Machine tool

A machine tool comprising:

• an artifact;
• a head including a rotatable workpiece holder;
• a probe configured to be mounted to the workpiece holder;
• a tool holder for holding a tool;
• a tool holder actuator operable to move the tool holder;
• a controller operably connected to the head, the probe, and the tool holder actuator, the controller configured to:
• calibrate the probe by moving the probe and the artifact relative to one another to bring the probe and the artifact into contact with one another;
• and
• determine a tool offset value for the tool using data from calibrating the probe and by moving the probe and the tool holder relative to one another to bring the probe and the tool into contact with one another;
• wherein one of the probe and the artifact includes a cylindrical surface and the other of the probe and the artifact includes a plurality of flat surfaces;
• wherein the controller is configured to calibrate the probe by moving the probe and artifact relative to one another to bring the flat surfaces and the cylindrical surface into contact with one another and determining a centerline of the probe;
• wherein the controller is configured to calibrate the probe by moving the probe and the artifact relative to one another including:
• turning the probe after bringing the flat surfaces and the cylindrical surface into contact with one another;
• bringing the flat surfaces and the cylindrical surface into contact with one another after turning the probe;
• wherein the controller is configured to determine a first centerline based at least in part upon moving the probe and artifact relative to one another before turning the probe;
• wherein the controller is configured to determine a second centerline based at least in part upon moving the probe and artifact relative to one another after turning the probe;
• and
• wherein determining the centerline of the probe includes determining the centerline based at least in part upon the first centerline and the second centerline.

A method of preparing a machine tool to machine a workpiece, the machine tool having a Z axis, a X axis extending perpendicular to the Z axis, and a Y axis extending perpendicular to the Z axis and the X axis, the machine tool comprising:

• a head;
• an artifact in the machine tool;
• a probe mounted to the head of the machine tool;
• a rotatable workpiece holder of the head, the head configured to rotate the workpiece holder around the Z axis;
• tool holders for holding tools in spaced apart relation to one another;
• a tool holder actuator operable to move the tool holders along the X axis and the Y axis relative to the workpiece holder;
• a memory configured to store locations of calibration surfaces of the artifact;
• the method comprising:
• determining a tool offset value for a tool of the tools received in the tool holders by moving the probe and the tool holders relative to one another to bring the probe and the tool into contact with one another;
• and
• prior to determining the tool offset value, calibrating the probe with respect to the Z, X, and Y axes by moving the probe and the artifact relative to one another to bring the probe and the artifact into contact with one another, wherein calibrating the probe includes:
• determining a Z-axis offset value and a centerline of the probe along the X and Y axes using the stored locations of the calibration surfaces of the artifact and the relative movement of the probe and the artifact.

A machine tool comprising:

• a calibration member;
• a head including a rotatable workpiece holder, the head including a drive operable to rotate the workpiece holder around a Z axis;
• a probe of the head;
• a tool holders for holding tools in spaced apart relation to one another;
• a tool holder actuator operable to move the tool holders along an X axis perpendicular to the Z axis and a Y axis perpendicular to the Z and X axes;
• wherein the tool holders are configured against movement along the Z axis;
• a controller operably connected to the head and the tool holder actuator;
• a memory of the controller operable to store location data of surface portions of the calibration member;
• the controller configured to calibrate the probe by utilizing the location data of the surface portions of the calibration member and moving the probe and the calibration member relative to one another to bring the probe and the calibration member into contact with one another;
• and
• the controller configured to determine a tool offset value for a tool of the tools held in the tool holders using data from calibrating the probe and by moving the probe and the tool holders relative to one another to bring the probe and the tool into contact with one another.