2D and 3D drawing techniques

Orthographic projections

are in either a first or third angle projection and show each side of a design without , ie a 2D drawing of a 3D object. They are used to show an object from every angle to help manufacturers plan production. Starting with a front view of a product, show where areas join and are used to draw a side and plan (top) view, ensuring that the drawing is accurate from all angles. These drawings are and must show .

First and third angle projections

and are the two types of orthographic drawing, also referred to as ‘working drawings’. The difference between first and third angle projection is in the position of the plan, front and side views.

Orthographic projections have a set of standard lines to show different aspects of the diagram. These lines allow complex shapes to be drawn simply in 2D.

Standard lines showing dark unbroken for outlines, light unbroken for construction lines, dotted for hidden details, dimension arrow intercepted with measurements and broken, dotted as centre lines.

In third angle, what you see from the right would be drawn on the right. In first angle, the view from the right would be projected through and drawn on the left. The views in first angle are depicted as if you were looking at an x-ray of the object.

A car drawn in first and third angle projections. Includes top and bottom, left and right side and front views. — Figure caption,
In a first angle projection the plan view is below the side view. In a third angle projection the plan view is above the side view.

First and third angle projections use these symbols on a diagram to indicate which projection they are:

Showing symbols that indicate First Angle and Third Angle drawings.

Showing the plan, front and side views of a shape using the standard lines and including hidden details.

Assembly drawings

Similar to exploded views, an will show how the parts of a product fit together and where components should go. They are often used to show how to put together flat-pack furniture or model kits.

Assembly drawing of plywood at right angles and two locks of drilled wood with six screws aligned to the drilled holes - an inset shows the direction the screws will turn in the holes. — Figure caption,
Assembly drawing

There are two types:

fitted assembly - shows the parts put together and can be drawn in 2D or 3D
exploded diagram - shows the parts separated, but in the correct relationship for fitting together, usually drawn in 3D

Exploded diagrams

show how a product can be assembled and how the separate parts fit together, with dotted lines showing where the parts slide into place. The diagrams also show components that would usually be hidden in a solid drawing.

Exploded diagrams can take the place of detailed written instructions, meaning they can explain the construction of something without the barrier of different languages. They are widely used as instructions for self-assembly furniture.

Communication of ideas - Edexcel2D and 3D drawing techniques