Shims and soundboardrepair.

[Brian Trout]

Hi Ron,

You bring up an interesting question.

I have taken old sections of soundboard and sawed shims out of them.  The
reasons I did so may or may not have been good ones.  (I haven't shimmed a
soundboard since I replaced my first one.  I guess it spoiled me.)

When we were doing more shimming, we used to dry the board out a bit, (I
don't think we had a specific RH or MC), put wedges underneath between the
board and the beams to force it up, and then start shimming.  We would open
up the cracks on the top side of the board as nicely and evenly as we could
with a tool that made a nice V-groove the right shape for a shim to go in.
We almost never had need of a shim that went all the way through the board,
so the old shims were tall enough for what we were doing.  We would glue
them in, and then when the glue was dry, take a sharp chisel and smooth them
out flush with the surface of the board.  What we were doing would probably
have been considered more of a cosmetic repair.

The initial attempt at making the shims from old soundboards had nothing to
do with expense.  We had two problems that we thought we might be able to
help with.  The first was appearance.  The new shims we were getting were
very white wood, and stood out on the old boards.  We thought that perhaps
the old wood might have a little more color.  It did tend to have a little
more color, but was still whiter than the surrounding board.  The second
thing that was bugging us was that the new shims did not come to a point on
the bottom.  They were often too wide to get into smaller cracks that we
didn't want to open up far enough to get the new shims into.  The shims that
I cut out were almost as tall as the old soundboard was thick, and most all
of them had a nice sharp edge on the bottom.

I don't know if these were good or bad.  I do know that the other techs
gravitated towards those shims.  It seemed that given the choice, they
always picked up the ones I had cut out.  I think they are used up by now,
and I never did make any more.  Like I said, I got spoiled putting in new
boards.  If I were to start shimming again, which I will probably do at some
point, I may re-evaluate my methods of shimming, and perhaps the new shims
might work better with a new method.

Interesting thoughts though, Ron.  Glad you piped in.

Brian Trout
Quarryville, PA
btrout@desupernet.net


----- Original Message -----
From: Ron Nossaman <nossaman@SOUTHWIND.NET>
To: <pianotech@ptg.org>
Sent: Monday, December 06, 1999 11:53 PM
Subject: Re: Shims and soundboardrepair.


> Danny,
> The old wood has also been under compression for a lot of years and has
> suffered some accumulated compression set. Actually, I doubt that there is
any
> harm at all in using old soundboard material from one board to shim old
> soundboard material in another. I doubt that there is any benefit either,
but I
> don't see any harm. The salvageable portions of the old panel will be the
> planks that haven't failed to the point of cracking, and if the board
being
> repaired still has some crown under string bearing load, and the budget
doesn't
> allow soundboard replacement, then why not? The shim material will be of
about
> the same degree of deterioration as the board being shimmed. Of course,
the
> fact that the board being shimmed *is* being shimmed means that it has
> deteriorated enough to crack in the first place and is at least somewhat
> suspect. I have a question though that is more practical than judgmental.
If
> you have a cracked panel that is quarter sawn, and want your shim to have
> roughly the same grain orientation as the panel, how are you going to cut
shims
> that are both deep enough, and with the proper grain orientation out of an
old
> quarter sawn soundboard panel without laminations?
>
>
>
> Ron N
>