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Introduction |
| Using auto direction on 1D
Points can lead to erroneous reported values if used
incorrectly. Auto direction relies on a smooth approach,
from you the operator, in capturing of a data point. The
process of determining the approach vector involves the CMM
interface card (ProCounter, Tech 80 or PMAC) to maintain a
rolling IJK vector based on the last five reported values.
These interface cards update the current position in the MCS
on a programmable time interval from 20 to 200 milliseconds. |
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Switching Reported Axis on
1 Points |
When you are approaching your
work piece, it is required that you make contact while
remaining in a ±45° approach, see figure 1. In this example,
if we remained in the approach zone we will capture a data
point that will be reported as a +Y point.
If the
operator did not remain in the approach zone the 1D Point
might report a + or - X Point from which we will have to
correct the probe compensation error. Most common occurrence
of a erroneous data point comes from operators who approach
the surface, and then pause during the approach and attempt
to make contact under extremely slow speeds, which while
approaching causes variations in the path toward the
surface.
To correct the reported direction of a 1D
Point, highlight the feature by left-clicking on it, then
right-click to bring up the feature menu, as shown in figure
2. Select [Point Direction] which will offer a sub-menu with
all six probing directions available. Choose the correct 1D
Point direction and your part inspection will update with
the correct 1D Point. Note: Once a feature has been
referenced it can not be changed or edited. For example, if
a feature was used in the construction of a PCS , it will be
locked from changes. This is identified by the inclusion of
a ¹ next to the feature number, example " 12¹ ".
Using Auto-Direction with multi-point features such as
circle, lines and planes can also incorrectly report feature
characteristics. This occurs when capturing data points in
an inconsistent method or by capturing data points at a high
rate. As previously mentioned, the calculation of the
direction vector for the probe works off the speed of the
interface and should that rate of point capture be to high,
the changes in direction going toward, then backing off the
data point will create a poor direction vector.
Since
touch probes can be effected by speed and our auto-direction
tool is also adversely effected by speed, we suggest the use
of a smooth consistent approach speed and rate when
capturing data points. |
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Activate Auto Direction Sensing |
To activate the Auto Direction
sensing go to
System Options, and locate the Auto Direction
sensing key.
To activate, change the choice to 'Yes' next to
the Auto Direction sensing key.
During the inspection
process you may require to control the Auto Direction
sensing manually. This can be accomplished through the
Feature Measurement Toolbar or by pressing the key on the
keyboard. The iconic button on the toolbar will indicate the
status of the sensing option. In figure 1, the button shows
an "X" through the button. This indicates that if the button
was pressed, you will take sensing off.
In figure 2,
we see the iconic button shows no "X" over it indicating
that if you press the button, it will turn the sensing back
on.
Although the visual appearance of these iconic
button appears to be backward it actually represents what
the button will do should it be pressed. The button is not
designed to represent the current state of the Auto
Direction Sensing. |
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| figure 1, Auto Direction is ON. |
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| figure 2, Auto Direction is OFF |
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Activate Auto Direction Sensing Alternative Method |
Auto-Direction can be toggled
when active directly on the Geomet Status bar. When
Auto-Direction is active, it is easily identified by its
green background.
When not active, red is displayed.
If Auto-Direction is not active on your CMM, then the Status
bar Button is labeled "Auto-Dir".
Click on the button
and the System Options will be displayed with the proper
entry available for change. |
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