Crack fillers - old soundboards

[jolly roger]

Hi Joe,
          I'm with you on this one, If the board has reasonable crown, and
the bridge has not rolled.  That is my criterion for shimming.  I dry the
board down with the piano tarped, 2 X 50watt  heaters for 48 hrs.  Shims
are also dried down.
I use the Spurlock system.
I lightly wedge the board from the beams to the ribs. and use go bars to
apply clamping pressure on the shim.  My G bars are made from 450psi 1" dia
PVC gas piping, I have made feet for the bars  I'' X 1" X 2 1/2" blocks
with a 1 1/8''  X 1/2" deep hole bored into it to recieve the end of the pipe.
I use hide glue, and have not seen any failures.
For panel glue joints that have let go clean, I use epoxy.  Same drying
process, tape the crack from the top with PVC electrical tape. Leave for
about 5hrs. and trim with a sharp chisel.  Rib to panel integrity is
important in both cases, as is the inner rim and belly rail glue joint.  I
have seen more than a few pianos where the treble belly rail glue joint has
failed.  
 The belly rail on a lot of pianos is quite thin in this area, and I will
make a big difference in both tone and sustain, if this joint has been part
of the problem.
If the board has no crown, then there is only one solution. A new board.
Roger


At 04:12 PM 4/30/01 -0700, you wrote:
>PR-J
>Not in my experience. I done too many boards with no/negative crown to
>varify that shimming, (if done properly), does do more than cosmetic. I
>firmly believe that shimming does add latent energy to the board. Although,
>it is definately not as good as a new board, sometimes it's the only
>alternative to scrapping an otherwise decent instrument.
>Regards,
>Joe Garrett, R.P.T.
>----- Original Message -----
>From: <Yardarm103669107@AOL.COM>
>To: <pianotech@ptg.org>
>Sent: Monday, April 30, 2001 1:52 PM
>Subject: Re: Crack fillers - old soundboards
>
>
>> In a message dated 4/30/2001 2:14:21 PM Central Daylight Time,
>> mfarrel2@tampabay.rr.com writes:
>>
>> << Sometimes cracks cause buzzing. Filling them or proper shimming
>>  will stop/prevent a buzz from a cracked soundboard >>
>>
>> The crack doesn't cause the buzzing but the pieces of splintered wood
>> adjacent to each other across the gap of the crack. Shims will always
>recrack
>> along the glued edges at some point, so now there are three cracks instead
>of
>> one. Delaminated ribs are indeed another issue and need to be addressed
>> appropriately. I guess I don't mean to be such a hardass about this, but
>over
>> the years I've concluded (always subject to correction) that shimming is
>just
>> about as close to purely cosmetic as you can get; it makes the customer
>(or
>> buyer) think that there is no longer a problem, but the problem (the cause
>of
>> the original cracking) hasn't been fixed, just sidestepped. I'd appreciate
>> your take on this.
>> PR-J
>