Micrometer

For specific instructions on how to take measurements with a dial/vernier caliper, refer to either the manufacturer’s instructions or to Tools and Their Uses, NAVEDTRA 10085-B2. Regardless of what type of caliper you use, be sure to take the following precautions to avoid damaging the caliper: 1. Wash your hands before you handle the vernier caliper to remove dirt and oils that might damage the caliper. 2. Wipe the caliper components clean both before and after you use the caliper. 3. Do NOT drop or otherwise mishandle the caliper. Doing so may damage or destroy the caliper. Figure 2-3 illustrates the use of a dial/vernier caliper in measuring the inside and outside diameters of two different components. Figure 2-3.—Measuring (A) inside and (B) outside diameters with a dial/vernier caliper. The micrometer is a precision measuring instrument used to measure distances between surfaces in thousandths of an inch Figure 2-4 shows the most common types of micrometers. Most micrometers have a frame, anvil, spindle, sleeve, thimble, and ratchet stop. Micrometers are used to measure the outside diameters; inside diameters; the distance between parallel surfaces; the depth of holes, slots, counterbores, and recesses; and the distance from a surface to some recessed part. There are other uses of micrometers, but those mentioned here are uses you are most likely to encounter. Instructions on how to read a micrometer are given in the manufacturer’s owner’s manual and Tools and Their Uses, NAVEDTRA 10085-B2. Whenever you use a micrometer, carefully observe the “DO’s” and “DON’Ts” in the following list to obtain accurate measurements and to protect the instrument: Figure 2-4.—Common types of micrometers. 2-3