INSTRUMENTS AND ITS 2 APPLICATIONS Dae 1st year

INSTRUMENTS AND ITS 2 APPLICATIONS Dae 1st year 

Dae Mechanical  1st year INSTRUMENTS AND ITS 2 APPLICATIONS nots summary and question and answer ,

A neat and correct drawing is drawn with the help of good drawing instruments. To record information on paper or any other surface, instruments and equipment are needed technical drawing is entirely a graphical language, hence instruments are essential to secure satisfactory results in drawing, the equipment should be of high grade to give accuracy and working efficiency. The drawing must be clear, neat, and liable in order to serve its purpose well. A neat and correct , drawing is drawn with the help of good drawing instruments, the list of which is given below.

a)	Drawing board.	(2)	Tee-Square.
(3)	Mini drafter.	(4)	Set squares.
(5)	Protractor.	(6)	Instrument box.
(7)	French curves.	(8)	Pencils.
(9)	Eraser.	(10)	Carpet cutter or pen-knife.
(11)	Drawing pins, adhesive tape or clips.
(12)	Drawing paper or drawing sheet, tracing paper.
(13)	Duster or dusting brush.	(14)	Sand paper.
(15)	Scales (engineering scales);
DRAWING BOARDS:			-

Drawing boards are usually rectangular in shape. They are generally made of well seasoned pine wood. In order to prevent warpage, the drawing board is made of narrow strips glued edge to edge. Care is taken to ensure that the surface of the board is absolutely flat and free from any crack. One the bottom side of the board, two battens are fixed by screws fitted in slots to allow for seasonal contraction and expansion. On the left hand side of the board, a straight ebony edge, called the working edge is fitted in the groove made on the edge of the board. This work edge facilitates the movement of T-Square.

The standard size of the drawing are given in table. S. No. Designation Dimension (mm)			Name
1	Bo	1500 x 1000	Antiquarian
2	B)	1000 x 700	Double Elephant
3	b2	700 x 500	Imperial
4	b3	500 x 350	Half Imperial
5	b4	350 x 250	Quarter Imperial

Uses of Drawing Board:

(1)    The flat surface of the board is used to hold the drawing paper while the drawing is being made.
(2)    The ebony edge of the board is used as a guide for the stock of the T-Square.

Cares of Handling the Drawing Board:

(1)    Handle the drawing board carefully so that the top flat surface of the board should not be spoiled.
(2)    The ebony working edge of the board must be straight against which the stock of T-Square moves.
(3)    Fasten an extra shut paper on the board to keep the surface clean.

T-Square:

The T-Square should be of hard quality wood. It consists of two parts the stock and the blade joined together at right angle 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 working edge is at the front and is beetled to facilitate drawing of lines. The T-Square is used for drawing horizontal lines.'

Usage of T-Square:

T-Square

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 as shown in fig. 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 position.

Cases irr Handling of T-Square:

(1)    T-Square should be placed in such a way on the drawing board that it may not drop on the floor, otherwise it will loosen the joint and as a result of that, the T-Square will no longer draw true parallel lines.
(2)    Clean the blade with moist cloth to remove pencil graphite lead.
(3)    T-Square should be hung on a nail against the wall or table when it is not being used.
(4)    Do not draw horizontal lines with the lower edge of the T-Square.
(5)    Do not use T-Square as a hammer.
(6)    Do not use the edge of the T-Square a& a guide for cutting the paper with a knife. .

Testing the T-Square*.

(1)    Check all head screws and tighten if necessary,

EDGE OF DRAWING BOARD

(2)    In' order to check the T-Square, first of all draw a horizontal line. Now reverse the T-Square and again draw a horizontal line with working edge. If both the lines coincide with each other, then the working edge of T-Square is alright.
If there is any difference in two lines,    Testing the r-square .
then working edge is not correct and the line gi ves twice the error of the working edge. This error should be rectified by scraping the edge with a scraper or a sharp knife.

Mini Drafter:

A mini drafter is a very convenient drawing instrument for students since it combines all the functions of a T-Square, set square and a protractor. It consists of two scales at right angles along with a protector the entire setup comes as a single unit fitted to one end of the double parallelogram of bars. The farther end of this parallelogram bar is fitted with a clamp the mini drafter is laid on the drawing-board and is clamped normally to the left side of the board. Thus by means of this mini drafter horizontal, vertical or inclined parallel lines of desired lengths can be drawn anywhere on the sheet with considerable ease and saving of time.

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 longer time.

