (originally
> compression-crowned) soundboard assembly short of removing
> the original ribs
> and replacing them with new crowned ribs. The soundboard
> assembly is flat
> because time, environment and compression set have taken
> their toll on the
> wood fibers within the soundboard panel. Nothing can change that.
>
> See my Journal articles on soundboard damage and the more
> recent series on
> the epoxy-coating treatment.
>
> Del
>
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