LIST OF DRAWING INSTRUMENTS, EQUIPMENTS AND MATERIALS ​ ​ ​ TO BE USED DURING TRAINING ​ Engineering Drawing is the language of engineers. The accuracy and neatness of the engineering drawing depends on the quality of the instruments, equipment and material used. Hence, preference should be given to standard instruments and equipment and draughtsmen should be able to use different drawing instruments. List of drawing instruments :- ● Drawing board ● Tee-square or Mini Drafter ● Set-square ● Scale ● Protractor ● French curves ● Templates ● Drawing instruments box List of equipments :- ● Drafting machine ● Computer for AutoCAD (Monitor, UPS, CPU, Keyboard, Mouse, etc.) ● Plotter / Printer List of Materials :- ● Drawing papers ● Drawing pencils ● Rubber / Eraser ● Drawing paper fasteners (Drawing pins, Cellotape) ● Tracing paper Drawing Board :- A drawing board (also drawing table, drafting table or architect's table) is, in its antique form, a ​ ​ ​ ​ ​ ​ ​ ​ kind of multipurpose desk which can be used for any kind of drawing, writing or impromptu ​ ​ sketching on a large sheet of paper or for reading a large format book or other oversized document or ​ ​ for drafting precise technical illustrations (such as engineering drawings or architectural drawings). ​ ​ ​ ​ ​ ​ Engineers and Draftsmen use the drawing board for making and modifying drawings on paper with ink or pencil. Drawing board is rectangular in shape and is made of strips of well-seasoned softwood about 15 mm to 25 mm thick. It is cleated at the back by two battens to prevent warping. One of the edges of the board is used as the working edge, on which the T-square is made to slide. Therefore, it should be perfectly straight. In some boards, this edge is grooved throughout its length and a perfectly straight ebony edge is fitted inside this groove. This provides a true and more durable guide for the T-square to slide on. The standard size should be as per IS:1444-1963/1977 of Bureau of Indian Standards :- But due to the gradual introduction of computer aided drafting and design (CADD or CAD) in the ​ ​ last decades of the 20th century and the first of the 21st century, the drawing board is becoming less common. The following precaution may be taken in handling the drawing boards :- ● Always keep an extra sheet on the top surface of the drawing board. ● Do not keep anything on the top flat surface of the drawing board. ● Take sufficient care in keeping up the straightness of the ebony edge. Drawing papers :- The standard size as per Bureau of Indian standards (B.I.S) :- 1) The size of the drawing sheets to be used depends on the size of the object to be drawn and the scale to be used. 2) The length of the drawing sheet can be horizontal or vertical while drawing. 3) A2 size of drawing sheet is most convenient for drawing purposes in the classroom. 4) The width to length ratio of drawing sheet is 1:✓2 5) Area of A0 drawing sheet is 1.00 square meters. T-square :- A T-square is made up of hard-quality wood. It consists of two parts :- the blade and the stock - ​ ​ ​ ​ joined together at right angles to each other by means of screws and pins. The stock is placed adjoining the working edge of the board and is made to slide on it as and when required. The blade lies on the surface of the board. Its distant edge which is generally bevelled, is used as the working edge and hence, it should be perfectly straight. The length of the blade is selected so as to suit the size of the drawing board. Now-a-days, T-square is also available of celluloid or plastic with engraved scale. Uses :- The T-square is used for drawing horizontal lines. The stock of the T-square is held firmly with the left hand against the working edge of the board, and the line is drawn from left to right. The pencil should be held slightly inclined in the direction of the line (i.e. to the right) while the pencil point should be as close as possible to the working edge of the blade. Horizontal parallel lines are drawn by sliding the stock to the desired positions. The working edge of the T-square is also used as a base for set-squares to draw vertical, inclined or mutually parallel lines. A pencil must be rotated while drawing lines for uniform wear of lead. The T-square should never be used on edge other than the working edge of the board. It should always be kept on the board even when not in use. Testing the straightness of the working edge of the T-square :- Mark any two points A and B spaced wide apart and through them, carefully draw a line with the working