Technical Drawing

Technical drawing, also known as drafting or drawing, is the act and discipline of composing plans that visually communicate how something functions or is to be constructed.

Technical drawing is essential for communicating ideas in industry and engineering. To make the drawings easier to understand, people use familiar symbols, perspectives, units of measurement, notation systems, visual styles, and page layout. Together, such conventions constitute a visual language, and help to ensure that the drawing is unambiguous and relatively easy to understand.

A drafter, draftsperson, or draughtsman is a person who makes a drawing (technical or expressive). A professional drafter who makes technical drawings is sometimes called a drafting technician.

Engineering drawings generally deal with mechanical engineered items, such as manufactured parts and equipment. Engineering drawings are usually created in accordance with standardized conventions for layout, nomenclature, interpretation, appearance (such as typefaces and line styles), size, etc. Its purpose is to accurately and unambiguously capture all the geometric features of a product or a component. The end goal of an engineering drawing is to convey all the required information that will allow a manufacturer to produce that component.

The two types of technical drawings are based on graphical projection.This is used to create an image of a three-dimensional object onto a two-dimensional surface.

Two-dimensional representation uses orthographic projection to create an image where only two of the three dimensions of the object are seen.

In a three-dimensional representation, also referred to as a pictorial, all three dimensions of an object are visible.

There are two types of computer-aided design systems used for the production of technical drawings” two dimensions (“2D”) and three dimensions (“3D”).

3D CAD systems such as Autodesk Inventor or SolidWorks first produce the geometry of the part, the technical drawing comes from user defined views of the part. Any orthographic, projected and section views are created by the software. Orthographic projection (or orthogonal projection) is a means of representing a three-dimensional object in two dimensions. It is a form of parallel projection, where all the projection lines are orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface.

It is further divided into multiview orthographic projections and axonometric projections.

2D CAD systems such as AutoCAD or MicroStation replace the paper drawing discipline. The lines, circles, arcs and curves are created within the software. It is down to the technical drawing skill of the user to produce the drawing. There is still much scope for error in the drawing when producing first and third angle orthographic projections, auxiliary projections and cross sections. Its greatest strength over direct to paper technical drawing is in the making of revisions.

Source: Wikipedia