Gone are the days of boxy, rigid or bulky design. Today, products are made with an eye towards user comfort. These design requirements necessitate a higher level of modeling than ever before and parametric modeling falls short.
When you hear the term “freeform” modeling, most CAD designer’s eyes glaze over because most feel that they do not need freeform capabilities nor do they understand the impact of freeform modeling in a design. When we think of freeform, we usually relate it to models of complex curvatures, such as humanoid figures, automotive car body pieces or anything organic/animalistic in form. While all of these apply as examples, there are many other forms that can utilize freeform capabilities. Everyday items such as dinnerware, eyewear, gaming controllers, or even the handle grips on a push mower can all be made using freeform modeling techniques. Autodesk Inventor 2015 introduced the freeform modeling toolset to the user base and now Autodesk Inventor 2016 enhances that toolset and streamlines the editing process.
It’s all in the algorithm:
To use the phrase ….again (Stargate Universe, Season 2, Episode 15: Seizure) “It’s all in the algorithm, so..” While most of us really have no need to learn or be able to decipher the algorithm behind our CAD software abilities, Figure 1 gives an example of the level of math that goes into defining, controlling and displaying a NURBS curve.
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Figure 1 |
Freeform modeling and NURBS are really close cousins. Both technologies deliver advanced curvature definition and control. Also, both technologies control the surface boundaries via control points of the vertices of the surface boundary. While NURBS interaction has traditionally been done by controlling these points, the freeform surface editing is done by either editing the surface as a whole, an edge or edges of the surface, or even the control points.
Starting with the basic shapes:
To start freeform shapes, Inventor 2016 gives you the basic forms to begin building from. In Figure 2, you can see the basic forms. From those, the editing tools allow you to press, pull, tweak, scale and warp the surfaces into the shape/form you desire. Looking at the “box” freeform shape, as an example, once you begin creating the object, the dialogue box (see Figure 3) appears, allowing you control of the overall size of the box as well as the face divisions. Each basic shape has its own definition options and each shape has face quantity/division control.
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Figure 2 |
Figure 3 |
Proper form needs proper controls:
To begin “tweaking” the freeform shape, you can isolate faces, edges or vertices or a combination of the three. Using the “Edit Form” command, a dialogue box is displayed (see Figure 4), allowing various controls over the selected geometry. You can filter your selections, choose selection options and control the transform abilities. It should be noted that all edits to a freeform model are not stored in the browser tree history. If a mistake is made, you may either use Undo or attempt to further adjust the geometry with more edits. The “Edit Freeform” command is just one of many editing capabilities available to tweak your geometry into the desire shape. Also check out the “Flatten” and “Symmetry” commands, which really simplify the design process.
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Figure 4 |
The final form:
Once all edits to the freeform are complete, you may exit and your freeform shape is either automatically converted to surface entities or, if you used the Thicken command within the freeform editing environment, your model will be converted into a solid body with volume, mass and center of gravity.
During the process of writing this article, I learned a great deal of information about the freeform tools that I did not previously know. For one, I never choked my Inventor. Even though I’m working on advanced curvature shapes, my Inventor performed flawlessly and never struggled to process a command or edit. I was most surprised by the level of control I had while also being able to create forms that I never thought would be possible in Inventor. To give you an example, I spent about 15 minutes creating this semi-representational model of a dog’s head (see Figure 5) in Inventor, using the Freeform tools within Inventor 2016. I want to give a thumbs up to the Inventor development team. They built a most impressive toolset with equally impressive capabilities and performance stability. Nicely done!
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Figure 5 |