1 Building the jig
A jig like the one shown at left will allow your router to cut hinge mortises quickly and accurately. To make the cuts, you will need to equip your router with a straight bit and a template guide. Build the template from a piece of  /4-inch plywood. Size it wide enough to support the router. Outline the hinge leaf on the template; remember to compensate for the template guide and the thickness of the fence, which is also made from 3/4-inch plywood. Cut out the template, then attach the fence with countersunk screws.