For an architect who cherished the era when drawings were exclusively done by hand, CAD drawing was a major revolution. I wouldn’t appreciate CAD drawing if I hadn’t first savored the pleasure and effort of drawing by hand.
Starting from the assumption that every project arises from a ritual, when discussing hand drawing, it’s important to distinguish between freehand drawing and technical drawing with a set square and ruler. The first type of drawing is the one that marks the beginning of an architectural project and is called heuristic drawing. Heuristic drawing represents what the client generally doesn’t see, what arises from a succession of second thoughts, erasures, gestures, and sketches. It’s where the designer pours his reasoning and hypotheses. Heuristic drawing is what arises from inspiration, and when an idea comes to you, you have to draw it immediately.
I never thought of abandoning freehand drawing, but I have gradually, though not completely, replaced hand-drawn technical drawing with CAD-supported technical drawing.
The use of CAD in design
The second type of drawing is the technical one. A technical drawing is a scale drawing, with precise dimensions, where the error is dictated by the thickness of the pencil or nib. Unlike freehand drawing, precise tools, such as rulers, set squares, compasses, etc., are used.
When drawing by hand, it’s natural to start with a large-scale drawing and gradually scale down to focus on the details. The design process imposes a fixed path that allows for several back-and-forths in the creative process.
Each representation scale corresponds to a more or less detailed definition of the project. Therefore, a 1:500 scale drawing usually represents simple volumes. A 1:200 scale drawing represents internal layouts and routes. At a 1:100 scale, wall thicknesses and furniture dimensions can be seen. From a 1:50 scale onward, executive and construction details begin to be represented. As mentioned, it’s a lengthy process where the client is only shown the final result.
CAD design, on the other hand, allows you to represent all the elements, previously defined at various scales, in a single, much more complex and detailed file. This is because CAD drawing allows you to work simultaneously at all scales, as it features a command that is now essential and common in all graphics programs: ZOOM.
The vector format
A vector drawing is composed of a set of lines called geometric primitives. Generally, these are lines whose points have a geometric location in space defined by Cartesian coordinates (x, y, z).
Vector file extensions are many:
svg: scalable vector graphics
dwg: abbreviation for drawing
dxf: Drawing Exchange format
Many programs, both paid and open source, can handle 2D or 3D CAD files. To name a few:
The most popular is undoubtedly Autodesk’s AutoCAD.
There are also other similar software such as IDMcad, or other free programs such as:
Kicad
Freecad
Qcad
Librecad
Nanocad
2D and 3D CAD drawing
Among the many features of technical drawing is the ability to draw a project or a component of a project in 2D or 3D. If we take, for example, a technical drawing program like AutoCAD, probably the most well-known and widely used, we find both features within it: both 2D and 3D drawing. However, this program differs from other 3D software, a topic we’ve already explored, in that it doesn’t create a model starting from geometric shapes. Instead, each 3D element must be created and studied directly by the designer. Only a few functions are available: extrusion, cone, cylinder, and parallelepiped.
Creating a 3D project using a CAD program isn’t much different from the axonometric representation of a hand drawing. Thus, the combination of hand drawing and CAD drawing returns, where what’s learned with the former becomes useful and fundamental for mastering the latter.
CAD design has undoubtedly simplified and accelerated the designer’s work. This doesn’t mean you don’t need to have a basic understanding of hand-drawn technical drawings to be able to represent them on a computer. Good graphic representation is the result of study and courses in learning the functionality of a CAD program, which increasingly requires attention and time.