Autodesk Inventor Degrees of Freedom

If you’ve ever built an assembly in Autodesk Inventor, you already know how important it is to control how parts move and how sketches in a part file need to be constrained for purposes of design intent. Many users, especially beginners, don’t fully understand the concept of degrees of freedom (DOF) or how to manage them effectively. Learning to use DOF not only prevents frustrating assembly and sketch errors, but also makes your designs cleaner, more accurate and easier to modify later.

In this blog, we’ll explore what degrees of freedom are, why they matter and how Autodesk inventor lets you manage them with precision.

Let’s start with a simple example using a sketch in a part file.

• Open a new standard mm ipt.
• Select Sketch and select the XY plane.

• Draw a line, as in the image below. For now, don’t worry about the dimensions or angle of the line.

• On the toolbar at the bottom of the screen, select DOF.

• On your screen you will now see 3 red icons. These icons are displaying the degrees of freedom for each point of the line. To fully constrain, you would need to remove all 3 degrees of freedom at each point.

• In this example, lets go ahead and do this. Select from the Sketch tab on the ribbon > Constraint Panel > Horizontal.

• Select the top end of the line and the origin point.

• You can no longer move this point above or below the origin, only along the origin.

• To remove the last DOF on this point, add a coincident constraint from the end point to the origin point.

• Notice the icon had been removed.

• Let’s add an aligned dimension. Select Dimension, then the 2 endpoints of the line. Right click and select Aligned, then place the dimension down and make it 10mm.

• Now you only have one degree of freedom left.

• Place a horizontal constraint on the line.

All icons have been removed as this step has removed all degrees of freedom. At the bottom right of the screen you will see Inventor is displaying that this is fully constrained.

• To end this session, select Finish Sketch.

In an Assembly (*iam)

• Open an Assembly and place two parts.
• Using the same methodology, you can constrain parts in an assembly using:
  • Mate/Flush
  • Insert
  • Angle
  • Tangent
  • Motion/Transitional Constraints
• In an Assembly, activate DOF under the View tab on the ribbon.

• DOF showing with the green icon.

• As you add constraints, the DOF icon will change accordingly. Once all DOF on a part have been removed, the icon will only display a green box on that part.

Degrees of Freedom (DOF) may seem simple, but they’re the backbone of every accurately functioning Autodesk Inventor sketch in parts and parts in assemblies. Once you understand how DOF work and how constraints manage them, you’ll design parts and assemblies that are stable, realistic and a pleasure to modify.