A drill tool for rotary and/or percussion drilling includes a drill string and a cutting apparatus connected to a lower end of the drill string. The cutting apparatus has an intermediate portion which is rotatable with the drill string and includes an outer surface, a reamer is mounted eccentrically on the intermediate portion for rotation relative thereto about a longitudinal axis. The reamer includes an inner surface facing the outer surface. The reamer is driven by an arrangement comprised of a tongue disposed on either of the inner and outer surfaces and a pair of circumferentially spaced shoulder surfaces disposed on the other of the inner and outer surfaces. The tongue is selectively engageable with the shoulder surfaces along an area of contact having an upper longitudinal end which terminates below an uppermost end of the reamer, and a lower longitudinal end which terminates above a lowermost end of the reamer.