Solid Edge: Making and Modifying Surfaces

Among the CAD packages on the market, each has its own unique features. For instance, Siemens PLM’s mainstream solid modeling CAD product, Solid Edge, is  known for its Synchronous Technology. The importance of these features, however, may depend on whether you plan to perform solid or surface modeling.

Whereas solid modeling involves the use of 2D sketches, revolutions, extrusions and other design tools, surface modeling incorporates the use of control points to define curves. With the former, the faces of a model drive the design process and function is the priority. With the latter, we let the curves do a lot of the talking, with curves defining surfaces and aesthetics being an important design driver.

Surface modeling may take on a more important role as 3D scanning becomes more mainstream. How has Solid Edge kept up with other CAD software, like SOLIDWORKS and Rhino? Let’s let the curves do the talking.

BlueSurf Command

Because it is the primary surfacing tool for Solid Edge, we will start out with the BlueSurf command. This is a very powerful command for creating a surface feature from curves, existing surface edges and solid model part edges, if working in an assembly.

The Bluesurf command enables the user to select cross sections (a minimum of two) and guide curves. Full control of blending conditions is available when other surface edges are present.

The BlueSurf command is like a Loft in other CAD applications or a Boundary surface in SOLIDWORKS. You can even cap off the ends to form a solid when working with closed objects. It’s also possible to combine open and closed elements in a single feature. At the closed end, you can modify what would typically be a single point in, say, a conical model to become a rounded end, which may be difficult to achieve in other software. You’re even able to create a closed-loop object, to generate such as a Moebius strip.

Shown below in Figure 1 is a Ship Hull from Surfaces, imported from Rhino using IGES. Though I have imported this model, it’s worth noting that, when sketching, Solid Edge makes it possible to snap to an intersection, providing a Pierce Point as you’re sketching.

I have extracted the hull cross sections to see how well the BlueSurf can handle this application. (See Figure 2.)

After a helpful phone call to Siemens in Huntsville, I was able to loft these profiles without the need for the connecting spine or guide curve at the base of the ship, which was impressive. At the time of this writing, I created the side of the hull in three pieces. Siemens support indicated that Solid Edge could do this as one surface feature using native Solid Edge geometry, as these profiles were imported from Rhino.

Other important capabilities possible with BlueSurf include the Insert Sketch step, which makes it possible to add new sketches to a BlueSurf feature by intersecting a reference plane defined with BlueSurf. The Use Pierce Points option ties the sketch to the guide curves or cross sections that it intersects. This allows you to change the cross sections or guide curves later on and the sketch will be updated. This may be useful for models used in engineering projects, such as the ship hull imported above.

With the Use BlueDots option, BlueDots elements tie the sketch to the elements that it intersects. By moving a BlueDot, you manipulate the area of the sketch connected to that dot and the BlueSurf updates. This option is more useful for industrial design in which aesthetics are of prime importance.

Figure 3 provides an example of a Solid Edge Bounded Surface. You can use the Bounded Surface command to create a surface using boundary elements that you define or, in the case of this example, that you import. The boundary objects can be curves, sketches or surface edges and they must define a closed area. Tangent and curvature continuous blends are options, as well.

The Sweep or Swept Surface command is similar to BlueSurf or a lofted surface. With this command, the guide curves or spine do not need to be connected with the cross sections. That should give you some freedom in modeling of your underlying wireframes.

In the example shown in Figure 4, it should be pretty obvious as to what guide curves are. And then there are cross sections, which are positioned horizontally. Here, I tried to make it interesting by transitioning from square to round using cross sections.

The Redefine Surface command can be used to create a new surface by replacing the existing model faces with a new bounded surface. It provides full control for blending conditions. All of the above surfaces can be thickened into a solid model given a specific wall thickness. Figures 5 and 6 show the before and after effects of the Redefine Surface command.

The Intersect Surface command is like a combination of Trim and Extend in one command. The best part about this command is that I can trim off parts of one surface and then extend others using the same boundary—all in the same operation.

Last, I will write a little bit about surface filleting. You will use the Solid Model Filleting command as it works with both solids and surfaces. In Figure 8, the object looks like a solid cube, but is actually three planar surfaces.

Shown in Figure 8 are three slab surfaces that I joined together with the stitched surface command. Then, I was able to select the interior edges to create this nice three-corner variable radius corner blend.

Though there’s clearly much more to explore with Solid Edge, the ease-of-use and flexibility of the software’s surfacing capabilities are impressive. I expect they will improve further with the recently released ST10, in which surface extraction will enable the conversion of mesh regions into faces that can be modified with Solid Edge surface design tools.

Siemens PLM has sponsored this post. They have no editorial input to this post. All opinions are mine. —Jeffrey Opel