This document discusses different types of scales used in engineering graphics for reducing or enlarging dimensions of objects to draw them accurately on a drawing sheet. It describes plain scales which use a line divided into equal units to measure two dimensions, such as meters and decimeters. It provides examples of how to construct plain scales with given reduction factors (R.F.) and measure distances on them. Diagonal scales are also introduced which allow measuring three dimensions on a single scale. Several problems are presented on constructing plain and diagonal scales meeting given criteria and measuring specific distances on them.

1. ENGINEERING GRAPHICS
PLAIN SCALE
DIAGONAL SCALE

2. Reduced scale:
Dimensions of large
objects must be
reduced to draw on
standard size
drawing sheet.
Example:
Map Of any country

4. Enlarged scale:
Similarly in case of
tiny small objects
dimensions must be
increased to draw
on drawing sheet.
Example: Drawing
of wrist watch
parts.

5. Plain scale
A plain scale consists of a line divided into suitable number of
equal units. The first unit is subdivided into smaller parts.
The plain scales give only two dimensions, such as a unit
and it's subunit or it's fraction.

6. LENGTH OF SCALE = (R.F. ) × (MAX. LENGTH TO BE MEASURED.)

7. PROBLEM NO.1
Draw a scale 1 cm = 1 meter to read meters and decimeters,
to measure maximum distance of 6 m.
Show on it a distance of 4 m and 6 dm.

8. SOLUTION:-

9.  R.F.= 1cm/ 1meter = 1/100
We know that, 1 meter = 10 decimeter = 100 cm
 Length of scale = (R.F.) X max. distance
= 1/100 X 600 cm
= 6 cms

10. ……ANSWER
Take height of scale 5 mm to 10 mm for getting a look of
scale

11. PROBLEM NO.2
In a map a 36 km distance is shown by a line 45 cms long.
Calculate the R.F. and Construct a plain scale to read kilometers
and hectometers, for measuring maximum 12 km distance.
Show a distance of 8.3 km on it.

12. CONSTRUCTION:-
Calculate R.F.
R.F.= 45 cm/ 36 km
= 45 cm/ (36 × 1000 × 100)cm
= 1/ 80,000

13. Length of scale = (R.F.) × max. distance
= (1/ 80000) × 12 km
= (1/ 80000) × (12 × 1000 × 100)cm
= 15 cm

14. Take height of scale 5 mm to 10 mm for getting a look of scale
……ANSWER

15. Problem 3:
Construct a plain scale to show kilometers and hectometers when
25 mm is equal to 1 km and long enough to measure up to 6 km.
Find RF and show a distance of 3km and 4 hectometer on the scale.

18. Problem 4:
Construct a plain scale of R.F. = 1:50 to show meters and
decimeters and long enough up to 8 meter. Indicate 6.7 m
distance on scale

21. Problem 5:
Construct a plain scale with RF = 1/5 to show decimeters (dm) and
centimeters. The scale should be long enough to measure 1 m. Show the
length of 7.4 dm on it.

24. 6. Construct a Diagonal scale of R.F= 1/500 to read meters and decimeters. It
should be able to read maximum up to 80 meters. Measure a distance of 47.8
meters.
8
7 0 70
Length of scale = (1/500) * (80*100 cm) = 16 cm
10 20
10
decimeter
Meter
40
47.8 meter
30 50 60
meter
1
3
5
10
2
4
6
7
9
1
2
5

25. 7. Construct a Diagonal scale of R.F= 3/100 to read meters, decimeters and
cm. It should be able to read maximum up to 5 meters. Measure a distance of
3.57 meters.
Solution

26. 3 meter 5 decimeter 7 cm
3.57 meter =
cm
Meter
dm