Abstract: A counterbore tool having a removable cutting tool in which the cutting tool is disposed in an open slot of the shank, the slot extending inwardly from the outer extremity of the shank and in which the pilot member is secured in telescoping engagement with the end of the shank, the pilot member being detachably held by fastening means which clamps the pilot member against the cutting tool and holds it firmly in place. The cutting tool has a transverse depth equal to the width of the slot so as to fit snugly within the slot. The cutting tool and shank are provided with interfitting male and female members which prevent movement of the cutting tool transverse to the axis of the shank. The pilot member snugly telescopes over the shank and is provided with a slot extending over the outer side edge of the cutting tool.