Two forms of set square are in general use. Thy are triangular in shape with one comer in each, a right angle. The 30°-60° set square of 25cm length and 45° Set-Square of 20cm length are convenient sizes for use. Set squares are used to draw vertical, inclined as well as parallel lines.

Uses of Set-Squares:

(1)    The Set squares are used for drawing all straight lines except the horizontal lines which are usually drawn with T-Square.
(2)    The perpendicular lines or the lines at 30°, 60° and 90° to the horizontal can
l
be drawn by using the set-square as shown in fig.

(3) The perpendicular lines or the lines inclined at 45° and 90° to the horizontal can be drawn by using the set-square as shown in fig.

(5) In general set square are used to drawn angles of 15°, 30°, 45°, 60°, 75°, 90° any multiples of 15° as shown in fig.

Drawing Lines 15°, 30°, 45°, 60°, 75° and 90°
(6) The set-squares can also be used for drawing lines parallel and perpendicular to any given line as shown in Fig.

Drawing Parallel and Perpendicular Lines with set squares
LARGE SIZE COHPASS:

Large Size Divider

This compass is used for drawing circles and arcs of circles of required sizes. It consists of two metal legs hinged together at its upper and by means of a joint known as knee joint.
An adjustable needle is fitted at the end of by    Lengthening Bar    Pencil Leg
where as the other end is arranged so that another attachment either one metal by carrying a pendl lead or in the form an inking device can rectify by fitted to it.

Uses oF Compass:

The compass is used for drawing circles and arcs of circles of required sizes. The following steps should be kept in mind while drawing circle.
(i)    Draw the centre lines of the required circle as shown in fig,
(ii)    Set the compass on the scale and adjust it to the required radius.
(iii)    Place the needle paint at the centre of the required circle with the help of left hand.

(iv)    Draw the circle clockwise in one sweep, rolling the handle with the thumb and free finger inclining the compass in the direction in which the circle is to be drawn. The pencil line can be brightened if necessary, by making an additional turn. Very large circles are drawn by using the lengthening bar as shown in fig.

For this, detach the pencil leg, and insert the lengthening bar its place and connect the detached part with the lengthening bar and finally draw the required circle. The large size compass is used for drawing circle of approximately 120mm radius.

Drop Compass:

.Drop compass is used for drawing very small circles it has interchange able lead and ink points. This compass is particularly useful by structure engineers in drawing rivets holes and heads.

Compass:

A compass is used to draw circles and arcs of circles. Two types of compasses are used in engineering drawing one has long leys for drawing big circles. Another type f compass with shorter leys, which can be fixed or adjusted to a particular radius, is used for drawing circles with smaller radii.

Pencil Sharpener:

To simplify the process of sharpening a pencil, mechanical sharpeners equipped with cutters and used. This sharpener ramous the wood only, leaving the lead exposed so that is may be pointed as desired shape.

Protractor:

Protractor is used for setting of angles other than those obtainable using set squares. Normally protractors are made of transparent celluloid protector can be flat, circular and semicircular. The circular and semicircular protectors are usually made of box-word or ivory.

Cares and Handling:

Handle the protractor carefully and wash it with soap and water before using.

Instrument Box:

An instrument box consists of the following drawings instruments for making various drawings.

(1)	Large size compass (150 mm long)	(2)	Large size divider (150 mm long)
(3)	Small bow compass (95 mm long)	(4)	Small ink bow compass (95 mm long)
(5)	Small bow divider (95 mm long)	(6)	Lengthening box
(7)	Pin point	(8)	Ink point t
(9)	Ruling pen or linear	(10)	Holder croquill (for lines)
(ID	Lead case (for storing lead)

Use oF Instruments:

(1)    For arcs, circles, intersecting arcs, and so on.
(2)    For division of long lines.
(3)    For small arcs, small circles, comer radius, and soon.
(4)    Useful along with ink on tracing sheet, for small works like arcs, circles, and so on.
(5)    Useful for dividing lines with ink on tracing sheet.
(6)    Used along with compass for increasing working length.

on.

(7)    Used for locating centres of arcs, circles, and so

Dividing a Line with Divider

(8)    Ink point used for ink application on tracing pap

Divider:

The divider is used for dividing straight or curved lines into desired number f equal parts this instrument also consists of two metal leys as in the compass, except for the fact that two steel points are provided instead of pencil point.

Uses oF Divider:

(1)    It is used to divide straight or curved lines into desired number of equal parts.
(2)    It is used to transfer dimension from one part to another part of the drawing.
(3)    It is used to set-off given distances from the scale to the drawing.