edge. Turn the T-square upside down as shown by dashed lines and with the same edge, draw another line passing through the same two points. If the edge is defective the lines will not coincide. The error should be rectified by planing or sand-papering the defective edge. T-square is used to draw only horizontal lines. Do not use the lower edge of the T-square to draw horizontal lines. While drawing horizontal lines, the pencil should be slightly inclined towards the right. Vertical and inclined lines are drawn with the help of set squares. Set-squares :- The set-squares are made of wood, tin, celluloid or plastic. Those made of transparent celluloid or plastic are commonly used as they retain their shape and accuracy for a longer time. Two forms of set-squares are in general use. A set-square is triangular in shape with one of the angle as right angle. The 30 -60° set-square of 250 mm length and 45° set-square of 200 mm length are convenient sizes for use in schools and colleges. Uses :- 1) Set-squares are used for drawing all straight lines except the horizontal lines which are usually drawn with the T-square. Vertical lines can be drawn with the T-square and the set-square. 2) In combination with the T-square, lines at 30° or 60° angle with vertical or horizontal lines can be drawn with 30 - 60° set-square and 45° angle with 45 set-square. The two set-squares used simultaneously along with the T-square will produce lines making angles of 15°, 75°, 105° etc. 3) Parallel straight lines in any position, not very far apart, as well as lines perpendicular to any line from any given point within or outside it, can also be drawn with the two set-squares. 4) A circle can be divided in six, eight, twelve and twenty four equal parts by using set-squares and T-square. Drawing Instrument Box :- Large-size compass with interchangeable pencil and pen legs :- The compass is used for drawing circles and arcs of circles. It consists of two legs hinged together at its upper end. A pointed needle is fitted at the lower end of one leg, while a pencil lead is inserted at the end of the other leg. The lower part of the pencil leg is detachable and it can be interchanged with a similar piece containing an inking pen. Both the legs are provided with knee joints. Circles upto about 120 mm diameter can be drawn with the legs of the compass kept straight. For drawing large circles, both the legs should be bent at the knee joints so that they are perpendicular to the surface of the paper. As the needle is required to be inserted slightly inside the paper, it is kept longer than the lead point. The setting of the pencil-lead relative to the needle and the shape to which the lead should be ground. To draw a circle, adjust the opening of the legs of the compass to the required radius. Hold the compass with the thumb and the first two fingers of the right hand and place the needle point lightly on the centre, with the help of the left hand. Bring the pencil point down on the paper and swing the compass about the needle-leg with a twist of the thumb and the two fingers, in clockwise direction, until the circle is completed. The compass should be kept slightly inclined in the direction of its rotation. While drawing concentric circles, beginning should be made with the smallest circle. Drawing Instrument Box :- Lengthening bar :- Circles of more than 150 mm radius are drawn with the aid of the lengthening bar. The lower part of the pencil leg is detached and the lengthening bar is inserted in its place. The detached part is then fitted at the end of the lengthening bar, thus increasing the length of the pencil leg. It is often necessary to guide the pencil leg with the other hand, while drawing large circles. Drawing Instrument Box :- Small bow compass :- For drawing small circles and arcs of less than 25 mm radius and particularly, when a large number of small circles of the same diameter are to be drawn, a small bow compass is used. Curves drawn by the compass should be of the same darkness as that of the straight lines. It is difficult to exert the same amount of pressure on the lead in the compass as on a pencil. It is, therefore, desirable to use a slightly softer variety of lead (about one grade lower, HB or H) in the compass than the pencil used for drawing straight lines, to maintain uniform darkness in all the lines. Drawing Instrument Box :- Large-size divider :- The divider has two legs hinged at the upper end and is provided with steel pins at both the lower ends, but it does not have the knee joints.