Hanging Door Hinges on Mortising

A few weeks back, while I was watching the NBA playoffs on TV, a friend (who only calls when he needs something) rang me up for the complete step-by-step procedure for mortising hinges. Engrossed in a close game, I gave him a quick brushoff: “Just lay the hinge on your door, trace around it with a sharp knife, and then chop out the waste with a chisel.”

Actually, there are much easier, more accurate ways to get the job done, but they are too detailed to go into during the playoffs. Now that the basketball season is over, however, I’ll be perfectly happy to pass them along.

If you have a lot of doors to hang, go to a good hardware store or Sears and buy a template set. With one of these and a router, you can set yourself up to knock out mortises in a matter of minutes. Just read the instructions.

If you only have one or two doors to hang, however, it doesn’t pay to invest in a template. Instead, do the job freehand with a router.

To make the job easy, start with the hinges. Get the kind that have corners rounded to a three-eighth-inch radius. Also, if you don’t already have one, get a straight router bit with a diameter of three-quarter inch. This combination will save you a lot of work because the bit will cut a mortise with the same radius as the corners of the hinges.

If you buy hinges with square corners, you’ll have to chop out the corners of the mortise by hand with a chisel. That means more work, and more chances to make mistakes.

OK, you have your hinges and you have your bit. Chuck the bit in the router, turn the router on its head and lay the hinges down on the base plate right next to the bit. Adjust the router depth so that the end of the bit is flush with a single leaf of the hinge. Your router is now set and ready to go.

Next, place your hinge in position on the edge of the door. Holding it firmly in place so it won’t skid, cut all the way around the hinge with a sharp utility knife. If the hinge tends to slide around while you do this, tack it in place with a couple drops of super glue.

If the door is a hardwood such as oak, you may have to go around the hinge two or three times with the knife. But for the typical pine door, one firm pass is usually enough. Once your cut is made, remove the hinge and you are ready to rout.

Turn the router on, place it in position on the edge of the door and start cutting. Try to rout right up to the line you have scored. Get your face right down where you can see what you are doing, but be sure to wear eye protection. As you cut up to the score line, you’ll see a tiny splinter of wood tear free. That’s the sign you have cut far enough.

Cut all around the score line like this, watching for that little splinter. Once you have routed out the perimeter, you can go back and rout out the rest of the mortise. Just be careful not to let the router tip.

If you have trouble keeping the base plate stable on the narrow edge of the door, you can clump scraps of wood on both sides of the door to pack it out and provide a wider surface to work on.

Once the mortise is cut, the only other trick to a neat job is driving the screws properly. If you drive these out of position, they will pull the hinges out of position. So I use a self-centering bit like the one shown in the sketch.

This bit--called a Vix or a Vike bit--has a conical nose piece that fits into the countersink in the hinge and guarantees that you’ll drill your pilot holes dead center. Good hardware stores often sell these bits, or you can get them through mail order tool catalogues such as Trend-Lines, (800) 343-3248, or Constantine’s, (800) 223-8087.