Re: [MMM] Practical matters

Hello Alison,

Below is a link, and some general tips.

http://www.taunton.com/finewoodworking/pages/bw0002.asp

This author and press are top notch. I hav'nt seen this book, but I'm sure
it's very good.

Basically, one must have accurate 90 degree angles from edge to board face,
and a good tight fit betwixt edges. Check for gaps, and or twist. Needless
to say, your boards should be as flat as possible. No twist or bow.

Use regular wood glue, or a yellow (aliphatic resin) wood glue. Both are
fine.

When you do clamp them up, just use enough pressure to keep them together.
No joint strength is gained from overclamping. You'll just crack the spruce
probably. You may need to apply (through gravity) some weight along the
joint as it dries. This will help keep the boards flat while the glue dries.
Concrete blocks on wax paper for instance.

Good luck, and ask all that you wish of me.

George

George Zelenz wrote:

> Hello Alison,
>
> Below is a link, and some general tips.
>
>
> http://www.taunton.com/finewoodworking/pages/bw0002.asp
>
> This author and press are top notch. I hav'nt seen this book, but I'm
> sure
> it's very good.
>
> Basically, one must have accurate 90 degree angles from edge to board
> face,
> and a good tight fit betwixt edges. Check for gaps, and or twist.
> Needless
> to say, your boards should be as flat as possible. No twist or bow.
>
> Use regular wood glue, or a yellow (aliphatic resin) wood glue. Both
> are
> fine.
>
> When you do clamp them up, just use enough pressure to keep them
> together.
> No joint strength is gained from overclamping. You'll just crack the
> spruce
> probably. You may need to apply (through gravity) some weight along
> the
> joint as it dries. This will help keep the boards flat while the glue
> dries.
> Concrete blocks on wax paper for instance.
>
> Good luck, and ask all that you wish of me.
>
> George
>
>
> Great stuff George and just the advice I need. I'll get looking for
> some long clamps and wait for a dry day....

Best wishes

> I have three 8" x 36" x 1/4" spruce tops that I want to make
> into one large board. Before I just glue and rub together I
> wonder if anyone has experience of this type of craftwork and
> can offer some tips. The tops are best quality and expensive
> and I don't want to botch up the job.

Alison! Yes - I have made harpsichord soundboards from
Sitka Spruce, starting with thick planks of spruce.

So I'll just cover the topic of large soundboard
construction and leave the topic of bracing to others.
Personally when doing bracing I just try to thiunk like
a string and I like making pretty braces that will
never be seen again -- like Pascal Taskin did.

1. Dry and age the spruce.

2. Plane the boards on both sides.

3. Join one edge of boards. I think I just did one...
maybe both though.

3. using a 20" bandsaw, slice the 1" spruce planks in
two 1/2" thinner boards - I think I got 2 pieces out of
1" material, though maybe it was three?? Long time
ago...

4. Plane remainder sides until I have 1/4" material, as
you do, but 8 feet long.

5. Carefully sort through the boards, looking for knots
and curvy grain. Cut boards into largest pieces I can
figure that are straight and knotfree on a cabinet
making (table) saw - BUT IMPORTANT NOTE!! Don't have 8"
wide sections -- that is too wide and will warp! 2-3"
seems to be how wide I cut the strips. Also, doesn't
have to be perfectly straight, a little ripple is ok,
just not too much.

Note that making these cuts straight is important --
ideally the boards are hand planed by a joiner (a
person not a machine) and are given a slight concavity
in the center of the edge. I don't recall if I joined
both edges. I have a vague idea that for some reason I
joined one edge on each as cutting along and then just
cut the opposite with a carbide blade to be a really
clean cut only. But seems like should join them.
Convexity is the bad thing you want to avoid as that
will promote splitting at the ends.

6. Layout your boards in the shape of your soundboard.
**Very Important note! ** You have to lay the *end*
grain to ALTERNATE while doing this -- one concave,
next convex. This will be tricky slightly since your
spruce is certainly quarter cut, but just do it so you
have the rigns down to the left on one, then down to
the right on the next. This will result in a soundboard
that does not warp -- if one short section warps a bit
one way, the one beside it warps in the opposite way,
canceling it out.

7. Now get a real straight edge or straight board and
clamp or nail it down to your work bench or (in the
case of very large soundboards), a sheet of plywood.
Place the spine piece against the edge board. Place the
next piece next to it. Put waxpaper under the joint.
Apply glue to edge. Rub two together to spread glue.
use a large set of flat triangular wedges between the
new glued piece and a straight piece of wood you've
tempararily nailed to your plywood -- you have maybe 20
of these two triangle sets (6"-8" by 1.5" rectangles
cut diagonally out of 1/4" thick material.) along the
edge. You tap the triangles together to cause pressure
against the spruce during gluing.

You should try this without glue to make sure it all
fits and you have enough triangels (are they called
spline clamps?) and you can do before doing it with
glue.

