Recessed screw heads and drivers

In combination, a screw having a recess at one end thereof and a driver, mateable with said recess to enable said driver to rotatably drive said screw, the improvement comprising:

• said recess including a central portion and a plurality of grooves extending generally radially and outwardly from said central portion, each of said grooves being defined at least in part by a pair of sidewalls;
• a projection formed on at least one sidewall of each of said grooves, said projection extending from its associated sidewall and being of sufficiently small dimensions as to be deformable in response to application of driving torque by said mated driver;
• said driver including a central core portion and a plurality of blades radiating therefrom, said blades being equal in number and spacing to the grooves of said recess, each of said blades being defined by a pair of surfaces on opposite sides thereof to face said sidewalls of said grooves when mated;
• and
• means defining a rib on that surface of each of said blades which faces its associated groove sidewall having said projection formed thereon, said ribs being located on said blades and with respect to said recess and said sidewall projections so that said ribs and sidewall projections may engage and interlock with each other.

In combination, a screw having a recess formed at one end thereof and a driver mateable with said recess to enable said mated driver to rotatably drive said screw comprising:

• said recess including a central portion and a plurality of grooves extending generally radially and outwardly from said central portion, said central portion of said recess being further defined in part by intermediate walls extending between the inner regions of adjacent of said grooves;
• said driver comprising a central core and a plurality of blades extending from said central core, said blades being equal in number and spacing to the grooves of said recess, said core being defined in part by an intermediate wall extending between each pair of adjacent of said blades;
• and
• a rib formed along the lower edge of each of said intermediate driver walls and extending between each of said pair of adjacent blades, said ribs being engageable with the intermediate walls of said recess.

In combination, a screw having a recess formed at one end thereof and a driver mateable with said recess to enable said driver to rotatably drive said screw comprising:

• said recess including a central portion and a plurality of grooves extending generally radially and outwardly from said central portion, said central portion of said recess being further defined in part by walls extending between the inner regions of adjacent of said grooves;
• said driver comprising a central core and a plurality of blades extending from said central core, said blades being equal in number and spacing to the grooves of said recess, said core being defined in part by an intermediate wall extending between each pair of adjacent of said blades;
• and
• the lower region of each of said intermediate walls being defined by a concave region of a configuration to define a relatively sharp edge at the lower end of each of said intermediate walls.