23 lead to an overhang of bearing area 21 in the transitional area as a result in the present example a reference surface 25 is produced at one of the two plane parallel side surfaces 34 the target dimension for the position of active edge 24 results here as well from the perpendicular distance a 0 of active edge 24 to reference surface 25 fig8 a and b show the state of wear arising over the course of comminuting operation the height of comminution area 23 declines compared with the unused original state dotted line 26 due to the gradual wear which results in a reduction of the distance a 1 between active edge 24 u2032 and reference surface 25 in main wear direction 33 the determination of the current distance a 1 occurs similar to the process and the embodiments of the invention described in fig1 to 6 so that the statements made there apply the resulting wear here as well is calculated by determining the difference between the distance a 0 and the distance a 1 in embodiments of the invention shown in fig1 a to 8 b the reference surface in each case is formed by a projection or shoulder in the side surface of the comminuting tool the fact that the invention is not limited thereto is shown by fig9 a to 9 c in the example of a shearing tool 1 already described in regard to fig1 to 3 the embodiment of shearing tool 1 as shown in fig9 a has at least on one side preferably on two.