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PowerPoint to accompany

Krar • Gill • Smid

Technology of Machine Tools6th Edition

Vernier CalipersUnit 10

10-2

Objectives• Measure workpieces to within an accuracy

of .001 in. using a 25-division inch vernier caliper

• Measure workpieces to within an accuracy of .001 in. using a 50-division inch vernier caliper

• Measure workpieces to within an accuracy of 0.02 mm using a metric vernier caliper

10-3

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Used to lock readings into place

Parts of the Vernier Caliper

Manufactured with both 25- and50-division vernier scales

Bar of 25-divisionvernier scale graduatedsame as micrometer

10-4

Measuring a Workpiece• Remove all burrs from workpiece• Clean surface to be measured• Open jaws enough to pass over work• Close jaws against work and lock right-hand

clamp screw• Turn adjusting screw until jaws just touch

work surface• Lock clamp screw on movable jaw• Read measurement

10-5

Reading the Measurement

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A 50-division inch vernier caliper reading of 1.464 in.

1 x 1.000= 1.0004 x 0.100= .4001 x 0.050= .050

14 x 0.001= .014

1.464 in.

10-6

Metric Vernier Caliper

• Many have both metric and inch graduations• Parts same as inch vernier• Main scale graduated in millimeters

– Every main division numbered, equal to 10 mm– Fifty graduations on sliding scale with every fifth

one numbered• 50 graduations occupy same space as 49 graduations

on main scale (49 mm)• 1 vernier division = 0.98 mm so difference between 1

main scale division and 1 vernier division = .02 mm

10-7

Reading a Metric Vernier Caliper• Last numbered division on bar to left of

vernier scale represents number of millimeters multiplied by 10

• Note how many full graduations showing between this numbered division and zero– Multiply number by 1 mm

• Find line on vernier scale that coincides with line on bar and multiply by 0.02 mm

• Add for total reading

10-8

Direct-Reading Dial Caliper

• Dial indicator, hand attached to pinion, mounted on sliding jaw

• Metric: 1 revolution of hand = 2 mm of travel• Inch: 1 revolution = .100 or .200 in. of travel

– Depends on manufacturer• Most have narrow sliding blade attached to

sliding jaw (and dial) used depth gage

10-9

Digital Electronic Caliper• Can provide readings to resolution of

.0005 in. or 0.01 mm at touch of button• No rack, pinion or glass scale• Can connect to Statistical Process Control (SPC)

equipment for inspection purposes• Measurements

– Inside diameter– Outside diameter– Step– Depth

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