The use of Metric Calipers

Acknowledgment: Thanks to Southwest Wisconsin Technical College, who provided material from which this PowerPoint presentation is derived.

Overview

In this presentation you will learn about:

The different kinds of calipers. The components of a typical caliper. Taking measurements from calipers.

Introduction

Calipers are used to make precise length measurements.

Several different kinds of measurements can be made with a caliper...

While both micrometers and calipers can make outside length measurements...

Calipers can also make inside measurements...

…and depth measurements.

There are three types of calipers. The vernier caliper:

The dial caliper:

…and the digital electronic caliper.

The vernier caliper takes the most skill to read, and this is the type you will be using in experiment X.3.

These are the main features of a typical vernier caliper:

Jaws (for outside measurements)

Small jaws (for inside measurements)Metric vernier scaleMetric fixed scale

English vernier scaleEnglish fixed scale

Beam

Depth gauge

Introductionand

Example 1

Reading a Caliper

As you are about to see, using a vernier caliper is not difficult.

You only need to make two readings: one from the fixed scale and one from the vernier portion.

Reading a caliper

Start by obtaining a measurement from the fixed scale...

This is the fixed scale used for the metric readings.

Reading a caliper

Use the zero line on the vernier to locate your position on the fixed scale.

Reading a caliper

Each number printed on the metric scale represents centimeters.

6 cm

However, since your final reading is normally in millimeters, you need view these amounts as millimeters.

7 cm 8 cm 9 cm 10 cmetc.

Reading a caliperJust mentally add a 0 (zero) by each centimeter number.

0

60 mm

0 0 0 0

70 mm 80 mm90 mm 100 mm

Reading a caliper: metricSince there are ten spaces between each numbered interval, these smallest spaces must be 1 mm each.

For example, note the ten spaces in this interval.The smallest interval on this

scale is 1mm.

For example, this would be 91 mm...…this is 92 mm...…93 mm etc.

Reading a caliper: metricAs you can see in this problem, we have a fixed scale measurement of 63 mm.

The reading is 63 mm since the zero line has gone just beyond the 63 mm mark, but hasn’t reached the 64 mm mark.

Reading a caliperTo finish we must obtain a reading from the metric vernier scale.On this scale, each line represents 0.05 mm.

.05 mm.10 mm.15 mm.20 mm.25 mm.30 mm.35 mmetc.

Reading a caliperWe need now to look for the point at which the fixed scale “lines up” with the vernier.

It appears that these two lines, “line up” the best.

This is read as .50 mm

Reading a caliperSo based upon the two readings (one from the fixed scale, and one from the ruler) the length must be 63 mm + .50 mm = 63.50 mm

63 mm.50 mm+

63.50 mm

Example 2

Reading a caliper

Let’s try another one

Reading a caliper

First take a reading from the fixed scale. Use the zero line from the vernier to help.

Remember that we need to read the fixed scale in terms of millimeters.

The zero line is close, but not quite up to, the 20 mm line. It has gone beyond the 19 mm line however.

19 mm

0 0 0

19 mm

Reading a caliper: metric

To finish, read the vernier scale.It appears that these two lines, “line up” the best.

This is read as .35 mm

.35 mm

19 mm

Reading a caliper: metric

The final reading then is 19.35 mm.

.35 mm+19.35 mm

Example 3

Reading a caliper: metric

Let’s go through one more example.

Reading a caliper: metric

Use the zero line from the vernier scale to help get a reading on the fixed scale.Remember that we need to read the

fixed scale in terms of millimeters.

The zero line is directly above the 8 mm line.

8 mm

Reading a caliper: metric

That’s it! Since the zero line on the vernier matched up with a line on the fixed scale, you quit right there.The final reading is 8.00 mm

Practice Problem

Reading a caliper

Do this one on your own. Click to see the answer.

Start with the fixed scale reading.Remember that we need to read the fixed scale in terms of millimeters.

The zero line is close to, but does not quite reach the 67 mm line. It has gone beyond the 66 mm line however. 66 mm

0 0 0

Reading a caliper

66 mm

Reading a caliper: metric

To finish, read the vernier scale.It appears that these two lines, “line up” the best.

This is read as .60 mm

.60 mm

66 mm

Reading a caliper: metric

The final reading then is 66.60 mm.

.60 mm+66.60 mm