CNC milling machines allow for intricate and precise cutting paths. When creating complex shapes that involve multiple arcs, subprograms can be used to streamline the process. This article will discuss the use of G02 and G03 for arc movements and G41 for cutter compensation.
Usage Format
The usage format for these codes in a CNC subprogram is as follows:
- G02 for a clockwise arc movement
- G03 for a counterclockwise arc movement
- G41 for cutter diameter compensation to the left of the defined path
Explanation
G02 and G03 require the definition of the arc’s endpoint and the center point (or radius). G41 is used when the tool needs to compensate for its diameter while cutting, ensuring the cut’s dimensions are accurate. It’s important to activate G41 before the arc commands if cutter compensation is needed.
Example
Consider a scenario where we need to join two arcs with a straight line, all while compensating for the cutter’s diameter.
(Start of the subprogram)
G0 X0 Y0 (Move to the starting point)
G41 D1 (Activate cutter compensation with tool diameter defined in D1)
G1 X50 Y0 (Straight line movement to the beginning of the first arc)
G3 X75 Y25 I25 J25 (Counterclockwise arc to the midpoint)
G2 X100 Y0 I25 J-25 (Clockwise arc to the end of the second arc)
G40 (Cancel cutter compensation)
G0 X0 Y0 (Return to the starting point)
(End of the subprogram)
Here’s a text diagram to illustrate the path:
Starting Point
|
| I
|<----+---->
| | J
| V V
| *----> Midpoint
| / \
| / \
| / G3 \ G2
| / \
|/ \
V V
Straight Line----> End Point
In this diagram, the asterisk (*) represents the center point of the arcs. The tool moves from the starting point to the midpoint with a counterclockwise arc (G3), then to the end point with a clockwise arc (G2), all while compensating for the cutter’s diameter with G41.