ENGINEERING DRAWING-Engineering Drawing Sheets
ENGINEERING DRAWING SHEETS
Drawing paper: These are of two types:
• Hand-made paper
• Mill-made paper
Hand-made papers have rough surfaces, pale in color and not used for regular work, but meant for charts.
Mill-made papers are most commonly used for regular work, and are available in different sizes and rolls. They are specified by their weight in kg per ream or density in grams per square meter.
SIZE OF DRAWING SHEETS (in mm):
While working or handling, the papers are liable to tear on the edges. So slightly large size (untrimmed) sheets are preferred. They are trimmed afterwards. IS:10811:1983 lays down such as designation of preferred trimmed and untrimmed sizes. The basic principle involved in arriving at the sizes of the drawing paper is as under. The area of the biggest size (A0) is 1m2 and its length and breadth are in the ratio 1: 2 . Let x and y are the sides of the paper. The surface area of A0 is 1m2, then the sides are x = 0.841 m and y = 1.189 m.
Two series of successive sizes are obtained by either halving or doubling along the length. The area of the successive sizes are in the ratio of 1:2.
DESIGNATION OF SHEETS:
The drawing sheets are designated by symbols such as A0,A1,A2,,A3,A4 and A5. A0 being the largest. Table 1 below gives the length and breadth of the above sizes of sheets. (Trimmed and untrimmed).
The relationship between two sides is same as that of a side of a square and its diagonal.
|A0||841 x 1189||880 x 1230|
|A1||594 x 841||625 x 880|
|A2||420 x 594||450 x 625|
|A3||297 x 420||330 x 450|
|A4||210 x 297||240 x 330|
|A5||148 x 210||165 x 240|
For drawings which cannot be accommodated in above sheets, elongated series are used. Elongated series are designated by symbols A1 x 3; A2 x 4 etc.
Special elongated series increasing its widths, double, treble etc. are designated as follows A3 x 3, A3 x 4, A4 x 3, A4 x 4, A4 x 5.
Special elongated series
|A3 x 3||420 x 891|
|A3 x 4||420 x 1189|
|A4 x 3||297 x 630|
|A4 x 4||297 x 841|
|A4 x 5||297 x 1051|
Exceptional elongated series
|A0 x 2||1189 x 1682|
|A0 x 3||1189 x 2523|
|A1 x 3||841 x 1783|
|A1 x 4||841 x 2378|
|A2 x 3||594 x 1261|
|A2 x 4||594 x 1682|
|A2 x 5||594 x 2102|
|A3 x 5||420 x 1486|
|A3 x 6||420 x 1783|
|A3 x 7||420 x 2080|
|A4 x 6||297 x 1261|
|A4 x 7||297 x 1471|
|A4 x 8||297 x 1682|
|A4 x 9||297 x 1892|
A4 x 3 means the length of A4 size is retained and the other side is 3 times the width of A4.
A4 x 3 = 297 x 630 (210 x 3)
The sheet sizes are formed by halving/ doubling and similarity of format.
White drawing papers which do not become yellow on exposure to atmosphere are used for finished drawings, maps, charts and drawings for photographic reproductions.
For pencil layouts and working drawings, cream color papers are best suited.
QUALTIY DRAWING PAPER:
Quality drawing paper: The drawing papers should have sufficient teeth or grain to take the pencil lines and withstand repeated erasing.
A backing paper is to be placed on the drawing board before fixing drawing/tracing paper, to get uniform lines. Before starting the drawing, the layout should be drawn.