Essential Joinery. Marc Spagnuolo
JOINERY
FLAT 45° MITERS: A FRAME | Butt Joints
4. After adjusting the saw and
making more test cuts, the gap is
removed and you’re ready to cut
the workpieces.
5. Cut the workpieces to size
using a stop block, if possible,
for repeatability.
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5
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ESSENTIAL JOINERY
MITER ASSEMBLY STRATEGIES
Miter joints can be tricky to assemble with nothing more than glue and standard
clamps. Because of the angles involved, the pieces tend to slide past one another
and it doesn’t take long before your carefully cut miters are overhanging and
creating odd angles. Here are two of my favorite ways to assemble miter joints.
BAND CLAMPS
TOOLS
Band clamp
Band clamps typically feature four corner cauls, a metal or fabric band,
and a clamping head that tightens the whole assembly by pulling on
the band.
1. Position the parts on a flat
work surface and arrange the
cauls in their approximate
positions around the frame (one
at each corner). With glue applied
to each joint, slowly tighten the
band clamp, making any slight
adjustments needed to keep each
corner aligned.
1
TIP
Always do a test assembly with no glue just to double-check the
workpieces and to familiarize yourself with the process.
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ESSENTIAL JOINERY
MITER ASSEMBLY STRATEGIES | Butt Joints
ANGLED BLOCKS
To assemble a miter using a regular clamp, we’ll need to use angled
cauls so that the clamps are oriented perpendicular to each joint.
1. Use thick CA glue to attach
the triangle cut-offs to the ends
of the mitered workpieces. A
layer of blue tape between the
frame and the blocks will help
prevent tearout when removing
the blocks.
2. Apply glue to the miters.
3. Apply clamping pressure to
each joint.
4. After the glue dries, use a
mallet to pop off the glue blocks.
1
2
3
4
TOOLS
Clamp
Mallet
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ESSENTIAL JOINERY
REINFORCING FLAT MITER JOINTS
Miter joints are essentially butt joints that are cut on an angle. As we know, butt
joints are not very strong with glue alone so miter joints are often reinforced for
the sake of durability. Fortunately, the reinforcement can also be a beautiful
decorative element.
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2
3
1. Mark a 45° V shape on the
face of a piece of plywood or MDF.
2. Place the frame on the
plywood using the lines. At the
bottom frame corner, use a small
piece of double-stick tape or a dab
of CA glue to secure the frame.
3. Add two clamps and use a
tall fence on the tablesaw if you
have one. Raise the blade so it
goes at least halfway into the
miter joint and make the cut.
4. The slot is usually centered
along the thickness, though you
have some creative flexibility. Use
a square-tooth blade. The slot will
provide a much nicer-looking joint
than an alternating bevel blade.
Miter keys are thin strips of wood that are inserted into the miter joint
after the joint is glued up.
4
MITER KEY REINFORCEMENT with SIMPLE GUIDES
TOOLS
Adjustable square
Tablesaw
Square tooth blade
Clamps
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ESSENTIAL JOINERY
REINFORCING FLAT MITER JOINTS | Butt Joints
1. Set the tenoning jig back
support to 45° and clamp the
workpiece in place.
2. Align the blade with the
center of the workpiece (or off-
center if you prefer) and raise the
blade to at least halfway into the
miter joint, then make the cut.
1
2
TOOLS
Tablesaw
Tenoning jig
Clamp
MITER KEY REINFORCEMENT with TENONING JIG
If you have a tenoning jig, miter keys are incredibly easy to make.
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ESSENTIAL JOINERY
Butt Joints | REINFORCING FLAT MITER JOINTS
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2
MITER KEY REINFORCEMENT with HOMEMADE CRADLE
If you make a lot of miter