Dimensioning and Tolerancing Engineers Notebook
Objectives:
-Define dimension
-Understand the different dimensioning terms
-Identify different types of size dimensions
-Explain location and orientation dimensions
-Apply the standard dimensioning practices for mechanical drawings
-Differentiate between current standards and past practices for dimensioning
-Produced a dimensioned drawing
-Compare contour and geometric breakdown dimensioning
Vocabulary:
Geometrics
Dimension Balance Dimensions Reference Dimension Dimension Line Arrows Extension Line Visible gap Leader line Limits of size Plus and minus dimension Diameter symbol Radius symbol Tolerance Datum Horizontal Vertical Diameter Radius Rectangular Coordinate- Dimensioning Tabular Coordinate-Dimensioning |
the science of specifying and tolerancing the shapes and locations of features on objects
the numerical value that defines the size, shape, location, surface texture, or geometric characteristic of a feature a numerical value defining the theoretically exact size, location, profile, or orientation of a feature relative to a coordinate system established by datums a numerical value enclosed in parentheses, providing information only and not directly used in the fabrication of the part a thin, solid line that show the extent and direction of a dimension symbols placed at the ends of dimension lines to show the limits of the dimension, leaders, and cutting plane lines a thin, solid line perpendicular to a dimension line, indicating which feature is associated with the dimension a space of 1.5 mm (1/16 inch) between a feature’s and the end of the extension line corners a thin, solid line used to indicate the feature with which a dimension, note, or symbol is associated the largest acceptable size and the minimum acceptable size of a feature the allowable positive and negative variance from the dimension specified a symbol that precedes a numerical value to indicate that the dimension shows the diameter of a circle a symbol that precedes a numerical value to indicate that the associated dimension shows the radius of a circle the amount that a particular dimension is allowed to vary a theoretically exact point used as a reference for rectangular coordinate dimensioning the left-to-right distance relative to the drawing sheet the up and down distance relative to the drawing sheet the full distance across a circle, measured through the center the distance from the center of an arc to any point on the arc, usually used on arcs less than half circles a baseline (or datum line) is established for each Cartesian coordinate direction, and all dimensions are specified with respect to this baseline involves labeling each feature with a letter and then providing information on size and location in a table |