#### Disk Stylus Calibration Notes and Procedure

When performing a discrete hit calibration of a disk stylus on an analog probe with the qualification sphere, you need to specify five hits in the Number of Hits box and two levels in the Number of Levels box in the Measure Probe dialog box. These do not apply for probes that use the Renishaw scan-based calibration.

Make sure when you define your probe, that you model a disk stylus and not a ball stylus. Once you click the Measure button on the Measure Probe dialog box, PC-DMIS will automatically recognize that you have an analog probe with a disk stylus and will go through this procedure:

- If you moved the sphere, or if you chose the Man + DCC mode, PC-DMIS will prompt you to take one manual hit on the very top of the qualification sphere (the north pole) with the center of the bottom of the disk stylus. If your probe configuration has an additional ball stylus attached to the bottom of the disk stylus, be sure to take the hit with that ball stylus.

- If you didn't move the sphere, and you chose not to use Man + DCC mode, PC-DMIS will take the hit on the top of the qualification tool in DCC mode.

PC-DMIS then finishes by doing the following in DCC mode:

- PC-DMIS will do one of the following based on the value of the ProbeQualAnalogDiskUsePlaneOnBottom registry entry located in the Probe Cal section of the PC-DMIS Settings Editor:

- If this entry is set to 1, PC-DMIS takes four hits on top of the sphere using a circular pattern on the bottom of the disk stylus and calculates a plane from it. Measuring a plane helps ensure that the hits for calibrating the face are oriented properly to reflect the actual plane of the disk. This is the default for the traditional calibration method using discrete hits.

- If this entry is set to 0, PC-DMIS does not attempt to measure a plane on the bottom of the disk's face. Instead it uses the design orientation of the disk. This is the default for the Renishaw scan-based calibration.

- After the hits are taken on top of the sphere it takes six hits on two levels to get a close location of the center point of the sphere.

- It uses the center point along with the vector from either the plane measurement or the design orientation to correctly position the subsequent measurement.

- For discrete hit calibration it takes five hits: four in a circular pattern around the equator of the sphere, and the fifth hit on the top, or the pole, of the sphere.

- For scan-based calibration it takes a series of scans at two different levels, one slightly below the equator and one slightly above the equator. Each level is scanned in both clockwise and counter-clockwise directions. Each direction for each level is also scanned using two different scan force offsets. This results in a total of eight scans.

PC-DMIS also provides two additional registry entries in the PC-DMIS Settings Editor in the Probe Cal section; you can use these to affect the location of the hits on the bottom of the disk stylus during calibration. These entries are:

- ProbeQualAnalogDiskBottomHitsDistanceFromEdge

- ProbeQualAnalogDiskPlaneStartAngle

See the "Modifying Registry Entries" documentation more information on these entries.