Quick Answer: What Are Datum Features?

What is a datum line?


datum line (plural datum lines) (engineering) A line which serves as a reference or base for the measurement of other quantities..

What does datum mean?

assumed thingdatum in American English 1. something known or assumed; information from which conclusions can be inferred. see also data. 2. a real or assumed thing, used as a basis for calculations or measurements, as a level (also datum plane) from which elevations and depths are measured in surveying.

What is a datum feature symbol?

The previewed Datum Feature Symbol consists of the frame, triangle, and leader connecting to the frame. You must select a surface reference to place the datum feature symbol to the surface at the selected point in the annotation plane that is currently active.

What is a datum feature simulator?

A datum feature simulator is the manufacturing or inspection equipment contacting the datum feature of the part. Datum feature simulators are used to establish the simulated datums. A simulated datum is a point, axis or plane established from the actual surface of the datum feature simulator. ASME Y14.5M Definitions.

What is a common datum?

A common datum is a single datum consisting of two datum features. Separate datum features are applied to a common practical datum feature.

Why do we use a datum?

A datum is a point, line, or surface from which dimensions are taken. It is the place to start. … The datum can be a single point eg the centre of a hole or face of a feature to a component. A datum is used to reduce errors when marking out, and measuring by reducing the accumulation of errors.

What is datum in design?

Datum: A datum is a form which ties together or anchors all other elements of the design. It can be a line, like a road with houses arranged along its length, a flat plane, or even a 3D space. Many buildings all share a plane which acts as a clear datum— it’s the ground on which they are built! Ordering Principles.

What are the types of datum?

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.

What is difference between datum & datum feature?

A datum feature is a part feature (or FOS), that contacts a datum during measurement. A datum is a theoretically exact plane (or axis or center-plane), from which dimensional measurement should be made. … During measurement, the datum feature will contact the simulated datum which in this case is a surface plate.

What is the most commonly used datum plane?

The most common reference Datums in use in North America are NAD27, NAD83, and WGS 84.

What types of features can be used as datums?

A datum feature is usually an important functional feature that needs to be controlled during measurement as well. All GD&T symbols except for the form tolerances (straightness, flatness, circularity and cylindricity) can use datums to help specify what geometrical control is needed on the part.

How do you select the datum features?

Datums are important and care must be taken when selecting them. They must be easily identifiable on the part. When parts are symmetrical or have identical features that make identification of Datum Features difficult, the Datum Features should be physically identified.

How do I find my datum?

Finding the datum used by your map On a USGS topographic map the datum information is in the fine print at the bottom left of the map. The datum will always be NAD 27. There may be information on how many meters to shift a position to convert it to NAD 83.

How do I create a datum point?

Creating a datum point by projecting a point onto a face. Select a point on the model and an edge or datum axis on which to project the point. Abaqus/CAE creates the datum point where the edge or datum axis intersects a line that is normal to it and passing through the selected point, as shown in Figure 7.

What are the 3 types of tolerances?

A tolerance is an acceptable amount of dimensional variation that will still allow an object to function correctly. Three basic tolerances that occur most often on working drawings are: limit dimensions, unilateral, and bilateral tolerances.