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How to Install Mortised Hinges
Tools and Materials
By Robert J. Settich
A box hinged with mortised butts appears tidy and effortless. And like many accomplishments, it looks easy until you try it for yourself. But if you have a basic knowledge of how a hinge’s geometry works and then follow a systematic approach, you’ll get good results with your first try. Great results come after practice.
In this article, I'll describe how to fashion a mortised butt hinge, piano hinge, knife hinge, and round hinge. I'll also describe a template for hinge mortising, and how to square a routed hinge mortise, rehabilitate common hinge mortise problems and install a passage door. As you'll see, learning how to craft mortised hinges will open up some amazing woodworking possibilities.
Photos by Robert J. Settich
This article originally appeared in Taunton's Complete Illustrated Guide to Choosing and Installing Hardware (2003).
How to Make
Mortised butt hinge
Measure the centerpoint: This demonstration shows how to hinge a small box, but you can adapt this same approach to hanging a door onto a carcase. In that case, you simply clamp the spacer between the side of the carcase and the door.
Measure hinge positioning: To properly position the hinge, you need to make sure that the centerpoint of the hinge pin will be slightly past the rear edge of the box. To do that, close the hinge, and measure the distance from the barrel to the opposite side of the hinge pin. Cut a spacer that is that thickness and at least as long as the box.
Template for Hinge Mortising
Center the hinges : To help ensure that you position the hinges squarely, measure the distance from the edge of the hinge’s leaf to the edge of the pin.
Squaring a routed hinge mortise
Clamp the spacer and lay out the hinges: Use a pencil to transfer this line to masking tape on the base and lid. Center the hinges between these lines and they will be square. These lines are for reference only—the spacer determines the actual positioning of the hinges.
Fixing hinge mortise problems
Secure the hinges: Clamp the spacer between the base and the lid. You’ll probably need to block up the lid to make it level with the base. Lay out the hinges so that you’ll install each one identically—one hinge leaf has an even number of knuckles, and the other is odd. It doesn’t really matter how you orient them as long as they are the same.
Installing a passage door
Mark the hinge outlines: Carefully position a hinge so that the barrel’s axis is centered over the spacer, then drill a pilot hole and screw down one leaf with a single screw. Double-check that the hinge is still square to the box, and secure the other leaf. Secure the other hinge using the same procedure, then finish drilling the remaining pilot holes
Label and remove the hinges: Use a striking knife or crafts knife to score the wood fibers along each hinge’s outline. Start with light pressure for the first cut, then slice deeper in a series of passes.
Rout the mortises : Lettering the hinges and the lid lets you quickly replace each hinge in its home. Remove the hinges and unclamp the parts.
Complete the mortises: There are two different ways to mortise the hinges—you can cut a full-depth mortise in the box’s base, or cut half-depth mortises in both the base and lid, as I did. When you set the router’s depth of cut, you’ll also want to create a slight clearance gap along the back edge of the lid. Clamp a scrap board to the box’s outer edge to prevent tearout and to increase the bearing surface for the router’s baseplate. Rout the mortises in the base and lid. I used a 1⁄8-in. bit in a laminate trimmer, a combination that provides adequate power with excellent control. How close you dare to rout to the layout lines depends on your courage, experience, and whether you drink espresso or decaf.
Secure the hinges: To complete the mortises, begin with a vertical chisel cut at each end. Next, put the chisel’s bevel against the routed bottom of the mortise to finish removing the waste at the ends. Now you’ll change tactics because a vertical chisel cut along the grain could split the delicate wall near the inside of the box. Use a crafts or utility knife to deepen that score line with repeated passes. Finally, remove the waste with the chisel, slicing along the grain with the bevel down.
Finishing touches: You already drilled the pilot holes for the hinges, so the only thing that remains is screwing the hinges into place.
Variation- add a built-in stop: The completed installation has an unobtrusive look. You’ll need to install some kind of stop to keepthe box lid from falling over backward.
Determine box dimensions: If you want to skip the lid support, you can use a hinge with a built-in stop. The geometry of this hinge is a bit different from an ordinary butt hinge because you have to leave the entire hinge barrel proud of the back of the box so that it will operate properly. In addition, you can’t lay it flat to utilize the method described above, so you’ll have to rely strictly on measuring and marking.
Check proportions with a carcase: Running the entire length of the box, a piano hinge adds an attractive edge to your box's hardware. Variations can also add ease and utility to construction.
Cut the hinge to length: To create an easy mortise for a piano hinge, simply make the back of the box narrower than the sides and front. To determine how much narrower, measure the diameter of the closed hinge’s knuckle, and subtract 1⁄16 in. That subtraction will help make sure that the front of the box always closes neatly.
