What place has 2D CAD in a 3D world?

3D CAD now costs less than the 2D CAD systems of five years ago. The ‘object’ of these powerful systems is a 3-dimensional product, so can 2D CAD continue to have a role as a design tool? Graham Lacey – head of technical design at PDD – thinks it can.

‘It’s hard to imagine a project where a 3D CAD solids database isn’t the preferred choice to store and describe design intent. 3D CAD, and particularly its Master Model concept, has integrated the design process and united team members through improved communication. It has accelerated projects by removing inefficiency and duplication and so lowered development cost. These factors have increased competitiveness; raising both the design and quality stakes so that 3D CAD’s position at the hub of the product development process is assured.

Although 3D CAD isn’t new, it is only recently so commonplace that today’s graduates regard it as the norm and their tool of choice. Moreover, they are less familiar with evolving and expressing design in 2D elevation than ever before.

The young 3D-literate bring new practices and many question whether 2D CAD continues to have a design role. It’s easy to conclude that superseded technology is obsolete, but is this the case, or does 2D CAD have unique strengths that redefine its purpose alongside its would be successor?

Its important to distinguish the two current roles 2D CAD has alongside 3D solids, since it is used both to ‘layout’ in early work and ‘specify’ at completion. Until seriously challenged by 3D CAD model annotation, the 2D ‘detail’ drawing remains a strong contractual means of specification thanks to its quality robustness and close association with the written word.

Prior to CAD, the drawn ‘layout’ (or GA) was the vehicle for technical design intent. Its unassociated views defined a ‘picture’ of parts, not parts themselves, described in a drawing code. 2D CAD didn’t change this, it just put it in electronic form and the primary purpose of the layout remained technical; to establish a feasible build arrangement given the various geometric and dimensional constraints.

The layout remains an effective communicator of technical design intent. It is fast to create, unconstrained relative to solids and allows artistic license. It’s easily transferable and lends itself to presentation and hardcopy.

The overall build arrangement of many products can be established in 1 or 2 critical sections and these form a powerful management tool. When reviewing these, the third dimension can be superfluous, raising the chance of not seeing the wood for the trees. The root of most 3D features is a 2D section. This holds key information that can be appraised before time-consuming 3D modelling.

Despite its technical purpose, ‘layout’ is a creative process. It is a fluid step in which initial sketches and ideas are developed and translated into a size-wise format. To be as effective as sketching the designer must work at the ‘speed of thought’: to be able to navigate instinctively, drag, scale, mirror and break the rules is a distinct benefit. Outlines want to be transferable from one ‘part’ to another and construction lines will want to switch on and off.

The optimal CAD tool for this is a spatially and geometrically accurate sketchpad that imports seamlessly into 3D solids. But the choice is limited; illustration packages are flexible but lack the precision required for serious CAD work. The 3D CAD vendors acknowledged the ‘detail’ function of 2D in their drafting modules but these aren’t directed towards front-end ‘layout’; their importing is cumbersome and they often can’t be used directly for 3D modelling. Some vendors offer sketching tools or 3D wireframe tools, but these either lack the full palette of shape creation and modification tools, or are burdened with stifling, parametric constraint.

In a ‘layout’ role, the 3D CAD modules lack the versatility and sketch layout power of the standalone 2D CAD systems.

If that is now, what trends might affect the relationship between ‘layout’ and 3D CAD? When 3D CAD emerged it offered strategic design advantage. Now it’s commonplace, the playing field is level and companies are rightly refocusing towards brand, user experience and innovation to provide product differentiation. There is every indication that within a few years 3D CAD modelling will be regarded by many as a service subcontracted to specialists. In this context there is renewed demand for a medium, such as the ‘layout’, that can be used to originate design efficiently and brief external parties.

The strength of the ‘layout’ to create and communicate the technical nub of design means that it must surely continue to have this niche role, yet 3D CAD vendors largely overlook its future development. Instead they concentrate efforts at the sharp-end; developing new 3D tools to compete for sales. If they could also further the power and value of integrated 2D CAD at the front-end, I am sure it would enjoy a renaissance amongst young designers and raise the profile of a currently undervalued step in product development.’