PowerPoint to accompany
Technology of Machine Tools
6th Edition
Krar • Gill • Smid
Vernier Calipers
Unit 10
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Permission required for reproduction or display.
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
Parts of the Vernier Caliper
Used to lock readings into place
Bar of 25-division
vernier scale graduated
same as micrometer
Manufactured with both 25- and
50-division vernier scales
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
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
1 x 1.000= 1.000
4 x 0.100= .400
1 x 0.050= .050
14 x 0.001= .014
1.464 in.
A 50-division inch vernier caliper reading of 1.464 in.
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.
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
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–
–
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Inside diameter
Outside diameter
Step
Depth
Copyright © The McGraw-Hill Companies, Inc.
Permission required for reproduction or display.