Orthographic Drawing

First and third angle projection

Orthographic Projection

Orthographic drawing shows a 3D object as separate 2D views: front view, side view and top (plan) view. In first angle projection (used in SA), views are arranged so the front view is central, side view is beside it, and top view is below it. Each view shows exact shape and dimensions.

Example

Drawing in First Angle

First Angle Projection layout: [Side view] [Front view] [Top view] Rules: • All views are drawn to the same scale • Use projection lines to align features between views • Hidden edges shown as dashed lines • Centre lines shown as dash-dot-dash • All dimensions in millimetres (mm) • Include a title block

Note

Remember

Orthographic drawings are essential for manufacturing — they show EXACT shapes and sizes. Practise by placing a simple object (box, cup) and drawing what you see from the front, side and top. Use drawing instruments (ruler, set square) for accuracy. SA uses first angle projection (international standard).

Key Vocabulary

Orthographic projectionDrawing separate 2D views of a 3D object

First angle projectionThe arrangement method for views used in SA

Plan viewThe view looking down on an object from above

Hidden lineA dashed line showing an edge you cannot see

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Orthographic projection

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