Wall Cabinet of Maple / How to Install Knife Hinges

Wall Cabinet of Maple / How to Install Knife Hinges

It’s all about the wood.

By Brad Holden

 

James Krenov, a legendary woodworker,
coaxed beauty from every board he touched.
Through his books, Krenov inspired a whole
generation of woodworkers to follow his
path. While recently leafing through Th e
Impractical Cabinetmaker (1979), I was
struck by a small cabinet Krenov had built
from spalted maple. It’s a master class in
design—simple, quiet and elegant.

It took me quite some time to find the
right wood for this project. Although I could
have used other species, I wanted to follow
in the footsteps of the master and chase the
elusive charm of spalted maple—wood that’s
been embellished by nature's rotting agent,
fungus.

During the hunt, I learned that spalted
maple’s personality can vary dramatically
from board to board. Krenov had chosen
pieces that spoke in a quiet voice, so that’s
what I looked for. When I found the right
boards, I slightly altered the dimensions of
Krenov’s cabinet to suit my wood. I’d urge
you to take the same liberty, too.

 

Preparing the wood

Building this cabinet is a golden opportunity to study
how wood works, in two important ways. First, you’ll be
paying close attention to how your wood looks—its figure.
Second, you’ll be watching how the boards react as
you plane them thinner or rip them into narrower pieces.
Their figure may change, for better or worse, and they
may cup or twist, which you’ll need to fix.

Let’s look at these two aspects of fine woodworking in
more detail. Usually, the first thing I do with roughsawn
boards is to cut them into smaller pieces roughly the size
of each part. This cabinet requires a different approach.
I recommend that you start milling the boards as whole
pieces, particularly if you’re working with spalted maple.
The idea is to keep your options open as you become
more familiar with your wood. It’s best not to crosscut or
rip your boards until you know them well.

Make sure that your lumber has been properly dried
and is well acclimated to its environment before starting
to work with it. When you plane the boards to thickness,
take them down in stages over the course of a few weeks.

As you mill your lumber, take every precaution that
the wood stays fl at. Why? Take a look at how the cabinet
is built. It’s basically a dovetailed box (Fig. A). If your
boards are warped—even a little—you’ll have a hard time
fitting the dovetails. You’ll also end up with a box that’s
twisted, and that means the door won’t close right. In
addition, the door itself can’t be cupped or twisted. If it’s
off , it won’t hang with a nice, even margin all around.

You’ll need boards about 10" wide for the door (A)
and back (B). Flattening their faces will be a bit of a challenge,
because the boards will be too wide for most jointers.
I wouldn’t recommend gluing these parts from multiple
boards, however. The whole point of the cabinet is
to show off the beauty of a single board.

When working with extra-wide boards, use your
planer as a jointer (Photo 1). Of course, you shouldn’t
just push the boards through the machine hoping they
will come out flat. You probably know the rule, “garbage
in, garbage out.” Applied to planers, it goes “twisted in,
twisted out.” Place the boards on a dead-flat sled and
shim them so they won’t wobble or bend. After flattening
the top faces of the boards, set aside the sled and plane
the wood the normal way, flat side down.

There’s nothing “normal” about working with spalted
maple, however. Its appearance can change dramatically
as you remove layers from its surface. The black lines that
make the wood so distinctive, for example, can get wider
or thinner or shift in unpredictable ways.

Each time you pick up a board during the milling
process, study its figure. Look for patterns that might
make a good door, side or back when viewed vertically,
at shoulder height (see the illustration below). I’ve found
that the best way to visualize how a part might look is to
cut out a cardboard “window” the same size as the part
(Photo 2). Place the window on a large board and move
the window up or down, or give it a twist, until the wood’s
figure looks balanced and even. If you see a pattern in the
wood’s figure that you like, stop right there. Outline the
part, then mark the side and leave it alone; from here on,
only plane the opposite side.

 

 

Krenov’s secrets

As designed by Krenov, this case is constructed in an
unusual way: It’s a four-sided box with a doubled-up top
and bottom. Th is ingenious design makes it much easier
to hang and fit the door, which swings on knife hinges. I’ll
show you how this system works later on.

