A technician is using a 2\text{--}3\text{ inch} vernier outside micrometer to measure the … — Armed Services Vocational Aptitude Battery (ASVAB)

A technician is using a $2\text{--}3\text{ inch}$ vernier outside micrometer to measure the diameter of a crankshaft main journal. The sleeve reveals the major graduation mark $7$ and two additional $0.025\text{-inch}$ subdivision marks past the $7$ . The thimble graduation aligned with the sleeve index line indicates $19$ , and the vernier scale on the sleeve aligns with a thimble mark at the $4$ line. What is the final measured diameter of the crankshaft journal?

A
$2.7444\text{ inches}$
$2.7694\text{ inches}$ Answer
C
$2.7194\text{ inches}$
D
$2.7944\text{ inches}$

Answer

2.7694\text{ inches}

The correct diameter is

2.7694\text{ inches}

. On a

2\text{--}3\text{ inch}

micrometer, the measurement starts at

2.000\text{ inches}

. The major mark

7

on the sleeve contributes

0.700\text{ inch}

, the two visible

0.025\text{-inch}

subdivisions add

0.050\text{ inch}

, the thimble line

19

adds

0.019\text{ inch}

, and the aligned vernier mark

4

adds

0.0004\text{ inch}

. Summing these values gives

2.000 + 0.700 + 0.050 + 0.019 + 0.0004 = 2.7694\text{ inches}

Step-by-Step Solution

Identify the base dimension from the micrometer frame size

Base size

= 2.000\text{ in}

2\text{--}3\text{ inch}

micrometer starts measuring at a baseline of

2.000\text{ inches}

when fully closed.

Read the major sleeve markings and minor subdivision lines

Sleeve reading

= 0.700\text{ in} + (2 \times 0.025\text{ in}) = 0.750\text{ in}

Each numbered line on the sleeve represents

0.100\text{ inch}

, and each subdivision line between numbers represents

0.025\text{ inch}

Read the thimble scale graduation aligned with the sleeve index line

Thimble reading

= 19 \times 0.001\text{ in} = 0.019\text{ in}

Each graduation around the circumference of the thimble represents one-thousandth of an inch (

0.001\text{ in}

Read the vernier scale on the sleeve for ten-thousandths resolution

Vernier reading

= 4 \times 0.0001\text{ in} = 0.0004\text{ in}

The matching vernier line on the sleeve adds ten-thousandths of an inch (

0.0001\text{ in}

) precision.

Calculate the total measured diameter

2.000\text{ in} + 0.700\text{ in} + 0.050\text{ in} + 0.019\text{ in} + 0.0004\text{ in} = 2.7694\text{ in}

Adding all scale components together provides the final precision measurement.

Key Concept

Precision scale reading using a vernier outside micrometer with sleeve, thimble, and ten-thousandths vernier graduations.

Estimated Time:1m 30s

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