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Difficulty: HardMeasuring and Layout Tools

A mechanic is measuring the thickness of a precision transmission spacer plate using a 0 to 1-inch vernier micrometer. On the sleeve, the major number 3 is fully visible along with two additional 0.025-inch subdivision lines exposed past it. The thimble has rotated past zero such that the sleeve reference line lies between 18 and 19 on the thimble, and the 6th line on the vernier scale aligns precisely with a thimble graduation line. What is the total measured thickness of the plate?

  1. A
    0.34360.3436 inches
  2. 0.36860.3686 inchesAnswer
  3. C
    0.39360.3936 inches
  4. D
    0.31860.3186 inches

Answer

0.36860.3686 inches
The measurement of 0.36860.3686 inches is obtained by adding the four components of the vernier micrometer: the sleeve major mark (0.300 in0.300\text{ in}), the two exposed sleeve subdivisions (2×0.025 in=0.050 in2 \times 0.025\text{ in} = 0.050\text{ in}), the thimble thousandths mark (0.018 in0.018\text{ in}), and the aligned vernier mark (0.0006 in0.0006\text{ in}). Summing these yields 0.300+0.050+0.018+0.0006=0.36860.300 + 0.050 + 0.018 + 0.0006 = 0.3686 inches.

Step-by-Step Solution

1
Read the major tenths division exposed on the sleeve
3×0.100 in=0.300 in3 \times 0.100\text{ in} = 0.300\text{ in}
Each numbered graduation line on the micrometer sleeve represents one-tenth (0.1000.100) of an inch.
2
Read the exposed subdivision lines on the sleeve past the major division
2×0.025 in=0.050 in2 \times 0.025\text{ in} = 0.050\text{ in}
Each unnumbered vertical line between major numbers represents twenty-five thousandths (0.0250.025) of an inch.
3
Read the graduation on the rotating thimble below the index line
18×0.001 in=0.018 in18 \times 0.001\text{ in} = 0.018\text{ in}
The thimble is divided into 25 equal increments, each equal to one thousandth (0.0010.001) of an inch.
4
Read the vernier scale line that aligns with a thimble graduation line
6×0.0001 in=0.0006 in6 \times 0.0001\text{ in} = 0.0006\text{ in}
The vernier scale on the sleeve provides ten-thousandths (0.00010.0001) of an inch precision.
5
Calculate the sum of all four individual readings
0.300 in+0.050 in+0.018 in+0.0006 in=0.3686 in0.300\text{ in} + 0.050\text{ in} + 0.018\text{ in} + 0.0006\text{ in} = 0.3686\text{ in}
The total measurement is the cumulative sum of the sleeve major divisions, sleeve subdivisions, thimble mark, and vernier alignment.

Key Concept

Reading an inch vernier micrometer to four decimal places
Estimated Time:1m 30s
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Topics

Measuring and Layout Tools

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