DE2341796

A novel drilling bit constituted by a cylindrical roller having a diameter which is smaller than the diameter and larger than the radius of the drilled hole. The roller is rotatably mounted on a tubular shaft which is parallel to but displaced eccentrically with respect to the axis of the drill stem and armed on the flat cutting face thereof with cutting elements and peripheral teeth, protection against radial wear being provided by anti-abrasive elements incorporated in the surface of the cylindrical zone which forms an extension of the teeth. A drill-sten connector which is coaxial with the hole balances the eccentric displacement of the roller by means of eccentric masses which are protected against wear and is provided with a duct for drilling fluid.