3D Workshop -
Use of Blender as NURBS/CAD Application
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The important aspect behind this comparison is that instead of modeling straight in Rhino for example, the designer could sketch out the basic model in Blender, import it into Rhino to finish it up there. Subdivided surfaces allows you to extrude faces whileNURBS can cut holes, trim parts away, and create blends which match perfectly the tangency of the two connecting edges of two objects. With the possibility to turn a polygon mesh into matching NURBS patches utilizing a subdivided surface algorithm, the best of both worlds are combined.
Case Study 1: Surface Shell and Chamfer creation
As a quick example, please take a look at the following image. It shows a very rough model of a water faucet. Modeled in Blender using a low polygon cage exported that is then imported into Maya and converted intoSDS and then into NURBS. From Maya exported as IGES into Cobalt. As you can see there is no loss in detail. Modeling this object in Blender including converting it through Maya was faster than building the object in Rhino straight with NURBS. Pay attention to how the surface between the horizontal 4 extrusions flow into each other and vertically along the main shaft of the faucet. A simple looking but quite labor intensive work.
Extrusion of profiles, creating fillets and chamfers, and creating planar surface fillings between different profiles. In addition, it made heavy use of Blender's snap and scale along axis constraints in conjunction with the 3D cursor. Working in proportions and using Blenders measurements.
In my last CAD class I introduced my students first to Blender as a modeling application utilizing subdivision modeling as a basic introduction into how to think in 3D and how to create surfaces. The first major project was to design the new I-Pod Shuffle. This product offers many aspects to learn:
Part 1
However, the supplied dimensions can be used as well. All that was required was to scale a box to 1.62 to 1.06 to .19 to create the rough dimensions which represent the iPod. While Blender does not supply you with any unit system, you can still use the Blender units and decide on your own what they represent. In this case 1.62 in Blender were equal to 1.62". We need to do this to the 3D object and afterwards also to the mesh inside. This way the 3D body has the same measurement values as the 3D mesh. Additional measuring of parts by hand helped to more carefully model all needed parts. Afterwards we scaled down the image to fit the box dimensions.
1. Pre-Planing: Measurements, the big concern in Blender for new users can be approached in a very simple way. Through utilizing a technical drawing of a newiPod Shuffle the students were quickly able to work in correct proportions.
2. Shelling Sides: We started with drawing out the top profile of the main body using the straight lines and for the sides half circle with 32 vertices. From the beginning we applied the subdivided surface modifier to create smooth curves. In the profile we also already built in the edge blends to form smooth transitions at the corners.
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Issue 11 | Jul 2007- Mechanical