a tool for the machining of workpiece surfaces includes at least one adjustable , geometrically defined cutting edge . the tool additionally includes an adjusting device for the adjusting of the distance of the cutting edge to the central axis of tool . the adjusting device has a drive shaft that acts on an adjusting slide via a gearbox , which determines the distance of cutting edge from the central axis of tool . the adjusting slide may be a round slide arranged eccentrically to the central axis of tool . the gearbox may have a high reduction and may directly act on the adjusting slide .