You can easily find the number of constraints required to fully constrain your sketches by using the Auto Dimension command, but how do you know when components in your assemblies are fully constrained?

First we need to know what assembly constraints control.
Inventor assembly components have 6 rotational and transitional movements that can be constrained. As with any 3-Dimensional object, a part in an assembly can move along the X, Y, and Z axes, and it can rotate about each of these axes. Each movement type is called a Degree of Freedom, so every part in your assemblies has 6 Degrees of Freedom. Assembly Constraints control the Degrees of Freedom of each part in an assembly.

What constraints are missing?
You’ve created and constrained an assembly, but you don’t know how many constraints you need or which constraints are missing. In fact, you’re really not sure how structurally intact the assembly is.

Typically the next bold step is to try to drag one of the components to see if you can move it. You might continue to probe other parts with your pointer, but you really can’t get a clear understanding of how the components in the assembly are constrained. So how do you find out how the components in an assembly are constrained?

Display the Degrees of Freedom of the components.
Open any assembly file you’ve created, and then go to the View pull-down menu and select Degrees of Freedom. To display the degrees of individual components and subassemblies, highlight them in the browser, right click and select Properties, and in the Occurrence tab check Degrees of Freedom.



This cube has the degrees of freedom symbol showing all six degrees of freedom. Each axis has a linear degree of freedom along the axis and a rotational degree of freedom around the axis. When assembly constraints are added to the part, some of these degrees of freedom are removed from the symbol.

Why is this important?
When the Degrees of Freedom symbol is visible on all the components of the assembly you can instantly see how the components are constrained. More importantly, you can see the freedom of movement that remains on each component. Once you have this information, you can gain more control over the assembly by adding or subtracting constraints.