What is the correct procedure for establishing a work coordinate system (WCS) using a touch probe on a CNC milling machine?

The correct procedure for establishing a Work Coordinate System (WCS) using a touch probe on a CNC milling machine involves several key steps to accurately define the origin for the part program. First, the touch probe must be properly installed and calibrated. Calibration ensures that the probe accurately measures distances in all directions. This involves running a calibration routine, typically using a precision ring gauge or a known reference surface, to determine the probe's stylus diameter and any offsets. Next, select an appropriate probing routine based on the feature being probed. Common features include part corners, edges, center of holes, or center of bosses. The CNC control provides built-in probing cycles (G-codes) designed for these features. For example, to find the corner of a rectangular workpiece, the probe would be moved close to the corner and then the probing cycle initiated. The machine will automatically move the probe in a predefined sequence, touching off on two adjacent surfaces. The probing cycle records the machine coordinates at the point of contact. The user then inputs the desired WCS origin location relative to the probed point. This offset is then stored in the machine's work offset table (e.g., G54, G55). For instance, if the probe touches the corner and the program requires the origin to be 1 inch away in both X and Y, that 1-inch offset is entered. After the probing cycle completes, the CNC control calculates the necessary offset values to align the machine's coordinate system with the desired WCS. The selected work offset (e.g., G54) is then activated in the CNC program, establishing the WCS for subsequent machining operations. Verification is important; running a simple test program to check the location of a known feature ensures accuracy.