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Fitting the back to the sides
If you haven’t yet leveled the back kerfed linings, do so now .
Use the 5° wedged sanding board .
When correctly installed, the guitar’s back will have an arch,
with curvature both longitudinally and laterally, and will
have a slight overhang of about 1/8" around the outside .
Double check that the outside distance of the sides from
the neck block to the tailblock measures the correct 19-1/4"
body length . If it doesn’t, the lower bout and tailblock end
may have “stretched” out of shape a little . This can happen
if the assembly sits too long without a top or back, or as a
result of high humidity in your work area . The assembly can
be pulled into length as the back is glued on .
At the neck block end, trim the back’s spruce center strip
until it butts up against the inner edge of the neck block .
The pencil mark should line up at the front edge of the guitar
at the neck block . Be sure the penciled back outline at the
tailblock end is also exactly 19-1/4" from the neck block mark .
Place the guitar’s back assembly onto the rim assembly,
align the center seam with the side seams, butt the trimmed
spruce reinforcing strip up against the neck block, and dry
clamp lightly . Next, carefully and lightly dry-clamp the
tailblock end of the back, making sure that the body length
pencil mark aligns with the sides, and that the centerlines
match . If the sides at the tailblock don’t align with the body
length pencil mark on the back, gently push the sides and
tailblock slightly until the body length mark meets the sides,
and lightly dry-clamp . You may find it easier to have a friend
help in case you need to manipulate the neck block and
tailblock into shape .
Use a white pencil to mark the positions of the ends of the
back braces on the sides . File .100"-deep notches in the
kerfed linings and the sides to accept the braces, as you did
for the guitar top . Now, chisel the spruce center strip so it
butts against the tailblock .
When the back assembly fits correctly, cut the cardboard it
lies flush with the guitar side . You may want to make a small
caul to help hold the strip and spread the clamping pressure,
Installing the back
In the waist area of the soundboard, trim away the 1/8"
overhang so the waist clamp will fit . Install the waist clamp
from the front of the guitar to hold the sides in shape while
gluing the back .
Clean up the inside surfaces of the body to remove dust and
glue . Dry-clamp the back into place with spool clamps and
cam-clamps or C-clamps, as you did for the soundboard .
Check and correct the fit if necessary, according to the
centerline and the body length marks . Unclamp, apply
Titebond to the kerfed linings and reclamp, starting at the
neck block . Follow the same clamping order as you did with
the top (pictured) . Let the glue dry overnight .
StewMac’s tool recommendation
StewMac Spool Clamps
Item #3715
Assembly clamps with a different twist! The simple spool clamp for soundboard
and back assembly, made faster and easier with a hardwood handle . (After all, glue
won’t wait forever while you fiddle with wing nuts .)
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