What does datum side mean?
What does datum side mean?
On a surface If it is on one side of a rectangular object like a box, the datum surface is only the side where the symbol is shown. However if the part is round like a cylinder, the datum would be the entire surface of the cylinder.
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 meant by datum in drawing?
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. Drawing Indications of Datum Features.
How are the letters tied to the datum feature?
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 framethat uses this datum feature as a reference. A feature control frame can reference multiple datums at once and each one can be referenced as many times as needed. Notation is Important on Drawings
What is the 3-2-1 rule for tertiary datum features?
– The tertiary datum feature has at least one point of contact with its datum plane. The 3-2-1 rule only applies to planer datum features. One may specify a datum feature that is at an angle other than 90 degrees relative to other datum features. These are called Inclined Datum Features.
What are the degrees of freedom of a part datum?
We refer to the translational degrees of freedom as X, Y, and Z and the rotational degrees as u, v, and w. The 3-2-1 rule defines the minimum number of points of contact required for a part datum feature with its primary, secondary, and tertiary datum planes. It only applies when all three plaines are used. The 3-2-1 rule says:
Which is the correct definition of a datum target?
You may also come across the term Datum Target, which is defined as, “A specified point, line, or area on a part used to establish a datum.” This one starts out simple: A Datum Reference Frame is a coordinate system, and preferably it is a Cartesian coordinate system. Coordinate systems are valuable because they’re used to locate objects.