Geometric Dimensioning and Tolerancing (GD&T)

Course instructor: Charles A. Gillis – Consultant, Design Engineering

Course Description
Geometric Dimensioning and Tolerancing (GD&T) is the universally accepted method of communicating part requirements on engineering drawings. This course will help students understand and use this universal engineering language to eliminate many of the communication problems prevalent in the design-to-manufacturing cycle.

Who Should Attend
This course is appropriate for CAD draftspersons, tool designers, technical inspectors, mechanical engineering technicians, machine shop and tool room supervisors. Design, manufacturing, and project engineers, quality control personnel, engineering managers and supervisors will also find the course beneficial.

Learning Objectives
Upon completion of the course, students will be able to:

  • Interpret drawing tolerances and calculate minimum and maximum allowable values for dimensions
  • Understand and apply the symbols used with the geometric system of tolerances
  • Recognize basic dimensions on prints and understand their meaning
  • Identify and properly read feature control frames
  • Account for bonus tolerance and calculate geometric tolerance values when bonus tolerance applies
  • Identify the datum reference frame including order of precedence
  • Identify and interpret geometric controls on location, orientation, form, profile & runout

Course Outline

  1. Fundamentals of GD&T
    • Types of variation and how they’re controlled.
    • Features of size and surfaces.
    • Rule #1. Definitions of maximum material condition (MMC) and least material condition (Least Material Condition) and how they are used to determine bonus tolerance.
  2. Tolerances of Form
    • Controls of flatness, straightness, circularity and cylindricity.
    • Examples on how they are specified, their meaning and principles of verification.
    • Straightness and flatness controls applied to features of size and surfaces.
  3. Concept of Datums and the Datum Reference Frame
    • The common point of reference for the part definition from design through manufacturing and inspection.
    • How imperfect parts are measured according to the design intent.
  4. Tolerances of Orientation
    • Controls of parallelism, perpendicularity, and angularity applied to surfaces and features of size.
    • Examples on their use and meaning as well as verification principles.
  5. Tolerances of Location
    • Controls of position, comparison and conversion from conventional tolerancing.
    • Applications and examples of position used for various features.
    • Composite position tolerances.
    • The classic examples of floating and fixed fasteners will be cited to demonstrate tolerancing for position to avoid interference problems of fit.
    • Projected tolerance zone.
    • Concentricity and symmetry interpretation and application.
  6. Tolerances of Profile
    • Controls of profile of a line and profile of a surface.
    • Equally disposed and unequally disposed profile tolerances.
    • Profile tolerances applied to multiple surfaces.
    • Examples of various simple and complex surfaces.
  7. Tolerances of Runout
    • Controls of circular runout and total runout. 

Course Format
16 hours
Combination lecture/discussion, individual and group work sessions, and large print review
Available at QSG’s training facilities and on-site at your organization

Textbook
Geometric Dimensioning and Tolerancing, 9thd ed., by David A. Madsen, Goodheart-Willcox


Payment Type
Date(s) Attending
Name(s) of Attendee(s)
Name of Company




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