HEIDENHAIN TNC 426 B User Manual page 137

Gradient angle of an arc
The gradient angle AN of an arc is the angle of the entry tangent.
See figure at right.
Chord length of an arc
The chord length LEN of an arc is the linear distance LEN between
its end points. See figure at right.
Centers of free-programmed circles
The TNC calculates a circle center for free-programmed arcs from
the data you enter. This makes it possible to program full circles in
an FK program block.
If you wish to define circle centers in polar coordinates you must
use FPOL, not CC, to define the pole. FPOL is entered in Cartesian
coordinates and remains in effect until the TNC encounters a block
in which another FPOL is defined.
A circle center that was calculated or programmed conventionally is
then no longer valid as a pole or circle center for the new FK
contour: If you enter conventional polar coordinates that refer to a
pole from a CC block you have defined previously, then you must
enter the pole again in a CC block after the FK contour.
Resulting NC blocks for FL, FPOL and FCT
7 FPO X+20 Y+30
8 F IX+10 Y+20 RR F100
9 FCT PR+15 IPA+30 DR+ R15
See figure at lower right.
HEIDENHAIN TNC 426 B, TNC 430
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Data on the circle center
X coordinate of the circle center
Y coordinate of the circle center
Polar coordinate radius of the
circle center
Polar coordinate angle of the
circle center
For data that are based on other blocks see "Relati-
ve data, " for auxiliary points see "Auxiliary points" in
this section.
Y
AN
Y
30
10
20
Soft key
X
30°
20
X
121