Plain scale Engineering Graphics Engineering Drawing

1. ENGINEERING GRAPHICS
PLAIN 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. TYPES OF SCALES
1. PLAIN SCALES
2. DIAGONAL SCALES

6. What is 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.

7. LENGTH OF SCALE = (R.F. ) × (MAX. LENGTH TO BE MEASURED.)
Two Formulas For The Calculations

8. 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.

9. SOLUTION:-

10.  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

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

12. 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.

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

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

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

16. 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

20. 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.