Fanuc G68.2 - Compost Wiki

Contents

• 1 Overview
• 2 Support
  • 2.1 Note
• 3 Future Support
• 4 Code
  • 4.1 Note

Overview

Fanuc G68.2 is a 3D coordinate rotation mode that is used by some milling machines. It defines a work-plane in a machine independent way by using 3 Euler angles (Alpha, Beta, and Gamma) to fully define a 3d coordinate system on the machine.

Support

Version10 (Ambassador) has preliminary support for work-planes that are not defined using machine rotations. The commands EulerAlpha#, EulerBeta#, and EulerGamma# provide the required angles for use in the I, J, and K parameters of the Fanuc G68 mode. The angles returned will define a work-plane that aligns with the operation's coordinate system, so the post processor must call SetUseOpCS when outputting in the work-plane in order to get the correct XYZ coordinates.

Work-plane functionality is only supported for 3 axis operations (XYZ) defined in rotated coordinate systems. No support is provided for 4 and 5 axis operations in rotated planes so the post must output these operations in machine coordinates (G54, or "D style").

Note

Version 10 (Ambassador) is only supporting Euler angles as used in the Fanuc G68.2 Tilted Work Plane (TWP) mode (or compatible modes on other controls). No other definition for Euler angles is supported in this version. (See Future Support below.)

Future Support

There are other controls that have similar work-plane modes that use different mathematical computations for the angle parameters. Future versions of GibbsCAM (GALAXY or later) will allow the post-processor to define how the work-plane is computed. This will allow for more generic support of work-planes across a wide range of control manufactures. Future versions will also allow for 4 and 5 axis operations to be output in any of the work-plane or work-fixture modes.

Code

Tilted Work Plane support requires the use of 3 codes on the machine.

G68.2 X Y Z I J K enables the rotated coordinate system on the machine, but does NOT cause the machine to rotate. The XYZ parameters are the CSoffset, and the IJK Parameters are the Alpha, Beta, and Gamma angles.

G53.1 forces the machine to rotate to the coordinate system defined by G68.2.

G69 cancels the work-plane mode.

Looper posts can call G68.2 at a different place then the call to G53.1 and get approach moves in the work-plane yet not rotate until the BMove? Boolean is true in order to match simulation. Non-Looper posts must call both G68.2 and G53.1 at the same time in order to be able to output correct Clearance Plane 1, 2, and 3 moves in a single axis.

Note

It is highly recommended that posts output the actual machine axis rotations as moves before using the G53.1 code to ensure that the machine will use the same rotary solution that GibbsCAM computes. This will prevent extra 'unwinds' and allow the use to use the axis limits and work-areas defined in the MDD.