Abstract: A core breaker that includes a support that contains at least one bore wherein the bore is defined in part by an axial forward frusto-conical wall and further defined by an axial rearward cylindrical wall that contains a groove therein. The core breaker has an elongate rotatable cutting tool that has an axial forward end and an axial rearward end, as well as a head adjacent to the axial forward end and a shank adjacent to the axial rearward end wherein the shank contains a reduced diameter portion. There is a frusto-conical shoulder mediate of the head and the shank. The cutting tool further includes a resilient retainer that has at least one radial outward protrusion. When the cutting tool is retained within the bore, the protrusions of the resilient retainer are received within the groove in the bore and the frusto-conical shoulder of the cutting tool is closely adjacent to the frusto-conical wall of the bore.