Major Rules of GD&T
Major Rules of GD&T provides an overview of the rules and concepts of geometric dimensioning and tolerancing, or GD&T. The major rules include Rule #1, or the Envelope Principle, which specifies how size controls form, Rule #2, or RFS and RMB defaults, and the 3-2-1 Rule, which defines the minimum number of points of contact in the datum reference frame. In addition to these major rules, other concepts described are bonus tolerances, virtual and resultant conditions, and the components of the datum reference frame.GD&T functions as a complex language used in blueprints to convey necessary information about a part. GD&T standards offer specific guidelines for part features, including projected tolerance zones, radii, controlled radii, tapers, threads, and gears. To accurately read a GD&T print, users must understand its many rules and principles. After taking this class, users should be able to explain key GD&T concepts and approaches for part inspection.
The training session will begin with a pretest to establish baseline understanding and prepare the learner for what to expect in the training material that follows. This module includes 24 lessons:
- Geometric Dimensioning and Tolerancing
- Key Terminology of GD&T
- Rule #1: Size Controls Form
- Rule #1: An Example
- Gaging for Rule #1
- Rule #2
- Review: Rules of GD&T
- Bonus Tolerance
- Virtual and Resultant Conditions
- Projected Tolerance Zones
- Review: Fit of Mating Parts
- The 3-2-1 Rule
- Demonstrating the 3-2-1 Rule
- Datum Feature Simulators
- Datum Selection Criteria
- Datum Review
- Datum Targets
- Datum Target Symbols
- Composite and Single-Segment Tolerancing
- Statistical Tolerancing
- Review: GD&T Terminology
- Dimensioning Radii
- Dimensioning Conical and Flat Tapers
- Dimensioning Threads and Gears
By the end of this course, learners should be able to:
- Describe geometric dimensioning and tolerancing
- Explain key terms used to describe GD&T relationships
- Define Rule #1
- Describe how Rule #1 affects the tolerancing of a feature
- Describe how Rule #1 affects the gaging of a feature
- Define Rule #2
- Describe a bonus tolerance
- Describe virtual condition and resultant condition
- Describe the characteristics of a projected tolerance zone
- Describe the 3-2-1 rule and how it restricts the six degrees of freedom for a part
- Define datum feature simulator
- Describe how the feature control frame locates a part in the datum reference frame
- Describe datum targets and their effect on gaging
- Describe composite and single-segment tolerancing
- Describe statistical tolerancing and its role in GD&T
- Describe a radius and a controlled radius
- Describe dimensioning rules for conical and flat tapers
- Describe dimensioning rules for threads and gears