SCALE

SCALE

What is a scale?

     A scale is defined as the proportion by which we either reduce or increases the actual size of the object on a drawing.

1) Full size scale: The scale in which the actual measurements of the object are drawn to same size on the drawing is known as full size scale.

Scale: 1:1

2) Reducing scale: The scale in which the actual measurements of the object are reduced to some proportion is known as reducing scale.

Scale: 1:n (where n=2,3,4,...)

3) Enlarging scale: The scale in which the actual measurements of the object are increased to some proportion is known as enlarging scale.

Scale: n:1 (where n=2,3,4,...)

What is the representative fraction (R.F.) or scale factor (S.F.)?

     The ratio of the drawing size of an object to its actual size is called the Representative fraction.

R.F. = Dimension of an object on sheet / Actual dimension of an object

What are the main uses of scale?

     The following are the main uses of scale in engineering practice.

(i) The scales are used to prepare reduced or enlarged size drawings.

(ii) The scales are used to set off dimensions.

(iii) The scales are used to measure distances directly.

What are the information necessary for scale?

     To construct a scale, the following informations are necessary.

(i) The representative fraction (R.F.) of the scale.

(ii) The units to be presented either in metric or British measures.

(iii) The maximum length of the scale.

What is difference between plane scale and diagonal scale?

Plain Scale: A plain scale is simply a line which is divided into a suitable number of equal parts, the first of which is further sub-divided into small parts. It is used to represent either two units or a unit and its fraction such as km, m and dm, etc.

Diagonal Scale: A diagonal scale is used when very minute distances such as 0.1 mm etc. are to be accurately measured or when measurements are required in three units; for example dm, cm, and mm.

What is the principle of a diagonal scale?

     The principle of diagonal scale is to divide a short line into any number of equal parts by following the diagonal divisions method of construction.

What is Map Scale or Map Distance Measurement?

     Naturally it is impossible for real world features to be drawn on the map as large as their true size. Therefore in order to represent the real world, maps are made to a specific scale. Map scale is defined as the ratio of the distance between two points on the map to the corresponding distance on the ground. Maps come in a variety of scales. Large scale maps cover a small area with great detail and accuracy, while small scale maps cover a large area in less detail.

Composed by:  R.Satheesh, M.E., Asst Prof., email: rsatheeshemail@gmail.com.