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REVIEW QUESTIONS Q1. Identify the different types of measuring tools. Q2. Describe the uses of different types of measuring tools. Q3. Describe the proper care of measuring tools. PRECISION MEASURING EQUIPMENT LEARNING   OBJECTIVES: Identify the different types of precision measuring tools. Describe the uses of different types of precision measuring tools. Describe the proper care of measuring tools. Maintain inventory and accountability of precision equipment. In  much  wider  use  by  ABEs  than  even  common calipers  are  the  various  types  of  micrometer  calipers. As was stated earlier, you can use micrometer calipers to   take   accurate   measurements   to   the   nearest   one ten-thousandth of an inch. However, in most applications    a    measurement    to    the    nearest    one- thousandth    of    an    inch    is    considered    acceptable accuracy. These measurements are expressed or written as a decimal (0.0001, 0.001, 0.01), so you must know how to read and write decimals. TYPES OF MICROMETER CALIPERS There   are   three   types   of   micrometer   calipers, commonly  called  micrometers  or  simply  mikes,  used throughout the Navy: the outside micrometer, including the  screw  thread  micrometer;  the  inside  micrometer; and the depth micrometer. (See fig. 2-21.) The outside micrometer is used for measuring outside dimensions, such as the outside diameter of a piece of round stock or the thickness of a piece of flat stock. The screw thread micrometer is used to determine the pitch diameter of screws. The inside micrometer is used to measure the inside   diameter   of   a   cylinder   or   hole.   The   depth micrometer is used for measuring the depth of a hole or recess. Outside Micrometer The   nomenclature   of   an   outside   micrometer   is illustrated in figure 2-22. The sleeve and thimble scales of a micrometer (fig. 2-23) have been enlarged and laid out for demonstration. To understand these scales, you need to know  that  the  threaded  section  on  the  spindle,  which revolves, has 40 threads per inch. Therefore, every time the    thimble    completes    a    revolution,    the    spindle advances or recedes 1/40 inch, or 0.025 inch. Note the horizontal line on the sleeve is divided into 40  equal  parts  per  inch.  Every  fourth  graduation  is numbered 1, 2, 3, 4, and so on, representing 0.100 inch, 0.200 inch, and so on. When you turn the thimble so its edge is over the first sleeve line past the 0 on the thimble scale, the spindle has opened 0.025 inch. If you turn the spindle  to  the  second  mark,  it  has  moved  0.025  inch plus 0.025 inch, or 0.050 inch. 2-8 Figure 2-21.—Common types of micrometers.

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