A key test is a simple one: print out a detailed set of drawings for a job, in different sizes, on paper and in PDF or other format you might use for portable tablets and laptops. Is everything there? In the second half of this two-part article on CAD buying tips, here are more questions to ask yourself consider before you buy or upgrade.

1. Does the workflow fit your style, or is it cumbersome?

If you have to manually flag a warning note as you are designing, will you actually do so?  Some packages make it easy. Others, especially add-on programs that sit on top of the base software, are cumbersome.

2. Are manufacturers’ symbols handled consistently?

What counts are the symbols your office uses. Some are images with no intelligence attached except data. Others allow size adjustments within your software, while keeping full symbol intelligence. Others automatically suggest associated needs in the structure itself. Beams suggest bolts and rivets. Doors suggest frame details and place light switches… but not always!

3. What about client specifications?

It is generally wise to “lock in” hardware a client wants to use, before you start designing. If this is a common need in your office, you’ll want software that can handle that.

4. Is migration to 3D an issue?

 The biggest advantage to 3D software, in my opinion, is not the ability to do a neat design presentation for the client or the zoning board. I like the idea that 3D is somewhat unforgiving. If your lines don’t quite meet in 2D, the drawing still “looks good enough” to follow. And if lines meet, the software wants to know exactly how you’re handling the join. This makes conversion of 2D legacy drawings to 3D dicey. Test the process on a few of your old artwork – some new CAD packages handle the errors easier than others, and different packages handle different errors. The latest version of AutoCAD directly imports 3D models from Catia and SolidWorks, but not from Autodesk’s own Inventor package!

There’s also the analysis factor. I narrated a segment of "Modern Marvels Engineering Disasters" on cable television a few years back. Seems a concave wall section of the Walt Disney Concert Hall in Los Angeles was magnifying and reflecting sunlight into a nearby residential block. The fix was easy—dull the wall finish—but the right 3D software would have made the check easy before the building was ever constructed.

5. Are there security issues?

Everyone knows enough about the design process to keep drawing files safe as they journey from one office to another. And almost all CAD software these days have ways to keep multiple designers from working on the same elements at the same time without knowing each other’s actions. But simpler packages just allow one designer to change a drawing, and may lock out huge sections of the structure’s design at one time. Does it matter? Not if you share files with only a restricted set of colleagues. But it can be a huge problem when hundreds of people need to edit at once.

There’s another big issue these days: Can you keep drawings from falling into the hands of potential terrorists? The security task is not trivial if you can’t lock drawings on a laptop or tablet. Many clients now specify third-party add-on scrambler software. Don’t ignore their concerns.

6. Is free software any good?

The short answer is that many “open source” design packages are terrific. But you have to know what you are doing, and where to get help fast if you need it. I love an open-source  statistics package called “R,” but I offer math help to other users who in return are better with interface questions. It took several years to make all the connections, and the connections evolve continually. The best bets: Open-source add-ons for mainstream proprietary CAD packages.

7. Is parametric design important?

It depends in part on how you work, and in part on client needs. If the client is presented with a lot of options or has to make a major use change in a structure, the whole redesign process is speeded up if the “design dependencies” are at least partially recalculated by the software itself. If a change in room width also changes the column spacing, does the roof beam’s web increase in thickness?

All too many CAD packages claim parametrics abilities, but sometimes they are quite limited. Many basically allow the “if A is this and B is that, then C can be calculated.” But what if C is fixed by the site and you have to back-calculate to A or B? Not all packages can handle that. Some can handle it in parts of a design, but not in others.

The bottom line: Just as manual drafters liked certain suppliers’ paper, ink and nibs, the choice of computer-based design tools is a personal one, at least in part. Get the best fit, and you’ll maximize productivity while minimizing errors.

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