1. P M E 3 0 1 B A S I C M A C H I N I N G
M E A S U R I N G T O O L S
2. OBJECTIVE
• The aim of this lesson is for students to understand and gain the
skill to use a Vernier Caliper
3. ON SUCCESSFUL COMPLETION OF THIS LESSON,
STUDENTS WILL BE ABLE TO:
• Identify the different parts of the Vernier Caliper
• Demonstrate the use of Vernier Caliper
• Demonstrate how to read a vernier Caliper
4. MEASURING LENGTH AND
TIME
• Lengths from a few millimetres up to a metre can be measured
using a rule.
• When using the rule, the scale should be placed right next to the
object being measured. Calipers can help us if it isn’t possible to
place object next to the rule.
• More accurate length measurements is Micrometer and Vernier
calipers ( p.14)
5. VERNIER CALLIPERS
• Standard vernier callipers measure to within 0.05 mm (0.002 in) and
0.02 mm (0.001 in). Digital callipers are available with an accuracy up
to 0.01 mm (0.0005 in).
• They can be used to measure outside, inside and depth features.
They must be stored in a clean, dry place preferably in the pouch or
box in which they were originally bought. It is essential that the
corners of the inside and outside jaws are protected against damage
otherwise inaccurate readings will result.
• Hold the Vernier so that you are looking at the scale at an angle and
in line with the graduated line. Look along rather than at the line.
Move into a position where the light strikes from the back of
the Vernier scale at about the same angle as your line of sight.
• Vernier callipers can be read from zero up to the length of the main
scale, often 250 millimetres or more. They may also have provision
for taking depth readings.
7. ZERO ERROR
• Vernier calipers are said to have a zero error if the zero marking
on the main scale is not in line with the zero marking on the
vernier scale.
• we are looking for the other marking on the main scale which is
in the line with the other marking on the vernier scale.
12. READING A VERNIER CALIPER
• Read the main scale to the left of the zero of the vernier in
millimetres.
• Now look at the vernier scale . Note which one of
the vernier divisions is opposite a line on the main scale.
• Each of the lines on the vernier scale represents a division that is
0.02 of a mm shorter than those of the main scale. Multiply the
number of the line on the vernier scale by 0.02 and add the
result to the reading
• of the main scale.
14. • Example of a vernier settings:
• The main scale reads 60 millimetres. The vernier shows the fifth
line which represents 0.5 mm, plus 3 extra divisions which
represent:
• 3 x 0.02 = 0.06 mm.
• Total reading is 60
• + 0.5
• +0.06
• = 60.56 mm
