Scale Introduction
Scale Introduction
Dimensions of large objects must be reduced to accommodate on standard-size drawing sheet. this reduction creates a scale of the reduction ratio, which is generally a fraction...
such a scale is called as reducing scale and that ratio called as representative factor. For full-size scale R.F = 1 OR ( 1 : 1 ), Means drawing & object are of the same size. other RFs are described as :
1:10 1:100
1:1000 1:1,00,000
Similarly in case of tiny objections must be increased for the above purpose. hence this is called enlarging scale. here the ratio called representative factor is more than unity.
Use the following formulas for the calculation in this topic:
(A) representative factor ( R.F ) :
= [katex]\frac{Dimansion\ of \ drawing}{Dimension\ of\ objects}[/katex]
= [katex]\frac{Lenght\ of \ drawing}{Actual\ length}[/katex]
= [katex]\sqrt{\frac{\ \ \ Area\ of\ drawing\ \ \ \ }{Actual\ area}}[/katex]
= [katex]\sqrt[3]{\frac{Volume\ as\ per\ drwg}{Actual\ volume}}[/katex]
(B) Length of scale = R.F × max length to be measured
Units of measurement
1 KILOMETER = 10 HECTOMETERS
1 HECTOMETER = 10 DECAMETERS
1 DECAMETRE = 10 METERS
1 METER = 10 DECIMETRES
1 DECIMETER = 10 CENTIMETERS
1 CENTIMETER = 10 MILIMETERES
Types of scale:
- Plain scales (for dimensions up to single decimal )
- Diagonal scales (for dimensions up to two decimals )
- Varnier scales (for dimensions up to two decimals )
- Comparative scales (for comparing two different units )
- Scale of cords (for measuring/constructing angles )