Servo controller

A servo controller which controls a machine tool that turns a workpiece by cooperative operation of a plurality of axes, the servo controller comprising:

• an oscillation command generating unit that generates an oscillation command for causing the workpiece and the tool to relatively oscillate;
• at least one of
• a position control unit that generates a position command for causing the workpiece and the tool to relatively move,
• a speed control unit that generates a speed command for causing the workpiece and the tool to relatively move, and
• a current control unit that generates a torque command for driving the plurality of axes;
• and
• a gain changing unit that changes a control gain,
• wherein the servo controller transmits a signal outputted when oscillating operation is started to the gain changing unit, and the gain changing unit changes the control gain.