http://bzuiam.webs.com/

1. TOPIC
Measurements and Steel Rules

2. For more help contact me
Muhammad Umair Bukhari
Engr.umair.bukhari@gmail.com
www.bzuiam.webs.com
03136050151

3. History of Measurement
 Units of measurement were literally at our finger
tips- hands, arms, feet, legs
 Common units of measurement is derived from
Europeans recorded history
 These familiar units of measure are results of
long evolutionary system

4.  Standards of inches, feet, and yards are
summarily divided by “common fractions”
(1/2,1/4,1/8,1/16 etc, or decimal fractions(1 in,
0.1 in, 0.01in etc) used now-a-days in US.
 Rest of the world use “SI metric system” or
“International system”

5. Basic unit conversions
 1 m=100 cm
 1 cm=10 mm
 1 m= 39.37 inch
 1 inch=2.54 cm
 1 inch=25.4 mm

6. Steel rules
 Steel rules are simple instruments of linear
assessment
Usage:
 Fractional inches, usually to 1/64th of an inch
 A decimal scale with a typical determination of
0.01
 mm and half mm

7. Types of steel rule
 Rigid rules
 Flexible rules
 Narrow rule
 Hook rule
 Narrow hook rule
 Rule set
 Tapered end rule

8. Types of measurements
 Direct : Direct comparison with an established standard
 Indirect : Indirect measuring system identifies the
difference between the object being measured and a
known dimension.
 This type of measurements use comparators- those
“transfer” instruments that contact and assess the work
piece and then compared with an external scale which
determines the amount of the expressed difference.
Which is the actual dimension of the object.
 E.g. Calipers

9. Reference point to measure
point
 Any linear measurement can be broken down
into two points
1.References point
2.Measured point
we set the instrument at reference point and move
the instrument –or read along it-until we find the
measure point

10. Errors in scale reading
 Look squarely at the face of a clock and read the
time
 Then walk several feet to one side and honestly
read the time
 The clock will read several mins slower or faster,
depending on angle you view it from, normally
done by all.
 It is called Parallax error.

11. Errors in scale reading
 Parallax error

12. Errors in scale reading
 If you move your head, nose, and eyes over a
several inches from reference point to the
measure point, you may find your hand,
holding the rule, has unconsciously traveled
with the body motion and moved the rule
across the work, thus make an error in the
measurement

13. Precautions in measurements
 Do not use dull and worn out instruments
 Do not cramp its style, be relax, loosen your
grip
 Set the reference point in position and read
the measured point
 Hold the rule lightly but firmly