Mill the wood for the sides (C), sub-top and sub-bottom
(D) to final size. While you’re at it, mill the top and
bottom (E) to final size, too. Rabbet the front edge of the
sides (Photo 3 and Fig E), then saw a groove along the
inside face of the sides, to receive the back (Photo 4). I’m
not sure how Krenov installed the back on his cabinet—
or what provision he made for hanging the cabinet on a
wall—but I think you’ll find my design for solving both
problems works very well.

Drill holes in the sides for shelf pins, using whatever
spacing you think best (Fig. A). Sand the inside faces of the
sides, the sub-top and the sub-bottom.

Lay out and cut half-blind dovetails to join the sides to
the sub-top and sub-bottom (Photo 5 and Fig. E). This is
Krenov’s method of construction—and it’s very sound—
but you could also use biscuits, dowels or pocket screws,
because these joints don’t show in the finished piece. Glue
all four pieces together.

Gently round the front edges of the sides with a block
plane (Photo 6). As you plane, leave the inside edge of the
sides alone; just round over the outside edge. (You may
have to do this again, aft er the door is trimmed to fit. These
edges should end up flush with the door.) Plane the front
and side edges of the top and bottom pieces in the same
manner (Fig. C).

Next, mill the back. It’s about the same size as the
door, so I began reducing the thickness of both pieces at
the same time. That way, I could hold off deciding which
would be the door and which would be the back until both
were 5/8" thick. At that point, I chose the better piece for
the door, set it aside and continued planing the back down
to its final thickness, 1/4". Trim the back to final size, then
rabbet it to fit into the grooves in the sides (Fig. E). Slide
the back in place (Photo 7). To allow for seasonal movement,
don’t glue the back. Screw it to the sub-top and subbottom
(Fig. A).

Mill two cleats for hanging the cabinet on the wall (F
and G). Rout mortises in the sides to receive the cabinet
cleat (Fig. B). Trim this cleat to fit, rip its bottom edge at
an angle and screw it in place (Photo 8). Trim the second
cleat to fit between the sides of the cabinet, angle its top
edge and set it aside.

 

Fit and hang the door

Here’s where the plot thickens. The actual top and bottom
of the cabinet are still loose pieces, right? Looking at the
whole design (Fig. A), you’ll see that these pieces are mortised
to receive the door’s knife hinges. Once the mortises
are cut, you can’t adjust them, or the door, to fine-tune
the gaps between the door and the sides of the cabinet. To
enhance the cabinet’s sleek appearance, you’ll be shooting
for gaps that are very small—about 1/32". So, how are you
going to pull this off?

The answer lies in those loose top and bottom pieces.
Once the knife hinges are installed, the pieces are connected
to the door. If you move the top and bottom pieces
side-to-side, you move the door, too, and that’s how you’ll
fine-tune the gaps. Now that you’ve got the general idea, let
me fill in the details.

Begin by planing or sanding the top and bottom surfaces
of the cabinet perfectly flat. Make sure that the mating
faces of the top and bottom pieces are flat, too. Clamp
the top and bottom to the cabinet.

Finish milling the door to final thickness (remember,
keep it flat!). Measure the door opening and cut the door
for a snug fit. Carefully trim the door so there’s an even
and consistent gap all the way around (Photo 9). The size
of this gap should be equal to the space between the two
leaves of the knife hinges. If you’re building this cabinet in
the winter, when humidity is low, increase the gap between
the door and the left side of the cabinet, so the door has
room to expand when humidity is high. If you need to replane
the front edges of the cabinet’s sides so they’re flush
with the door, now’s the time to do it.

Cut mortises for the knife hinges in the door and in
the top and bottom pieces (see Source, below). For full
instructions, see “How to Install Knife Hinges,” below.
In addition, install bullet catches in the same pieces.

