Graphics – Sectioning, dimensioning, and computer graphics


Engineering Studies – P4  Biomedical Engineering – Graphics

This topic develops the skills in representing engineered objects using graphics. Sectioning and dimensioning of orthogonal views, threaded parts and the use of computer graphics to describe and communicate biomedical objects are key concepts.

Key Concepts

  • Orthogonal drawing:
    • Sectioning
    • Dimensioning
    • Computer graphics
  • Pictorial sketching methods
  • Using AS1100 standards to represent threads parts
  • Sectioning threaded assemblies

Discussion Questions

  1. Why are orthogonal drawings relevant in engineering design and manufacture?
  2. What angle of projection is used for orthogonal drawings?
  3. Describe the symbol that is drawn as the 3rd angle indication on orthogonal drawings.
  4. Why is sectioning an object governed by AS1100 rules?
  5. Explain what is meant by a protocol.
  6. List the items that are not drawn as ‘cut’ when a section plane passes through them.
  7. What is a dimension tolerance?
  8. How are ‘surface finishes’ indicated on technical drawings?
  9. How is a ‘spotface’ indicated on a technical drawing?
  10. From where-to-where is the length of a bolt measured?
  11. How is an ‘angle’ indicated using AS1100 rules?
  12. What are the correct ways to dimension a ‘radii’ and a ‘diameter’?
  13. How should the depth of a hole be indicated in technical drawings?
  14. How is a metric thread indicated on a technical drawing?
  15. Describe what advantages a computer aided drawing has compared to a traditional instrument drawing?
  16. Describe a situation where the ability to draw a technical freehand sketch would be a valuable skill?
  17. What tolerances might apply to dimensions on a biomedical product?


  1. What AS1100 standards apply to the drawing of threaded parts?
  2. Why is sectioning of a technical drawing relevant?
  3. How are component materials specified in a technical drawing?
  4. How is the size and thickness of the nut and the bolt head determined?


Freehand pictorial drawing