Use of Caliper

HOW TO READ THE METRIC VERNIER CALIPER

1. READ THE VALUE OF THE MAIN (stationary) BAR SCALE WHICH IS JUST TO THE LEFT AND

ABOVE THE '0' ZERO READING ON THE VERNIER (moveable) SCALE. VALUES WILL BE IN mm

2. THEN ADD THE VALUE ON THE VERNIER (moveable) SCALE WHICH EXACTLY COINCIDES WITH

A LINE ON THE MAIN (stationary) BAR SCALE. VALUES WILL BE IN 0.1 OR 0.15 mm

Internal measurement, or if threads = minor diameter

Depth measurement

0

10

20

30

50

40

60

70

80

90

100

110

120

130

140

Value on main bar scale = 12 +

Value on vernier scale =

0.3 +

Total =

12.3 mm

150

0.05 mm

0

1

2

3

4

5

6

7

8

9

10

MAIN (stationary) BAR SCALE

0

10

20

30

mm

40

External measurement,

or if threads = major diameter

value reading from main bar scale

0

1

2

3

4

5

6

7

8

9

10

VERNIER (moveable) SCALE

value from vernier scale which

EXACTLY COINCIDES

with a line on the main bar scale

HOW TO USE A THREAD PITCH GAGE

1. SELECT THE INDIVIDUAL THREAD GAGE FROM THE SET WHICH EXACTLY MATCHES

THE PITCH OR NUMBER OF THREADS PER INCH ON THE ITEM TO BE MEASURED.

2. NOTE THE MARKING ON THE INDIVIDUAL GAGE. IT MAY BE IN METRIC PITCH (P) OR IN

THREADS PER INCH (TPI)

Example: If the major

1.25 mm READING ON

1.25

diameter value is 8 mm

LEAF FROM PITCH

and the pitch is 1.25 mm

GAGE SET

then the thread is:

M8 x 1.25

P

METRIC PITCH (P) IS THE DISTANCE IN mm FROM THE

CENTER POINT OF ONE THREAD TO THE

CORRESPONDING POINT ON THE NEXT THREAD.

A helpful formula is:

25.4

TPI =

P

READ THE VALUES FROM THE VERNIER CALIPER, AND THE DATA FROM THE

THREAD PITCH GAGE. THEN DETERMINE THE SIZE AND IDENTITY OF THE THREAD

(metric, USA, or British) FROM THE THREAD IDENTIFICATION CHART DATA.

Note: If you are measuring an internal (female) thread; then this yields the minor diameter of the item. The

necessary (external male) major diameter (OD)...