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AutoCAD 3D Conceptual Design 141

Whew! We’ve covered a lot of content in this series of 40 posts! Have you been following along? I hope you’ve found it informative and EASY. The tools you’ve learned through this series should enable you to accomplish your most common 3D design tasks. That is not to say we’ve covered most of the 3D functionality available in AutoCAD. Really, we’ve just scratched the surface…. (actually, we didn’t even touch surfaces). There’s a whole world of surface modeling and many more tools and options for solid and mesh modeling that we only skimmed. And visualization possibilities with materials, lighting, rendering, walk-throughs, and slide-shows are virtually limitless.

If you haven’t had the opportunity to follow along or if you want to review the postings off-line, you can download the AutoCAD 3D Conceptual Design PDF.

I hope you'll learn to enjoy modeling in AutoCAD as much as I do!

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When you’re ready to document your design, you can take advantage of your existing data by creating 2D sections from the 3D model. It’s easy to do using the Section Plane tool, which is available on the Home Tab, in the Section panel. 

You can define a section plane using various methods. You might want to pick points or select from standard orthographic options. 

If you choose the Orthographic option, you can then specify front, back, top, bottom left or right. AutoCAD automatically creates a section plane aligned with that view. You can then select the section plane and use grips to flip its direction, or change its location.

A right-click menu offers additional options including the ability to generate 2D or 3D sections from the model.

You can control how sections are displayed using the Section Settings dialog box, which is accessible from the right-click menu.

 

Once you’ve created the 2D sections, you can use your familiar 2D drawing editing tools to add dimensions and create the necessary 2D documentation.

Key Concept:

• Section planes

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To convey your design intent and help others visualize your ideas, you can apply materials to your conceptual designs in AutoCAD. The AutoCAD materials library is easily accessible from the tool palette and it includes more than 300 materials that you can simply drag and drop onto your model. If you don’t find exactly the material you’re looking for in the materials library, you can create your own using the Materials editor. Access the Materials editor from the dialog box launcher in the lower right corner of the Materials panel on the Render tab.

To view materials on your model, you’ll need to set the Realistic visual style (available from the upper left corner of the Render ribbon tab). The Realistic visual style displays the model with Isolines turned on. If you’d like to view it without Isolines, you can select No Edges in the Edge Effects panel of the Render tab.

 

Key Concept: 

• Apply Materials

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One of the greatest benefits of using AutoCAD for your 3D conceptual designs is the ability to reuse the drawing for many different purposes. For example, you can create a 3D prototype using 3D Printing functionality which is integrated into AutoCAD 2010. It provides improved output of stereolithography (STL) files and easy access to 3D printing services. You can produce STL files using the traditional STLOUT or EXPORT commands as well as the new 3DPRINT command. All of these methods for producing STL files enable you to select more than one solid and the model is no longer required to lie in the positive XYZ octant of the world coordinate system.

You can access the new 3DPRINT command from the output tab of the 3D Modeling workspace. 

The 3D Print tool displays two options. If you select the option to learn more about preparing a 3D model for printing, a Help window displays valuable guidelines to help you avoid printing errors or broken parts when sending your model to a 3D printing service.

When you’re ready to send the 3D model to a printing service, choose the Continue option and select the objects (solids or watertight meshes) you want to print. The Send to 3D Print Service dialog box is displayed with a preview image and output dimensions, which you can modify. Select OK to specify a name and location for the STL file.

 

After creating the STL file, AutoCAD automatically launches a browser window where you can request a quote from one of the featured 3D Printing Service Providers. The result is a 3D prototype of your AutoCAD model.

Key Concept:

• 3D Printing

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We’ve reached the final step in designing the rubber grip for an air hockey paddle. The rubber grip is currently a solid mass that passes right through the handle of the air hockey paddle, which you can see if you view the paddle from below. We need to remove the excess material from the rubber grip so that it can slide over the plastic paddle.

If we subtract the paddle geometry as it stands now, it will only remove a thin shell from the rubber grip because the paddle is hollow on the inside (from the shell operation we performed previously). 

Since we want to move the inner material as well, we need to create temporary solids for the subtraction operation. To make it as easy as possible, I set the 0 layer current and turned off the Rubber layer. Then I drew a solid cylinder and sphere (modeling panel of the Home tab) by snapping to the center and quadrants of the existing geometry.

Turning on the Rubber layer and turning off the Plastic layer, we’re ready to subtract! If you view the model from an isometric viewpoint you can easily select the appropriate geometry. Select the Subtract tool from the Solid Editing panel of the Home tab and then select the rubber grip as the object you want to subtract from. Don’t forget to press enter to end the first selection set (the objects you want to subtract from). Then use implied windowing (left to right) to select the cylinder and sphere that you want to subtract from the rubber grip. 

