What is datum plane in GD?

A datum is a plane, a straight line, or a point that is used as a reference when processing a material or measuring the dimensions of a target. ISO Definition. Types of Datums.

What is the datum plane?

A datum plane is a plane on the target that is established as a datum. It can be a target’s external plane (datum plane) or center plane (datum center plane). “Datum plane” is defined as follows in ISO and ASME standards: A datum that is a theoretically exact plane.

What is a datum plane used for?

Datum planes are features used to provide references for other features, like sketching planes, dimensioning references, view references, assembly references, and so on. Datum planes are not physical parts of the model, but are used to aid in model creation.

Which type of datum is used?

There are two main datums in the United States. Horizontal datums measure positions (latitude and longitude) on the surface of the Earth, while vertical datums are used to measure land elevations and water depths.

How do you identify a datum?

The datum features on a drawing are denoted with a series of capital letters. These letters are in boxes and tied to the datum feature with a black triangle. This letter will also show up in any feature control frame that uses this datum feature as a reference.

What is the definition of a datum in GD & T?

Definition of a Datum. A Datum is a plane, axis, or point location that GD dimensional tolerances are referenced to. Typically, multiple features will be referenced by each datum, so they’re a very important part of the whole thing. Nearly every GD symbol except for form tolerances (straightness, flatness, circularity,

What’s the difference between a datum and a plane?

A datum feature can be a plane, line, or point—these are selectively used depending on the tolerance and feature you need to specify. Datum Plane. A datum plane is a plane on the target that is established as a datum. It can be a target’s external plane (datum plane) or center plane (datum center plane).

Do you know the basics of GD & T?

Nevertheless, the understanding of datums is a necessity to understanding GD. This section introduces the characteristics of datums and the basics of common datums and datum systems, both of which are made up of multiple datums. Bridging the gap between hand tools and CMMs.

Which is the best description of a datum feature?

A datum feature can be a plane, line, or point—these are selectively used depending on the tolerance and feature you need to specify. A datum plane is a plane on the target that is established as a datum. It can be a target’s external plane (datum plane) or center plane (datum center plane). A datum that is a theoretically exact plane.