Chucking reamers, sometimes called machine reamers, enlarge or finish an existing hole to an exact tolerance or size for a precise fit when installing fasteners or other parts. They have a straight or Morse taper shank that mounts to a compatible machine such as a drill press, lathe, or screw machine. Chucking reamers usually have a 45° chamfer on the cutting edge to help ensure accuracy as the reamer enters the hole during metalworking tasks.