Abstract: An improved drilling machine for cutting holes for knobs and latches in metal-clad doors comprises a supporting framework for the door and a hollow drill arranged to be moved upward from the underside of the door to cut the knob opening. The drill is hollow in construction and is supported on a drive shaft by a plurality of support members spaced a sufficient distance apart to effect an easy discharge of the core which is cut and drops through the center of the hollow drill bit or cutter. In addition, the drill bit or cutter, which is hollow in construction, has the individual cutting teeth cut at an angle such that the innermost part of the cut is completed through the metal cladding on the door before the cutter begins to cut the wooden portion thereof.