G03 cuts a circular arc counterclockwise. It works exactly like G02 but in the opposite rotation, using the same center-offset (I, J) or radius (R) form.
Format
G03 X__ Y__ R__ F__ (radius)
How it works
- Direction is judged looking down at the active plane.
- I and J locate the arc center relative to the start point; R sets the radius directly.
- Pick G02 or G03 by which way the arc curves around its center.
Example
FAQ
How do I know if an arc should be G02 or G03? G02 cuts clockwise and G03 cuts counterclockwise, as viewed looking down the tool axis onto the selected plane. If an arc comes out the wrong direction, swapping between G02 and G03, and correcting the I/J/K or R value’s sign, usually fixes it.
Can I program a full circle with G02 or G03? Yes, using I and J to define the center with the start and end point being the same coordinate, though many controls require splitting a full circle into two semicircular moves if a full 360-degree arc in one block isn’t supported.
Related: G02 and the G-Code Cheat Sheet.