## Home the Unit

Type of Operation area showing the Home the Unit option

Some wrist devices¾such as the Renishaw PHS¾do not have predefined zero positions and use potentiometers instead of scales to position the wrist. These types of wrist devices need to have the zero redefined every time power to the probe head controller is interrupted. In order to redefine the wrist zero position, you may choose the Calibrate the Unit option (see “Tip Calibration”) or the Home the Unit option.

Selecting Home the Unit will calculate the angular error offset from the previously calculated wrist zero position by qualifying one or more probe angles on a previously calibrated sphere position. The advantage to this is you can use a minimum of one probe tip angle making the process much faster than a wrist calibration.

It is recommended that you use more than one probe angle to accomplish Home the Unit since PC-DMIS will average the errors of the homing procedure to provide a more accurate adjustment to the wrist error map.

To perform a Home the Unit:

1. Access the Probe Utilities dialog box by selecting the Insert | Hardware Definition | Probe menu option.

2. Select the same probe file that was used to calibrate the unit.

3. Select the angles you wish to use for the calibration check from the Active Tip List.

4. Click the Measure button. The Measure Probe dialog box appears.

5. Provide the parameters you wish to use during the calibration check including selecting the same calibration tool used during Calibrate the Unit.

6. Select the Home the Unit option from the Type of Operation area.

7. Click the Measure button.

Note: After calibrating the unit and prior to homing the unit, you shouldn’t move the calibration sphere. If it is moved, you must re-calibrate the unit (see “Tip Calibration”).