INTRODUCTION TO DRAWING QUESTION ANSWERS CLASS NOTES

 INTRODUCTION TO DRAWING

QUESTION ANSWERS

CLASS NOTES

Engineering drawing is the graphical

language of engineers. Its basics help in

reading the various types of drawings used

in the manufacture of items. Question

answers on engineering drawing increases

the understanding and knowledge. This

helps to draw various types of practical

drawings. In engineering drawing,

lettering plays an important role. It

explains certain parts which cannot be

shown by lines or curves. A poor writing

mars the appearance of a drawing.

Lettering is talk of drawing. It should be

simple, easy, uniform and legible. Different

proportions are used in different

situations. Use reduced and enlarged scales

for large and small objects. Full scale is

used for objects whose dimensions are

manageable on the drawing sheet.

Dimensions are very important for a

drawing. Without dimensions, it is not

possible to know the size and shape of the

object. Without dimensions, an object

cannot be manufactured.

Q1 – What is lettering?

Ans

The art of writing the alphabets A, B, C,…….Z and numbers such as 0,1, 2, 3……  is lettering.

Q2 – What are the main requirements of lettering?

Ans
1) The knowledge of shape and proportion of each letter.
2) The knowledge of the order and direction of the strokes used in making letters.
3) The knowledge of the general composition of letters.
4. The knowledge of the rules for combing letters into words and words into sentences.
5. The knowledge of writing letters in plain and simmer manner. It is done with free hand and speed.

Q3– What do you mean by composition of letters?

Ans3 – The composition means the composing of letters into words and words into sentences. Arrangement in which open area between two letters of a word appears equal to the eye.

Q4 – What do you mean by uniformity of letters?

Ans 4 – The uniformity of lettering means keeping same

(i)  Height

(ii) Inclination

(iii) Spacing

(iv) Strength of lines of letters

It is very essential for good lettering in engineering drawing.

Q5 – What do you mean by normal, compressed and extended lettering?

 (a) Normal lettering

The normal lettering has normal height and width and are used for general purposes. The width of the normal letter is about 0.67 times of the height of the letter.

(b) Compressed lettering

The compressed lettering is writing letters in the narrow space. Space limitation use compressed letter writing. The width of the condensed letters is much less than height as compared with normal lettering.

(c) Extended lettering

The extended lettering is that which is much wider than normal letters but with same height.

Q6 – What are the guidelines and why are these necessary in lettering?

Ans6:- The guidelines regulate the height and inclination to the letters and numerals. The guidelines are necessary to maintain the uniformity of the letters.

7. What are a single and a double stroke letters?

A letter written in one stroke of the pencil is a single stroke letter.

Further, a letter written in two strokes of the pencil is a double stroke letter.

8 Describe types of lettering.

Letter writing in drawing is of great importance. It can be single, double stroke, Gothic and Roman.

These be written with H*B or H* grade pencil.

Q9 – What do you mean by single stroke letters and what are its types?

Ans 

Letters can be single and double stroke.

Single stroke letters means that the thickness of the line of the letter should be such as is obtained in one stroke of the pencil.
Single stroke letters are of two types.
1) Vertical
2) Inclined (minimum 800 With horizontal)

Q10 – What is the Gothic and Roman lettering?

Ans

Gothic lettering – The lettering in which all the alphabets are of uniform width or uniform thickness is known as Gothic lettering. It can be divided into following groups.
(i) Vertical/ upright Gothic lettering
(ii) Inclined or Italic Gothic lettering
Roman lettering – The lettering in which all the alphabets are composed of thick and thin elements is known as roman lettering and can either be vertical or inclined.

Q11 – What do you mean by freehand lettering?

Ans

The art of writing the alphabets without the use of drawing instrument is called freehand lettering. The freehand lettering is of the following types.
(a) Vertical or upright freehand Gothic lettering.
(i) Single stroke vertical freehand Gothic lettering.
(ii) Lowercase vertical freehand Gothic lettering.
(b) Inclined or italic freehand Gothic lettering.
(i) Single stroke italic freehand Gothic lettering.
(ii) Lower case italic freehand Gothic lettering.

Q 12 – What should be the grade of pencil used for lettering?
Ans

HB and H grade pencils, sharpened to a conical point, should be used for lettering.

Q13. Discuss size of letters.