 

Add the top and bottom

Once you’re done with the hinge mortises, glue the top
and bottom pieces to the cabinet. It’s prudent to glue only
one at a time, so let’s start with the top. To begin, screw all
of the knife-hinge leaves into their mortises (Photo 10).
Next, lay the cabinet on its back and stand the bottom
piece in place. Place the door in the cabinet and engage the
two leaves of the lower knife hinge.

Brush glue on the sub-top (Photo 11). Place the top
in approximate position and engage the two leaves of the
upper knife hinge. Add clamps, but use very little pressure.
Tap the top side-to-side in order to fine-tune its position
(Photo 12). The door will move along with the top. Your
goal is to position the top so that the gap on the hinge side
of the door is correct. (You may have to tap the bottom
piece, too, to even up the gap.) Once the top is situated,
tighten the clamps. Aft er the glue is dry, repeat the procedure
for the bottom piece. When the glue dries, stand the
cabinet up and check the door’s swing. If the hinged side
rubs against the rabbet behind it, remove some wood from
the door with a plane or sanding block.

Make as many shelves (H) as you’d like and shape
their front edges to please your eye. Apply a finish of your
choice (I used wax, which allows spalted maple’s figure to
remain sharp and crisp), then attach a handle (J) of your
own design. To hang the cabinet, screw the loose cleat to
the wall, beveled side facing in. Make sure the cleat is level.
Place the cabinet against the wall and slide it down onto
the cleat. The two bevels will engage, and your cabinet is
ready to be enjoyed!

Cutting List

Fig. A: Exploded View

Fig. B: Back View of Cabinet

Fig. C: Detail of Typical Corner

Fig. D: Knife-Hinge Mortise in Door

Fig. E: Case Joinery

Source

Note: Product availability and prices are subject to change.

Lee Valley, leevalley.com, 800-871-8158, Double-Off set Knife Hinges,
3/4" x 1-3/4" x 1/8", #05H01.36.

Click any image to view a larger version

Measuring only 10" wide, this cabinet is designed to display
the beauty of two wide boards: the door and the back.

1. Flatten rough-sawn lumber as whole boards using your planer
and a sled. This piece measures 10" across—wide enough for the
cabinet’s door, but probably too wide for your jointer.

2. Outline the parts using cardboard “windows.” These simple
devices help you to visualize how the figure of each piece will
look before crosscutting or ripping the boards.

3. Rout a rabbet in the front edge of the sides. The door sits in these
rabbets, making the sides appear thinner than they really are.

4. Saw a groove in the back edge of the sides. The back of the
cabinet will slide into this groove, like the lid of a pencil box.

5. Cut half-blind dovetails for joining the sides to the sub-top and
sub-bottom pieces. You could also use biscuits, dowels or pocket
screws for these joints because they won’t show.

6. Glue the sides to the sub-top and sub-bottom. Shape the front
edges of the sides into a gentle curve using a block plane.

7. Slide the back into place. The grooves allow the back to expand
and contract, similar to the construction of a frame and panel door.

8. Attach a cleat for hanging the cabinet on a wall. The bottom of
this cleat is angled to fit on top of a second cleat, which will be
fastened to the wall.

9. Temporarily clamp the cabinet’s top and bottom pieces
in place, then trim the door to fit. Use playing card shims to
establish a consistent gap on all four sides of the door.

10. Remove the top and bottom pieces. Cut mortises in them, and
in the door, for knife hinges. Knife hinges come in two parts;
screw each part in place.

11. Place the door in the cabinet, then glue the top to the subtop.
The two halves of the knife hinges will engage each other.

12. Fine-tune the position of the top by tapping it with a mallet.
Adjusting the top side-to-side also adjusts the position of the
door, since the knife hinge connects the two pieces. This process
ensures that you have an even gap on both sides of the door.
Repeat these steps when gluing on the bottom piece.

 

_______________________________________________________________________________________

 

How to Install Knife Hinges

They’re a sure
sign of good
craftsmanship,
but are almost
invisible.

By Brad Holden

 

Small and discreet, knife hinges
lend a tidy, refined look to your project.
They’re ideal for a small cabinet if you
want the hinge hardware to virtually
disappear.

