A device for determining a location on an elongated workpiece, characterized in that the device comprises: a frame movable in a first direction, preferably in a longitudinal direction of the workpiece, positioning means to position the frame in relation to the sides of the workpiece, movable means movable in a second direction, preferably in a transverse direction with respect to the frame, a measuring point, the movement in first direction and second direction used to move measuring point in said directions, measuring equipment for determining the location of the measuring point in transverse and longitudinal respect to the workpiece.