| By Aaron Foster, a finish carpenter in Southern California
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| Most of the casing I install is too small for biscuits, and
much too small to use a Clam Clamp. I've always wanted to pre-assemble
these smaller moldings, just like I do large casing. But I don't
have time to glue up the joints and leave spring clamps on until
the glue dries.
If you want to pre-assemble smaller casings, as well as crown,
base, jamb extensions, try this technique. You'll be amazed at how
easy it is, and how well it works.
And if you can't afford enough Clam Clamps (they're $55.00 each!),
remember this method works even better on hardwood and larger casings.
On a recent job, I assembled 20 sets (after all cuts were made)
in about 45 minutes using the stitch method. I would have needed
a 'ton' of clam clamps to move that fast, but all I used was a $150.00
stapler and about $1.00's worth of staples. |
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| These are the tools. 23ga micropinner (left), 20ga 1/2"
crown pneumatic
stapler loaded with 3/8" long staples (center), T-50 compatible
3/8"
crown manual stapler loaded with 1/4" long staples (bottom
right), and
a glue bottle (top right).
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1) Start by applying glue to the surfaces to be joined.
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| 2) Use the micropinner to pin the inside and outside of the
miter to keep the face of the joint registered until the glue cures.
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3) Staple the back of the casing as shown with the 20ga pneumatic
stapler (the same type of stapler/staples used for applying flashing
paper or stapling upholstery). This type of stapler uses the flat-style
staples. This is important as the flat staples do not countersink
and
thus do not set deep and blow out through the face of the moulding.
Do
not staple in the thin part of the profile or the staples will penetrate
the face of the molding. Trial and error (guess who's?) has found
the 3/8" long
staples to be the ideal length. Any shorter and they don't hold
well.
Any longer and they are more likely to blow out the front of the
molding. This step is important as the strength of the joint is
created
by the staples bridging across the seam and acting like mini clamps.
The staples also create a pivot point that forces the face of the
miter
to close tightly as the casing is nailed onto the wall. In situations
where the drywall is 1/16" proud of the jamb, the staples actually
suck
the miter unnaturally tight as the assembly is nailed to the jamb,
which
makes this technique ideal for all those times when you need to
beat
drywall to get the casing to contact the jamb. If you use enough
staples, the joint will never open.
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Normally, I do not flip the assembly over to staple it. Rather,
I
find it faster to nail the back of the molding upside down by hanging
the corner off the edge of the assembly table. This particular type
of
molding (lightweight mdf) is very prone to splitting and flaking,
so
even the micropins caused cracks between the flake layers and had
very
little hold. However, the staples hold extremely well in lightweight
mdf as they do not penetrate the edge between layers but instead
the
staple points are penetrating the face - a much stronger hold
with no splitting. This is significantly quicker than biscuits with
no
down time waiting for glue to dry. Also, no miter clamps are necessary,
saving a step and time.
NOTE: The manual stapler can be used for this
step if the appropriate pneumatic stapler is unavailable
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| 4) This is an optional step, but I like to use
it on mdf moldings as a little insurance until the molding is carried
to the opening and installed. Use the manual T-50 stapler to put
one or two "temporary"
staples across the exposed face of the miter. The temporary staple(s)
act like mini clamps and help to stabilize the joint while you carry
the assembly through a house and potentially bump into walls and
obstructions. The reason I prefer the manual stapler with 1/4"
long T-50 staples over the pneumatic stapler is because the lower
power of the manual stapler won't leave a driver blade mpression
on the finish face of the material. After the molding is installed
and nailed off, the temporary staples pop off with the orner of
a chisel leaving behind two very small holes that require minimal
filling. On stain grade, I'd skip this step to avoid extra nail
holes. Besides, on stain-grade work, the micropins hold much better
so this step is unnecessary.
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Voila! You have just created the superman of miter joints. Though
the glue is still wet and only staples and micropins were used,
this
joint easily supports over 5 feet of casing hanging in mid air!
Now the final step is to spread your assembled casings to their
respective
openings. To prevent a miter from popping open during transportation,always
carry the assembly "sunny-side down". By twisting the
casing so that the bottom
aims slightly up, you create positive tension on the staples which
forces the miters
closed. |
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I also use staples to stiffen up large jamb extensions, too.
In this photo
I've stapled the the butt joint in a frame.
Once all four butt joints are stapled off, the entire unit becomes
rigid. First, I use 18ga brads to nail the jamb together, then it
only
takes seconds to staple all the joints. This technique prevents
the
joints from developing gaps from racking during transportation.
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| The photo above shows how the staples can be applied in
areas that will later be hidden by casing (beyond the reveal) or
on the back of the
extension jamb.
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I've mated these two boards side-by-side (and penciled over
the joint for clarity). If
you staple perpendicularly across the joint, the seam will stay
closed
but can shift and slide, causing a mis-registration of the two pieces.
Instead,
staple in a zig-zag or X pattern and the material won't be able
to
shift. Combine both square and zig-zags for the ultimate in strength
and stability.
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My favorite place to reenforce joints with staples is on outside
corner crown miters
when building templates or preassembling. The joint was first assembled
with glue and micropins. To prevent the the outside point of the
miter
from ever opening, I shoot a couple of 20ga staples there. The staples
are on the surface that will contact the ceiling and so they will
never
be seen after installation. |
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| But to really beef up an outside miter, run a
row of staples right in the crotch of the miter on the back side
of
molding, taking care not to staple in thin part of the profile.
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| I also like to make crown corner templates for laying out crown
on inside and outside corners, rather than using gauge blocks. I
use gauge
blocks, too--sometimes, but because drywallers build up the mud
so much at
the corners, gauge blocks are never very accurate. The template
I use ensures
that the corners are laid out just the way the crown will sit, so
all the miters are tight.
I snap chalk-lines at these marks prior to installation.
I used to use glue and brads to make these templates, but if I
didn't wait for the
glue to dry my corner templates would fall apart; even if the glue
did dry the templates
would break if I dropped them from a ladder.
Now I staple the inside and outside of the miters and the
templates are indestructible. |
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