Knife hinges are also a hallmark of
good craftsmanship. Precisely laying
out their mortises takes patience and
a steady hand. You’ll be using some
classic hand tools, such as a marking
knife, a marking gauge and a few sharp
chisels. There are no short cuts, and
practically no room for adjustment once
the mortises are cut.

Don’t let me scare you, though. If
you follow the steps outlined below, you
really can’t go wrong.

There are two styles of knife hinges:
straight and off set. Straight hinges are
used for overlay doors. Off set hinges let
a door swing out farther than straight
hinges, so they’re used for cabinets with
inset doors. I’ll be showing you how to
install off set hinges.

 

Before you start

All knife hinges are composed of two parts, or “leaves,”
that are easy to separate. One leaf is mortised into the
top and bottom edges of the cabinet’s door; the mating
leaf is mortised into the cabinet itself. It’s extremely difficult
to cut the mortises in the cabinet after the cabinet
is assembled. Your best bet is to hold off gluing the cabinet
together until you’ve completed all the mortising.

Begin by temporarily clamping the cabinet together.
Cut the door so that it’s a snug fit in the opening.

Next, determine the size of the gap you’ll want all
around the door. This isn’t an arbitrary measurement:
It’s determined by the gap between the two leaves of your
hinges, which is the thickness of the washer between the
leaves. Make shims that are the same thickness as the
washer. (I use a stack of cut-up playing cards. The washers
on my hinges were three cards thick.)

Carefully cut the door smaller, ending up with gaps
that are the same size on all four sides. I use a hand plane
when I get close to final size in order to avoid taking off
too much wood.

 

Door mortises first

The most accurate way to lay out the mortises is with a
marking knife and a marking gauge. Making shallow
grooves in the wood, these tools allow you to positively
register a chisel in a way that a pencil line cannot.

We’ll start with the door mortises, because the thickness
of the door determines the position of the hinge.
Clamp the door in a vise at a comfortable working height.
Position one leaf of the hinge on the door’s top or bottom
edge, so that the hinge is flush with the door’s edge.
Using a marking knife, mark the hinge’s end with a short,
shallow cut (Photo 1). Locate your knife in the cut, slide
a small square against the blade and scribe a line all the
way across.

Adjust a mortising gauge to the width of the hinge
(Photo 2; see Sources, below). You could also use a
marking gauge with a single pin or a single wheel, but
you’ll have to re-adjust it for each side of the mortise.

Adjust the gauge’s head so that the mortise will be centered
on the door. Test the setting on a piece of scrap the
same thickness as your door. When you’ve got the setting
right, scribe the mortise’s long sides (Photo 3).

Hold the hinge in place again and mark its off set arm
(Photo 4). As before, make a short cut first, then scribe the
line using a square.

The best way to remove most of the waste inside the
mortise is to use a 1/8” bit in a laminate trimmer or other
small router (see Sources). You could chop the mortise
with a chisel, but it’s risky. The walls of the mortise are
usually very thin and could easily split out. The depth of
the mortise should exactly match the thickness of one
hinge leaf. To set the bit’s depth of cut, turn your router
upside down, set a hinge leaf on the router’s base and slide
the leaf against the bit (Photo 5).

Rout the mortise (Photo 6). Clamp boards on both
sides of the door to keep your router from wobbling.
Extend the boards about 1” past the edge of the door to
ensure that the router is steady before you start cutting.
Rout freehand, staying about 1/32” inside the lines. You’ll
find that a 1/8” bit is very easy to control. Don’t push too
hard, though; this bit is fragile.

Clean up the mortise by gradually paring to the layout
lines. Use a wide chisel on the long sides to make straight,
crisp edges (Photo 7). I use a 1-1/4” butt chisel.

