Work Offset (Fixture Offset)

Work offset is a CNC controller parameter that defines the position of the workpiece coordinate system relative to the machine coordinate system, ensuring that G-code cutting coordinates align correctly with the actual part location. During CNC machining setup, technicians use a probe or dial indicator to locate a reference feature (usually a datum surface or hole established earlier), then enter the X, Y, and Z offsets into the CNC controller so the part program references the correct part location.

Incorrect work offset entry is one of the most common sources of part errors, the program might be correct, but if work offset is wrong, the machine cuts in the wrong location and scraps the part. Multi-setup parts require multiple work offsets (one for each setup), and experienced setup technicians carefully document and verify each offset to prevent costly mistakes.

Modern CNC machines often include automatic probe systems that measure work offset values directly, improving accuracy and reducing the potential for manual entry errors.