Mount the hinge to the lid: When you assemble the box, the narrower back makes a full-length mortise. In this example, I knocked together a quick plywood carcase to check the proportions of a blanket chest I’m designing.
Fasten leaf to the back of the box: Mark the cutline on the hinge, and cut it to length by using a hacksaw with a blade that has 32 teeth per inch. Cutting the hinge about 1⁄16 in. shorter than the mortise will help ensure that the hinge will be able to move without scraping against the carcase. Screw the hinge to a scrap block to ensure that it won’t flex while you’re cutting. File away any cutting burrs.
Check out the finished product: Keep construction simple by planning the size of the top so that you can mount the hinge flush with the top’s rear edge. That way, the only measuring involved is centering the hinge end to end. Drill pilot holes, and drive the screws
Variation: surface mount for added strength: Position the other leaf of the hinge on the back of the box—flush with the inner edge is a typical position— and fasten it in place. For neatness and maximum strength, use a screw in every hole.
Variation- simplify construction with slotted screwholes: A back view of the completed installation shows how the lid is slightly above the back edge of the box so that it will always shut completely at the front.
Prepare the hinge: For utility applications— where strength is more important than appearance—you can surface mount a piano hinge using the same procedure that you would for individual hinges. Making toolboxes or shop cabinets are two typical applications for surface-mounted piano hinges.
Tighten the template: Piano hinges available from Rockler, including the specialized flange-leaf type shown here, have slotted screwholes that provide easier positioning and installation. They are available in a variety of sizes for any application.
Determine mortise width: It’s always a good idea to test the settings of a jig on scrap stock instead of immediately routing a completed door or carcase. Once you have the adjustments dialed in, you’ll be able to move through your project quickly and confidently.
Mark the door: To allow the hinge to fit easily into the adjustable template, unscrew the finials or withdraw a removable pin. Clamp the vertical wood fence of the jig to your door, and lightly tighten the knobs.
Check for square: Put the hinge into the opening of the template, slide the bar snugly against it, and tighten the knobs.
Prepare the router and set the depth of cut: With the finials on this hinge, I could bury the hinge only up to the barrel. If your hinge doesn’t have finials, you can go further. Transfer this measurement to the edge of the door.
Rout the mortise: Loosen the knobs under the fence, and move the jig forward or back until its back edge touches the width line you marked on the door. Tighten the knobs, and check for square by measuring the distance from the edge of the jig to the fence. When the measurements are equal at both ends of the jig, it is square to the fence and therefore square to the door.
Fine-tune the mortise: Loosen the clamps that hold the fence to the door, and move the edge of the jig’s opening where you want to install the first hinge. Use a utility knife to score the wood fibers at each end of the opening. This will help prevent tearout when you rout the mortise.
Variations: inserts accommodate multiple hinges: Put the piloted bit (supplied with the jig) into your router, place the router atop the jig, and hold the hinge under the jig to set the depth of cut. I set the depth of cut at slightly less than half of the hinge knuckle’s thickness so that the latch side of the door would close snugly.
Mark the mortise: When you rout the mortise, start with a light pass along the edge of the door, rout clockwise around the perimeter of the jig’s opening, and finally clear out the waste in the center of the mortise.
Work on the back wall: The completed mortise is nearly ready to receive the hinge. If this test mortise isn’t long enough to accept the hinge, you can easily fine-tune the fit. Simply loosen the knobs that hold the sliding bar, and again place the hinge in the opening. But this time, add a piece or two of self-stick notepaper between the end of the hinge and the jig. Try another test mortise until you have the setting perfect. Routing mortises into a carcase follows the same procedure described above. But bear in mind that the length of the jig may create a clearance problem, requiring you to cut the mortises in the carcase components before assembling them.
Carve the mortise and clean out the waste: With this jig from Rockler, you can purchase inserts that match a variety of hinges. The insert shown in the photo matches the butler-tray hinge resting on the jig.
Variation- a corner chisel speeds up work: Using a template to rout a mortise can be a great convenience, and if the hinge has radiused corners, you can immediately install it. But if your hinge has square corners, you’ll have to do a little bit of chisel work. Interestingly, this is one of the few cases where cutting corners means making them square instead of rounded. This technique is fast and easy if you have a razor-sharp chisel but slow and difficult with a dull tool. So the first job is to hone your chisel.
