An Introduction to
Within most fields of engineering, the primary means for communicating graphically is by multiview drawings produced using orthographic projection. (Orthographic means to draw at right angles) Orthographic Projection is a method that describes the shape and dimensions of a component completely with one or more views. It is essential that an engineer or designer knows and understands the principles of Orthographic Projection regardless whether he/she will be producing drawings on a computer-aided draughting (C.A.D.) system or using manual techniques.
Conventional Linestyles and BS 8888:2002
An engineering drawing showing views of a component produced in orthographic projection must be drawn using the types of lines recommended in BS 8888:2002. This is the relevant British Standard for defining, specifying, and graphically representing products. It is known as “BS 8888:2002 – Technical Product Documentation” (TPD) and is aligned with the standards established by the International Standards Organisation (I.S.O.).
After completing this section, the student should be able to: • • • Understand the difference between the two Orthographic projection systems, First Angle and Third Angle. Be able to recognise and use the conventional line types and styles. Produce and also “read” a simple engineering drawing of a component.
The Theory of Orthographic Projection
First Angle Projection Drawing Planes.
First Angle Projection Layout
Third Angle Projection Drawing Planes.
Third Angle Projection Layout.
A Comparison of First and Third Angle Projection.
Commonly Used Linestyles and their Application
Components with little interior detail can be represented satisfactorily in orthographic projection by exterior views, the interior construction being shown by hidden detail lines. When the...