Sunday, July 22, 2007

Introduction to Orthographic Projection drawing

Learning program: Introduction to Orthographic Projection drawing

Developed from CUVCR S04A: Produce technical drawings -Element 3.

Our typically everyday environment is made up of man-made commercially produced objects.
All of these objects have been designed at some time and their manufacturing process has been specified and documented, this normally includes the production of some form of technical drawing.

If we too wish to contribute to the built environment and have our designs commercially realised by others, we must be capable of communicating our creative intentions effectively.
This presents the challenge of how to accurately represent a 3D object in a 2D form.

In the initial stages of design, freehand sketches are a very efficient tool to depict 3D objects. However the perspective sketch, like the photograph, can only convey part of the information that would be required by the manufacturer, who will need a more accurate and less ambiguous form of communication such as a technical or working drawing.

One of the most common and reliable methods of verifying a concept and communicating the design intent is to use orthographic projection (multiple view) drawing.

An object can be accurately portrayed in 2D by treating it as if viewed from an infinite distance (to eliminate perspective) and from predetermined directions, (also called plane or view) typically these views are from the front and side as well as from above, also know as a plan view.

This may be best described by imagining that we could fix the object in a glass case or box.

Fig.1 and Fig.2





We could view the object from the front and from a single perspective, then trace or project what we see on to the front glass or plane.

Fig.3


We could repeat the same procedure for the top (or plan) and again for the side(s) rear and bottom if necessary.

Fig.4





If we could then unfold the top view on to the same plane as the main front view and again do the same with the sides, the result would be an accurate depiction of the object in a series of related projected views.

Fig.5 & Fig.6



If the object we are drawings is too large or too small to fit our drawing sheet we can represent it’ size proportionally, know as scale, to suite our requirements.
We can add more information to the drawing, such as numerical sizes known as dimensions, and specify materials and manufacturing processes to be used. The end result will depend upon the nature of the object and the purpose of the drawing.



Assessment task:

Question 1.

Fig.7 Shows a component that is to be represented by orthographic projection drawing.
Fig.8 Shows the same component’s incomplete orthographic projection drawing with a FRONT VIEW and PLAN VIEW but the SIDE VIEW missing.


Fig.9 Shows a selection of drawings, please select an appropriate SIDE VIEW for the component by answering (A) (B) (C) or (D)


Question 2.

Fig.10 Shows an incomplete orthographic projection drawing of a building with it’s FRONT VIEW and PLAN VIEW but the SIDE VIEW missing.

Fig.11 Shows a selection of drawings, please select an appropriate SIDE VIEW for the building by answering (A) (B) (C) or (D)