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.
6. Methods of Dimensioning
Method – 1: Aligned method:
Dimensions should be placed
parallel to and above their
dimension lines and preferably
at the middle.
Dimensions may be written
so that they can be read from
the bottom or from the right
side of the drawing
7. Method 2: Unidirectional
dimension system :
In this system ,
all dimension figures and
notes are lettered
horizontally and are read
from the bottom of the
drawing.
Dimensional lines are
broken to place the
dimension.
21. 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.
22. LENGTH OF SCALE = (R.F. ) × (MAX. LENGTH TO BE MEASURED.)
Two Formulas For The Calculations
23. 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.
27. 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.
29. Length of scale = (R.F.) × max. distance
= (1/ 80000) × 12 km
= (1/ 80000) × (12 × 1000 × 100)cm
= 15 cm
Each Division length
= 15cm/12
= 150mm/12
= 12.5mm
30. Take height of scale 5 mm to 10 mm for getting a look of scale
……ANSWER
31. 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.
33. Each Division length
= 15cm/6
= 150mm/6
= 25 mm
= 2.5 cm
Now, Prepare Scale yourself
0 1 2 3 4 510
3 Km 4 Hm
KilometerHectometer
34. 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
35.
36. 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.