Few problems give a more accurate measurement of a home worker's skill than the fitting of a pair of hinges. In doing this the only mark or cut that is "good enough" is that which is as near absolute accuracy as the worker can make it.

The exact length of the hinge AA in Fig. 40 should be marked from the hinge itself with a knife point. Never use a pencil where such accuracy is required. Line B should be made with a sharp gage set about the thickness of a piece of paper less than the parallel thickness of the hinge from the joint as shown at E, which will prevent the joint from becoming hinge bound. The gage line C should equal the distance between the edge of the hinge plate and the pin, as shown at E; if very fine work is desired, the distance should be as at C1, but C is commonly used.

In cutting to the lines, use a thin edged chisel about 1/8 in. wider than the distance C. Make the first cuts as shown at 2, which will allow cuts A to be made accurately as at 3. Cut the wood away by using the chisel as at 4 and work carefully to depth line B. Place the edge of the chisel in line B, as shown at 5. Cut the wood away back to the line C; hold the chisel as at 6 and cut gently, for there is danger of breaking out the wood back of C.

Trim the cuts carefully, making the lower surface or bed of the hinge ABC and the back cut straight and smooth as at 7. Fasten the hinges with screws as at 8. Be sure the pin is in accurate alignment with the corner D.

Lay out the distance C where each hinge is to be placed on the other member of the joint, and locate the exact endwise relationship. Set the hinges at these marks and drill a hole in the wood at the center of one hole in each hinge. Drive the screws until each hinge is pulled down to its place. Inspect the surface relations of the members of the joint. Small inaccuracies may be remedied by loosening the first screw of one or both hinges as may be necessary and drilling a hole for the other screw of each hinge close to that side of the hole, which will tend to force the hinge endways or sideways as may be needed.

Fig. 40. - The steps to follow in marking and chiseling hinge mortises on box lids and cabinet doors.