Routing a Door for Hinges

Here's a simple way to create an inexpensive jig that lets you cut hinge mortises for multiple doors.

- Andy Engel

Today, most interior doors are “pre-hung” in their frames, with the hinges that connect the door to the jamb already in place. While a pre-hung door like this can be retrofitted into an old house, it's also common to need to fit a new door into an existing frame. In that case, it is up to the installer to match the door's hinge locations to the frame's. That means making the hinge mortise, the recess that the hinge sits in, on site. Traditionally, carpenters cut hinge mortises by hand with a chisel—and that's a good method if you have only one door to do, and if you have a sharp chisel. But if you have more than one door to hang, it's better to make a simple jig for a router, and it doesn't take long.

MAKE THE JIG

1 Measure the offset. Measure across the radius of the router base to the bit's edge. The smallest measurement is the right number.

2 Locate the side fences. Double the measurement from step 1 and add it to the hinge height to find the side-fence spacing.

3 Fasten the back fence. For a back fence, align a scrap of 1x to the edge of the plywood and fasten with screws driven from the bottom of the jig.