What does basic dimension mean?

In Geometric dimensioning and tolerancing, basic dimensions are defined as a numerical value used to describe the theoretically exact size, profile, orientation or location of a feature or datum target. Basic dimensions are currently denoted by enclosing the number of the dimension in a rectangle.

What is a basic dimension used for?

Basic dimension: A basic dimension is a numerical value used to describe the theoretically exact size, profile, orientation, or location of a feature or datum target. Basic dimensions are used to define or position tolerance zones.

Are basic dimensions measured?

BASIC dimensions can be thought of as the movement of a processing or measuring tool, the shift is always in absolute values (without plus or minus). The BASIC dimensions of the location and position of the tolerance zone remain unchanged, so there is no value in noting them in the measurement report.

When Should basic dimensions be used?

Basic dimensions are used to establish the “true profile” which a profile tolerance will then control. So if a profile tolerance is applied to a hole, the diameter MUST be a basic dimension. There are two methods of dimensioning described in Y14.

Can you tolerance a basic dimension?

Basic dimensions are used to locate True Positions. There is no tolerance or deviation in the basic dimensions themselves, as they are theoretically perfect. The tolerance zone for the feature comes through the geometric tolerance shown in the feature control frame for that feature.

What is the difference between a reference and basic dimension?

Basic dimensions are associated with another tolerance or dimension. While they don’t have a tolerance tied to themselves, they are used to calculate another toleranced feature such as the true position of a hole. Reference dimensions are simply placed on a drawing or blueprint for reference.

Can you put a datum on a basic dimension?

RE: Selecting a Basic dimension as a datum It can be attached to a reference dimension and still serve as a valid datum.

What is a zero basic dimension?

(k) A zero basic dimension applies where axes, center planes, or surfaces are shown coincident on a drawing, and geometric tolerances establish the relationship among the features.

What are the only two purposes basic dimensions?

What are the only two purposes Basic dimensions serve? Basic dimensions serve to orient and locate 1) tolerance zones and 2) Datum Targets. Flatness requires all points on the considered surface to lie within a slab-like tolerance zone of thickness 0.2mm with no external constraints.

What do you understand by the nominal size and basic size?

The term nominal size refers to the size of a part specified in the drawing for convenience to shop floor. 5. Basic Size: The term basic size refers to the size from which the limits of size are derived by the application of tolerance (i.e. upper and lower deviation).

Can you make a centerline as datum?

You cannot. So a centerline cannot be a datum. To sum up, a datum can indeed be a centerline, but it is never to be labeled as such on a drawing.

When to use basic dimensions?

Basic dimension: A basic dimension is a numerical value used to describe the theoretically exact size, profile, orientation, or location of a feature or datum target. Basic dimensions are used to define or position tolerance zones.

What is the definition of basic dimension?

Basic dimension. In a technical drawing, a basic dimension is a theoretically exact dimension, given from a datum to a feature of interest.

Do basic dimensions have tolerances?

A basic dimension itself does not have a tolerance . General tolerance blocks do not apply to a basic dimension. Instead its value is used to compute another characteristic such as angularity, profile or true position. Basic dimensions are associated with another tolerance or dimension.

Do basic dimensions have a tolerance?

Basic dimensions are used to define or position tolerance zones . Title block tolerances do not apply to basic dimensions. The tolerance associated with a basic dimension usually appears in a feature control frame or a note. The Basic Dimension has a box around the dimension.