How to Mortise Box Hinges

If you have spent a long time making a nice box, it is frustrating when the hinges don’t look just as nice as the rest of the box.

mortising hinges
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While a badly installed hinge might work, it will detract from the box, rather than being unobtrusive or adding a decorative element. Because of this, it is important for your woodworking to know how to install hinges.

Follow along to learn how to mortise box hinges by hand.

mortising hinges close-up example

Step 1: Marking

Start by marking where you want your hinge to be. Hold the hinge in place (I like to fold it down so that I know it is fully open and flush with the edge). Make your mark with a sharp pencil or marking knife.

mortising hinges

Step 2: Begin the mortise

Next take a sharp chisel and make a cut all the way around on the inside of your line. It’s best to cut the ends first because it is easy to split the wood when you are going with the grain. If you cut your ends first you are less likely to split the wood when you cut the long side of the hinge mortise.

align chisel cut inside lines

Step 3: Chop the mortise

Now line up your chisel parallel with your end cut. Keep the bottom of the chisel facing towards the front of the mortise (relative to your cut). Angle the chisel just a bit, in toward the mortise, and make a series of cuts from one end of the mortise to the other. Keep the angle and the chisel taps consistent. At this point it is better to have a cut that is a bit shallow, rather than one that is too deep.

mortise box hinge

Once you’ve cut across the mortise, turn your chisel so the bottom is facing down and, using a sideways shearing motion, cut away the chips. Check that the bottom of the mortise is even and clean up any high spots.

mortising box hinges mortise for hinges

Check the fit of your hinge. If it is not deep enough, repeat what you just did until you get the right depth. The final depth should be half the thickness of the barrel of the hinge. On some hinges that will mean the hinge will be flush when in place, but on other hinges the mortise will be deeper than the hinge itself. It’s also nice to sand off the pencil marks, which I did not do below.

mortising hinges result

Once you are satisfied with your mortise, screw the first side in place. I always pre-drill. I use brass screws and they are very soft. I have snapped more than one and it is frustrating and time consuming to dig out the broken screw, fill the hole and put another screw in place. So, after way too long, I learned my lesson and now I pre-drill.

Step 4: Begin the second side

Once the first side is screwed in place, mark your lines for the other half of the hinge. Remember to keep a gap, the width of the barrel of the hinge, between the two hinge flaps. I often use a shim between the pieces to keep the distance consistent for each hinge.

mortising hinges

Repeat the process of chopping and cleaning for the second side. Test your fit and, if you like it, drill and screw for that side as well. That’s it, you now know how to mortise a box hinge.

mortising hinges

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