Modeling Challenge: Faceted Geometrical Shapes
What if you wanted to model a shape like this? where would you begin? This is certainly complex, but all of the faces are planar.
Well, this challenge isn’t an F-117, but it could be used as a study for where to start and how to proceed. There are plenty of options, both solid and surface techniques that you could use for this kind of work.
Some of the things to keep in mind are that you can loft a solid from a closed profile to a point, but you can’t loft from a closed profile to an open profile (a line for example). The same is true of surfaces, plus you can loft a surface from a line to a point. If you have a 3D wireframe, you can loft the faces of the wireframe using the wireframe itself, whether it is curves, 2D sketches or 3D sketches.
You could also make a series of planar surfaces and trim them to enclose a faceted solid. You have seen competitions in different places to create mathematical forms such as icosahedrons.
Here are some simplified sample faceted parts I created. What kinds of faceted parts can you create, and what are the methods you use? Can you recreate these shapes? Send your entries to matt at dezignstuff dot com.
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Entry #1 is from Garrett Brooks. Garrett modeled a bucky ball. There have been various contests and tutorials on how to model these constructions on the web and forums. In this case, Garrett chose to build a planar surface from a sketch, then a plane from the sketch, and a couple of planar surfaces, along with some patterning.
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Entry #2 comes from Phil Sluder. Wow, I dare you to follow along with this one.
- Extrude a box
- Loft a series of surface bodies to create the wedge shape solid inside the box solid, using edges from the block and a single shared sketch only for the first two, then edges for the rest
- Shell out the wedge shape solid
- Loft solids from inside face to outside face of the shelled wedge, without merging.
Very interesting technique. Click the picture above to download Phil’s part. Here’s what Phil has to say:
Your latest blog is one of my favorite SW subjects. Curvy surface stuff where the curve is y = m*x + b. Here is a really simple example of a technique without starting with a whole bunch of sketches, and also shows a neat way to break up the part into mitered sheets (useful if your part will actually be built out of sheet goods). I have used these techniques on several faceted speaker enclosures in the past.
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Entry #3 comes from Alexander Fee.
This part was built originally as an assembly, and then saved as a part, which is why each panel appears as a separate imported surface body.
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Entry #4 is from Bruce Buck. Bruce created a series of intersecting faceted lofts. This is a nicely done model, it looks like it is a few years old, from 2005. This is a great model to download and examine. Bruce did a nice job, much nicer in fact, than the next model down the list…
Notice that the Shape feature has a warning on it. This is not a modeling error, but rather a warning from SolidWorks Corp. The shape feature will be removed in SolidWorks 2010. Anything you could do with Shape you can do better with Freeform or Dome.
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Entry #5 is from Matt Lombard. This is one that I did when I worked for a reseller in NY probably in 1998. The customer did some decorative glass, and this was meant to show what could be done. I don’t have the actual SolidWorks file for this part any more, but it was done by lofting a diamond sketch to a point, and then patterning that around, using the V between adjacent diamonds to make a plane for the next diamond.
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Entry #6 is from Andy Hall. Notice Andy starts out with a combination of 2D and 3D sketches, and then builds surfaces from the sketches. Andy has chosen to use the Fill surface, which is a good choice. I think in cases where Fill is bounded by coplanar curves, it actually produces a Planar surface. Click the image to download the part.
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Entry #7 again from Andy Hall. Again driven by sketches, but this time uses a single loft and multiple patterns.
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Entry #8 is from Matt Sass. This is done with a series of 2D sketches and planes, with planar faces. I always assumed this would be done with 3D sketches, but I guess it depends on the type of data you have to work from. This is a nice model. Download it and see how he did it.
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Entry #9 is from Ales Svoboda. This one was created in a version of SolidWorks prior to 2009 (I know because of the yellow circle with the exclamation mark on the Save icon). When it opens, it also loses its color. This is a long standing bug, that maybe Deelip can look into for me. SolidWorks probably assumes that people will be less concerned about this as fewer old version files will be converted over time.
In this one, Ales lofted between straight lines in two sketches to create flat panels. One thing I’d like to point out here is that you don’t need to use straight line guide curves if there are just two profiles with no end conditions. The default is a straight line guide equivalent. Kind of like a Ruled surface.
Ales make great use of the Selection Manager in this example. You can’t really see it unless you watch the selection process, but the upshot is that you can use sketch segments from various sketches. It’s kind of like a Composite Curve feature (composite curve is likely to be removed from the software in the future).