Mark out the new width: With your workpiece securely clamped, register the backside of your chisel against the end of the mortise, rock it to extend the line of the mortise, but don’t overshoot the back wall of the mortise. As the chisel approaches vertical, gently push downward to deepen the mark. Repeat at the other end of the mortise.
Remove waste from the mortise: Switch your attention to the back wall of the mortise. Again, use the register and rock motion to extend the line. But be careful because too much pressure could make the cut run with the grain instead of in a straight line.
Measure your progress: Work back and forth between the end of the mortise and the back wall until the lines meet. Hold the chisel vertical at the end of the mortise, and push down to further deepen the line. Now you can turn the chisel bevel down and clean out the waste.
Attach hinges and finish the job: If you need to clear a lot of mortises (or just want a cool tool), consider a corner chisel. You simply register it against the routed mortise, and lightly tap with a hammer to mark a perfectly square corner.Then you use your regular chisel bevel down to clear the waste. Some corner chisels are spring-loaded, but this one from Lee Valley uses rare earth magnets to hold the cutter against the registration block.
Variation- use shim to adjust the mortise: Sometimes, you’ll need to fine-tune a hinge mortise to achieve a perfect fit. The lid of the box shown in the photo hangs over the base—a dentist would call this an overbite problem. There are two possible cures—either move the hinge in the base backward, or move the hinge in the lid forward. I figured that shimming the back wall of the base mortise might be more visible, so I opted to fix the lid.
Assemble equipment : The size of the overbite indicates the amount that you’ll need to increase the mortise. Measure or mentally note this dimension, and remove the lid from the box. Set a cutting gauge to score a line indicating the new width of the mortise and remove the waste with a chisel.
Prepare the template: By placing a sharp chisel on its side, you can use it like a miniature cabinet scraper to remove tiny shavings of wood.
Prepare the router: As you work, you can check your progress by sliding the lid onto the hinges that are still attached to the base.
Measure mortise positions: You’ll have to plug the old screw holes so you can attach the hinges in their new positions. Cut or split strips of wood, and glue them into the old holes. Snap the strips sideways, and clean up any splinters above the surface of the mortise with your chisel. Drill new pilot holes, and attach the hinges to complete the installation.
Set up the gauge and hinge jamb: Sometimes you’ll need to add a shim to change the depth, width, or length of a mortise. The photo shows a wide range of shopmade and purchased shim stock: masking tape, chipboard recycled from a cereal box, index cards, sheet veneer, handplane shavings, veneer edgebanding, aluminum foil, sheet brass from hobby shop, and metal flashing.
Rout the mortise: The idea of hanging a passage door intimidates some people, but it’s really not a scary project. By using a mortising jig, you can set the hinges quickly and accurately.
Drill the pilot holes and drive the screws: The Porter-Cable 59370 jig shown in the photo works for hinges that range from 2-1⁄2 in. to 41⁄2 in. in 1⁄2-in. increments. You can use hinges that have square corners or a 5⁄8-in. radius. Move the spacers to match the size of hinge you’ll use, and keep the spacers centered in the opening. For a square-cornered hinge, you’d swap the spacers end for end. To install a 4-1⁄2-in. hinge, you’d omit the spacers. If you’re hanging a batch of doors, you’ll save time and possible errors by purchasing three jigs and attaching them to a 3⁄4-in. plywood upright.
Variation- handle heavier doors with an extra long screw: Remove the washerlike plugs from the template, and use them to secure the duplex (doubleheaded) nails to the body of the template. Without these plugs, you’d be constantly juggling the nails every time you moved the jig.
Knife hinge: The bit supplied with the jig has a 1⁄2-in. cutting diameter and a 5⁄8-in. top bearing. Chuck it into your router, turn it upside down, and place the hinge on the jig atop the baseplate. Make certain that the bent (swaged) portions of the hinge don’t interfere with setting the bit’s depth.
Mark out the center of rotation: Tape a quarter to the head jamb of the door and measure downward for the position of the hinge mortises—7 in. from the top, 11 in. from the bottom, and the third centered between those two. Measure all locations from the coin taped to the head jamb. The quarter establishes the reveal at the top of the door because when you transfer the measurements to the door you simply hook the tape over the end of the door. As a result, each location will be automatically offset by the thickness of the quarter.
Set up the router: The side-to-side position of the gauge on the jamb is dictated by the thickness of the door. Align the ends of the rectangular openings in the gauge with the edge of the hinge jamb. Tap the nails to hold the template to the jamb. Align the top of the hinge opening with the mark on the jamb, then drive the nails. The lower head of the duplex nail secures the template firmly.
