Cadalyst - August 2008 - (Page 40)

mcadmodeling Figure 3. A bad model will result in bad FEA. A good model, supported by consistent standards, will give you good results. Get together with a few of your coworkers and come up with some ideas for things you’d like to see enforced. If you have problems agreeing, then divide the ideas into two groups: Must Do and Would Be Nice. More than likely, none of the ideas is going to be downright horrible (although there are exceptions from time to time). The list you come up with may not seem like much, but it’s a good start. If nothing else, you can print the list and give it to new employees. I will warn you that the more people you get involved in this process, the longer it’ll take. Instead of jumping right to a company-wide, all-encompassing list of standards, I would start with your own department, an area you should know well. Besides, when you bring up the subject of standards, people are going to ask several questions. They’ll ask why they’re needed. They’ll want to know what it’s going to cost or save (both in money and time). And they’re going to ask if you plan to follow those suggestions yourself. If you can pull a sheet off your cubicle wall and hand it to them with the comment that you wouldn’t suggest what you hadn’t already worked out, you’ll be well ahead of the game. Another advantage of having written standards is that they can serve as orientation materials for new employees. Having a printed list of guidelines regarding how to set up a model will speed the training process, provide a reference for questions that come up in the future, and offer insight into how your office runs. Post your modeling standards at every workstation so they can be referenced easily. By naming your features, you leave a road map for those who will work on your models in the future. Here’s another good question: Do you have to name every feature? If you did, the problem then would be the amount of time it would take. If there’s a good reason for it, do it. If not, organize it in a different way. If you keep your features together with what they interact, you can get away with just naming your sketches (figure 2, p. 38). In other words, if you keep your Extrude feature next to its Unite and you put the Blend on next, then by naming the Extrude “Upper Tab” it is going to be easier for someone else to find that feature and edit what’s associated with it. You can organize your models many ways. Think about how you build. Think about what you like. Think about what you dislike. Get creative. Go on, you can do it. No matter which approach you take, when you determine how to organize your models, you are building the foundation for your standards-writing process. Downstream Success One really important reason for standards is to create quality models that will stand up during downstream applications. By having models that are easy to understand and edit, you not only build in intelligence but do it in such a way that it will be easier to access. Anyone who uses the model downstream will have a head start in knowing where the things are supposed to be. What kinds of downstream applications will benefit from quality modeling? Analysis is one. Finite-element analysis (FEA, figure 3) is a growing and important downstream application. Bad models undoubtedly will result in bad FEA. If you model sloppily, you’ll end up with tiny imperfections — such as open gaps or leftover projections — that the FEA program will either explode on or have to fix. Your modeling program may have tolerances that are loose enough to allow a modeling error to stand out, but your FEA program may have tight enough tolerances that it chokes on the error. You also need good models for good simulation. A funky model will yield unexpected results. A model that has a modeling error usually will cause problems with all its uses. How about CAM (computer-aided machining)? If your models freak out, you’re liable to have major problems. A sloppy model invariably will have unintended features — repairs done to cover up problems that you couldn’t solve. When you go to a program’s tool paths, the computer will see these features even if you want to ignore them. Organize! One of the best ways to make life easier is to organize. Organization is the very life’s breath of modeling standards. Without proper organization, your models will quickly become quite a mess. You’d be surprised how many people ignore organization when modeling. For example, take layers. Do you give descriptive names for your layers (figure 1, p. 38) that make it easier for others to see what is where in your files? No? Why not? This one little thing can be so helpful. If you are using a parametric modeler, do you name your features? Believe me, “Extrude 437” isn’t terribly useful when you’re trying to find a particular feature to edit in a coworker’s drawing. The Answer Is Obvious Modeling standards? Yes, you do need them. If you put good rules in place and adhere to them, you will have consistently good results and downstream success. And that’s what you want, isn’t it? Mike Hudspeth, IDSA, is an industrial designer, artist, and author based in St. Louis, Missouri. 40 www.cadalyst.com cadalyst August 2008 http://www.cadalyst.com

Table of Contents Feed for the Digital Edition of Cadalyst - August 2008

Cadalyst - August 2008 Contents Editor's Window CAD Central Tech Trends: Rotor Bug Strikes Again Cadalyst Labs Reviews: Digital Dreams — Visualization Software: Make Your Design Visions a Reality Maple 12 — Math Software AutoLINE 2009 — Linetype Management Add-On Deep Access — Digital-Media Asset Management Software View Point: Examining the Autodesk–Bentley Agreement CAD Manager: Managing Multioffice Mayhem MCAD Modeling: Do You Need Modeling Standards? AEC Insight: Modeling Technology for Building Engineers CAD Cartoon Issue Indexes Hot Tip Harry: Better Living with Objects and Smart Entities

Cadalyst - August 2008

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