Dear Owen,

Thank you for answering me. You're the first by the way!

In the meantime, using an endoscope in order to search for the bottom bars
(unable to get a decent plan in decent timing), I've started like a surgeon
to open up the instrument from the bottom. Taking in consideration the
damage, I'll have to make 3 "windows" in order to be able to repair the
damage.

One is now ready. It's late now, I'm going to bed and post more later on.

Greetings,

Chris.


-----Oorspronkelijk bericht-----
Van: Harpsichords and Related Topics [mailto:[log in to unmask]] Namens
Owen Daly
Verzonden: maandag 12 december 2016 17:47
Aan: [log in to unmask]
Onderwerp: Soundboard repair

It can be shimmed (I recently had occasion for the first time to do so much
shimming that I got pretty handy at the process), but you will want to apply
some kind of pressure and backing from underneath to bring the two sides of
the split to an even level. In my case, where there were openings with easy
access in the bottom of the instrument, I made blocks of scrapwood thick
enough not to flex, and with relief grooves where the crack/shim is/will be
so the shim could go all the way in and be proud underneath, and then jacked
the whole thing up from below with enough pressure to bring the two sides
level with each other.

In a couple of cases I was able to do this with a set of tiny "go-bars"
wedging the support block up from below, but in others I used one of those
handly little screw jacks that piano folks use to support wrestplanks of
pianos during the pounding of tuning pins into their holes during stringing.
They're not cheap, but work like a dream. Made by Starrett.

For the shimming, you will need to practice on something but the basic
outline, as I learned it went like this:

1. Open up the crack so that it has a clean, uniform width, wide enough to
take a shim of some substance, perhaps a bit more than 1mm wide. I used two
expedients: a Japanese Azubiki saw, which is made to initiate cuts in floors
or big carpentry mortises (q.v.) and the BACK of an XACTO blade burnished
like a cabinet scraper.  Google will show images of azebiki saws. Mine has a
very thin kerf.

2. If you compress the shims, as described below, they will be flexible
enough to follow any slight curvy waviness of the opened cracks, so those
cracks do not need to be enlarged until they are dead straight.

3. Make your shims out of soundboard stock, and make their width slightly
too great to enter the prepared open crack.

4. Compress the shims until they are so squished that they will slide all
the way down into the crack and can be pulled back out again, going proud
both top and bottom easily. A colleague simply rolls the shims with the
round handle of an XACTO handle, but I came up with a really handy and
better-controlled solution you'll love:  I ran the shims through my
Italian-made Atlas Pasta Machine, which has thickness settings for the
rollers, for different thicknesses of homemade pasta sheets, from "1" (about
2mm thick for ravioli) all the way up to "9", which is very, very thin,
presumably for Angel Hair pasta. I found that in general my shims (cypress
for a cypress board) were just right for easy insertion when rolled at "7."
Works a dream, and the shims are flexible enough lengthwise to follow the
wavy curve of a non-straight crack.

5. My colleague and I found that for this application, the best glue is,
yes, I say (eating some crow) very fresh Franklin Liquid Hide glue. I put
masking tape very close to the edges of the crack, applied the glue deep
into the crack, very quickly inserted the shim to the desired depth (so a
little sticks out up top and down underneath inside) and then wiped the
excess glue clean with a wet cloth.

6. What happens, and you DO need to work quickly, even with the liquid glue,
is that the shim, once it gets wet from glue and mopping-up, swells to its
original size and locks itself into the crack with a great deal of strength.
One shim I tried on scrap WITHOUT ANY GLUE AT ALL, proved, once it had
dried, to be pretty much impossible to remove. Same principle as with modern
so-called "biscuit joiners."

Although we all like to say that minor cracks in soundboards have little or
no acoustical impact, in the case of the repairs I made (I found over 40
splits to shim in that soundboard) once things were "reconnected" the whole
board generated a degree of acoustic response it had lacked previously.

At first it will be a source of anxiety, but once you get the hang of it,
you'll find the process rather enjoyable.

owen


On Dec 11, 2016, at 9:00 PM, HPSCHD-L automatic digest system
<[log in to unmask]> wrote:

> There is 1 message totaling 27 lines in this issue.
> 
> 
> Dear members,
> 
> I have a pianoforte which has water damage. One of the problems is the 
> soundboard which has cracked in several places.
> The problem is the boards are now "wavy": 1 board is relatively 
> straight, the adjoining plank makes an arc wel below the adjoining plank.
> I wonder if this can be repaired without further damaging the soundboard?
> 
> Greetings,
> 
> Chris.



Owen Daly Early Keyboard Instruments
557 Statesman St. NE
Salem, OR 97301
http://www.dalyharpsichords.com
(503)-362-9396

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