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Category: GD&T Symbol Rules and Examples

Articles related to GD&T symbol rules and walk-through examples of GD&T Symbols and their uses


by Jason Richter on March 9, 2022.

The Independency Symbol is used on drawings to declare that the requirement for perfect form at MMC or LMC is removed and the form tolerance may be larger than the size tolerance. This symbol only exists in the ASME Y14.5 standards, not the ISO GPS standards.

GD&T Rule #1: Envelope Principle

by Jason Richter on March 3, 2022.

GD&T Rule #1, also known as the Envelope principle, states that the form of a regular feature of size is controlled by its “limits of size." Limits of size, or otherwise known as size tolerances, can be seen in many forms. A few of them are symmetric, unilateral, and bilateral.

Circularity – The Tolerance Zone

by Brandon John on June 22, 2021.

There can be a lot of confusion when dealing with circularity – especially when identifying the tolerance zone compared to how Rule #1 of Geometric Dimensioning and Tolerancing controls it.  In this video, we provide...

Virtual Condition – Does it apply at RFS?

by GD&T Basics on May 5, 2021.

In this question line video, Brandon discusses Virtual Condition and whether it can apply at Regardless of Feature Size (RFS). What is Virtual Condition (VC)? When a feature is controlled with the Maximum Material Condition...

Profile of a Line Tolerance Zone

by GD&T Basics on April 6, 2021.

This video is in response to a question that we received on our question line from Amar. Amar’s question is as follows: “If we are given a BASIC radius of 10mm, and on the radius,...

Flatness – Surface vs. Feature of Size

by GD&T Basics on February 12, 2021.

In this video, Brandon discusses the difference between measuring Flatness of a Surface and Flatness of a Feature of Size (FOS). Flatness of a Surface Surface flatness is the type of flatness that most people...

Position Tolerance and Basic Dimensions

by Seth Elder on November 12, 2020.

The video below is in response to a question that we received on our question line from Ash.   The question is as follows: “I regularly see drawings where spacing between a pair of holes is...

Using Runout to Measure Concentricity

by Seth Elder on October 29, 2020.

The video below is in response to a question that we received on our question line from Jeff.   Jeff asked us if concentricity is always equal to half of the runout value.  ASME Y14.5 defines...

Unilateral Tolerance and Bilateral Tolerance

by Seth Elder on October 12, 2020.

In this article, we explain the differences between bilateral, unilateral, and unequally disposed tolerances. What is a Tolerance? Tolerances on technical drawings communicate the amount of variation permitted from a target dimension.  The allowable variation...