French Curves:

French curves or irregular curves are generally made of wood or plastic, they are used to draw different curves, other than circles of known radius French curves are available in different shapes and sizes.
They are composed of successive segments of geometrical curves, such as ellipse, parapobola, hyperbola, involutes,
logarithmic spiral, ship curves and rail road cures. Proper use of French'curves will require skill, especially, when the curves are to be drawn in ink.

Pencils:

The neatness, quality and accuracy of a drawing greatly depends upon the type and condition of the pencil used for drawing. Pencil leads are made of graphite with clay added in varying amounts to make 18 grades from 9H to 7B. These grades can be divided into 3 groups.

(1)	Flard	9H to 4H
(2)	Medium	3H to B (3H, 2H, H, HB, B)
(3)	Soft	2B to 7B

Pencil 9FI is the hardest and 7B is the softest. Hardner pencils have leads of small diameters and softer pencils have larger diameter to give adequate strength.

9H 8H 7H 6H 5H 4H 3H 2H H F HB B 2B 3B 4B 5B 6B 7B HARDEST    SOFTEST
Different Grades of Pencils
Great care should be taken in mending the pencil and sharpening the lead, as the uniformity in thickness of lines depends largely on this. The lead may be sharped to two different forms.
(i) Conical point    (ii)    Chisel edge

The conical point is used in sketch work and for lettering etc, with the chisel edge, lung thin lines of uniform thickness can be easily drawn and hence, it is suitable for drawing work.
To prepare the pencil lead for drawing work, the wood around the lad end, other than that on which the grade is marked, is removed with a Pen-knife or carpet cutter, leaving about 10mm of lead projecting out.

Erassr:

Soft rubber is the most suitable kind of eraser for pencil drawings. It should be such as not to spoil the surface of the paper rubber crumbs should be swept away with a duster and should not be brushed off with hands.

Drawing Pins:

These are used to fix the drawing paper on the drawing board. The needle part of the pin is generally made of steel, while the head may be of plated mild steel or brass. Pins should be so inserted that the heads sit on the surface of the paper. Clips or adhesive tapes are also often used instead of the pins.

Drawing Papers:

Drawing papers are available in many varieties. For ordinary pencil-drawings, the paper selected should be tough and strong. It should be uniform in thickness and as which as possible when the rubber eraser is used on it, its fibres should not disintegrate. Good quality of paper with smooth surface should be selected for drawings which are to be inked and preserved for a long time. It should be such that the ink does not spread. Thin and cheap quality paper may be used for drawings from which tracing are to be prepared.
The following are the standard sizes of trimmed sheets recommended.
Designation    Dimensions (mm)
A₀    841 x 1189 '
A] ‘    594x841
A₂    420 x    594
A₃    297 x    420
A4    210x297
A₅    148 x    210

Duster:

Duster should preferably be of towel cloth larger in size than the drawing board. Before starting work, all instruments and material should be thoroughly cleaned with the duster. The rubber crumbs formed after the used of the rubber should be swept away by the duster and not hand. The underside of the T-square and the set-squares which continuously rub against the paper should be frequently cleaned.

Scales:

All measurements of lengths or distances on a drawing are made with the scales. The scale is a measuring stuck, graduated with different divisions to represent the corresponding actual distances of ground according to some fixed proportions, therapy giving rapidly in making off distances on drawing. The scales are either flat or triangular d the material used in their construction may be wood, celluloid, metal, card-board etc.
Scale which is graduate on both the edges with 1:1, called full size scale and 1:2 called half fall size scale.
On the scale the figure such as 1:1, 1:2, 1:5, 1:10, 1:15, 1:20, 1:50, 1:75, 1:100,
1:200, 1:500 .......are written thus, the proportion 1:5 means that if 1 centimeter is to
be shown on drawing, it will represent its corresponding actual distance of 5 centimeter

on ground. Full Size Scale	Reducing Scales		Enlarging Scale
1:1	1:2	1:20	10:1
	1:2	1:25	5:1
	1:10	1:50	2:1
		1:100

MULTIPLE CHOICE QUESTIONS: INSTRUMENTS AND ITS 2 APPLICATIONS Dae 1st year 

1.    The shape of drawing boards are usually:
(a) Square    (b)    Rectangular    (c) Both of above

2.    Drawing sheets are fixed on drawing board for making:
(a) Drawing    (b)    Painting    (c) Both of above

3.    Drawing horizontal lines on drawing sheet we used:
(a) Scales    (b)    Set square    (c) T. Square

4.    To draw perpendicular, oblique and parallel lines we used:
(a) Scales    (b)    Set Square    (c) T. Square

5.    Dividing lines into equal parts and transferring distances with the help of:
(a) Protractor    (b)    T-Square    (c) Divider

6.    The instrument used for measuring the length or distances:
(a) Scales    (b)    Set Square    (c) Divider

7.    Instrument used for measuring the angles is:
(a) French curve    (b) Set square    (c) Protractor

8.    For removing unwanted lines we used:
(a) Eraser    (b)    Sand paper    (c) both of above

SHORT QUESTION / ANSWERS:

Q.l Enlist various drawing instruments.

