Abstract: A cutter assembly has an adapter, a cutter body, a central drill and two positioning screws. The cutter body is detachably attached to the adapter. A first facet is defined in the outer periphery of the post. A cylindrical saw is formed on and extends from the bottom of the base. The central drill is detachably mounted on the adapter and extends through the cutter body. A second facet is defined in the outer periphery of the central drill. The positioning screws are screwed into the adapter and respectively abut against the facets on the cutter body and the central drill. With such an arrangement, the cutter body can be easily detached from the adapter when the cutter body is damaged or worn.