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By Chris McAndrew, January 24, 2013
I felt nervous to work with data imported into Solid Edge ST5, because working with imported data in SolidWorks was never something I looked forward to. Imported models always seemed to me to be more hassle than they should be.
In SolidWorks, the imported model’s features must be defined to control and edit the features, and for non-native files this can be a nightmare. I and other designers and engineers with whom I have spoken prefer to recreate a model, rather than work with data that’s been imported. I tend to use the imported model only as a template, on which I rebuild it from scratch and have a much better understanding of the relations and dimensions that control the model. This is even necessary, because most of the time SolidWorks imported data as "dumb" solids, with no relations, dimensions, or symmetry driving the model. Even though there may be relations inherent to the design that are obvious to an observer, the SolidWorks software has no way of recognizing them.
In Solid Edge nearly any model feels like it was imported, but this turns out that is a good thing. Even the most complex models built natively in Solid Edge have no feature tree, so it is possible to delete dimensions after a part is built and let it stand as a "dumb" solid. The software still views the model the same way; information about features is locked to the solid. Regardless if it is imported or native, the result is a solid body.
There are many different CAD programs that create solid body data, each with their own proprietary format, and so figure 1 shows the list of proprietary and standard formats that can be read by Solid Edge ST5.
|Figure 1: Import file types supported by Solid Edge ST5|
How a part is created and what the name of its file extension is do not matter to Solid Edge. Indeed, the order of the features is also irrelevant. All that Solid Edge needs to work with is the end result, and so because of this ability, I was able to import even IGES files and immediately begin editing them.
Once a non-native file is loaded into Solid Edge, making edits is straight forward due to the push-pull nature of Synchronous Technology. I found that it’s an easier way to work with shapes and dimensions that are undefined.
Basically, once the file is open, it no longer matters if it was imported; nothing changes about how to make an edit. Furthermore, the Live Rules built into Solid Edge help identify some of the underlying design rules automatically, making imported data already feel like a native file with some innate memory and intelligence. Ultimately, these capabilities make transitioning between Solid Edge files and other file types simple, and they give Solid Edge an advantage over MCAD systems such as SolidWorks.
To show how Live Rules add intelligence to a model, the Siemens training team showed me this fun example. First they pulled up an imported part, a dumb solid with no linked dimensions, no feature tree, no relations... nothing. Then they posed this question to me: "What can you tell us about the relations of this model?" Figure 2 shows the model, although the exercise can be done with nearly any design.
|Figure 2: Solid Edge shows that design rules exist even on dumb solids|
I noted a few relations that appeared to be part of the design.
Sure, each of my observations was accurate, but the best part was that the software could "see" them as well. To be honest, the software saw more relations than I did, more than I could ever articulate, such as the following:
There were no dimensions or relations locking the model, and yet the very nature of the design included the relations listed above. (Somewhere in the code it must be possible to see these correlations.) By contrast, in SolidWorks I would have had to input all the relations immediately and manually, if I wanted to change anything; in Solid Edge, this is not required.
Before I placed any relations or defined the features, I went straight to synchronous editing. Figure 3 shows a single face that I selected for edit, note that nothing about the body is actually defined and only one face is selected for edit (the opposing symmetrical face is not selected).
|Figure 3: Editing with Live Rules|
Figure 4 shows the part after I changed the angle of the highlighted face. On the right side of the screen, notice the Live Rules menu bar. Even without me defining the two faces as co-planar and symmetrical, Solid Edge saw the relations. As I edited one, it made the change to both faces.
|Figure 4: Solid Edge ST sees that the opposing face is co-planar|
Similar things occur with holes and other features. When I selected one of the holes and then moved it to a different location, Live Rules caused the other holes to move as well. I can turn off Lives Rules to override them, but I kept them turned on, because I found it amazing the number of relations the software saw, even on parts with no relations or dimensions. Indeed, I found it was harder to figure out exact relations on my own without Live Rules.
To make the concepts clearer, the Siemens team provided me with a chart that explained of all Lives Rules (see figure 5).
|Figure 5: Types of Live Rules|
Any time a face, edge, or feature is selected for editing, the Live Rules toolbar pops up. The relations found by Live Rules are the highlighted icons on the toolbar. The part that I showed you in figures 3 and 4 is an example of a few of these being applied automatically. The power of automatically finding and assigning relations kept showing up as I worked with imported files.
Live Rules can be hard to understand without first understanding how Synchronous Technology works, especially for those more familiar with SolidWorks and other traditional 3D modelers. When I worked with imported models in SolidWorks, for instance, I found myself wondering why I couldn’t just push or pull surfaces. The solution that SolidWorks-owner Dassault Systems implemented over the past few years is called "Instant 3D." I found it limiting, because the features I created by pushing and pulling surfaces showed up at the end of the ordered feature tree. This meant that I still had to employ best practices of how and when to add parts or features; in addition, I had to consider all driving dimensions and underlying sketches – not to mention the limited options as to how I could push or pull a surface.
Naturally, the Siemens trainers were eager to explain why Instant 3D was not the same as Synchronous Technology, and why ST was much easier to use. I’ll give in to them on this one, because they were right: Solid Edge ST has an easier work flow for instantly editing imported parts. The Live Rules give the software enough knowledge of the parts that they can be changed even while maintaining design intent.
The process of making edits with Synchronous Technology is super simple, because Solid Edge ST has something called "the steering wheel." It controls instant editing (see figure 6).
|Figure 6: The steering wheel at work|
The steering wheel is a set of axes that help me push, pull, and edit faces and features. In figure 6, I selected a face to move (shown in green); the steering wheel shows up automatically. There is no need to turn on or off ST; it just is there, although technically I could jump back into an ordered feature tree for some necessary edits.
To move the face or alter it in another way, all I have to do is grab one of the white axes of the steering wheel, and then drag it. How the part reacts is very intuitive:
The biggest challenge to me was to figure out from where to start the edit. It turns out that the starting point relies on where the steering wheel is placed, something I got the hang of after a few minutes. Orienting the steering wheel and placing it where I want is critical, but after I figured it out making sweeping changes to models became a breeze.
(There is an update coming in ST6 that will add additional white handles to the steering wheel. I expect this will make it easier to figure out, but for any engineer some simple trial and error will also do the trick.)
The best part of using Solid Edge for imported data was using the streamlined Synchronous Technology for editing. Once an edit is made with the steering wheel, the part immediately updates and there is no record of the edit. (Ctrl+Z works to undo edits, of course.) At first, I found the lack of record confusing, because in SolidWorks every edit requires a corresponding feature. But in Solid Edge ST the order of features has no meaning. With imported data, this meant that I could start making edits wherever I wanted, adding relations and dimensions on the fly, and never having to deal with annoying rebuild errors caused by deleting a referenced edge or sketch entity in products such as SolidWorks.
There is no guarantee that vendors, customers, and engineers use the same MCAD package as you. Being able to handle imported data well is critical to a good MCAD modeling system. For me, this means getting right to the task of making changes and improvements to the imported model, rather than wasting time fixing, repairing, or redoing the hard work of the original designer.
I found Solid Edge ST made it much easier to work with imported data files than with SolidWorks. By removing the ordered history of how parts are created, Solid Edge focuses attention on making changes; the instant editing of Synchronous Technology makes the changes easy to implement.
|Christopher McAndrew develops and markets toys and children's products. He has a bachelors degree in mechanical engineering from Tulane University. Chris writes the 3 Dimensional Engineer blog. More...|
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