Computer-Aided Design: Introduction to CAD — CSEC Technical Drawing

CAD (Computer-Aided Design) uses computer software to produce, edit and store technical drawings and 3D models.

What CAD can do

• Produce accurate 2D drawings and 3D models.
• A 3D model can be rotated and viewed from any angle and used for analysis and manufacture.
• Use coordinates, a grid and snap to place points precisely.
• Organise a drawing into layers (e.g. dimensions, hidden detail, centre lines) that can be controlled separately.

Common commands

Draw (line, circle, arc), copy, move, mirror, trim, erase, zoom and dimension.

Hardware

• Input: mouse/digitiser and keyboard.
• Output: a plotter produces large-format paper copies; a printer for smaller sheets.

Advantages of CAD over manual drawing

• Easy to edit, copy and reuse drawings.
• Highly accurate and consistent.
• Drawings stored electronically and shared quickly.
• Faster production of repeated or modified designs.

Disadvantages

• Initial cost of computers and software.
• Training is needed to use it well.
• Reliance on power and equipment.

Exam tips

• CAD = Computer-Aided Design — produces both 2D and 3D.
• Advantages: easy editing, accuracy, electronic storage, reuse.
• Disadvantages: cost and training.
• A plotter outputs large CAD drawings; layers organise the drawing.