Countersink assembly

A countersink assembly comprising:

• a countersink sleeve body with a distal cutting edge, a longitudinal bore through the sleeve to receive a drill bit, at least one flute extending from the distal cutting edge along at least a part of an outer surface thereof, and a mechanism for selectively securing the sleeve to a drill bit disposed in said longitudinal bore;
• and a depth stop collar having a longitudinal bore to receive and be slidable along the countersink sleeve body, and a mechanism for selectively securing the depth stop collar to said sleeve disposed therein, wherein each flute includes a flat surface and a part cylindrical surface extending from the distal cutting edge along the length of the flute at an angle to the longitudinal bore of the countersink sleeve body so as to present a slight down-cut spiral.

A depth stop collar comprising:

• a cylindrical sleeve body having an annular end face and an aperture defined axially therethrough defining a longitudinal bore for selectively receiving a countersink sleeve body,
• said depth stop collar including at least one cutout for defining a radial opening that communicates the longitudinal bore thereof to a radial outside thereof so as to allow chip egress radially through a side of the depth stop collar.