• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
MICROMETER-READING EXERCISE - 14001_67
Depth Micrometer

Aviation Boatswains Mate E 3 & 2 - Aviation theories and other practices
Page Navigation
  53    54    55    56    57  58  59    60    61    62    63  
Figure 2-25.—Reading sleeve and thimble scales of a micrometer. Figure 2-26.—Vernier scale of a micrometer. READING THE VERNIER SCALE ON A MICROMETER.— Many times you are required to work to exceptionally precise dimensions. Under these conditions it is better to use a micrometer that is accurate to ten-thousandths of an inch. This degree of accuracy is obtained by the addition of a vernier scale. The vernier scale of a micrometer (fig. 2-26) furnishes the fine readings between the lines on the thimble rather than requiring you to estimate the reading. The 10 spaces on the vernier are equivalent to 9 spaces on the thimble. Therefore, each unit on the vernier scale is equal to 0.0009 inch, and the difference between the sizes of the units on each scale is 0.0001 inch. When a line on the thimble scale does not coincide with the horizontal reference line on the sleeve, you can determine the additional spaces beyond the readable thimble mark by finding which vernier mark matches up with a line on the thimble scale. Add this number, as that many ten-thousandths of an inch, to the original reading. In figure 2-27 see how the second line on the vernier scale matches up with a line on the thimble scale. This means that the 0.011 mark on the thimble scale has been advanced an additional 0.0002 beyond the horizontal sleeve line. When YOU add this to the other readings, the reading is 0.200 + 0.075 + 0.011 + 0.0002, or 0.2862, as shown. Figure 2-27.—Reading a vernier state micrometer. Inside Micrometer The inside micrometer, as the name implies, is used for measuring inside dimensions, such as pump casing wearing rings, cylinder, bearing, and bushing wear. Inside micrometers usually come in a set that includes a micrometer head, various length spindles (or extension rods) that are interchangeable, and a spacing collar that is 0.500 inch in length. The spindles (or extension rods) usually graduate in 1-inch increments of range; for example, 1 to 2 inches, 2 to 3 inches (fig. 2-28). 2-10







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.