It is important to remember the 3-2-1 Rule with Datum Targets. The real world set up will need to mimic these requirements. The drawing will specify the requirements for locations, quantities, sizes, and orientations of the datum targets.
DATUM SYMBOL FULL
Full outline dimensions for non-circular areas on the drawing.A circular, crosshatched area dimensionally located.Can be designated in the following ways:.
DATUM SYMBOL SIMULATOR
A designated area location specified on a part where the datum simulator and the part should make contact.If necessary, the length of line can also be dimensioned.ĭatum Target Areas (Datum Targets “A1 and A2” above).If necessary, datum references and modifiers applicable to the feature or the datums are also contained in the box. Datum Target Lines are frequently represented by using the edge of a cylindrical gauge pin. Tolerance Control Frame - The Tolerance Control Frame symbol is a rectangular box containing the geometric characteristics symbol, and the form, runout or location tolerance.The adjacent of the Datum Target Line can be designated with an “X” to show its location on the part.Shown using dimensionally located phantom line designating a line contact between the datum simulator and the part.Simulated with spherical-tipped featureĭatum Target Lines (Datum Targets “B1, B2, and C1” above).No value in the upper half of the Datum Target Symbol.If there is no direct view, the point is dimensioned on two adjacent views. Dimensionally located in a direct view of the surface. A datum feature symbol consists of a marker, leader, and datum reference letter.An X-shaped symbol, referred to as the datum target point symbol, that locates a single point of contact between the datum simulator and the part.If the line is dashed, then the target is on the “far” side of the drawing.ĭatum Target Points (Datum Target “A3” above) If the line is solid, the target is on the “near” side of the drawing. Radial lines for datum targets are either solid or dashed. If the target is defining a target area, the size and shape of the area is defined in the upper half.ĭatum Target Radial Line – Datum Targets identified on a drawing by connecting the datum target symbol to the feature using radial lines. The upper half of the symbol is left blank if the target is a point or a line. The lower portion contains the letter associated with the datum it is defining followed by a sequential number (starting at 1) for each datum target. The symbol is defined by a circle divided horizontally in half. A leader line can also be used to connect the datum feature symbol to the view in some applications.The Datum Target Symbol is used to define a specific point, line, or area to be used in order to establish a datum on a drawing. When a surface is designated as a datum feature on a part, the datum feature symbol is placed on the edge view of the surface or on an extension line in the view where the surface appears as a line. Tangent plane: A plane that contacts the high points of the specified feature surface. GD&T Planar Datums Datum targets are symbols that describe the shape, size, and location of gage elements that are used to establish datum planes, axes, and. The leader line can be shown as a dashed line if the datum feature is not on the visible surface. The datum feature symbol can also be placed on a leader line directed to the surface. The datum feature symbol is placed on the edge view or on an extension line in the view where the surface appears as a line. Methods for placing datum feature symbols on datum feature surfaces. Chapter 3 Datums 81 Angled Surface Datum feature symbol placed on edge view of surface or extension line from edge view Surface datum feature symbols must be clearly separated from dimension line arrowheads The Drawing The Meaning The Drawing The Meaning Example 3-3.
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