Drawing
A drawing is a graphic representation of an object, or a part of
it, and is the result of creative thought by an engineer or
technician. When one person sketches a rough map in giving
direction to another, this is graphic communication. Graphic
communication involves using visual materials to relate ideas.
Drawings, photographs, slides, transparencies, and sketches
are all forms of graphic communication. Any medium that
uses a graphic image to aid in conveying a message,
instructions, or an idea is involved in graphic communication.
One of the most widely used forms of graphic communication
is the drawing.
Technically, it can be defined as “a graphic representation of
an idea, a concept or an entity which actually or potentially
exists in life. Drawing is one of the oldest forms of
communicating, dating back even farther than verbal
communication. The drawing itself is a way of communicating
all necessary information about an abstract, such as an idea
or concept or a graphic representation of some real entity,
such as a machine part, house or tools.
There are two basic types of drawings: Artistic and Technical
drawings.
Artistic Drawings -
Artistic Drawings range in scope from the simplest line
drawing to the most famous paintings. Regardless of their
complexity, artistic drawings are used to express the feelings,
beliefs, philosophies, and ideas of the artist.
In order to understand an artistic drawing, it is sometimes
necessary to first understand the artist. Artists often take a
subtle or abstract approach in communicating through their
drawings, which in turn gives rise to various interpretations.
Technical Drawings -
The technical drawing, on the other hand, is not subtle, or
abstract. It does not require an understanding of its creator,
only an understanding of technical drawings.
A technical drawing is a means of clearly and concisely
communicating all of the information necessary to transform
an idea or a concept in to reality. Therefore, a technical
drawing often contains more than just a graphic
representation of its subject. It also contains dimensions,
notes and specifications.
Types of Technical Drawings -
Technical drawings are based on the fundamental principles
of projections. A projection is a drawing or representation of
an entity on an imaginary plane or planes. This projection
planes serves the same purpose in technical drawing as is
served by the movie screen. A projection involves four
components
1. The actual object that the drawing or projection represents .
The eye of the viewer looking at the object
3. The imaginary projection plane
4. Imaginary lines of sight called Projectors
The two broad types of projections, both with several sub-
classifications, are parallel projection and perspective
projection.
Parallel Projection -
Parallel Projection is a type of projection where the line of
sight or projectors are parallel and are perpendicular to the
picture planes. It is subdivided in to the following three
categories: Orthographic, Oblique and Axonometric
Projections.
♦ Orthographic projections: are drawn as multi view
drawings, which show flat representations of principal
views of the subject.
♦ Oblique Projections: actually show the full size of one
view.
♦ Axonometric Projections: are three-dimensional
drawings, and are of three different varieties:
Isometric, Dimetric and Trimetric.
Purpose of Technical Drawings -
To appreciate the need for technical drawings, one must
understand the design process. The design process is an
orderly, systematic procedure used in accomplishing a
needed design.
Any product that is to be manufactured, fabricated,
assembled, constructed, built, or subjected to any other types
of conversion process must first be designed. For example, a
house must be designed before it can be built.
C. Application of Technical Drawing
Technical drawings are used in many different applications.
They are needed in any setting, which involves design, and in
any subsequent forms of conversion process. The most
common applications of technical drawings can be found in
the fields of manufacturing, engineering and construction.
For instance, Surveyors, civil engineers, sanitarians use
technical drawings to document such works as the layout of a
new subdivisions, or the marking of the boundaries for a piece
of property. Contractors and construction personnel use
technical drawings as their blue prints in converting
architectural and engineering designs in to reality.
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