Patent ID: 8299743

Claim:
A machine tool comprising: a tool supporting member relatively movable to a workpiece along a predetermined axis; a servo motor configured to drive said tool supporting member to said workpiece along said predetermined axis; a sizing sensor configured to measure a profile of said workpiece machined by said tool and to output a size deviation of measured values from a target profile; a position detector configured to detect at least one of a relative position of said tool supporting member to said workpiece along said predetermined axis and a rotational position angle of said servo motor; a servo driver configured to drive said servo motor and comprising: a first feedback control having an output based on said size deviation output from said sizing sensor and configured drive said servo motor to make said size deviation to zero; a second feedback control based on an output of said position detector, wherein said servo driver is configured to switch from control based entirely on said second feedback control to control based entirely on said first feedback control.