Siemens SINUMERIK 840DE Programming Manual page 320

Tool offsets
8.8 Tool radius compensation (G40, G41, G42)
Example 1 milling
N10 G0 X50 T1 D1
N20 G1 G41 Y50 F200
N30 Y100
Only tool length compensation is activated in block N10. X50 is approached without
compensation.
In block N20, the radius compensation is activated, point X50/Y50 is approached with
compensation.
Example 2 milling
The "conventional" approach:
Call tool, load tool, activate working plane and tool radius compensation.
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Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals