274 Machine Trades Print Reading Copyright Goodheart-Willcox Co., Inc. The tolerance zone is centered on the true position and extends through the hole. When produced, the axis of the hole must be within the tolerance zone. Profile Tolerances Profile tolerances establish a tolerance zone relative to a true profile. Profile tolerances can be applied to con- trol the individual elements defining a surface or all points making up an entire surface. Parts of any shape and contour can be controlled with profile tolerances. A tolerance zone established by a profile tolerance may or may not be related to datums. Profile tolerances are always applicable RFS. There are two types of profile tolerances: profile of a line and profile of a surface. Profile of a Line A profile of a line tolerance is a two-dimensional geo- metric tolerance used to control variation of the indi- vidual elements defining a surface. Elements defining a surface include straight lines, arcs, and other types of curved entities. A profile of a line tolerance establishes a uniform tolerance zone that extends along the true profile. All elements of the surface must lie within the tolerance zone. See Figure 15‑29. Profile of a line is also referred to as line profile. A profile of a line tolerance is used when control of the entire surface is not required. It can be used to con- trol shapes with varying cross-sectional dimensions along their length or width. The between symbol, Figure 15‑30, can be used to specify a profile tolerance that applies between two points. The symbol is shown with the designated points below Ø.028 tolerance zone Drawing Interpretation Goodheart-Willcox Publisher Figure 15-28. Position tolerancing establishes a round tolerance zone. Drawing Interpretation .010 tolerance zone Goodheart-Willcox Publisher Figure 15-29. Profile of a line. Between symbol Goodheart-Willcox Publisher Figure 15-30. The between symbol is used to indicate the extent of control for a profile tolerance. It is shown below the feature control frame.