An operating facility for a CNC control system controls a machine tool with a plurality of machine axes. A tool inserted into a tool receptacle of a tool spindle can be displaced relative to a workpiece and/or rotated about a tool spindle axis. A rotary controller manually operated by an operator can set a feed rate with which the tool is moved relative to the workpiece and/or a spindle rotary speed. A graphical user interface is used to adjust the effect of an operating action carried out by the rotary controller on the feed rate or the spindle rotary speed. This improves the flexibility with regard to adaptation to the requirements of the individual user.