Tolerancing rules for screw threads, gears and splines

Screw threads

Each tolerance of orientation or position and datum reference specified for a screw thread applies to the axis of the thread derived from the pitch cylinder. Where an exception to this practice is necessary, the specific feature of the screw thread (such as “MAJOR DIA” or “MINOR DIA”) shall be stated beneath the feature control frame, or beneath or adjacen to the datum feature symbol, as applicable. See Fig. 7-35.


Gears and Splines

Each tolerance of orientation or position and datum reference specified for features other than screw threads, such as gears and splines, must designate the specific feature of the gear or spline to which each applies (such as “MAJOR DIA,” “PITCH DIA,” or “MINOR DIA”). This information is stated beneath the feature control frame or beneath the datum feature symbol, as applicable.


  • References: