Step 5: Measure Datums B and C
In this step, the software measures the for Datums B and
C. Based on the intersection of the two lines,
a is also constructed
to establish the XY origin.
To measure Datum B:
Select the Magnification
tab 
, and adjust
the magnification to about 25% of maximum. The actual magnification
value varies based on your lens.
Select the Illumination
tab 
, and set
the Top Light to 0% (Off). Set the Bottom Light to 35%.
Select the CAD
tab.
From the Graphics
Modes toolbar, if it's needed, select Scale-To-Fit
(
).
From the Graphics
Modes toolbar, select the Curve Mode
button (
).
From the Auto
Feature toolbar, click the Line button
(
) to open
the Auto Feature (line) dialog box.
Click a
for the left anchor point of the line and on the front edge towards
the left end.
Click a
for the right anchor point of the line and just to the left of the
slot (to the right of the upside-down "V" as show in the
image below). The software displays the target.
Since the line stretches across
a void (the upside-down "V"), this region must be excluded so
no points are taken in that segment.
Right-click inside the rectangular
target. From the popup menu, select Insert Hit
Target. This divides the single rectangular target into two
targets.
Repeat the above step to insert
a third target.
Drag the two target dividers
so that one is on each side of the upside-down "V".
Select the Vision
tab.
Position the camera over the
part.
From the Illumination
tab , adjust
the Top Light to a value that makes the
surface visible but not too bright. Move Z to focus as necessary.
Select the Hit
Targets tab 
.
Notice three targets are shown: EA1, EA2, and EA3. You should not
use the second target (EA2) that crosses the void. Double-click on
Normal in the EA2 density field, and select
None.
Notice that the EA2 target segment
shows hash lines to indicate the area where no data will be taken.
From the Auto
Feature dialog box, rename the default Line Auto Feature name
to DATUM B.
Click Create
and then Close.
To measure Datum
C:
From the Auto Feature
toolbar, select the Line button () to open the Auto Feature
(line) dialog box.
If you want to reset the number
of targets to 1, close and then reopen the Auto Feature
dialog box.
Click two points
on the left edge (one in the front and one in the rear).
Change the default name to DATUM
C.
Click Create to add
this line to the measurement routine.
Click Close to exit
the Auto Feature dialog box.
To construct a point from
the intersection of the lines:
Select the Insert
| Feature | Constructed | Point menu item or Constructed
Point (
)
from the Constructed Features toolbar (View | Toolbars | Constructed Features). The Construct Point dialog box appears.
Select the 
Intersection option.
From the feature list, select
DATUM B and DATUM C.
Change the ID to FRNT
LEFT CORNER, click Create, and then
click Close.
The datum features are now created.
Next Step ...