I am trying to find the inertia of a particular instance of a part in an assembly. I can not use GetMassProperties or CreateMassProperty because those both access the part's modelDoc and will output the same mass properties regardless of the instance. My plan was to get the Mass Moment about the part's center of mass and then measure the distance between the origin of the assembly and the origin of a particular part instance and used parallel axis theorem. However, this requires that the coordinate system of the part model doc is the same as the coordinate system of the assembly so that the axes are actually parallel. Can anybody help me devise a method to check and change every part's model doc coordinate system if it does not align with the assembly coordinate system?