Controlling Inventor Assemblies
by David Melvin, PE, TEDCF Publishing
You can easily find the number of constraints required to fully constrain your sketches by looking at the status bar on the bottom of the Inventor window. The image below shows that one dimension or constraint is needed to fully constrain the sketch.
When the sketch is fully constrained the status bar will show Fully Constrained.
It is very important that you fully constrain all your sketches to assure that they are structurally sound. If you don’t, the geometry can change without your knowledge. So be sure to take control over your sketch geometry by fully constraining each sketch.
What do 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 axis. 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.
To display the degrees of individual components and subassemblies…
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