The invention concerns a method for determining a deviation of at least one regulating variable on chip removal machines with a mechanical drive for a tool and/or a workpiece, regulated by a control system, wherein the regulation comprises a plurality of values C, X, Z of at least three spatial axes c, x, z for the control system and for the drive, and the values C, X, Z have a functional relation such as Z=fbi (C, X) with the axes c, x, z. A protocol is prepared from a plurality of control system actual values (Cp,s, Xp,s, Zp,s) detected by measuring means and/or selected drive actual values (Cp,a, Xp,a, Zp,a) and a control system nominal value according to Zbi,s=fbi (Cp,s, Xp,s) and/or a drive nominal value according to Zbi,a=fbi (Cp,a, Xp,a) is calculated at least in relation to the z-axis, and a control system differential value according to Dz,s=Zp,s−Zbi,s and/or a drive differential value according to Dz,a=Zp,a−Zbi,a is calculated at least in relation to the z-axis. The invention also pertains to a chip removal machine which implements such a method.