Sketching is one of the most important parts to using Autodesk Inventor, and understanding the tools provided can help you improve your sketching and of course your productivity. Using the degrees of freedom feature in the sketch environment can also help you achieve better quality sketches.
When 2D sketching in Inventor software it can be challenging to see where dimensions are still required, especially for new users of the software or those that have only just have completed their Inventor training, and may have a lot of new knowledge to sift through.
The end goal of course is to get a fully constrained sketch that's totally accurate as the basis of your design.
If it's not fully constrained then naturally accuracy cannot be guaranteed as the sketch could very easily and inadvertently be modified, and if this occurs the error may not be noticed until much later in your design process.
A great workflow here is to use degrees of freedom, as this feature allows the user to analyse movement that exists in a sketch whilst flagging up potentially missing dimensions or geometric constraints.
First of all if you were not aware you get dimension feedback on the status bar, this informs the user how many dimensions are required (see Fig 1).
TIP! Make sure you constrain your geometry to the origin point of your sketch with a dimension or constraint (the origin point is the 0,0 datum of the sketch where X & Y intersect. If the sketch isn't constrained it will be able to move in any direction, meaning the sketch will have complete degrees of freedom.
Degrees of freedom analysis can be accessed when in sketch mode from the right click menu or from the status bar in inventor 2013 (see Fig 2). Selecting the icon from the status bar or selecting show all degrees of freedom from the right click menu activates and displays degrees of freedom in the active sketch (see Fig 3).
Once activated degrees of freedom will be displayed on the sketch with linear or rotational arrows (see Fig 3). As you apply dimensions and constraints to a sketch degrees of freedom will disappear. Once the degrees of freedom arrows have gone you have a fully constrained sketch.
The status bar will also confirm this if you need a sanity check (see Fig 5)
Please Note: In some cases it is not possible to get a fully constrained sketch if you're using construction lines, centre lines, mirror lines etc.
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