Formal drawing and computer aided design (CAD)

Formal drawings are a more precise style of drawing. They can be produced by hand or with computer aided design (CAD) packages.

Formal hand drawings use tools such as rulers and set squares to ensure accuracy and neatness.

Using computer aided design (CAD) allows the user to quickly make changes, and the drawings can be digitally shared and copied with ease.

Formal drawings are used when showing an idea to a client, showing measurements or getting feedback from a user group.

Design and development involves creating working drawings and parts lists to enable a third party to manufacture the design. Working drawings are sent from a designer to a manufacturer to enable them to build a product.

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.

Elevations are the sides of an item you can see on the drawing, e.g. front elevation or side elevation. The top is referred to as the ‘plan’. These drawings enable detailed measurements to be added for every section of the product.

This isometric drawing shows the plan and front and side elevations of the shape.

• Horizontal lines should be drawn at a 30° angle
• Vertical edges should be drawn as vertical lines
• Parallel edges drawn as parallel lines

You can find more information about isometric drawings in sketching and modelling

Orthographic projections are working drawings in either a first or third angle projection and show each side of a design. They are used to show an object from every angle to help manufacturers plan production.

Starting with a front view of a product, construction lines 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 to scale and must show dimensions.

Third angle projections

Third angle projection is an accurate method to produce ‘working drawings’. The position of the plan, front and side views are important in this method of drawing.

In third-angle projection, the view of a component is drawn next to where the view was taken.

What you see from the right would be drawn on the right and what you see from looking at the top will be drawn above.

First Angle Projections

In first-angle projection, the view is drawn on the other end of the component, at the opposite end from where the view was taken.

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.

Computer aided design (CAD) is the use of computer software to design new products in both in 2D and 3D. Some of the software commonly used in schools is 2D TechSoft and SolidWorks for 3D designs

CAD software allows you to easily visualise what a product is going to look like when it is made. The designs made on this software can be easily transferred to machines such as a laser cutter of 3D printer. This is known as Computer aided manufacture (CAM).