Geometrical Dimensioning & Tolerancing to BS 8888 & ISO Standards – Level 1


Organisation profile


IMR is Ireland's leading independent research and technology organisation, RTO. All Irish Manufacturing Research’s projects focus on translational innovation projects, in collaboration with industry, to demystify, de-risk and deliver emerging concepts, processes and technologies.

Training aim

GD&T Level 1 ISO Overview Geometrical Tolerancing to BS 8888 & ISO standards – Level 1 is a three-day course which can be delivered either in a classroom environment or online. The course uses some examples of drawings or components from the client, where available, to help to illustrate the course material and as the basis of some worked examples and exercises.

Learning objectives

  • Read and understand basic GD&T symbols on a drawing.
  • Under basic GDT concepts and the application in engineering
  • Identify minimum and maximum tolerances 
  • Understand GD&T standards

Course outline

Section 1: Description of Module 1 

Standards in context

• BS 8888 and the ISO system

• The GPS Method

• What is Geometrical Tolerancing?

• Benefits of Geometrical Tolerancing

Section 2: Module 2 

Features and Features-of-Size

• Nominal, real, extracted and associated features

• Linear size tolerances

• ISO 14405-1 and the Envelope Requirement

• Markings on drawings

Section 3: Module 3

Datums and datum systems

• the distinction between datums and datum features

• selection of datums

• datum systems and six degrees of freedom

• identifying datum features on drawings

• using datum targets

• Tolerance frames

• Tolerance features & symbols

• Tolerance frame modifiers (CZ etc)

• To positioning the tolerance frame on the drawing                                              

Section 4: Module 4

Theoretically exact dimensions

• Tolerance characteristics (including what they will and won’t control)

• Location tolerances

• Orientation tolerances

• Form tolerances

• Profile tolerances

• Run-out tolerances

Section 5: Module 5

Finding your way through the system – how to choose which tolerance to use

Section 6: Module 6

Applying geometrical tolerances to interfaces

• ‘Worst Case Boundaries’

• Maximum Material Requirement (m) and Bonus Tolerance

• Virtual Condition & Virtual Size

Section 7: Module 7

•Current BS & ISO standards

• Future developments

Trainer's profile

Iain Macleod provides training and consultancy services to organisations in all areas of industry, including the Aerospace, Defence, Nuclear, Automotive, Medical, and Oil & Gas sectors, as well as organisations making scientific instruments and consumer products.

Iain chairs ISO Technical Committee TC 213, responsible for international standards for Geometrical Tolerancing and Geometrical Product Specification, and BSI technical committee TDW/4/8 , responsible for the BS 8888 standard for technical product specification. He is also a Contributing Member of ASME technical committee Y14, subcommittee 5, responsible for the ASME Y14.5 standard.

His company is an Approved Supplier to BAE SYSTEMS and an Accredited Training Provider for the National Physical Laboratory training courses in Geometrical Tolerancing and Dimensional Measurement.

His clients include Formula 1 racing teams, many of the major companies in the aerospace and defence sectors, and numerous SMEs across a wide range of industries.

Specialties: Iain provide training for engineers, designers and technicians in:-

- Geometrical Tolerancing / Geometric Dimensioning & Tolerancing (GD&T)

- Geometrical Product Specification (ISO GPS)

- BS 8888

- ASME Y14.5

- Tolerance Stack Calculations

- Stress Analysis

- Surface Texture specification

- Engineering Drawing

Audits, assessment, information and advice.

Course duration

4 days virtual classroom or 3 days face to face

Assessment & certification

CPD and the course can be certified by the Institution of Engineering Designers, and can also be delivered, through the National Physical Laboratory training framework, with each delegate receiving a certificate from NPL on completion. To maximise the effectiveness of the training, an upper limit to the class size of 10 delegates is recommended for the geometrical tolerancing courses.

Who should attend

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

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