Chapter 2 Dimensioning and Tolerancing Symbology 27
Copyright Goodheart-Willcox Co., Inc.
and the diameter value. The diameter value is the
size of the fl at created on the surface and excludes
any corner radius that may be included within
the spotface. This is explained in greater depth in
Chapter 4. The depth of the spotface may be speci-
fi ed in the notation or by a dimension, as shown in
Figure 2-8. If the depth is not specifi ed, the spot-
face depth is the minimum necessary to produce a
fl at surface across the entire diameter of the spot-
face. This is a typical process when a fl at surface
is needed on a rough casting. When the depth is
not defi ned in a CAD model, the model may be
queried to determine the depth.
The letter X may be used to indicate the num-
ber of instances, or places, a feature is required. See
Figure 2-9. The countersunk hole shown in this fi g-
ure is required in six places; the notation for the hole
is preceded by 6X to indicate the required number
of holes. There is no space between the 6 and the X.
The meaning is changed if there is a space between
the X and the preceding number.
The letter X may be used in a way that it means
“by.” It is used in this way when noting chamfer
sizes and countersinks. See Figure 2-9. The coun-
tersink shown in this fi gure is noted to have a size
.438″ diameter by 100°. An X has the meaning of “by”
when there is a space preceding and following (before
and after) the letter. In the shown countersink nota-
tion, the letter X is used in one location to mean
six times and in another location to mean .438″
by 100°. Care must be taken to control the spaces
around the letter X to ensure the proper meaning.
Figure 2-7. Counterbore, diameter, and depth symbols
are used to specify the diameter and depth of the
Figure 2-8. The spotface symbol has the letters SF
within the symbol that is used for a counterbore.
Figure 2-9. Two applications and meanings for the
symbol X and an application of the countersink symbol.