Abstract: A locking device for releasably securing a first member to a second member which second member has an opening therein for receiving a portion of the first member, a groove in the portion of the first member within the opening, a cylindrical pin in the second member extending across the opening in the first member and in the groove in the second member in one angular position thereof, a portion of which pin is removed so that in another angular position the pin does not extend into the groove in the first member. In one modification, the pin is bowed slightly to provide spring like interference to movement thereof. In another modification, the central portion of the pin is eccentric whereby the central portion of the pin extends into the groove in the first member in one rotated position of the pin, and is completely out of the groove in another rotated position. In a further modification, the second member includes a cylindrical selecting part and a rotatably mounted securing part.

Abstract: Rotary scalpel blade and blade protector structure. The rotary scalpel blade in one embodiment is circular and has a sharpened outer periphery and an opening through the center thereof for securing the blade to means for rotating the blade. In modifications of the circular scalpel blade the sides of the scalpel blade may be concave, depressed or flat with an annular groove around the outer periphery thereof. The rotary scalpel blade may also be a linear radial scalpel blade sharpened on one or both edges. The blade protector structure in one embodiment includes a disc having a disc shaped pocket in the center thereof split centrally to receive a scalpel blade, held together with a living hinge and locked in closed position by a split cylinder positioned over a cylindrical flange on one side of the blade protector.