Abstract: Two machine tools are provided with control systems for machining two different types of pieces to be matched to each other. In order to obtain small batches of relevant pieces that basically can be completely matched to one another, the control systems are independent from each other and each of them comprises post-process and in-process checking stations; the first station, besides checking the proper operation of the in-process station progressively and at short regular intervals changes its zero condition, so as to obtain machining pieces having dimensions evenly distributed within the relevant tolerance range.