**Circular Interpolation**

Circular interpolation uses the G02 or G03 code word for the calculation of table positions required to produce a circular tool path. For the clockwise arc shown below the CNC controller must calculate thousands of positions along the path and correspondingly accelerate and decelerate the X and Y axes to achieve the smooth and constant motion required.

Example: G02 X0Y8 R8 (arcs are always begin at the current coordinate)

Where G02 is the code for *clockwise* arc, X0Y8 is the terminus of the arc, and R8 is the radius of the arc. G03 would be used for a *counterclockwise* arc.

Note that Y axis motor must start out at a pretty brisk speed while the X axis motor is barely moving. This changes throughout the arc until at completion the Y axis motor is barley moving and the X axis motor is running fast. Two G-codes use circular interpolation, G02, and G03.

See also linear interpolation, rapid, I-J arcs