In pursuit of the perfect miter joint? These tips for tighter miters cover common situations you’ll undoubtedly encounter in your workshop.
By the DIY experts of The Family Handyman Magazine:February 2014
It’s dang near impossible to get the
length and position of a mitered part
right unless you can butt it up against
the adjoining miters. To provide a
guide, tape or clamp mitered scraps
in place. Remove the scraps as soon
as you glue the part in place—otherwise,
stray glue might make those
temporary guides permanent.
Whether you’re banding a tabletop or
making a picture frame, make sure the
wood color and the grain pattern match
at the miters. Selecting matching wood
at the lumberyard takes only a few
extra seconds and gives you much
It’s not easy to align and
clamp miters, especially
when they’re lubricated with
a coat of slippery glue.
That’s why woodworkers
often use biscuits on miter
joints even where extra
strength isn’t needed.
Cutting biscuit slots is a
minor job that provides
major help at glue-up time.
With some miter-clamping
methods, you need to grab
a square and make sure
the corner is exactly 90
degrees. Not so with corner
clamps; they automatically
hold parts perfectly square.
They’re available at home
centers or online.
Shaped moldings can
be tough to miter, align
and clamp. So make
life easier by starting
with plain square
stock. Then, after
assembly, grab your
router and shape the
edges. The risk with
this method is that
you’ll gouge or splinter
parts that are already
in place. The best way
to avoid disaster is to
make a series of shallow
passes instead of
one full-depth cut.
It’s hard enough to align and clamp miters without
rushing to get it done before the glue begins to set
(in five to 10 minutes, and even faster in warm, dry
conditions). That’s why there are slow-setting wood
glues, which give you an extra 10 minutes or so.
If you can’t find a slow version at your favorite
home center, make your own. If you add one part
water to 20 parts wood glue, you’ll gain about five
minutes of working time. The water will also weaken
the bond very slightly. So if strength is critical, order
slow-setting glue online. Titebond Extend is one
A dry run—complete assembly with clamps but without glue—is the
best way to ensure a smooth, successful glue-up, whether you’re
assembling miters or anything else.
When you’re dealing with small or other hard-to-clamp parts, your hands
make the best clamps. Simply rub the glued surfaces together and hold them
tightly on a flat surface for about a minute. Let go and allow the joint to set for
30 minutes before handling it.
If you’ve ever tried to adjust the angle of your miter saw by one-tenth of a degree, you already know how hard micro-adjustments
are. Here’s an easier way: Slap a few sticky notes on the fence, make test cuts and add or remove sheets until you get exactly the
angle you want.
When you’re building a box or frame, the opposite sides have to be exactly
the same length. To make sure they are, do the touch test: Set the parts
side by side and run your finger over the mitered ends. You may not be
able to see a slight length difference, but you’ll feel it.
You can close a small miter gap by rubbing it with a screwdriver
shank or any hard, smooth tool. We used the end
of a utility knife. That crushes the wood fibers inward to
make the gap disappear. Even professional woodworkers
sometimes resort to this crude trick.
This is an old favorite
Clamp on notched
blocks, then add a bar
clamp or two to
squeeze the joint. This
allows you to put a lot
of pressure on the joint
without buying any special
clamps. If you’re
assembling a four-sided
project such as a picture
frame, join two corners
first. Then, after
the glue has set, join the
two halves of the frame.
Ever cut that last part just a bit too short? There’s a solution for
that: First, trim off the inside edge of the too-short part. By cutting
off the short edge, you effectively make the mitered part longer.
Then trim the same amount off the outer edges of the other three
sides. Your edging will be a little thinner than you had planned, but
nobody will notice.
Trim carpenters have used this system for years: Apply a few
dabs of cyanoacrylate adhesive (aka “superglue”) to one
surface and apply activator (or “accelerator”) to the other.
Immediately press the parts together and they’ll bond in seconds.
No waiting, no complicated clamping setup. Activator is
sometimes sold separately ($5 and up), sometimes with the
glue. Look for it at home centers or shop online; rockler.com carries a good selection of glues and activators.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.
Copyright © 2014 The Family Handyman. All Rights Reserved.