System information

SECTION FOUR - PREPARATORY FUNCTIONS (G CODES)
Arc End Points
The radius is always specified as its true value. The end points are incremental or absolute
depending on G90 and G91. If a radius is used without a center point, there are two types of arcs
that can be generated. One is less than 180°, and the other is greater than 180°, as shown in the
figure that follows. When the arc exceeds 180° the radius must be specified as a negative value.
Examples:
For arc 1 (less than 180°)
G2 X6 Y2 R5 F30
For arc 2 (greater than 180°)
G2 X6 Y2 R-5 F30
Note: If the arc cannot span the start and end points, an error 505 “radius too small to span
given points” will occur.
Method III
Describing an Arc Using Absolute Center and Trig Help
G17 G02 X___ Y___ XC___ YC___ R___
G18 or X___ Z___ XC___ ZC___ R___
G19 G03 Y___ Z___ YC___ ZC___ R___
End Point Center Point Radius
200