A calibration method for machine tools comprises: providing a workpiece on a machine tool; rotating the workpiece around a first rotation axis parallel to a main shaft of the machine tool and processing the workpiece by a first machining mode; measuring a first dimensional error of a shape of the workpiece along directions of first and second linear axes perpendicular to the first rotation axis; calculating a positional error of the first rotation axis according to the first dimensional error; rotating the workpiece around a second rotation axis perpendicular to the main shaft and processing the workpiece by a different second machining mode; measuring a second dimensional error of the shape of the workpiece along a direction of a third linear axis perpendicular to the second rotation axis; calculating a positional error of the second rotation axis according to the second dimensional error.

A method for setting a null position of a scanning probe mounted to the rotatable spindle of a machine tool. This method may be performed as part of a probe qualification process. The method includes setting the null position using probe measurement data collected by the scanning probe when mounted to the spindle. In one embodiment, a stylus tip of the scanning probe may be located in a conical recess whilst the probe measurement data is collected. The set null position is arranged to be away from the rest position of the scanning probe and to substantially coincide with the axis of rotation of the spindle. The need to measure and use a probe offset value in subsequent measurement cycles can thus be avoided.

A calibration method for machine tools comprises: providing a workpiece on a machine tool; rotating the workpiece around a first rotation axis parallel to a main shaft of the machine tool and processing the workpiece by a first machining mode; measuring a first dimensional error of a shape of the workpiece along directions of first and second linear axes perpendicular to the first rotation axis; calculating a positional error of the first rotation axis according to the first dimensional error; rotating the workpiece around a second rotation axis perpendicular to the main shaft and processing the workpiece by a different second machining mode; measuring a second dimensional error of the shape of the workpiece along a direction of a third linear axis perpendicular to the second rotation axis; calculating a positional error of the second rotation axis according to the second dimensional error.