HEIDENHAIN IK 5494-2D - Manual (Page 171)

5
Measuring
149
Circles
A minimum of three probed points is required
to measure a circle. There is no practical limit
to the number of points that can be probed,
and in general accuracy is increased by prob-
ing more points.
When 185 degrees or more of the circle is
probed, Measure Magic will correctly recog-
nize the circle feature. However, when less
than 185 degrees is probed, it is likely that
Measure Magic will assign the arc feature
type to the data. If the
wrong feature type is as-
signed, it can easily be changed by right-clicking the Results window and selecting the
circle feature alternative.
A best-fit algorithm is used to define the circle when more than three points are
probed. The circle fit to the probed data can easily be changed by right-clicking
the Results window and selecting the desired fitting algorithm. Please refer to Ap- Ap-
pendix C: Data Fitting Algorithms pendix C: Data Fitting Algorithms for details regarding the algorithms.
Measurement results are
shown in the Features tem-
plate, Part View window and
Results window. The Results
window shows the feature
identification number, the
number of points used in the
measurement, the radius and
diameter of the circle, the co-
ordinate location of the center
of the circle and the form
error. When only the three
required 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 op-
posing error magnitudes.
Ninety points are probed using the Circle probe to measure a
circle feature
Probing and Measuring Features