Articles related to GD&T symbol rules and walk-through examples of GD&T Symbols and their uses
The Free State Symbol is in used GD&T to indicate that a specific dimension and its associated tolerance are to be assessed in an unrestrained state.
The Projected Tolerance Symbol is in used GD&T to indicate the tolerance zone of a feature is to be assessed beyond the surface extents of the feature.
The Continuous Feature Symbol is used to indicate that a group of disjointed features or surfaces are to be considered as one continuous feature.
The Datum Target Symbol is used to define a specific point, line, or area to be used in order to establish a datum on a drawing.
The Envelope Requirement Symbol is used on ISO drawings to declare that size is to control form with respect to perfect form at MMC.
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, 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.
The unequally disposed profile tolerance symbol is used to apply unilateral or unequal tolerance zones to a profile of a part.
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...
This video is in response to a question that we received on our question line from Alex. His question is as follows: “Is there a best-practice way to use Position (instead of Symmetry) to control...
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...
What is the difference between unilateral and bilateral tolerance in a profile of a surface callout? In this post, Brandon explains the difference and gives examples of how they are used. Profile of...
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,...
This video is in response to a question that we received on our question line from Tim. Tim’s question is as follows: “We tend to use true position on threaded holes. Is this valid? If...
This video is in response to a question that we received on our question line from Jamee. Jamee’s question is as follows: “For parallelism of a circular feature of size (axis) can you use two...
This video is in response to a question that we received on our question line from Lokesh. Lokesh asked us if a material modifier can be used with cylindricity. Geometric Dimensioning and Tolerancing modifiers are...
This video is in response to a question that we received on our question line from Ignacio. Ignacio asked us if it is a bad practice to reference three datums in a single drawing callout...
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...