SCALES AND SCALE DRAWING, SIMPLE BLUE PRINT READING
TERM: FIRST TERM
SUBJECT: BASIC TECHNOLOGY
CLASS: JSS 3
TOPIC: SCALES AND SCALE DRAWING, SIMPLE BLUE PRINT READING
DEFINITION OF SCALE DRAWING
Scale drawing can be defined as the accurate representation of objects in a determined proportion .Scale drawing is different from ordinary drawing in that it presents the object either reduced or enlarged. There are scales for reduction and for enlargement of the size of the object.
MATERIALS AND INSTRUMENTS FOR SCALE DRAWING
This has two flat straight edges. It is usually 30cm long. Each main division on the metric rule is equal to one centimeter (1cm =10mm) and each division is sub divided into 10 units being 1mm .Always start from 0 as the beginning of your measurement.
These have three straight edges and are triangular in shape. Each edge is graduated and each scale designation is marked on the rule.
Some objects are too big for the actual size to be contained on a drawing paper, while some are too small for the parts to be clearly seen. Hence, such objects should be drawn to an appropriate scale.
Scale is usually given as a ratio and they are stated in the title block.
TYPES OF SCALE DRAWING
Ascale is used to draw or read a scale on a drawing paper
We have the following scales:
Therefore a cupboard of size 1800mm long drawn as 18mm has a reduced scale drawing of 1:100mm.
ENLARGED SCALE DRAWING
This is used when the object to be drawn is too small to be clearly seen.Here, the actual size of the object is enlarged in the proportion to the drawing.
Examples include 2:1, 10:1, 100:1,
Drawing size 100:1 actual size
REDUCED SCALE DRAWING: this is used when the object to be drawn is too big. Here the actual size of the object is reduced in the proportion of the drawing. Examples include 1:2, 1:5, 1:10, 1: 100 etc.
FULL SCALE DRAWING: This is when the object to be drawn is the same size as the size of the object the scale used is 1:1.
TOPIC: SIMPLE BLUE PRINT READING
Blueprint is the means of communication between the builders and building designer(architect). They are finished plans of what is to be produced or built,i.e. it is the complete drawings builders use at their building site to build. In building industry, the blueprint is also called the working drawing. The blue print is prepared by the architect while the builder interpretsit correctly. Blue print reading requires high-level knowledge of architectural and engineering drawings. It also requires ability to understand measurements and to measure accurately. Any mistake error could be too costly.
The following are to be interpreted by the builders.
COMMON SYMBOLS USED AND THEIR INTERPRETATIONS.
Earth or soil
Mass concrete floor slab
Wash hand basing
READ “SIMPLE BLUEPRINT READING” AND SCALE DRAWING
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