Introduction to Basic Manufacturing Processes and ... - always yours

378 Introduction to Basic Manufacturing Processes and Workshop Technology
5
0
M A D E
IN
1 0
6 9 08
90
0
10
1 5
IN D IA
5
1 0
80
20
70
60
MADE IN
INDIA
50
40
30
Fig. 19.23 (a) A continuous type
dial indicator
19.2.3.10 Combination Set
Fig. 19.23 (b) A dial indicator of
Brown and Sharp Co.
Combination set is an important instrument which has the combination of instruments
namely square head, a centre head, and a bevel protractor and sprit level as depicted in Fig.
19.24. It is a very useful instrument frequently utilized in the bench work and machine shop
measurements. The three portions of the combination set are used separately being held
in at any desired position by nuts which engage in a slot machined on the whole length of
the beam at its back. The beam of the instrument acts as a rule, which is marked in inches
or centimeters or in both for measuring the length and height as and when required. The
square head possesses one edge square to the rule, giving a right angle, where as the other
edge form an angle of 45°. It is provided with a spirit level. The scale on the protractor may
be divided into degrees or a vernier attached whereby the angle can be measured in degrees
and minutes. It is also fitted with a spirit level to help in leveling the work of setting it
at an angle. The centre head with the rule fastened to it is called a centre square. It has
two arms at right angles to one another and is so set on the rule that this angle is exactly
divided in two by the edge of the rule. It may be used to find the centre of a round bar or
shaft. Spirit level is commonly used for checking levels and other measurement. It is
designed to handle measurements, layout and checking of angles. The square head is used
for checking 90° angle or as a square as shown in Fig 19.25. The protractor head may be
utilized with a rule to measure angles or to measure the slope of a surface as shown in
Fig. 19.26.
19.2.3.11 Semi-circular Protractor
It resembles with a semi-circular protractor and is commonly used is geometrical drawings.
Protractor used in sheet metal work is made from steel and often required for making or
measuring angles.