Patent ID: 8695221

Claim:
Utility knife comprising: a handle having an upper edge and defining a handle axis generally parallel to said upper edge and a remote end provided with an opening; a carriage slidably mounted within said handle for movements through said opening between a retracted position, in which said carriage is substantially fully received within said handle, and a fully extended position, in which said carriage is fully extended through said opening to increase the effective length of said handle by a distance Δl; an actuating element coupled to said carriage for moving said carriage by engagement with a user's thumb for movement of said carriage between said retracted and extended positions; and a blade mounted on said carriage for sharing the movements of said carriage and having an operative portion that can fully penetrate a work to be cut when said handle axis is inclined at an angle α relative to a surface of the work; wherein the handle includes a forward portion closest to the operative portion of the blade, the forward portion being configured for positioning a finger of a user so that a center axis of the finger is a distance h above the work surface when the operative portion of the blade fully penetrates the work to be cut, Δl and α being selected so that the distance h is equal to at least 1.0 inch.