Be sure to remove all glue from the top edge with a wet
sponge before it dries! And realize the bottom edge
will have glue stains, so make sure the bottom while
gluing is the real bottom.

8. Wait to dry, then do the next one, moving both the
wax paper and the board that stops the spline clamps.
Repeat.

9. Use bricks set on towels to hold down the soundboard
from warping from the pressure as your total glued area
gets large.

10. Now you have a large sheet of spruce in the rough
approximation of the size you want. If you did a good
job gluing and did consistent planing early on, the
boards will be pretty much flat where they are joined
and need minor touchup. However, you may need to bring
the thickness down a bit. You can do this by running
each side through a commercial panel finishing sander
(these look like an enormous planer but have a 4-6 foot
wide sanding belt inside.) with just the most minute
amount of take off setting. Running something so thin
through a regular planer is strongly discouraged.

But the ideal thing to do is hand finish it using a
plane (will need old-time planing talent for this) and
shape it a bit to be thinner at the edges than in the
center. Perfectly even thickness in the soundboard of
anything other than a modern piano is not ideal -- even
thickness tends to produce thin sounds. Rich sounds
come from hand finishing at this point. X-rayed
blueprints of classical instruments from the
Smithsonian are helpful for this task as they show the
exact thicknesses throughout the soundboard which the
old masters used to get the richness of tone they did.

11. I'll stop now, leaving out discussion of the
fitting of the soundboard to the instrument, which just
needs to be done carefully but is straightforward.

12. Oh, forgot, when you affix the brigde and the ribs
it will be helpful to make a raised table or workbench
to place the board on -- then you make some spars that
are a little bit longer than the distance from top of
bridge to ceiling. Then jam the spars between bridge
and ceiling to provide clamping pressure during gluing.

Good luck and let us know how you end up doing it!
Soundboard construction is a wonderful topic and so
important to getting the right sound out of an
instrument.

Oh here's a tip -- instead of buying all the equipment
needed, can be helpful to either take a night class at
the local trade college, or hire a local carpenter to
let you have access to large bandsaws, joiners and
planers. (though a small 6" joiner, a good
cabinetmaking quality table saw, a 14" bandsaw and a
drill press are all pretty good to have and any
instrument maker will get a lot of use out of each of
these.)

- Jeff

Clarification:

> Cut boards into largest pieces I can
> figure that are straight and knotfree on a cabinet
> making (table) saw - BUT IMPORTANT NOTE!! Don't have 8"
> wide sections -- that is too wide and will warp! 2-3"
> seems to be how wide I cut the strips. Also, doesn't
> have to be perfectly straight, a little ripple is ok,
> just not too much.

the word straight in this section refers to straight
*grain*. Obviously, the edges must be much more
straight than the grain.

And ditto what Gearge said on 90 deg between edge and
face when doing the joining and/or ripping.

- Jeff

Alison!
In general, I will have to say that Partch's string instruments were not
his strong point. Most are not very loud and have required support to be
heard with close miking or sound reinforcement. One of the problems with
the Harmonic Canons is the use of guitar tuning pins which are not as good
as autoharp pin enabling more string tension hence more volume and stay in
tune longer which his didn't. In Madagascar they deal with balancing the
string tension by using both sides of the board which keeps the pressure on
both ends and even to prevent twisting.
I have found hammer dulcimers quite good, louder, and with a wider pitch
spectrum. I have always found them cheaper to buy than build and enjoy the
fact i have have one less thing to build. I make it so each bridge in
independent as i rarely use pure 3/2. Recently i found a chromatic cymbolum
which although is unbelievably heavy, is as loud as any of my vibraphones.
It uses three piano stings per mote and with it i feel it approaches
everything i have wanted to do with strings. Well almost

Alison Monteith wrote:

> George Zelenz wrote:
>
> > Hello Alison,
> >
> > Below is a link, and some general tips.
> >
> >
> > http://www.taunton.com/finewoodworking/pages/bw0002.asp
> >
> > This author and press are top notch. I hav'nt seen this book, but I'm
> > sure
> > it's very good.
> >
> > Basically, one must have accurate 90 degree angles from edge to board
> > face,
> > and a good tight fit betwixt edges. Check for gaps, and or twist.
> > Needless
> > to say, your boards should be as flat as possible. No twist or bow.
> >
> > Use regular wood glue, or a yellow (aliphatic resin) wood glue. Both
> > are
> > fine.
> >
> > When you do clamp them up, just use enough pressure to keep them
> > together.
> > No joint strength is gained from overclamping. You'll just crack the
> > spruce
> > probably. You may need to apply (through gravity) some weight along
> > the
> > joint as it dries. This will help keep the boards flat while the glue
> > dries.
> > Concrete blocks on wax paper for instance.
> >
> > Good luck, and ask all that you wish of me.
> >
> > George
> >
> >
> > Great stuff George and just the advice I need. I'll get looking for
> > some long clamps and wait for a dry day....
>
> Best wishes

-- Kraig Grady
North American Embassy of Anaphoria island
http://www.anaphoria.com

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