The key to a Machine Design file that properly simulates the target machine lies in the correct placement of the various UCSs. These UCSs are used to control both mating and movement. Mating controls how various components are positioned and oriented with respect to each other.
Some of the important mate interactions are:
Some UCSs affect the direction of linear or rotational movement of machine components. Linear movements in the machine simulation take place in the coordinate system for the top-most table. That is, if you've used Specify Movement to indicate that a tool post slide can move in X, it is the X direction of the top-most table UCS that indicates the direction of translational freedom.
Rotational motion, however, is determined by a UCS specifically associated with the particular solid that is rotating. This is done in the Local Coordinate System dialog.