A self-aligning counter bore cutting tool for cutting a counter bore in a subfloor, the tool comprising:
- an annular frame defined by a perimeter region and a concentrically disposed central shaft extending along a rotational axis, which defines a forward axial direction and a rearward axial direction, the perimeter region including an outer peripheral surface extending between a forward end surface and a rearward end surface, the central shaft protruding, in the axial forward direction, beyond the forward end surface, the central shaft includes a first central aperture;
- a shaft bushing mounted on and extending co-axially from the central shaft in the axial forward direction, the shaft bushing includes a second central aperture coaxial with the first central aperture;
- a drill bit located within and extending through the first central aperture and the second central aperture such that a cutting edge of the drill bit protrudes beyond the shaft bushing in the forward axial direction, the drill bit is fixed relative to the frame, whereby a drill causes rotation of the drill bit and the frame about the rotational axis;
- a plurality of arms extending between the perimeter region of the frame and the central shaft, each of the plurality of arms includes:
- exactly one arm slot defined by a sloped wall and a flat wall, the flat wall is parallel to a plane parallel to the rotational axis and the sloped wall is inclined relative to the plane, the sloped wall and the flat wall meeting at an inner junction point, and the sloped wall and the flat wall extending out to an open end at the forward end surface;
- a cutting blade mounted in direct contact against the flat wall within the exactly one arm slot, the cutting blade defined by a cutting edge;
- a fastening block defined by a tapered shape corresponding to the sloped wall and the flat wall, the fastening block mounted within the exactly one arm slot and retaining the cutting blade at a fixed position, the fastening block located in front of the cutting blade in a rotation direction;
- at least one, but not all, of the plurality of arms includes a respective depth restriction bar protruding from and beyond the forward end surface in the forward axial direction, the respective depth restriction bar of the at least one, but not all of the plurality of arms:
- is located between the shaft and the perimeter region;
- and
- is capable of restricting the cutting blades from cutting into the subfloor beyond a predetermined depth;
- whereby the cutting blades are capable of engagement with the subfloor to cut the counter bore;
- and
- whereby the shaft bushing is capable of aligning the frame with a hole cut by the drill bit.