HEIDENHAIN ND 1300 VED and Crosshair Systems - Manual (Page 109)

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6
Measuring
Probing arcs
A minimum of three probed points is required to measure an arc. There is no practical limit to the number
of points that can be probed, and in general accuracy is increased by probing more points.
When the arc is less than 185 degrees, Measure Magic will correctly recognize the arc and assign the cor-
rect feature. However, when the arc is 185 degrees or more, it is likely that Measure Magic will assign the
circle feature type to the data. If the arc is shallow, Measure Magic might mistakenly assign a line feature.
If the wrong feature type is assigned, it can easily be changed by selecting the correct feature from a menu
of alternatives in the DRO window. Points must be gathered in sequence from the beginning to the end of
the arc when the Multiple edge probe is used. More details are contained in Chapter 5: Probes.
View window shows the feature and the points used to define it. Errors are shown as whiskers connecting
the probed points to the feature. The arc will be shown with data point form errors in blue and the greatest
two opposing form errors in red.
The DRO window shows the number of points used, the radius and diameter of the arc, the coordinate loca-
tion of the center of the arc and the form error. The feature graphic in the View window shows the feature
and the points used to define it. Errors are shown as whiskers connecting the probed points to the feature.
The maximum errors are shown in red and are used in the calculation of form. When only three points are
probed, the form error is zero. When more than three points are probed, the form error is the sum of the
two greatest opposing error magnitudes.
Three points are probed to measure an arc
Touch the feature type... to display the menu of alternative
types
Probed points are shown in the
View window
Probing and Measuring Features