Ta-dah… A composite shape with both style and precision!

To better visualize how the rubber grip and plastic air hockey paddle work together, turn on the Plastic layer and move the paddle down the Z-axis.

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The previous posts in the 3D Conceptual Design series stepped you through a modeling process where you used solid modeling tools to create precise primitive-based objects and mesh modeling tools to create free-form shapes. At some point you may want to integrate free-form mesh shapes with the precision solid shapes. For example, while we want the rubber grip to fit the shape of a hand, it must also fit snuggly over the plastic air hockey paddle.

Conversion tools on the Mesh Modeling tab enable you to convert mesh objects to solid objects. You can select from different combinations of smooth or faceted; optimized or not optimized. First we’ll look at smooth versus faceted. Notice the smoothness of the original mesh object is maintained when you choose one of the Smooth conversion options. If you choose one of the faceted options, the original smooth mesh faces are converted to flat faces, which can cause the model to become angular. 

Next we’ll look at optimized versus not optimized. When you choose the optimized option, coplanar faces are merged together. If you choose not-optimized, each face in the original mesh object is retained in the converted solid. 

After choosing the conversion option, you can select the Convert to Solid tool. There’s also a Convert to Surface tool.

I converted the rubber grip mesh to a solid using the smooth optimized option.

 

After you convert a mesh to a solid, you can use solid editing tools to combine the free-from shape with the precision of solids. 

Key Concept:

• Convert mesh to solid

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We’re almost finished creating the free-form shape for the rubber grip of our air hockey paddle. As a final step in the mesh editing process, we’ll use the Move gizmo to stretch one side of the rubber grip where the thumb wraps underneath it. As I described in a previous post, you can use the ViewCube to set a viewpoint that makes selecting the appropriate faces easy. 

Ensure the 3D Move gizmo is active and then select the appropriate axis (in this case, the X-axis) to constrain movement. 

Key Concepts:

• 3D Move Gizmo

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The mesh object for the air hockey paddle has many small faces. Even with subobject selection set, it can be tedious to select each face individually. Fortunately you can use implied windowing just as you probably do for 2D design. Since this is a 3D model, however, you might find it helpful to view the model from different angles as you select the subobjects. You can use the ViewCube to easily change to a standard viewpoint. As you pass the cursor over different areas of the ViewCube, they highlight indicating which viewpoint will be applied.

 
I selected Top to view the air hockey paddle from a top view. Then, using implied windowing (left to right), I selected the faces I want to edit.

 
You can continue changing your viewpoint as necessary to view and select subobjects. The ViewCube includes hotspots at the very corners of the cube to display isometric viewpoints.

 
If you accidentally select unwanted subobjects, you can press the Shift key and click on the red grip of the unwanted subobject. The grip turns blue indicating that it’s cold and won’t be used in the editing operation. If your window selection missed some subobjects, you can press the CTRL key to continue adding subobjects to the selection set.

 
To create the finger impressions, I experimented with Move and Scale operations, relocating the gizmo to various locations. Ultimately, I decided to scale the selected faces towards the lower back of the rubber grip, making them more pronounced at the upper front. I also decided to constrain the scale operation to the YZ axis.

 
Using a similar process, I created the remaining finger impressions.

 
Key Concepts:

• ViewCube
• Shift-pick to deselect subobjects

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The rubber grip for the air hockey paddle is taking shape. With the additional faces created by refining the top part of the mesh, we’re ready to make the finger impressions. This is a creative process where you can experiment by selecting different subobjects (faces, edges, and vertices) and using different gizmos (move, rotate, scale) to form the finger impressions. As you select subobjects on the mesh, you can filter on which type of subobject to select. 

If you leave the subobject selection filter as the default, No Filter, your selection is less predictable. For example, if you pick on the corner of a face, AutoCAD could potentially select the face, edge, or vertex. When you use a window selection, it selects all the subobjects that fall within the window, which may or may not be what you intended.

I set the subobject selection to Face to select the faces for making the narrow finger impressions.

Key Concept:

• Subobject selection filters

 

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The next step in designing the rubber grip for the air hockey paddle is to make the finger impressions. You can push and pull subobjects of a mesh (faces, edges, and vertices) to create that type of ergonomic/organic shape. However, the amount of detail that you can create is limited by the number of editable subobjects. Currently, the top of the rubber grip doesn't have enough editable subobjects to enable the detail required for the individual finger impressions.

 
 
The key for adding detail to a mesh it to have more editable subobjects in the area that needs detail. To do this, you can use the Refine tool. When you refine a mesh, AutoCAD converts the facets on the selected faces into editable faces with corresponding editable edges and vertices. I selected the subobjects at the top of the rubber grip, which included five faces, and then choose the Refine tool.

Key Concept:

• Refine mesh objects