G2 adds a clockwise arc move to the planner; G3 adds a counter-clockwise arc. An arc move starts at the current position and ends at the given XYZ, pivoting around a center-point offset given by I and J or R.
allows G2/G3 to operate in the selected XY, ZX, or YZ workspace plane.
This command has two forms:
I J Form
- I specifies an X offset. J specifies a Y offset.
- At least one of the I J parameters is required.
- X and Y can be omitted to do a complete circle.
- The given X Y is not error-checked. The arc ends based on the angle of the destination.
- Mixing I or J with R will throw an error.
- R specifies the radius. X or Y is required.
- Omitting both X and Y will throw an error.
- X or Y must differ from the current XY position.
- Mixing R with I or J will throw an error.
Arc moves actually generate several short straight-line moves, the length of which are determined by the configuration option MM_PER_ARC_SEGMENT (default 1mm). Any change in the Z position is linearly interpolated over the whole arc.
‘ARC_P_CIRCLES’ enables the use of the ‘P’ parameter to specify complete circles
G2 [E<pos>] I<offset> J<offset> [P<rate>] R<radius> [X<pos>] [Y<pos>] [Z<pos>]
The amount to extrude between the start point and end point
An offset from the current X position to use as the arc center
An offset from the current Y position to use as the arc center
Specify complete circles - requires ARC_P_CIRCLES
A radius from the current XY position to use as the arc center
A coordinate on the X axis
A coordinate on the Y axis
A coordinate on the Z axis
G3 command geometry
This illustrates a counter clockwise arc, starting at [9, 6]. It can be generated either by G3 X2 Y7 I-4 J-3 or G3 X2 Y7 R5
Move in a clockwise arc from the current position to [125, 32] with the center offset from the current position by (10.5, 10.5).
G2 X125 Y32 I10.5 J10.5
Move in a counter-clockwise arc from the current position to [125, 32] with the center offset from the current position by (10.5, 10.5).
G3 X125 Y32 I10.5 J10.5
Move in a complete clockwise circle with the center offset from the current position by [20, 20].
G2 I20 J20