Utility knife

A utility knife comprising a casing, a blade holder moveably mounted within the casing, means for moving said blade holder from a fully extended position outside the casing to a fully retracted position inside the casing, means for incrementally moving the blade holder between said fully extended and fully retracted position, said moving means comprises a gear mechanism operatively associated with the blade holder, said gear mechanism comprises a driven worm gear, a rotating mechanism operatively associated with the driven worm gear to rotate said driven worm gear to move said blade holder, said rotating mechanism comprises a drive worm gear operatively associated with said driven worm gear, a first interconnecting mechanism associated with said drive worm gear, a second interconnecting mechanism associated with said driven worm gear, said first and second interconnecting mechanisms being operatively associated with each other whereby rotation of the drive worm gear will rotate the driven worm gear, an activating mechanism moveably mounted on said casing, said activating mechanism being operatively associated with said drive worm gear whereby movement of said activating mechanism will rotate said drive worm gear, said activating mechanism comprises a slide button adapted to slide along the casing, said slide button being operatively associated with said drive worm gear whereby sliding the button along the casing will rotate said drive worm gear, said blade holder being operatively associated with said driven worm gear whereby rotation of said driven worm gear moves the blade holder along said casing, said first and second interconnecting mechanisms being gear wheels, said slide button having an engaging mechanism adapted to engage with the thread of said drive worm gear whereby movement of said slide button will rotate said drive worm gear, said blade holder being engaged with the driven worm gear whereby rotation of said drive worm gear will move said blade holder along said casing.