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G68.2 in mill turn simulation

Valued Contributor
Valued Contributor

I'm having a really odd behaviour with G68.2 command.


G68.2 coordinate system shift works correctly.

Rotation angles are calculated correct from post.

Rotation of coordinate system in CSE siulation corresbond correctly 90 rotation is 90 degree rotation.


But Origin of this rotated coordinate system does not match to G54 or Main MCS.

E_1 picture shows G54 location and  movement according that.


E_2 picture shows shifted and rotated coodinate system from G54.

This new Csys rotated coodinate system lies inside (is child of) G54 coordinate system (Geometry view).


Post calculates coordinate system translation correct and so does CSE G68.2 command.

So this meand it translates this according G54 zeropoint.


Rotation is another thing.

I made two rotation first shown in E_2: 45 degrees around Y axis: I0.0 J45.0 K0.0

See movements after that.

And E_3: I90.0 J45.0 K0.0

It seems that I component rotates around G54 Z axis???

MCS_Main is parallel to G54.


What could cause this?

G68.2 is locked so can it be fixed ?




Re: G68.2 in mill turn simulation

Siemens Phenom Siemens Phenom
Siemens Phenom

Hello Jussi,


the 2nd picture looks correct to me.

G68.2 is defined with J45 --> rotate 45 degree around the X (!) axis.


This is how we understood the Fanuc documentation where it mention G68.2 deals with Euler angels.


First rotate  Z (I value) --> new csys'
aroundSecond rotates around X (J value) of the coordinate system csys' --> new csys''

Third rotates around Z (Z value) of the rotated coordinate system csys''


Would that explain what you see?


Thomas Schulz
Siemens PLM
Manufacturing Engineering Software

Re: G68.2 in mill turn simulation

Valued Contributor
Valued Contributor

Hello Thomas


Thank you for quick answer,and you are correct againg.

I did not take G18 account.


But this does not solve my problem.


I still need to make my own command.

In Mazak it's named G68.5 and there is a litle pit different behaviour.

It going to be a long night...






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