AW #131.pdf - Karatunov.net

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Check edge joints with one centered clamp.
Like dry-fitting a joint before you glue, this technique highlights
imperfectly jointed boards that may otherwise be hard to see.
Here, one slightly crowned edge causes a noticeable gap. Even
if no gaps appear, test all the joints by lifting one board while
lowering the other. lf the boards move without resistance, the
.ioint is too loose. Re-joint one or both boards and try again.
Square a crooked frame.
Experts recommend "checking diagonal measurements"
to make sure your glued-up frames are square. So what do
vou do when the measurements don't match? Reposition
the clamps to apply uneven pressure across the joints.
Watch the change in dimension of one diagonal as you
tighten the angled clamps. The goal is to split the difference
between the two original measurements. For example,
diagonals off by 1/B-in. require a 1/16-in. change. lf the
dimensional difference grows when you apply pressure
instead of shrinking, the clamps are angled the wrong way.
Create
parallel
clamping
shoulders
for curved
shapes.
Make custom
clamping blocks
by tracing and
.r ritinn fhA
curved profiles.
Then mark and
cut cramprng
shoulders parallel
to the joints.
Be proactive:
Self-hanging
clamp blocks
free both hands
for clamping.
Tape
pl€'
ventS
black
marks
from
clamps.
Drive glued-up panels flat.
Applying clamp pressure often causes panels to lift
off the bar and creep up the clamp head. Cupped or
twisted panels are the result. Keep panels flat by
rapping them back onto the bar with a dead-blow
mallet. Each rap usually reduces the clamp's pressure,
so be prepared to tighten the clamp.
Black stains result when
ferrous metal, moisture and
wood come together.
lf your clamps have
untreated steel bars
or black pipes,
make it a habit to
cover their surfaces
before you glue.
Tho lano incr rlatoc
the metal from moisture
in the glue and
damn 2raaa nn tha
wood's surface.
American Woodworker ocToBER zooz 49