Trepanning and boring head

Claim 1

IN AN APPARATUS FOR FORMING HOLES WHEREIN A HOLLOW HEAD HAVING A LONGITUDINALLY EXTENDING PASSAGE IS BROUGHT INTO CONTACT WITH A WORKPIECE AND RELATIVE ROTATION IS PRODUCED BETWEEN THE WORKPIECE AND HEAD ABOUT THE AXIS OF THE HEAD TO FORM THE HOLE, THE IMPROVEMENT WHEREIN SAID HEAD HAS AN AXIALLY EXTENDING OPENING THEREIN HAVING GENERALLY RADIAL PARALLEL SIDE FACES, SAID OPENING EXTENDING RADIALLY INWARDLY TO THE PASSAGE AND RADIALLY OUTWARDLY TO THE PERIPHERY OF SAID HEAD, ONE SIDE FACE OF SAID OPENING HAVING A GENERALLY AXIALLY EXTENDING KEY SLOT FORMED THEREIN, SAID KEY SLOT BEING GENERALLY RECTANGULAR IN CROSS SECTION AND BEING INCLINED TO THE AXIS OF SAID HEAD, A CUTTER BODY HAVING GENERALLY PARALLEL SIDES AND A CUTTER ON ONE END THEREOF, SAID CUTTER BODY BEING POSITIONED IN SAID OPENING, A GUIDE KEY OF RECTANGULAR CROSS SECTION ON ONE SIDE OF SAID CUTTER BODY INTERMEDIATE THE SIDE EDGES THEREOF AND INTERENGAGING SAID KEY SLOT ON SAID HEAD, AND MEANS FOR CLAMPING SAID CUTTER BODY AGAINST SAID ONE SIDE FACE OF SAID OPENING IN ADJUSTED POSITION RELATIVE TO SAID KEY SLOT.