Rout out the mortise: To rout the hinge mortise, first make a light cut along the edge of the jamb. Rout clockwise around the perimeter of the template, and clear out the waste in the center. Be sure to hold the router baseplate flat against the template as you rout.
Use a chisel: When you remove the jig, you’ll notice that the end of the mortise doesn’t meet the pencil line because the router bit’s cutter is a smaller diameter than its guide bearing. This doesn’t make any practical difference as long as you always position the jig consistently for each cut. The completed mortise is a very good fit for the radiused hinge. Simply drill the pilot holes and drive the screws
Arrach the hinge leaf: To help prevent a door from sagging, replace one of the standard hinge screws with an extra long screw that will reach the stud. This procedure is a must when hanging heavy exterior doors because of their extra weight.
Scribe the leaf outline: A knife hinge consists of two leaves—you install the leaf with the pin to the carcase, and the one with the hole to the door. With the technique I developed, you use the leaf with the hole to lay out the hinge locations in both the door and carcase.
Rout the mortise into the carcase: You’ll need to rout the hinge’s location in the carcase before you assemble it. This hinge has a pin diameter of 3⁄16 in., and I wanted to place the hinge’s center of rotation just past the end of the door. To do that, tape a 7⁄64-in.- dia. drill bit to the edge of the door, and place its shank inside the hole of the hinge leaf. Hold the leaf approximately centered in the width of the door, and use a crafts knife to scribe its end.
Square the mortise and secure the hinge leaf: Chuck a 3⁄8-in. straight bit into your router, and set the height of the bit to match the thickness of a leaf.
The finished product: Position your router’s edge guide to center the bit in the thickness of the door, and rout the mortise. Clamp a piece of scrap wood to the edge of the door to help prevent chipout. Always register the router’s edge guide against the front of the door—you’ll see why in a moment.
Variation- change the center of rotation with an L-shaped hinge: Complete the mortise with a chisel.
Prepare the base and lid for drilling: Drill pilot holes, and attach the leaf.
Drill in the holes: Following the same layout technique you used on the door, scribe a line on the carcase top and bottom at the end of the leaf. You don’t need to be concerned with the front-to-back position of the leaf because the router’s edge guide will take care of that.
Add the hinge and screws: For a door that’s flush to the front edge of the carcase, leave the edge guide positioned as it was when you routed the doors. Even if it’s not perfectly centered in the door, the same offset will be transferred to the carcase, and you’ll get a flush fit. I wanted to set the door back about 1⁄64 in., so that’s the amount of distance I added between the router bit and the edge guide. Rout the mortise into the carcase.
A unique touch: Square the mortise, and screw the pinned hinge leaf to the carcase. To install the door, screw all of the leaves in place except the top one on the door. Put the hole of the bottom door leaf onto its mating pin, and hold the door in its open position. Gently tilt the top of the door toward you far enough that you can place the last leaf onto its pin. Hold it in place with your finger while you slide the leaf into its mortise.
The finished product: When you've completed installation, the hinge is barely visible.
To hang an inset cabinet door, use the L-shaped knife hinge to move the center of rotation past the front of the door.The same drill-bit technique you used for the straight hinge will accurately position the hinge on both the door and carcase. Use a piece of plastic laminate to set the distance from the carcase side. Scribe the outlines of the mortises, and chisel them. Once you’ve installed the hinges, there’s no tidy way to change their position.
Installing a round hinge requires a bit of careful setup at the drill press, but once you’ve done that, the rest of the steps are so fast and easy you may almost feel guilty that you’ve finished so quickly.
Begin by putting four thicknesses of self-adhesive notepaper near the ends between the base and lid so they won’t interfere with hinge placement. Carefully align the edges and ends of the base and lid, and tape them together, using package sealing tape or masking tape. Clamp a high fence to your drill-press table so that the base and lid cannot move while you’re drilling them. Make certain that the fence is square to the table. Decide on the placement of the hinges, and center the tip of a 35-mm Forstner bit in the middle of the base-lid gap.
Drill the hole 1⁄32 in. shallower than the thickness of the hinge so it will sit slightly proud of the wood.
Drop the hinge into the hole, and align its pin with the joint between the base and lid. Drilling pilot holes and driving the screws completes the job. You can purchase an optional stop for the hinge (it’s shown by itself in the center and installed on both hinges in photo. Use the longer screw supplied with the stop to install it atop the bottom half of the hinge.
When you untape the box and open it, you’ll notice that the tip of the Forstner bit made tiny V-shaped notches in the base and lid. This adds an interesting detail, and I mention it only so that you’re not surprised by it.
The completed box has a clean and sophisticated look.