Category: Misc Items

by GD&T Guy on December 23, 2014.

Symbol: Definition: A datum is theoretical exact plane, axis or point location that GD&T or dimensional tolerances are referenced to. You can think of them as an anchor for the entire part; where the other features are referenced from. A datum feature is usually an important functional feature that needs to be controlled during measurement as…

by GD&T Guy on December 13, 2014.

Symbol: Category: Feature of Size Definition: Maximum Material Condition or for short, MMC, is a feature of size symbol that describes the condition of a feature or part where the maximum amount of material (volume/size) exists within its dimensional tolerance. The callout also removes GD&T Rule#2 which states that all geometry tolerances are controlled independently…

by GD&T Guy on December 13, 2014.

Symbol: Category: Feature of Size Definition: Least material condition is a feature of size symbol that describes a dimensional or size condition where the least amount of material (volume/size) exists within its dimensional tolerance. The callout also overrides GD&T Rule#2 or the Regardless of Feature Size rule.  For simplicity: If it is a hole or internal feature: LMC…

by GD&T Guy on December 11, 2014.

Symbol: None – Always Implied default condition (abbreviated: RFS) Category: Feature of Size Definition: Regardless of Feature Size (RFS) is the default condition of all geometric tolerances by rule #2 of GD&T and requires no callout. Regardless of feature size simply means that whatever GD&T callout you make, is controlled independently of the size dimension of the part. This…

by Tommy on December 9, 2014.

Example Frame:  Definition: In GD&T, a feature control frame is required to describe the conditions and tolerances of a geometric control on a part’s feature. The feature control frame consists of four pieces of information: GD&T symbol or control symbol Tolerance zone type and dimensions Tolerance zone modifiers: features of size, projections… Datum references (if…