When Allow Assumptions is selected (the default) during component assembly, constraint orientation assumptions are automatically made. For example, only two coincident constraints are required to fully constrain a bolt to a hole in a plate. After an Coincident constraint has been defined between the axes of the hole and the bolt and a Coincident constraint has been defined between the bottom face of the bolt and the top face of the plate, the system assumes a third constraint. This constraint controls rotation about the axes, thereby fully constraining the component. The component will remains in the place it is in now in the graphics window.

When the Allow Assumptions check box is cleared, the third constraint must be defined before the component is considered fully constrained. You can leave the bolt packaged, or you can create another constraint that explicitly constrains the bolt’s rotational degree of freedom.

When Allow Assumptions is disabled, you can use the Move tab options to move a component out of a previously assumed position, where it will remain.