Current Help System: PC-DMIS CMM (View Core Help)

#### Performing an Upper Level Matrix Calibration

After you've finished calibrating the lower level matrix, you can perform the regular calibration. This upper level calibration will calibrate the actual probe tips. It will also send another matrix of numbers to the controller that give small corrections to the lower level matrix based on the current probe configuration and orientation.

To achieve greater accuracy, PC-DMIS should take probe hits, measuring a full sweep, all around the equator of the calibration sphere. If you have good angle of coverage on the sphere, you will get better results. The start and end angles for the sweep around the sphere's equator can be controlled from these settings within the [ProbeCal] section of the PC-DMIS Settings Editor:

FullSphereAngleCheck=25.0

ProbeQualToolDiameterCutoff=18.0

ProbeQualLargeToolStartAngle1=50.0

ProbeQualLargeToolEndAngle1=310.0

ProbeQualSmallToolStartAngle1=70.0

ProbeQualSmallToolEndAngle1=290.0

For information on modifying registry entries, please view the "Modifying Registry Entries" section.

Calibration Procedure

Follow this procedure to do an upper level matrix calibration:

1. At the Probe Utilities dialog box (Insert | Hardware Definition | Probe).

2. Click the Measure button.

3. Select Calibrate Tips from the Type of Operation area.

4. Select User Defined from the Calibration Mode area. Since the Default method only takes hits around the diameter and one hit on top of the calibration sphere it doesn't give a very good 3D relationship of the probe center. However, if you want to calibrate using the Default method, be sure to read the "Notes on SP600 Default (2D) Calibration Mode" topic below.

5. Type 3 in the Number of Levels box. You can type in additional levels as long as they don't exceed the number of hits you'll be taking. But the minimum number of levels should be at least three.

6. Type 0 in the Start Angle box.

7. Type 90 in the End Angle box.

8. Type 25 in the Number of Hits box. You can have PC-DMIS take as few as 12 hits, but it's generally recommended to take 25 hits.

9. Click the Measure button when ready to begin.

10. If you have turned on the analog probing hits option inside the PC-DMIS Settings Editor, then PC-DMIS will automatically take 5 hits around the calibration sphere to better define the center of the calibration tool.

11. PC-DMIS then calibrates the AB angle positions and automatically writes the upper level matrix numbers to the controller. These numbers will automatically be correct if you've correctly followed the lower level matrix calibration procedure.

PC-DMIS then displays the Probe Utilities dialog box. The active tips are now calibrated and you're ready to program your part using the newly calibrated SP600 probe.

Notes on SP600 Default (2D) Calibration Mode

If you decide to select Default from the Calibration Mode area, PC-DMIS will insert five hits into the Number of Hits box. When you begin the calibration procedure, PC-DMIS will take these hits on the axes normal to the probe position.

Caution: Be aware that in the Default calibration mode, calibrating tips with an A90 angle will cause the probe to crash into the shank of a calibration sphere in spheres where the shank comes out of the bottom (shank vector of 0, 0, 1). This will happen because the probe tries to take a hit in the Z- position of the sphere. To fix this, use an inclined shank, don't calibrate tips that have A90 angles, or choose to use the User Defined calibration mode.