Method for generating control command data for controlling a cnc-lathe

A method for generating control command data for controlling a CNC-lathe to perform a turning operation by means of a turning tool, the method comprising the steps of:

• selecting a representation of a metal blank;
• selecting a representation of the turning tool;
• selecting a volume of material from the metal blank to be removed by means of the turning tool, said volume being limited by an inner surface and an outer surface, said metal blank being limited by a peripheral surface, wherein the peripheral surface comprises the outer surface;
• based on the selections above, generating the control command data and commanding the turning tool to perform a first turning pass and a second turning pass based on the generated control command data, wherein the first and second turning passes are parallel or substantially parallel, wherein the first turning pass includes turning of the peripheral surface, and wherein a maximum cutting depth of the second turning pass is greater than a maximum cutting depth of the first turning pass, wherein selecting the volume of material such that the inner surface includes a plurality of part surfaces, each respective part surface being cylindrical, conical or planar;
• calculating a respective length of each of the plurality of part surfaces;
• setting a base line along a part surface, of the plurality of part surfaces, having the greatest length;
• and
• generating the control data for commanding the turning tool to move at least partly along or parallel to the base line during the first and second turning passes.