the international engineering language of Geometric Dimensioning
& Tolerancing (GDT), GDT symbols is essential for communicating
in today's highly competitive global marketplace. This tutorial
builds the ability to read and interpret GDT symbols, which
provide detail information about the function and relationship
of part features such as, dimensioning, tolerance, runout,
datum, profile etc.
I : Introduction to
Dimensioning and tolerancing GDT
is a numerical value expressed in an appropriate unit of measure.
It is indicated on a drawing along with line, arrow, symbols
and notes to define the size and specification of an object.
(Fig. 1 )
dimension is used only for information purposes. The definition
REF shall be indicated immediately under or beside the dimension.
Normally it is either a duplication of a dimension or it is
the accumulated value of other dimensions.
is the allowable variation of a dimension. It is the difference
between the maximum and minimum limits. All dimensions except
basic, reference, nominal, maximum or minimum shall have a
See Fig. 1.
Part II . Maximum & Minimum metal condition