HEIDENHAIN TNC 620 (81760x-02) ISO programming - Manual (Page 94)

Programming: Fundamentals, file management
3.1 Fundamentals
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TNC 620 | User's ManualDIN/ISO Programming | 2/2015
Polar coordinates
If the production drawing is dimensioned in Cartesian coordinates,
you also write the NC program using Cartesian coordinates. For
parts containing circular arcs or angles it is often simpler to give the
dimensions in polar coordinates.
While the Cartesian coordinates X, Y and Z are three-dimensional
and can describe points in space, polar coordinates are two-
dimensional and describe points in a plane. Polar coordinates have
their datum at a circle center (CC), or pole. A position in a plane can
be clearly defined by the:
Polar Radius, the distance from the circle center CC to the
position, and the
Polar Angle, the value of the angle between the angle reference
axis and the line that connects the circle center CC with the
position.
Setting the pole and the angle reference axis
The pole is set by entering two Cartesian coordinates in one of the
three planes. These coordinates also set the reference axis for the
polar angle H.
Coordinates of the pole
(plane) Reference axis of the angle
X/Y +X
Y/Z +Y
Z/X +Z