User Manual

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CHAPTER 1 Inventor DesIgn PhIlosoPhy
Parametric AutoCAD
Starting with AutoCAD 2010, you can create 2D parametric dimensions and constraints much as
you can in Inventor.
Dr i v i n g Di m e n s i o n s
The workflow in Inventor sketching is substantially different from that in traditional AutoCAD,
even beyond dimensions. In Inventor, you create sketches in 2D and then add geometric
constraints such as Horizontal, Vertical, Parallel, and so on to further define the sketch enti-
ties. Adding the geometric constraints allows line work to adjust in a predictable and desired
manner and helps control the overall shape of the sketch. Once geometric constraints are in
place, you add parametric driving dimensions to the sketch geometry. By changing the value of
the dimension, you change or drive the size of the sketch object. As you can see, the Inventor
dimension is far more powerful than the standard AutoCAD dimension because it not only con-
veys the value of a feature or part but also serves as a design parameter, allowing you to change
the dimension to update the design. Figure 1.6 shows dimensions being edited in a sketch on the
left and the result of changing three of the dimensions on the right.
Part Modeling Best Practices
A solid sketch is the foundation on which stable parts are built. Many new users do not under-
stand the importance of having fully constrained sketches, and they find it highly frustrat-
ing to have a model fail when a simple change is made, all because a sketch was not properly
constructed.
Ke e p sK e t c h e s si m p l e
The most effective way to create a healthy sketch is to keep it simple. The purpose of keeping
your base sketch simple is to get it fully defined, leaving no part of it up for interpretation.
Under-defined sketch entities (lines without defined lengths, circles without defined diam-
eters, and so on) will most likely not update properly and will cause your sketches to distort
and break when you try to update them. And because you often base the rest of you model on
the initial sketch, your entire feature tree might come crumbling down, requiring you to stop
and spend time rebuilding it again. Examine the sketch in Figure 1.1 and compare it to the
finished shape shown in Figure 1.5. As you can see, the simple sketch containing two
Figure 1.6
Editing Inventor
sketch dimensions
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