Ans:

1. Drawing Board                   2. Technical Square    3. Mini drafter             4. Set sq.       

5. Protractor                            6. Instrument box        7. French Curves         8. Pencils

9. Eraser                                  10. Carpet cutter or Pen & Knife        11. Drawing pins

12. Scotch Tape                      13. Sand paper.                       14. Drawing sheet, tracing

15. Duster or Dusting brush             16. Scales (Engineering scales).

 Q.2 Explain Drawing boards, uses.

Ans: Uses of Drawing Board:

(1)   The flat surface of the board is used to hold the drawing paper while the drawing is being made.

(2)   The ebony edge of the board is used as a guide for the stock of the T-Square.

Q.3 Describe care of handling the Drawing Boards?

Ans: Cares of Handling the Drawing Board:

(1)   Handle the drawing board carefully so that the top flat surface of the board should not be spoiled.

(2)   The ebony working edge of the board must be straight against which the stock of T-Square moves.

(3)   Fasten an extra shut paper on the board to keep the surface clean.

Q.4 Sketch T-Square and list its parts.

Ans: The T-Squaie should be of hard quality wood. It consists of two parts the stock and the blade joined together at right angle 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 working edge is at the front and is beetled to facilitate drawing of lines. The T-Square is used for drawing horizontal lines.

Q.5 Describe usage of T-square?

Ans: T-square is used for drawing horizontal line. The stock of the T-square is hold firmly with the left hand against the working edge of the drawing board, and the line is drawn from left to right.

Q.6 State cares handling of T-square.

Ans: (1) T-square should be placed in such a way on the drawing board that it may not drop on floor. ^J

(2)                                          Clean the blade with moist cloth to remove pencil graphic lead.

(3)                                          Do not draw horizontal lines with the lower edge of the T-square.

(4)                                          Do not use T-square as a hammer.

(5)                                          Do not used the edge of the T-square as a guide for cutting the paper with a knife.

Q.7 Describe the uses of set squares?

Ans: (1) Set squares are used for drawing all straight lines except horizontal lines, which are usually drawn with T-square.

(2)                                 The perpendicular or the lines at 30o, 45o, 60o, 90o to the horizontal can be drawn by using the set square.

(3)                                 In general set squares are used to drawn angles of 15o, 30o, 45o, 60o, 75o 90o

any multiples of 15o.

                                                                                 • _

Q.8 Describe the uses of compass?

Ans: The compass is used for drawing circles and arcs of circles of required size.

Q.9 Describe the uses Care and handling of Protractor?

Ans: Protractor is used for setting of angles other than those obtainable using set squares. Normally protractors are made of transparent celluloid protractor can be "flat circular and semi circular.

Handle the protractor carefully and wash it with soap water before using.

Q.10 Enlist items in Instrument box?

Ans: An Instrument box consists of the following drawing Instruments for making various drawings.

(1)                                         Large size compasses (150mm long)

(2)                                         Large size divider (150 mm long)

(3)                                         Small bow compass (95 mm long)

(4)                                         Small ink bow compass (95 mm long)

(5)                                         Small bow divider (95 mm long)

- (6)                  Lengthening box.

(1)                                         Pin point.

(2)                                         Ink point.

(3)                                         Ruling pen or linear.

(4)                                         Holder croquill (for lines)

(5)                                         Lead case (for storing lead)

                                         

Q.l1 State uses of Divider?

Ans: (1) It is used to divide straight or curved lines into desired number of equal parts.

(2)                                 It is used to transfer Dimension from one part to another part of the drawing.

(3)                                 It is used to set off given distances from the scale to the drawing.

Q.12 Whish Instrument is used for drawing horizontal lipes.

Ans: The T-square is used for drawing horizontal lines.

Q.13 Which are the hardest and softest pencils?

Ans: Hardest pencil 9H & softest pencil 6B.

Q.14 Why drawing is called language of Engineer?

Ans: He represents his idea in this language in such a way that others can read it.

INSTRUMENTS AND ITS 2 APPLICATIONS Dae 1st year 

Dae Mechanical  1st year INSTRUMENTS AND ITS 2 APPLICATIONS nots summary and question and answer ,