That Evil CAD

Chris Ebbert/ Product Design/ Otago Polytechnic



3D-CAD – pro and con

Ever consider that 3D-CAD use in product design can have disadvantages? Here they are, and what to do against them:

Lack of sensory exploration in the development process:

• Touch: When you make things by hand, you develop a feeling for it as you progress towards completion of the object. You get a feel for how the object handles, what it weighs, and you pick up on subtle things like “does it feel good when you rotate it this way and that in your hand?”, “is that edge pleasant to touch?”, etc. In CAD, you have no such options. Possible solution: Either build on experience (takes a few years) to choose the right radii and curvatures when you design things on screen; in the meantime, outputting through a 3D-printer for verification purposes might do the trick, expenses permitting. Otherwise, make sure you’re aware of existing standards (see semantics/ semiotics handout) and use them: “1mm minimum radius for moulded housings”, etc.)

• Human perception: When you build an object in 3D-CAD, you normally get perfectly scaled and dimensioned objects, often constructed without fault. You can also expect perfect Bezier curves. But what you don’t get is a feel for how the object will actually look. True, there are perspectives, there are renderings, and you can turn it on screen. But all that is seen through the simulation of a camera lens, which is no match for what happens when you walk around an existing object and watch as the object’s shape works in different angles, different proximities to the onlooker, and when you’re moving (ever moved your head sideways while looking at a glowing LCD-display? The numbers seem to dance. Similar things happen when you look at objects while on the move, due to the reflections caused by imperceptibly pulsating AC lighting; CAD can not show you that). Possible solution: Either imitate something someone has done, and which works well, such as a certain sloping angle on chair legs; there will be a reason for it. Or create 3D-printed outputs, expenses permitting, for repeat-verification.

Compatibility Trouble:

• Software wrong for project: This can happen and is most likely going to happen at the workplace, when management does not understand the needs of designers and forces them to use limiting software (e.g. Solid Works for a freeform sheet metal vacuum cleaner housing project – useless!). It can also happen if you’ve spent all your energy learning one software package only with limited capabilities, because then you’re stuck with it. Solution: Communicate clearly at your job interview what software you can handle and what software you require training for. Later, when new software is introduced while you are part of the firm, immediately sign up for training for it. If computers are something you are being associated with, make sure you are being regarded as knowledgeable about the subject; that way, when new projects begin, and you feel you haven’t got the right software, management is more likely to make the necessary purchase of suitable software when you ask them to.

• Files incompatible with connecting applications: Depending on the quality of communication and competence in the work process, you may be presented with file outputs that mean nothing to you and cannot be processed by any of the computers available. It happens when people send you data without asking first what you can actually open, but the same goes for you, too. Solution: When giving out a data-CD to a rapid prototyping facility or any other agent for further processing, save the file several times on the same CD, in different file types. A good, universal one is IGES, which can normally be read by most software, if you have only one choice.

Company-internal, political issues:

• Lack of CAD competence among management: Commonly seen in small to medium companies of long standing which are run by the founder and a few of his old boys. Usually leads to the young designer becoming the official “computer genius” in the company. The difficulty of mastering 3D CAD software is often underestimated in such scenarios, and the value of your work can be, too. Traditional, old bosses are suspicious of workers who seem to sit still all day, looking at a screen, with very little happening and all output being a little file. Solution: Involve management by explaining to them what it is you’re doing, why it seems to take long and result in seemingly small things, and what it equals in terms of traditional methods. Once they understand that you’re actually doing the work of 5 engineers, a few craftsmen and an entire prototyping facility alone and in a week, they will appreciate your work.

• Inappropriate emphasis on certain software suites: A company may be entirely outfitted with software X and expect you to use it, because the licence is expensive, they’ve always used it, it’s perfect, blah-blah. If you disagree, download a trial version of the software of your choice onto your office workstation and demonstrate its advantages. In the end, nobody cares what you use to get the job done, as long as the result is right. They just don’t want to lose money and time. So, if you can download a free version and get the job done more quickly because it’s the appropriate software, then pop it into the official company software, everybody will be happy.

Advantages of 3D-CAD use:

• It’s precise;

• You can generate and visualize a large number of variants with great ease, showing different ways of constructing, proportioning, or colourising the product;

• You can generate photorealistic visualizations of a finished CAD model and hand it straight to marketing;

• It lets you exchange elements with a few clicks if testing shows that a re-design is indicated;

• Some software lets you test your product in virtual space. You can realistically crash cars, detonate buildings, age products (run a vacuum cleaner for 500 years in a second), or simulate stress situation handling with some programs;

• Direct output though 3D-printers gives you mature prototypes in hours which used to take weeks and months to make.

• For yourself: There is more, and safer money in CAD services and visualization than there is in design. If you can do both, you’re at an enormous security advantage.