Offset Knife Hinges for Inset Doors

14 July 2025 Stan

In my article in #318, on pp. 46–53, I show how to install straight knife hinges, which are used with overlay doors. Here, I’ll explain everything else you need to know to install the offset type of knife hinges, which are used for inset doors. There are a few extra steps involved, but the process isn’t any more difficult. I’ll be skipping over some of the steps described in the main article, so be sure to read that one carefully before working your way through this one.

To install these hinges, you’ll need your case built and dry-fit, but not glued up, because you’ll assemble and disassemble it during the hinge-mortising process. Have your door built as well. Make it oversized by 1/8 in. or so in width and height. If the case ends up at all out of square, you’ll need extra door material for successful fitting.

Template has an L-shaped opening

The template approach I demonstrate in the main article works just as well for these L-shaped offset hinges, though the template includes a few more parts. Also, because of the L-shaped hinge mortises, the template must be flipped over to rout mortises in both ends of the door. Because of that, it has a fence groove on both faces.

You can also use the same pattern-routing bit I used in the main article—Amana’s No. 45475 3/8-in.-dia. flush-trim bit—which has a slight offset between the bearing and cutters. This needs to be factored in when you’re cutting the parts for the template. A set of dial calipers is indispensable for fine-tuning the fit.

After cutting a test mortise with the template, cut the shallow grooves for mounting the fence. Then form a tongue on the fence that fits the slot, and drill and countersink screw holes as before.

Note that the long part of the hinge might not end up centered on the door’s thickness this time. What matters is that the pivot point of the hinge is centered on the front edge of the door. This will ensure that the door functions properly without binding.

Template for Accurate Mortises

This template is a little more complex than the one for straight hinges. You’ll be cutting two strips out of your template board, and crosscutting and aligning those to create the L-shaped opening needed here.

Using table saw to cut thin wood planks — Rip the two strips and chop to length. Cut your template board in half, and then rip a strip off each one. Crosscut short pieces from the strips to create the L-shaped spacer (see blue area in drawing above) that will align the strips during glue-up.

Using clamps to hold to pieces of glued wood together — Glue two strips together first. To make sure the spacer parts end up aligned, glue two of the long adjacent strips together beforehand, and cut one of their ends square. That square end will keep the spacer parts aligned when you push everything together.

Make a setup block for case mortises

Mortising the setup block — Mortise the setup block. With the setup block in a vise, clamp the template to it so the end of the L-shaped opening aligns with the end of the setup block. Rout mortises at both ends of the setup block, changing the fence to the other face of the template for the second mortise.

Board and shim align the setup block. Clamp a board to the front of the case to locate the front of the door (left).

Leave a gap below the board for the knuckle of the hinge when it’s mounted in the setup block. Tape a shim inside the case (right) to create a gap between the door and the case.

Locate the hinge leaf. Insert a hinge leaf into the setup block, and add a piece of double-stick tape to its face.

Register the setup block against the alignment board and the shim, and press down firmly. When you raise the setup block, the hinge leaf will stay behind in perfect position. Mark around it with a sharp pencil.

carve in a place for the gold leaf hinge

As with the straight hinges, you’ll install the case parts of these hinges first. And you’ll use a similar method to lay out the hinge locations.

Again, you’ll need to dry-fit the case and make a setup block the same thickness as the door. Cut hinge mortises at both ends of the block, with the template’s fence referenced off the same face for each one. You’ll need to switch the fence to the other face of the template to cut the second mortise.

Use the block to position one leaf of each hinge properly on the top and bottom of the case, using double-stick tape. Mark around each leaf to record its position, and you are ready to cut the case mortises. As before, the fence comes off here—to allow the template to reach the mortise locations—and you’ll align it with your pencil lines the same way.

Start with the case. Remove the fence and use the pencil lines to align the template. After routing, square the corners with a chisel, insert hinge leaves, and drill pilot holes for the hinge screws.

Glue up the case and fit the door

When you are happy with how the hinges fit into the case, you can glue it up. When fitting the door to the case opening, go for a 1/32-in. gap on the top, bottom, and hinge edges (but not the latch edge just yet). Start by trimming the door until it just barely fits into the opening. A crosscut sled or track saw works well here. As you trim the bottom edge, make sure the hinge side of the door lines up parallel with the hinge side of the case. Next, with the door sitting in the case on its bottom edge, mark the top edge, then trim it. The hinges have a built-in washer that creates a 1/32-in. gap between the door and the case, so if you trim 1/16 in. from the top edge at this point, you’ll get the desired 1/32-in. gap above and below the door, once it is resting on the hinges. Leave the latch side of the door untrimmed and tight at this point.

Cut the door mortises and hang the door

Fit and mortise the door. Trim the door 11⁄1616-in. shorter than the height of the case opening to allow for the 11⁄3232-in. washer in each hinge. Reattach the fence to the template and clamp it to the front face of the door, aligning the hinge opening with the door’s edge.

Hang the door. Screw all of the hinge leaves in place, except the leaf in the top edge of the door. Drop the lower end of the door onto its pivot pin.

Next, while holding the top door leaf on the pivot pin of the upper case leaf, tilt the door inward to push the top door leaf into its mortise. Then screw it in place.

You’re ready to cut the hinge mortises in the door. The fence goes back on for this step—first on one face of the template, then the other. Once the hinge mortises are routed, their corners are squared, and pilot holes are drilled, you can hang the door. Then mark the latch side of the door for that same 1/32-in. gap, and plane it for a perfect fit.

I hope this encourages you to use knife hinges, which offer unmatched looks and performance. The template approach eliminates the difficulty and risk usually associated with these elegant hinges, leaving you to enjoy all of their benefits.

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