Restoring crown in old soundboards

[Delwin D. Fandrich]

----- 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