The G03 command is used to perform a counterclockwise circular motion.

The arc starts from the current position, and the arc centre is defined using either:

• I, J, K values as incremental offsets from the start position, or

• R value to define the radius.

The X, Y, and Z values define the end point of the arc.

MASSO uses incremental I, J, and K values for all arc movements.

G03 is a modal command and belongs to Group 1.

Syntax & Parameters

G03 starts an arc move beginning at the current X, Y, Z position.

Position Parameters

• X Value
  Defines the X-axis end point of the arc.

• Y Value
  Defines the Y-axis end point of the arc.

• Z Value
  Defines the Z-axis end point of the arc.

Arc Centre Parameters

• I Value
  Incremental offset defining the X-axis centre relative to the start position.
  (Valid in G17 and G18 planes)

• J Value
  Incremental offset defining the Y-axis centre relative to the start position.
  (Valid in G17 and G19 planes)

• K Value
  Incremental offset defining the Z-axis centre relative to the start position.
  (Valid in G18 and G19 planes)

• R Value
  Defines the arc radius.
  (Valid for arcs up to 90 degrees)

Example Program – Arc Movement

N10 G00 X20 Y10 Z-1
N20 G03 X50 Y40 I0 J30

Explanation:

• Line 1 moves the machine to X20 Y10 Z-1.

• Line 2 creates a counterclockwise arc from X20 Y10 to X50 Y40.

• The arc centre is located at X20 Y40.

• The Z-axis remains unchanged during the move.

Arc centre calculation:

• X centre = 20 + 0 = 20

• Y centre = 10 + 30 = 40

Example Program – Spiral Arc

N10 G00 X20 Y10 Z0
N20 G03 X50 Y40 Z-3 I0 J30

By including a Z value in the G03 command, a spiral arc is created.

Explanation:

• Line 1 moves to X20 Y10 Z0.

• Line 2 creates a counterclockwise arc with the same XY path as the previous example.

• During the arc, the Z-axis moves evenly from Z0 to Z-3, forming a spiral path.

Arc centre calculation:

• X centre = 20 + 0 = 20

• Y centre = 10 + 30 = 40