SELECTING THE PROPER MICROMETER The types of micrometers commonly used are made so that the longest movement that the micrometer spindle or rod can make is 1 inch. This movement is called the range; for example, a 2-inch micrometer has a range of from 1 inch to 2 inches, and can only measure work with a thickness or diameter within that range. Therefore, it is necessary to first determine the approximate size, to the nearest inch, of the work to be measured and then select the proper size micrometer. The size of a micrometer indicates the size of the largest work it can measure. CARE OF MICROMETERS Keep  micrometers  clean  and  lightly  oiled.  Make sure they are always stored in a case or box when not in use, to protect them from damage. Never clean any part of a micrometer with emery cloth or other abrasive. The measuring tools that have been described in this chapter are  the  ones  that  you,  as  an  ABE,  will  routinely  use while   performing   your   assigned   duties.   You   may, however,  occasionally  be  required  to  use  other  less commonly used measuring tools. Some of these are the dial   indicator,   telescopic   (snap)   gauge,   the   vernier caliper, or screw thread gauge. The description of these tools and instructions for their use can be found in the training   manual   Use   and   Care   of   Hand   Tools   and Measuring Tools, NAVEDTRA 12085. INVENTORY AND ACCOUNTABILITY All   measuring   tools   will   be   marked   in   some manner, etched, stenciled, etc., to comply with standard inventory   instructions. These   standard   instructions may be found in Aircraft Launch and Recovery Equip- ment (ALRE) Tool Control Manual, NAEC- MISC-51-OR732. Some  measuring  tools  such  as  tapes  and  calipers may  be  part  of  a  specific  toolbox  inventory.  Other precision measuring instruments such as micrometers, snap   gauges   and   vernier   calipers   will   normally   be maintained    in    the    division's    central    tool    room. Regardless of the tool's permanent location, it is always the  user's  responsibility  to  maintain,  care  for  and  use the tool properly. Damage,   loss,   or   an   improperly   working   tool should be reported immediately. Loss of a tool becomes especially   critical   when   working   on   or   around   the catapult or arresting gear machinery. The tool may be "lost"  in  the  machinery  and,  if  not  found,  may  cause catastrophic   damage   to   the   equipment   and   serious injury to personnel. Always double-check the inventory ensuring    every    tool    is    accounted    for    upon    job completion.  The  proper  tools  will  help  you  maintain your  equipment  but  only  if  you  maintain  your  tools properly. REVIEW QUESTIONS Q4. Identify the different types of precision measuring tools. Q5. Describe    the    uses    of    different    types    of precision measuring tools. Q6. Describe the proper care of precision measuring tools. Q7. All precision measuring tools will be ________________  in  some  manner  to  com- ply  with  the  standard  inventory  instructions found in NAEC-MISC-51OR732. SUMMARY This  chapter  has  introduced  you  to  some  of  the most often used measuring tools and the techniques for using   them.   Selecting   the   proper   tool;   using   and maintaining  the  various  tools;  and  inventorying  the tools have all been discussed. By thoroughly understanding and comprehending this chapter, you, as an ABE, will be able to perform your daily duties more efficiently and safely. 2-12