Siemens SINUMERIK 840D sl Programming Manual page 235

Examples
Example 1: Counterclockwise involute from the starting point to the programmed end point
and back again as clockwise involute
Program code
N10 G1 X10 Y0 F5000
N15 G17
N20 INVCCW X32.77 Y32.77 CR=5 I-10 J0
N30 INVCW X10 Y0 CR=5 I-32.77 J-32.77
...
Fundamentals
Programming Manual, 09/2011, 6FC5398-1BP40-2BA0
9.8 Involute interpolation (INVCW, INVCCW)
Comment
; Approach of the starting position.
; Selection of the X/Y plane as
working plane.
; Counterclockwise involute, end
point in Cartesian coordinates.
; Clockwise involute, starting point
is end point from N20, new end
point is starting point from N20,
new circle center point refers to
a new starting point and is the
same as the old circle center
point.
Motion commands
235