Technical drawing principles and standards

Technical drawing principles and standards

Technical Drawing Principles

  • Technical drawing is a form of communication for expressing and recording design information that is clear, concise, and able to be interpreted by others.
  • All drawings must be drawing standards-compliant. This ensures uniform interpretation of drawings across industries.
  • There are several types of viewing projections such as orthographic, isometric, oblique, and perspective.

Drawing Scales

  • All drawings should use a consistent scale to allow for accurate interpretation.
  • The scale chosen for a drawing must be appropriate to the size of the object being represented and the size of paper being used.
  • Classic construction-based scales include, 1:50, 1:100, 1:200, and 1:500.

Types of Lines in Technical Drawing

  • Lines such as visible lines, hidden lines, centre lines, and cutting planes lines are utilized to communicate specific information in technical drawings.

Dimensioning and Annotations

  • Dimensions are added to give size information about the object being represented while annotations provide additional detail or explanations.
  • All dimensions and annotations must follow standard conventions to ensure clarity and precision.

Construction Details

  • Details should be shown clearly and fully, with all necessary measurements and materials specified.
  • Construction details can include information about structural members, insulation, services, and various connections/junctions

British Standards and International Standards

  • A thorough understanding of British Standards (BS) and International Standards (ISO) for technical drawing is necessary to create accurate and professional drawings.
  • These standards specify methods for drafting, presentation, and also discuss various aspects such as scales, line types, dimensions, symbols, and colour codes.

Using CAD Systems

  • Computer-Aided Design (CAD) systems are often used in technical drawing, effectively creating, modifying and optimising designs.
  • CAD produces 2D or 3D diagrams which can be rotated and viewed from any angle.
  • Familiarity with various CAD features including layers, line types, dimensioning tools, labelling and blocks is key.