Similar to fully defined sketches for parts, assemblies should be fully constrained. At most, only one component should be fixed. Typically it  is preferred that all components are fully constrained. This tutorial will detail how to unfix a component and identify components that are not fully constrained.

This tutorial uses the assembly from “How to mate gears in SolidWorks?”.

Items, that are fixed, appear with a (f) in front of their name in the model tree. Items that appear with a (-) are not fully constrained.

To unfix a component(s), right click on them and select “Float”.

Moving a component within fully constrained assembly will move the entire assembly. Any components, that have not been fully constrained, may appear out of position.

There are two exceptions to using a fully defined assembly. One is where rotation has not been constrained, but does not impact fit, form or function (e.g. orientation bolts or hydraulic fittings). Another is when motion is required. In the gear example, only rotation should be unconstrained.

Where motion of the component is not essential, a quick fix is to set concentric mates to “Lock rotation” (e.g. orientation bolts or hydraulic fittings). Note: Lock rotation is not configurable.

Use configurations to keep both options available. Move to the configuration tab of the model tree. Rename Default to “Fully Constrained”, and then create a derived configuration called “Flexible rotation”.

The mates for this have not been shown. Use any mates to fully constrain the gears.

Return to the model tree and expand the mates, click the five mates that will be configured. Right click and then select “Configure Feature”, this will allow suppression of the mates per configuration.

Use the flexible configuration when motion is required, otherwise use the fully constrained configuration.