Global offset compensation for a cnc machine

A method for loading a part on a four-axis CNC machine having six degrees of freedom comprising:

• mounting a fixture on a table for the CNC machine;
• clamping a part to the fixture;
• machining a plurality of features and surfaces on the part and using the machined features and surfaces to determine an actual part center position;
• calculating a table offset, a fixture offset, and a rotary axis offset of the actual part center position to a nominal part center position;
• translating the table and the fixture by the table offset, the fixture offset, and the rotary axis offset in order to determine a position of the actual part center to the nominal part center for a coordinate system for each of the four axes of the CNC machine;
• and
• programming a controller with a global offset compensation based upon the calculated offset amount for each of the six degrees of freedom to translate the coordinate system on each of the four axes to the actual part center position.

A method for loading a part on a five-axis CNC machine having nine degree of freedom comprising:

• mounting a fixture on a table for the CNC machine;
• clamping a part to the fixture;
• machining a plurality of features and surfaces on the part and using the machined features and surfaces to determine an actual part center position;
• calculating a first table offset, a second table offset, a fixture offset, a first rotary axis offset, and a second rotary axis offset of the actual part center position to a nominal part center position;
• translating the first table offset, the second table offset, the fixture offset, the first rotary axis offset, and the second rotary axis offset in order to determine a position of the actual part center to the nominal part center for a coordinate system for each of the five axes of the CNC machine;
• and
• programming a controller with a global offset compensation based upon the calculated offset amount for each of the nine degree of freedom to translate the coordinate system on each of the five axes to the actual part center position.