#### Step 3: Re-measure the Datum Features

Since the approximate location of the part is known, the Datum Features can be re-measured under computer control with different Vision parameters to more accurately define them.

If you are using a DCC machine, select DCC Mode from the Probe Mode toolbar. Otherwise, you can use AutoShutter to measure using a manual machine.

To re-measure the arc datum feature:

1. Click the Circle button from the Auto Feature toolbar. This opens the Auto Feature (circle) dialog box.

2. Select the tab.

3. Select the Magnification tab and adjust the magnification so it is decreased to the minimum setting (zoomed out).

4. Move the machine so the lower edge of the Arc (Datum B) is within the FOV.

5. Adjust the magnification to 75% of the maximum zoomed in value.

6. Select the Illumination tab and set the Top Light to 0%(Off) and the Bottom Light to 35%.

7. Focus Z if necessary.

8. Pick the first anchor point on the arc's edge using the mouse.

9. Move the machine so the middle of the Arc (Datum B) is within the FOV.

10. Move the machine to the upper edge of the Arc (Datum B) is within the FOV. The target is displayed.

11. Change the Start and End angle to 5 and 85.

12. Edit the location parameters to exact values: X=0, Y=0, D=16

13. Select the Hit Targets tab .

14. Double-click Normal under Density and select High from the drop-down list to change the density. Collecting a high density of points on this arc will improve its accuracy.

15. Set the Strength value to 6 by double-clicking and typing the value in the edit box.

16. Edit the Focus parameter set to automatically re-focus prior to measuring the circle feature. First, select the Focus from the drop-down list as show below.

17. Change the Focus parameter set as follows: Focus = Yes, Range = 5, Duration = 4

18. From the Auto Feature dialog box, rename the default Circle Auto Feature to DATUM B.

19. Click Test to test feature measurement.

20. Click Create and then Close.

To remeasure the line datum feature:

1. Click the Line button from the Auto Feature toolbar. This opens the Auto Feature (line) dialog box.

2. Move the machine so the left end of the Front Edge (Datum C) is within the FOV.

3. If necessary, adjust the Z axis to regain focus.

4. Pick the first anchor point on the left front edge using the mouse.

5. Move the machine so the right end (just before the "V") of the Front Edge (Datum C) is within the FOV. Pick the second anchor point using the mouse. The target is displayed.

6. From the Auto Feature dialog box, rename the default Line Auto Feature name to DATUM C.

7. Click Test to test feature measurement.

8. Click Create and then Close.

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