Geometrical Tolerancing to BS 8888 and ISO standards – Level 1

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  • Level 1 (BS 8888 & ISO version)

What is it?

An intensive three-day course introducing the fundamental principles of geometrical tolerancing to BS 8888 and ISO standards.

  • Discover how the system of geometrical tolerancing works.
  • Find out how to annotate drawings correctly
  • Learn how different types of tolerance control different characteristics, and how to choose the right tolerance for your application.

The course covers the fundamental concepts of geometrical tolerancing and its application and interpretation. It is suitable for anyone who is familiar with the conventions of engineering drawing and limit (or ±) tolerances on dimensions, and is relevant to anyone who has to produce or interpret mechanical engineering specifications.

Where possible, the course uses examples of drawings or components provided by the client to help illustrate the course material and as the basis of some worked examples and exercises.

The course is based on BS 8888 and ISO standards (a version is also available based on the American ASME Y14.5 standard). Delegates are provided with comprehensive course notes, and a workbook with questions and exercises to accompany the training material.

The course is also available as a fully accredited course through the National Physical Laboratory training framework.

To maximize the effectiveness of the training, an upper limit to the class size of 10 delegates is recommended.


3 days (available for classroom or on-line delivery).

Who is it for?

Mechanical, production and design engineers, drawing office and inspection personnel.

Some familiarity with engineering drawing practice and conventional dimensioning and tolerancing is required.

What does it cover?

  • standards in context
    • BS 8888 and the ISO system
  • what is Geometrical Tolerancing?
    • benefits and advantages
  • features and features-of-size
  • size tolerances
    • ISO 14405-1 and the Envelope Requirement
  • datums and datum systems
    • what is a datum?
    • constructing a datum
    • datum targets
    • selection of datum features
    • controlling 6 degrees of freedom
    • annotation and symbology
  • tolerance frames
    • tolerance features & symbols
    • tolerance frame modifiers
    • tolerance frame placement
  • Theoretically Exact Dimensions (TEDs)
  • tolerance characteristics – what they will and won’t control
    • location
    • orientation
    • form
    • profile
    • run-out
  • how to choose which tolerance to use
  • tolerancing for parts that fit together
    • Worst case boundaries
    • Maximum Material Requirement and Bonus Tolerance (BS EN ISO 2692)
    • Virtual Condition and Virtual Size
  • restricted application of tolerances
  • current BS & ISO standards
    • future developments