my own Soundboard

[Erwinspiano@AOL.COM]

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In a message dated 1/19/2002 1:51:33 AM Pacific Standard Time,=20
JD@Pianomaker.co.uk writes:


> Subj:Re:y own Soundboard=20
> Date:1/19/2002 1:51:33 AM Pacific Standard Time
> From:<A HREF=3D"mailto:JD@Pianomaker.co.uk">JD@Pianomaker.co.uk</A>
> Reply-to:<A HREF=3D"mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> To:<A HREF=3D"mailto:pianotech@ptg.org">pianotech@ptg.org</A>
> Sent from the Internet=20
> .   J D Writes
> As to the crown in the other direction, I'll quote from Wolfenden,=20
> writing in 1916:
>=20
>    "Modern practice all over the world, aims to put the board itself=20
> into a state of compression, to that it is constantly acting to=20
> assist the bars [belly bars =3D American: ribs] to do their duty.
>    The writer's own formula is: Arch the bars to about the usual=20
> curvature [60 ft radius], keep the board warm at say 100=B0 to 120=B0 F.=20
> for a few hours to shrink it.
>   Place it on a frame or board hollowed out a trace deeper than the=20
> curve of the bars, and while the board is hot, glue the bars down.
>    When the pressure is released, the rounding will be greater than=20
> the original curvature of the bars, and the board in a considerable=20
> state of compresssion, which it will retain and which will increase a=20
> little.
>    The backs of the bars which by this process become a little hollow=20
> in the length, are afterwards planed straight.
>    The whole structure thus becomes a highly elastic spring"
>  > =20
   Hi JD
 I totally agree with Samuel and can relate having made many boards this way=
=20
with the exception that his drying method is archaic and unpredictable or=20
just not clearly presented. As he subscribes to cutting 60 ft. radius ,which=
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is good, it however needs to be coupled with more predictable and moderate=20
E.M.C in the panel after drying. I however no longer think it a must that th=
e=20
caul or dish radius be greater than the radius of the ribs. Even with 60 ft.=
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soundboard cauls or dish and drying to 30% R.H./6 % emc,  the long ribs will=
=20
still hollow a bit. If its tooooooo dry using his method one would still end=
=20
up with too much panel compression and defeat the purpose of significant rib=
=20
crowning by introducing the destructive crushing cycle again.
>  You wrote
> For gluing the belly bars, I'd forget about clamps and pneumatic=20
> arrangements.  Good old go-bars are fast and efficient and you can=20
> easily construct a gluing press that can be quickly dismantled when=20
> you're not using it.  Some of the German makers have invested=20
> millions in fancy machinery for special tasks but there are cheap and=20
> efficient traditional ways of doing almost everything.  All the=20
> finishing work on the bars is done with a hand plane and good=20
> pre-1914 chisels.
> >
        WoW JD Have you used a go bar deck verses a fire hose press? I've=20
used both and find the go bar deck (I still have a very nice one)all though=20
possible and feasible with good results. However  superior glue joints occur=
=20
with the absolutely even pressure of air. Less glue applied to get glue=20
coverage in the  joint and way less glue squeeze and clean up. Also the setu=
p=20
time and teardown time is less.=20
   Physically  go bars are more demanding and more dangerous ,Crack split oh=
=20
wow there is another rsoundboard dent to fix as the bar slides off . No more=
=20
ribs sliding around when the first go bar presses to the rib. See what I=20
mean?

> I'll write an article one day on sharpening knives, chisels and plane=20
> irons so that you can shave with then and tell you a story of how I=20
> was too clever by half when demonstrating these skills to an=20
> apprentice!  J D
>  =20
              J D I'd Love to see this in print. Always new tricks or old to=
=20
sharpening.

       Best--Dale Erwin




> JD
>=20


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