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Wall Cabinet of Maple / How to Install Knife Hinges

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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.

 

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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.