G02 (clockwise) and G03 (counter-clockwise) are modal CNC G-codes that command cutting tools to follow circular and helical arcs along defined coordinate planes.
Engineering Specifications & Parameters
G02 Motion
Clockwise (CW) Circular Arc
G03 Motion
Counter-Clockwise (CCW) Circular Arc
Helical Milling
Add Z coordinate for thread milling
Standard Format
G02/G03 X__ Y__ I__ J__ F__
Programming Syntax
Circular interpolation can be programmed using either I, J, K center offsets (incremental distance from start point to arc center) or R (radius) values.
; Clockwise arc using I, J center coordinates (Recommended)
G17 G02 X50.0 Y25.0 I25.0 J0.0 F300
; Counter-Clockwise arc using R radius
G03 X10.0 Y40.0 R15.0 F300
Plane Selection
G17: XY Plane (Z-axis arc normal)
G18: XZ Plane (Y-axis arc normal)
G19: YZ Plane (X-axis arc normal)
Frequently Asked Questions
Why is I, J programming preferred over R radius in production?
I, J definitions are mathematically unambiguous for full 360-degree circles, whereas R cannot reliably distinguish between arcs greater or less than 180 degrees.
