Orthographic Projection

Introduction

In the Junior School CBC (KICD), Pre-Technical Studies develops graphic communication. Orthographic projection shows an object using several flat views at right angles, so makers can read exact shapes and sizes.

The three main views

• Front elevation (FE): seen from the front.
• End elevation (EE) or side view: seen from the side.
• Plan: seen from above.

First-angle projection layout

1. The front elevation sits at the top left.
2. The end elevation, seen from the left, is placed on the right of the front elevation.
3. The plan sits below the front elevation. Projection lines align the views.

Steps in drawing

1. Study the object and choose the front view with the most detail.
2. Draw the front elevation.
3. Project light lines down for the plan and across for the end view.
4. Draw the plan and the end elevation using the same height and width measures.
5. Add hidden detail with dashes and centre lines.
6. Dimension and label the views.

Worked example

A wooden block 40 mm long, 20 mm wide and 30 mm high.

• Front elevation: a rectangle 40 mm by 30 mm.
• Plan: a rectangle 40 mm by 20 mm below it.
• End elevation: a rectangle 20 mm by 30 mm to the right. Notice the same height (30 mm) in front and end views, and the same length (40 mm) in front and plan views.

Drawing conventions

Use thick outlines, thin construction lines, dashed hidden detail and a title block giving scale and projection symbol.

Related drawings

Isometric drawings show a 3D look using 30-degree lines; orthographic drawings give precise, measurable views.

Try it

• Sketch the three views of a matchbox.
• Draw a cylinder in front elevation and plan.
• Explain why two views alone may not be enough for a complex object.