Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 379)

Axis Motion
Chapter 12
12-7
Figure 12.4
Results of Circular Interpolation Example 12.4
X
Z
50
15
R15
45
20
start
point
12030-I
When programming an arc using the radius (R) value, two arcs are possible
(Figure 12.5). Program the R--word with a positive or negative value to
distinguish between these arcs.
Example 12.5
Arc Programmed Using Radius
Arc 1 Arc 2
center angle less than center angle greater than
180 degrees 180 degrees
G90G02X25.Z40.R18.F.1; G90G02X25.Z40.R-18.F.1;