Abstract: A cylinder lock having a barrel and a cylinder and being actuable by a key having a round shaft. The round shaft has provided along its one longitudinally extending planar surface a plurality of substantially rectangular recesses which correspond with pin portions of lower tumblers normally extending into the keyhole of the cylinder and biased by springs and upper tumblers in the barrel, such that when the key is inserted into the keyhole and rotated to a predetermined position to allow the pin portions to be received in the corresponding recesses, the cylinder can be driven to rotate relative to the barrel by the turning force of the key transmitted to the pin portions through their contact with the side walls of the recesses if the key is further rotated, thereby locking or unlocking the cylinder lock.

Abstract: A key manufacturing method, which includes a first procedure to produce key bodies through material shape molding, side-edge cutting process, thickness, curvature and length milling process, bitting forming process, and numbering and classification process according to shape of bitting; a second procedure to produce sheaths through copper rod planing process, conical front end milling process, groove lathing process and opposite inner wall trimming process; and a third procedure to fixedly fasten a key body in a sheath to form a unitary round key.