Datum plane1/27/2024 Use this option to set the default datum plane format. Otherwise, the datum takes its attributes from the user's configuration. If this box is checked, the line attributes are assigned to the datum. This option set color, line type and line width of the datum. Use these options to specify the new datum plane's angle of rotation about its X, Y and Z axis individually. If this option is not used, then the x axis is specified as parallel to the U direction of the curve, edge or face at the selected point. The z axis is fixed by the normal vector of the selected geometry or the z axis of a selected datum plane. Use this option to select a point that will determine the direction of the x axis of the new datum plane. Datums are used as the starting reference point for surveying jobs and put your work in a larger context. If this option is not used, then the datum plane is tangent at the point where the face or curve/edge was originally selected. If the reference geometry selected is a face or curve/edge, then this point will be projected onto the geometry and the new datum plane will be tangent at this point. Use this option to specify an alternate datum plane origin. The center of the indicated datum feature becomes the datum axis or datum center plane.For the Plane and 3 point methods above, use this option to align the new datum plane with the XY plane of a coordinate frame implied by the selected geometry.įor the Plane and 3 point methods above, use this option to align the new datum plane with the XZ plane of a coordinate frame implied by the selected geometry.įor the Plane and 3 point methods above, use this option to align the new datum plane with the YZ plane of a coordinate frame implied by the selected geometry.įor the Plane and 3 point methods above, use this option to specify the amount to offset the new datum plane from the target geometry. The dimension line of a datum feature and the datum are indicated apart from each other. The center of the indicated datum feature becomes the datum axis or datum center plane. Annotating an Axis or Center PlaneĪ datum feature is indicated by combining the dimension line and datum. To express the design intention with strict accuracy, pay attention to the position where you indicate the datum. Sketch in standard position calculator Reference Angle and Quadrant Calculator. Once established, the datum plane will be used for the duration of the project. Though the location of a datum plane is precise, its placement is arbitrary and is determined during the survey stage of a project. The position of the datum symbol on the drawing is also relevant to the target area. a specific parts central axis needs to be to a datum plane or axis. A datum plane is a horizontal or vertical reference point on which surface elevations are based. The letters indicating the datums are always oriented to the direction the reader looks at the drawing. Datum symbols use either a white or black triangle. Drawing Indications of Datum Featuresĭatums are indicated using the following symbols (datum symbols). Therefore, a surface plate, gauge, or mandrel, which has a more precise surface, must come into contact as a simulated datum.Į Surface plate, gauge, mandrel, etc. The surface of a part indicated as a datum is not an exact shape. Datum System A group of datums created by combining more than one individual datum in order to use it as a reference for toleranced features. Simulated Datum Feature An actual surface with sufficiently precise shape that comes into contact with a datum feature and is used for establishing a datum (e.g. Datum Feature A real (non-ideal) integral feature of a target used for establishing a datum (e.g. Multiple datums can also be combined to make a datum system that specifies a feature. 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.Ī datum is defined as follows in the ISO standard: ISO 5459:2011 “One or more situation features of one or more features associated with one or more real integral features selected to define the location or orientation, or both, of a tolerance zone or an ideal feature representing for instance a virtual condition.” Types of Datumsĭatums are established using datum features and simulated datum features.
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