MICROMETERS

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UNIT 9

• MICROMETERS

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ENGLISH OUTSIDE MICROMETERS

• The figure below shows an English outside
  micrometer graduated in thousandths of an inch.
  The principal parts are labeled
• Note A micrometer is read by observing the
  position of the bevel edge of the thimble in
  reference to the scale on the barrel and adding
  the thimble measurement that coincides with the
  horizontal line on the barrel scale

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ENGLISH MICROMETER EXAMPLE

• Read the English micrometer shown below
• On the barrel scale, seven 0.100-inch divisions
  0.700 inch
• On the barrel scale, one 0.025-inch division
  0.025 inch
• On the thimble scale, thirteen 0.001-inch
  divisions 0.013 inch

• Add 0.700" 0.025" 0.013" 0.738 inch Ans

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ENGLISH VERNIER MICROMETER

• Barrel and thimble scales of a vernier micrometer
  are identical to that of a 0.001-inch micrometer
• Vernier scale is added to the barrel
• Adding a vernier scale to the barrel of a
  0.001-inch micrometer increases the degree of
  precision of the instrument to 0.0001 inch.

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VERNIER MICROMETER EXAMPLE

• The figure below shows a setting on a flattened
  view of an English vernier micrometer. Read
  this setting
• Read the barrel scale reading (5 x 0.100") (0
  x 0.025") 0.500"
• Read the thimble scale 15 x 0.001" 0.015"
• Read the vernier scale 7 x 0.0001" 0.0007"

• Add 0.500" 0.015" 0.0007" 0.5157 inch Ans
  

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METRIC MICROMETER

• The figure below shows a 0.01-millimeter outside
  metric micrometer
• Note The thimble has a scale that is divided
  into 50 parts. One revolution of the thimble
  moves 0.5 millimeter on the barrel side. A
  movement of one graduation on the thimble equals
  1/50 of 0.5 millimeter along the barrel

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METRIC MICROMETER EXAMPLE

• Read the setting on the metric micrometer shown
  below. The scale is graduated in 0.01 mm
• On the barrel scale read 24 millimeters
• On the lower barrel scale read 0.5 millimeter
• On the thimble scale read 0.43 millimeter

• Add 24 mm 0.5 mm 0.43 mm 24.93 mm Ans

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METRIC VERNIER MICROMETER

• The figure below shows a flattened view of a
  metric vernier micrometer
• Reading a metric vernier micrometer is the same
  as reading a 0.01-mm micrometer except for the
  addition of reading the vernier scale. The
  vernier scale consists of five divisions. Each
  division equals one-fifth of a thimble division,
  or 0.002 millimeter

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VERNIER MICROMETER EXAMPLE

• Read the metric vernier micrometer below.
• Scales graduated in 0.002 mm
• On the barrel scale read 8.5 millimeters
• On the thimble scale read 0.08 millimeter
• On the vernier scale read 0.006 millimeter

• Add 8.5 mm 0.08 mm 0.006 mm 8.586 mm Ans

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PRACTICE PROBLEMS

• Read the settings on these English micrometer
  scales graduated in 0.001"

1.
2.
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PRACTICE PROBLEMS

• Read the settings on these English vernier
  micrometer scales graduated in 0.0001 inch

3.
4.
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PRACTICE PROBLEMS

• Read the settings on these metric micrometer
  scales graduated in 0.01 mm

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6.
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PRACTICE PROBLEMS

• Read the settings on these metric vernier
  micrometer scales graduated in 0.002 mm

7.
8.
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PROBLEM ANSWER KEY

• 1. 0.365 inch
• 2. 0.549 inch
• 3. 0.4907 inch
• 4. 0.4480 inch
• 5. 18.78 mm
• 6. 22.93 mm
• 7. 11.464 mm
• 8. 7.358 mm