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By Chris McAndrew, January 22, 2013
No review of MCAD software packages is complete without understanding how they create 2D engineering drawings from 3D models. During my Solid Edge ST5 training sessions with Siemens PLM Software, we spent a fair amount of time working on draft files and in discussing the ways in which Solid Edge and SolidWorks differ in creating part drawings.
(Despite many predictions of the day when 3D models will replace 2D prints entirely, that day is a long way away. It’s been nearly 25 years since 3D parametric MCAD modeling burst onto the CAD scene, yet Pro/ENGINEER, SolidWorks, Solid Edge, and their competitors continue to include 2D documentation in the base MCAD package. It is still reality today that many design reviewers, machine shop operators, production workers, and engineers prefer - even require - engineering drawings in 2D to complete their jobs.)
Solid Edge ST is similar to the way by which SolidWorks handles drawings: it links part files directly to draft files so that they can be updated. The difference in Solid Edge, however, is that draft files live independently of linked parts, and so must be updated manually. (I’ll explain later how this works.) This is due to draft files recreating all necessary geometry and data. A benefit to Solid Edge’s manual approach is that while I am working on drawings, I can email or otherwise send drawing files without first saving them as .dwg or .pdf files, or doing a pack-and-go. In addition to this, there are some other practical implications that I discovered while working with drafting files.
One of the major problems I have with drawings (a.k.a. "drafts") has to do with file relations. When I am not using a file management system, I typically generate revisions manually; in this way, I keep a copy of every drawing and part sent out for quotes or is otherwise stable.
To replicate my SolidWorks practice in Solid Edge, I created a sample drawing and then intentionally renamed and edited the related part file. In SolidWorks, this action would have caused the original drawing (or draft file) to break down, because it no longer knew how to reference the linked file (from which it creates views); a similar problem occurs when I email a SolidWorks .slddwg file without the part file. In Solid Edge, this breakdown does not happen.
In figure 1, I show a drawing before (on the left) and after I edited it (on the right) in Solid Edge.
|Figure 1: Drawing file before (at left) and after (at right) being updated in Solid Edge|
On the right, there are boxes around each view; these are alerts. Even though the draft file is a standalone file, it notices that the views are not up to date, and so it highlights the views by putting boxes around them - without losing the detail. I can still edit this drawing file, add dimensions, and send it out for quotes without repairing the link to the part.
To update the views, I restore the linked part file association, something which in Solid Edge is done through the Revision Manager. (Revision Manager is a separate program that I access by right clicking any Solid Edge file.) Figure 2 shows the Revision Manager panel in which I update file associations.
This process works fine, but to me it feels clunky to leave a program, open a type of file manager, and then update a file link. I would much prefer to update links directly within CAD program; I cannot imagine how the Solid Edge process is possibly a benefit! But then Solid Edge tech support pointed out that this occurs only when the model file is renamed, and that the same thing happens in SolidWorks (where you are prompted to browse for the file or suppress the components).
|Figure 2: Revision Manager is a separate program that updates links between files|
After I updated the linked files, I assumed that the drawing files would immediately update as well, but they did not. When I opened the file, the boxes were still in place around the views; then I remembered the workflow the Siemens PLM guys taught me: because draft files are not dynamically linked to part files, they cannot update automatically. As soon as I clicked Update Views, the drawing was corrected; figure 3 shows the ribbon displayed by Solid Edge for draft files.
|Figure 3: Update Views button in the ribbon used for draft files|
Even though it adds a step in the process, updating views manually is useful. I found it nice to go back to the draft view and then watch as the changes were implemented. I can imagine a handful of situations where this would be preferred, such as tracking changes to part prints.
Other than manual updates and file management in Solid Edge ST, the drawing/draft module is very similar to the one in SolidWorks. I found myself quickly editing and saving template files, as well as adding annotations. I’ve never worked in an organization that required strict adherence to a certain set of drawing standards, but ST has the tools and standard callouts for efficiently communicating designs. For those who need ASTM-compliant prints, these are easily accessed from the ribbon and toolbar (see figure 4).
|Figure 4: Draft view optionally shows the curves and edges in the style of patent office drawings|
The simple tasks of adding dimensions, annotating features, highlighting detail views, and adding BOMs were all straight forward; they took me as a SolidWorks user only a few clicks to figure out in Solid Edge.
Also in figure 4 is one of the features I like best about drafts in Solid Edge. Notice the rendering style I selected for curves and edges: the line art is the shading style required for patent drawings. Most of the time, prints of parts requires simple line art and dimensions; Solid Edge has the option to render prints in color, with custom material finishes.
Overall, I found the Solid Edge ST drawing module entirely functional in communicating the details of 3D models in 2D drawings. The benefits of its file management system make it easier to work with files that change constantly. Solid Edge’s draft file capabilities do not appear to have any holes in its functionality. In any case, part prints and draft files are handled differently in every organization.
When it comes to drawings, Solid Edge has some differences from SolidWorks, and so users switching from SolidWorks may have to alter some of their workflows and design methods. Overall, there are enough similarities that I ended without a preference for either program for generating 2D drawings.
|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...|