Fishing Craft Technology

Practical 2 - Introduction to drawing & drawing instruments

Drawing is the graphical representation of a real thing. The purpose of the drawing is to define and specify the shape and size of a particular object by means of points, lines, curves and other information’s about the object, which can not be expressed by lines are given side by side on the drawing in a simplest and shortest way. A good type of drawing gives full information about the object in a shortest and simplest way.

Classification of Drawing:
The drawing may be classified into two distinct categories.

1) Artist drawing:
It is the drawing or art of a person who draws sketches of a object by his imagination or keeping the object before him. An Artist tries to produce the object in the shape of a picture. He is so perfect in his art that he can prepare the picture of a object by imagination without measuring the size and the picture looks quite proportionate. He requires only his pen or pencil and a paper to prepare the picture. Dimensions and other details are not given in it. It is not a simple drawing and the artist requires a great practice to prepare it.

2) Engineering Drawing:
A drawing worked out by an Engineer having engineering ideas for the Engineering purpose is called as an Engineering drawing. It is a universal language of Engineers. It is spoken, read and written in its own way. We have to learn to write a language first so that we may be able to read it. If we know how to draw a drawing we will be able to read and explain it.

Drawing Instruments:
Following are the instruments required for drawing purpose.

• Drawing board with stand
• T – square
• Set squares
• Instrument box
• Scales
• Pencils
• Clips or clamps
• Eraser
• Drawing paper
• Pencil sharpner or blade

1. Drawing board:
Drawing board is rectangular in shape and is made of strips of well-seasoned soft wood about one inch (1") 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. It should therefore be perfectly straight. The drawing board must be placed on the table with the working edge always to be at the left side.

2. T-Square:
T-square is made up of well seasoned hard quality wood. It consists of two parts (1) Head or Stock (2) Blade
Both these parts are joined together at right angles to each other by means of screws and pins. The head 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. The blade is grooved at the end to hang it when it is not used. The T-square is used for drawing horizontal lines.

Testing the straightness of the working edge
First place the T-square on the board in any position and draw a line along the working edge of the blade. Now reverse the T-square on the same line. If the edge is defective the lines will not coincide.


3. Set squares:
The set-squares are made up of wood, plastic or celluloid. Those made of transparent celluloid or plastic are commonly used, as they retain their shape and accuracy for longer time. Set squares are normally triangular in shape. Two forms of set squares are in general use (30^o - 60^o, 45^o- 45^o)
Set squares are used for drawing all straight lines except the horizontal lines. Vertical lines can be drawn with the help of T-square and set square.

4. Instrument box:
A drawing instrument box contains the following items.
(a) Compass (b) Divider (c) Bow pen (d) Bow Compass etc.

a) Compass:
It is used for drawing circles and arcs. It consists of two legs hinged together at its upper end.
b) Divider:
It is used
(i) To divide curve or straight lines into desired number of parts.
(ii) To transfer dimensions from one part of the drawing to another.
(iii) To set off given distances from the scale to the drawing.

5. Scales:
The scales are made up of wood, steel, celluloid or plastic. They are usually six or twelve inches in length. The scale is used to transfer the true or relative dimensions of an object to the drawing. The scale should never be used as a straight edge for drawing lines.

6. Pencils:
Neatness, accuracy and quality of the drawing greatly depends upon the type and conditions of the pencils used for drawing. Pencil leads are made of graphite with clay added in varying amounts to make 18 grades from 9H to 7B. These grade can be divided into three groups.
(a) Hard -- 9H -- 4H
(b) Medium -- 3H -- B
(c) Soft -- 2B -- 7B
Drawings are done using 2H pencils and finished with H or HB pencils.

7. Drawing pins / Clips:
These are used in securing the drawing sheets to the drawing board firmly. The use of pins must be avoided, as it will spoil the surface of the board.

Pinning / fastening the drawing sheet to the drawing board:
Place the paper at about equal distances from the top and bottom edges of the board and one of its shorter edges at about 25mm from the working edge of the board. When the paper is of a much smaller size than that of the board, it may be placed with its lower edge at about 50mm from the bottom edge of the board. Insert a drawing clip in the left hand top corner of the paper and at about 10 mm from its edges. Adjust the paper with the right hand, bringing its upper edge in line with the working edge of the T-square. Stretch the paper gently to make it perfectly flat and insert the second clip at the right hand bottom corner. In the same manner fix two more pins at the remaining corners. Push the clips down firmly till their heads touch the surface of the paper.

Borderlines and name plate:
Perfectly rectangular working space is determined by drawing the border lines. These may be drawn at equal distances of about 20 to 25 mm from the top, bottom and right hand edges of the paper and at about 25 to 40mm from the left hand edge. More space on the left hand side is provided to facilitate binding of the drawing sheets in the book form if so desired.

Aim: To draw the single stroke vertical capital letters.



Procedure:

• With the help of T-square and pencil draw the horizontal lines at a distance of 4mm apart (9 lines).
• With the help of T-square and Set square draw the vertical lines at a distance of 4 mm apart.
• In the first 8x8 block, write the capital letter ‘A’ as shown in the Figure.
• Leave 2 blocks after the letter ‘A’.
• Repeat the same procedure to write the other letters.

Aim: To draw the single stroke vertical small letters

Procedure:

• With the help of T-square and pencil draw the horizontal lines at a distance of 4mm apart (9 lines).
• With the help of T-square and Set square draw the vertical lines at a distance of 4 mm apart.
• Select 8 x 8 block and by using 4 x 4 block write the small letter ‘a’, as shown in the figure.
• Similarly write the other letters.
• By using 8 x 8 blocks, write the numerical numbers.