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G2, G3 - Controlled Arc Move

1.0.0-beta planner Add an arc movement to the planner

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.

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 Form

  • 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.


Usage

G2 [E<pos>] [F<rate>] I<offset> J<offset> R<radius> [X<pos>] [Y<pos>] [Z<pos>]

Argument Description
[E<pos>]

The amount to extrude between the start point and end point

[F<rate>]

The maximum rate of the move between the start and end point

I<offset>

An offset from the current X position to use as the arc center

J<offset>

An offset from the current Y position to use as the arc center

R<radius>

A radius from the current XY position to use as the arc center

[X<pos>]

A coordinate on the X axis

[Y<pos>]

A coordinate on the Y axis

[Z<pos>]

A coordinate on the Z axis

Examples

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