PRECISION MEASURING AND GAGING - OD1642 - LESSON 1/TASK 2
(15) Classes and Standards for all Makes of Gages.
Class X - Precision lapped to close tolerances for many types of masters and
the highest quality working and inspection gages.
Class Y - Good lapped finish to slightly increased tolerances for inspection
and working gages.
Class ZZ - (Ring gages only).
Ground only to meet the demand for an
inexpensive gage, where quantities are small and tolerances liberal.
Table 1 below lists the tolerances for ring gages in each class:
TOLERANCES FOR RING GAGES.
(16) Thread Measuring Wires.
The most accurate method of measuring the fit or pitch diameter of threads,
without the use of the expensive and sophisticated optical and comparator
equipment, employs thread measuring wires.
These wires are accurately
sized, depending on the number of threads per inch, so that when they are
measure the distance between