1. Vernier Calipers
Unit 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

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
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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

5. Reading the Measurement
1 x 1.000= 1.000
4 x 0.100=
1 x 0.050=
14 x 0.001=
1.464 in.
A 50-division inch vernier caliper reading of in.
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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

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

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

9. Digital Electronic Caliper
Can provide readings to resolution of 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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