In a method for controlling a tool during machining a work piece using the tool, a first measuring arrangement which has a first ultrasonic probe for emitting ultrasonic waves is used, the first measuring arrangement being arranged ahead of the tool with respect to the relative tool movement direction and being moved relative to the work piece in the relative tool movement direction. The ultrasonic waves emitted by the first ultrasonic probe are transmitted to the work piece, and are transmitted back to the first ultrasonic probe, by a first column of liquid which is created by the first measuring arrangement and situated between the first ultrasonic probe and the work piece for measurement. The measurements are used for automatically adjusting the position of the tool relative to the work piece during machining the work piece.