A system of dimensioning which requires all numerals, figures, and notes to be aligned with the dimension lines so that they may be read from the bottom (for horizontal dimensions) and from the right side (for vertical dimensions).
A tolerance in which variation is permitted in both directions from the specified dimension.
A dimensioning system where each dimension originates from a common surface, plane, or axis. Also known as baseline dimensioning.
Where alternate units are displayed within the same dimension (both metric and standard dimensions can shown at the same time).
A dimension, usually without a tolerance, used for information purposes only. A reference is a repeat of a given dimension or established from other values shown on a drawing. Reference dimensions are enclosed in ( ) on the drawing.
Limits of Dimension
The largest and smallest possible boundaries to which a feature may be made as related to the tolerance of the dimension.
Maximum Material Condition (MMC)
The largest size limit of an external feature and the smallest size limit of an internal feature.
A tolerance in which variation is permitted in only one direction from the specified dimension.
American National Standards Institute (ANSI)
A private, non-profit organization that coordinates the development and use of voluntary consensus standards in the United States.
American Society of Mechanical Engineers (ASME)
1. A professional engineering organization that is known for setting codes and standards for mechanical devices in the United States. ASME drawing standards are found in the Y-14M publications. 2. The acronym for the American Society of Mechanical Engineers.
System of dimensioning in which all dimensions are placed from a datum and not from feature to feature. Also referred to as Datum Dimensioning.
Also known as point-to-point dimensioning where dimensions are established from one point to the next.
Lines that are thin lines capped with arrowheads, which may be broken along their length to provide space for the dimension numerals.
Thin lines used to establish the extent of a dimension. Extension lines begin with a short space from the object and extend to about .125 inches past the last dimension line. Extension lines may cross object lines, center lines, hidden lines, and other extension lines, but may not cross dimension lines.
Least Material Condition (LMC)
The smallest size limit of an external feature and the largest size limit of an internal feature.