1. A method of positioning the operating region of a tool component at a pre-determined, random grid element in a nominally regular grid of nominally identical grid elements, whereby the positioning occurs with the aid of an adjusting mechanism, comprising the steps of: a. finding an initial position reference in the grid; b. performing a displacement of the tool component with respect to the grid; c. subsequently finding a position reference in the grid; d. testing if the pre-determined grid element is within a pre-determined distance of the operating region of the tool component, and; e. depending upon the result of the test, repeating step b , and, if necessary, repeating steps c and d, characterized in that: the displacement takes the form of a displacement jump; a maximum jump size is determined on the basis of: the positional uncertainty of the displacing mechanism expressed in units of the grid period or, the uncertainty in the periodicity of the grid expressed in units of the grid period, and; the displacement jump is chosen to be smaller than the maximum jump size.