# G03 – Circular Interpolation (Counter Clockwise)

This command runs a circular motion in a counter clockwise direction. The arc starts at the current position and the center is defined by the I, J values as an offset of the current position or R for radius. The X & Y values define the finish point. Masso uses Incremental I & J values for Arcs

## Syntax & Parameters

• G03 starts an arc movement beginning at the X & Y coordinate location where the G03 was issued.

• X Value – This is the X coordinate defining the end point

• Y Value – This is the Y coordinate defining the end point

• I Value – are relative coordinates and define the X center coordinate as an offset of the starting point X coordinate.

• J Value – are relative coordinates and define the Y center coordinate as an offset of the starting point Y coordinate.

• Z Value - The addition of a Z value will describe a helical move.

• R Value - Is used to define the arc radius for arcs up to 90 degrees.

Caution: The use of R Value for arcs greater than 90 degrees do not work as it defines multiple centre points. For arcs greater that 90 degrees use IJK values for G03 commands.

## Example program for making an Arc

`N10 G00 X20 Y10 Z-1N20 G03 X50 Y40 I0 J30`
• In the above example in the first line moves to position X20 Y10 Z-1

• An arc is made starting at position X20 Y10 and ending at coordinate X50 Y40 with center at position X20 Y40 moving in a counter clockwise direction. The Z height does not change.

• The Arc center is calculated as follows

• Starting position X20 + I0 = Center X coordinate X20

• Starting position Y10 + J30 = Center Y coordinate Y40

## Example program for making an Spiral

`N10 G00 X20 Y10 Z0N20 G03 X50 Y40 Z-0.5 I0 J30`
• In the above example in the first line moves to position X20 Y10 Z0

• An arc is made starting at position X20 Y10 and ending at coordinate X50 Y40 with center at position X20 Y40 moving in a counter clockwise direction. The arc is the same as in the diagram above but the Z axis will decend from its current height to -0.5 units at a uniform rate over the arc to form a spiral path.

• The Arc centr is calculated as follows

• Starting position X20 + I0 = Center X coordinate X20

• Starting position Y10 + J30 = Center Y coordinate Y40

INFORMATION: Units are defined as either inches or mm depending on your machines setup or G20 or G21 command in use.