Abstract: In one embodiment, the bodies of the mandrel and the drill have radially opposing portions thereof which are threadedly engaged about the axis of the drill. Through bores in the respective body portions make it possible to latch the drill to the mandrel for the drilling operation, using a pin that is inserted through the bores, and then when the drilling operation is completed, withdrawn from the bores to enable the core of work material to be ejected from the drill by advancing the mandrel on the threading while the drill is restrained against rotation. In other embodiments, the bodies of the mandrel and the drill have axially opposing portions thereof which are equipped with raised steps on the axially opposing faces thereof. The steps enable the drill to be latched to the mandrel for the drilling operation by engaging the faces of the body portions with one another so that the steps abut in one axial plane of the drill.