According the machine kinematic it is not always possible to define « directly » orthonormal trihedron X,Y,Z (controller) motion with the machine joints definition.

In this case you have to define "non-command" joints and add "kinematic relations" to be able to simulate XYZ orthogonal motion with non orthognal joints

in the zip, you have the methodology, the videos to be able to create the turret and the 3DXML (final result)