 

Cabinet mortises second

The cabinet is still clamped together, right? The first step
in marking the cabinet mortises is the same as marking
the door mortises: Begin with one end of the hinge. Here,
though, the hinge won’t be flush with the cabinet’s side,
because you have to allow for a gap between the door and
the cabinet. On my cabinet, the gap is the thickness of
three playing cards (the thickness of the washer between
the hinge leaves). Place the cards, or whatever shims
you’re using, between the hinge and the side of the cabinet
(Photo 8). Then mark the opposite end of the hinge, shallow
and short at first, followed by a squared line.

If the door is set back from the cabinet’s top and bottom,
use a square to measure this distance (Photo 9). (If
your door is flush with cabinet’s top, bottom and sides,
skip this step.) Slide your mortising gauge’s head further
away from the pins by this distance. Test your new setting
on scrap to make sure it’s right.

Now you can remove the clamps and disassemble the
cabinet. Scribe the mortise’s long sides on the cabinet’s top
and bottom (Photo 10). Lay the hinge in place, then mark
its opposite end and the off set arm. Scribe these lines, as before, using a square and marking knife. Rout the mortises.
Clean them up using a chisel (Photo 11 ).

Next, set the hinge leaves in the cabinet mortises and
pre-drill pilot holes for the screws (Photo 12). I use a self-centering
bit for this operation to ensure that the holes
are perfectly aligned. That’s not so critical for the cabinet
mortises, because the hinge is trapped, but centered holes
are critical for the door mortises, where the hinge could
slide.

If you’re using brass screws, “thread” the pilot holes
first with steel screws of the same size, then install the
brass screws. Use a screwdriver, not a drill/driver, to avoid
stripping out or breaking the screws.

You may want to re-assemble the cabinet one more
time, just with clamps, to make sure the door hangs right.
(Or if you’re feeling confident, glue it!) Reassemble the
hinges by slipping the door leaves back onto the pins of
the cabinet leaves (Photo 13).

Lay the cabinet on its back and slide the door onto
the hinges (Photo 14). You might need some help here,
because you can’t see both hinges at the same time. Once
the door is in place, pre-drill pilot holes for the screws,
then install the screws (Photo 15).

Stand up the cabinet and check the door’s fit and gaps.
Make any necessary adjustments using a hand plane or
sanding block.

 

Sources

Note: Product availability and prices are subject to change.

Rockler, rockler.com, 800-279-4441,
Micro-Adjustable Rosewood Marking Gauge, #22206.

Freud, freudtools.com, 800-334-4107, 1/8” dia. Double Flute
Straight Bit, #04-100.

These stories originally appeared in American Woodworker June/July 2012, issue #160.

Knife hinges go undercover when installed—you can barely see
them. They’re perfect for the type of cabinets whose hardware
shouldn’t distract from the piece’s design or the beauty of the wood.

1. Lay out the door mortises first. Position
one hinge leaf flush with the door’s edge,
then scribe across the end of the hinge.

2. Set the pins on a mortising gauge to the
width of the leaf.

3. Scribe the mortise from the face side of
the door.

4. Scribe the hinge’s offset arm, again using the hinge itself as a
template.

5. Adjust the height of a 1/8” router bit to match the thickness of
the leaf.

6. Rout about 1/32” shy of the mortise’s layout
lines. Clamp two support boards to the door
to prevent the router from tipping.

7. Pare to the lines using a wide chisel. Take
thin shavings, so you don’t split out the
mortise’s thin walls.

8. Temporarily assemble your cabinet, then
lay out its hinge mortises. Place shims
next to the hinge to determine the gap
between the door and cabinet side.

9. If the sides and door of your cabinet are set back, measure this
distance. Move the head of the mortising gauge away from the
pins by the same amount.

10. Disassemble the cabinet, then scribe mortises on the pieces
above and below the door. Remove most of the waste using
your router.

11. Clean up the sides of the mortise with a
chisel.

12. Place the leaves that have pins in the cabinet
mortises. Pre-drill the screw holes using a selfcentering
bit. Install the screws by hand.

13. Re-assemble the cabinet and add the
other hinge leaves.

14. Slide the door onto the hinges.

15. Install the screws in the door leaves. If everything fits right, glue
the cabinet together.