Drilling and tapping screws

Claim 1

A DRILLING AND TAPPING SCREW COMPRISING A GENERALLY CYLINDRICAL SHANK HAVING AN ENTERING END PORTION THAT INCLUDES A DRILLING TIP PORTION AHEAD OF A TAPPING PORTION, THE LATTER HAVING A PLURALITY OF PARTIAL ENTERING THREADS DEFINED THEREON, SAID ENTERING END PORTION BEING AHEAD OF A HOLDING PORTION OF THE SHANK ON WHICH A PLURALITY OF FULL SIZE HOLDING THREADS ARE DEFINED AS A CONTINUATION OF THE ENTERING THREADS, AND AN ENLARGED HEAD INTEGRAL WITH THE SHANK AT THE OPPOSITE END FROM THE DRILLING TIP MADE TO ACCOMMODATE A SCREW DRIVING TOOL, THE EXTERNAL DIAMETERS OF THE FULL SIZE THREADS ON THE HOLDING PORTION BEING CONSTANT OVER THE AXIAL EXTENT OF SAID PORTION, THE EXTERNAL DIAMETER OF THE PARTIAL THREADS ON THE TAPPING PORTION DIMINISHING TOWARD THE DRILLING TIP, THE OPPOSITE SIDES OF SAID DRILLING TIP PORTION BEING REMOVED TO FORM EQUALLY SPACED PLANAR PARALLEL PORTIONS WITH RESPECT TO A DIAMETRICAL PLANE THROUGH THE AXIS OF SAID SHANK TO DEFINE A DRILL BIT, ONE OF SAID SIDES BEING CUT AWAY HIGHER UP ON THE SHANK THAN ON THE OTHER SIDE TO A LEVEL TO REMOVE AT LEAST THE CREST OF TWO PARTIAL ENTERING THREADS, SAID DRILL BIT HAVING ITS EXTREMITY V-SHAPED TO DEFINE A TIP ON THE AXIS OF THE SCREW AND DEFINING CUTTING EDGES ON OPPOSITE SIDES OF THE ENTERING END THEREOF WHICH FACE IN OPPOSITE DIRECTIONS AND IN SUCH A RELATIONSHIP TO THE AFORESAID THREADS TO DRILL A HOLE IN A PIECE OF WORK WHEN THE SCREW IS TURNED IN THE DIRECTION OF THREADING SAID SHANK INTO THE SAID HOLE, THE CUT AWAY PORTIONS ON OPPOSITE SIDES OF SAID DRILLING TIP PORTION HAVING DEFINED AT THE UPPER EXTREMITIES THEREOF OPPOSITELY-INCLINED CHIP DEFLECTING SURFACES, EACH OF WHICH IS INCLINED IN THE SAME DIRECTION WITH RESPECT TO THE CUTTING EDGE ON THE SAME SIDE OF THE DRILL BIT, SAID ONE SIDE CUT AWAY HIGHER UP ON THE SHANK BEING CONFIGURED TO PRESENT MORE THAN 180* OF BEARING AREA IN A DIAMETRICAL PLANE IN THE SHANK AREA HAVING SAID TWO PARTIAL THREADS.