The combination lock described has been used for years on lockers and letter boxes in a large public building. The details of a lock with three disks are given, and in Fig. 4 the use of two disks is suggested. The lock is made as follows: From a piece of ³⁄₁₆ or ¹⁄₄-in. hard wood, saw out three disks, A, Fig. 1, from 1 to 4 in. in diameter, according to the size of lock desired. For one with 2-in. disks, as shown, cut slots, B, ¹⁄₂ in. wide and deep, in the edge of the disks. For axles use ³⁄₈ by 2-in. hardwood dowels, C, with a six-penny headless wire nail in one end, leaving about ¹⁄₄ in. of it exposed.
Fig. 1
Fig. 2
Fig. 3
Fig. 4
This Wooden Combination Lock Gives Good Service and is Easily Made
The case of the lock is shown in Fig. 1. It is made large enough to mount the disks, as shown. Around the edges of the inside surface of the lid fasten strips a trifle thicker than the disks. Place the disks in the positions shown, drilling small holes in the baseboard for the nail axles. The bolts, D, and the piece, E, are made of hard wood, fastened with a lap joint. On each side of the bar, D, fasten cleats, F, to hold it in position. The handle, H, moves in a slot in the lid, and is fixed to the bar, E.
The door, or lid, on which the lock is to be used, is provided with openings, J, as shown in Fig. 3. The axles C, project through openings, as bearings. When the windows J, through which the combinations are read, are made, place the ends of the bolts in the slots of the disks and screw the lock in position. Mark on each disk the point exactly in the center of the window, enabling one to work the combination temporarily. To lock the device, push the handle to the left and turn the axles. To unlock it, turn the axles until the pencil marks appear in the middle of the windows, and throw the bolts.