Size of letter means height of letters. As per ISI, sizes are as given in the table.

Sr. no.

Purpose

Height of alphabets in mm

1.
Main titles
6, 8,10  and 12
2.
Sub-titles
3, 4, 5 and 6
3.
Notes such as materials, legends and dimensions
2, 3, 4 and 5

Q14. Define engineering drawing. Why drawing is called universal language of engineers?
Ans

Engineering drawing is a graphical language of an engineer. It  conveys one’s ideas most effectively, easily, conveniently and fast.  Engineering drawing is a starting point for all engineering branches. It is spoken, read, and written in its own way. Engineering drawing has its own grammar in terms of projections. It has conventional representations & types of lines. There are abbreviations, symbols and various geometric constructions.

Q15. Name different drawing instruments..
Ans

Drawing board, drawing sheet, mini-drafter, scale, pencil and sand paper block, cello-tape, eraser and compass.

Q16.  What are the standard sizes of drawing sheets according to I.S.I. and which is suitable for drawing work?

Ans

The standard size of sheets according to I.S.I. are
A0 (1189 X 841),
A1 (841 X 594),
A2 (594 X 420),
A3 (420 X 297),
A4 (297 X 210) and
A5 (210 X 148).

Drawing sheet of size 594 X 420 i.e. A2 size is generally used by engineering students as it is very handy and easy for drawing work in class.

Q17. What are the ways of sharpening a pencil for good and accurate work?  Which type of pencil is more suitable for drawing work?

Ans

There are two ways of sharpening a pencil
(i) a small piece of sand paper of zero grade, pasted upon a piece of wood.
(ii) Sharpener.

Q18.  Why cello-tape is used instead of drawing pins, nowadays?

Ans

Nowadays, cello tapes are used in place of drawing pins for its practical convenience as the drafter,

can be moved easily over the tape and the drawing board is spoiled by the use of drawing pins.

Q19. What is layout of drawing sheet?

Ans 

(i) Leave the following margins
From the top 1 cm
on bottom, 1 cm
From right 1 cm
on left, 3 cm
(i) Make a title block(rectangle) of size 65 mm high and 185 mm width on the right bottom side for title block, parts list

Q20. Why is the layout of sheet is necessary?
Ans

Layout of the drawing on the drawing sheet is necessary in order to make its reading easy and fast.

The title blocks, parts list will provide all the required information.

Q21. List out the contents of title block.

Ans

The title block should contain the following information.
(i) Name of the institution
(ii) Title of drawing
(iii) Name, Branch, section and Roll no. of the student
(iv) Type of scale used
(v) Drawing number
(vi) Type of symbol for the method of projection

Q22.  What do you mean by convention/ code?

Ans

The representation of any matter by some standard sign or symbol on the drawing is known as convention or code. The conventions make the drawing simple and easy to draw.

Q23. What do you understand by thickness of lines?

Ans

There are three distinct thickness of lines used in engineering drawing. These lines are specified as thick, medium and thin lines. A thick line is 3 times thicker than thin line. A medium line is 2 times thicker than a thin line. 

Q24. What is a scale?

A scale by which we keep same or reduce or increase the actual size of the object on a drawing.

Scale = Size taken on the drawing / Actual size

Q25. Discuss various types of scales in a drawing.

There are three types of scales.

1) Full size scale

 Full size scale uses actual measurements of the object.

 For example 1:1

2) Reducing scale

  Reducing scale uses shorter than actual measurements of the object. For example 1:4

3) Enlarging scale

 Enlarge scale uses larger measurements than actual dimensions of the object. For example 2:1.

Q26. What is the representative fraction (R.F.) or scale factor (S.F.)?

Ans

The ratio of the size on drawing to its actual size is Representative fraction.
R.F. = Dimension of an object on the drawing sheet / Actual dimension of an object
For example 1/10.

Q27. What are the main uses of scale?

Ans – The following are the main uses of scale in engineering practice.
(i) The scales prepare reduced or enlarged size drawings.
(ii) The scales set off dimensions.
(iii) The scales measure distances directly.

Q28. What are the information necessary for scale?

Ans – To construct a scale, the following information is necessary.
(i) The representative fraction (R.F.) of the scale.
(ii) The units used.
(ii) The maximum length of the scale

Q29. What is difference between a plain scale and a diagonal scale?

Plain Scale

A plain scale is a line divided into a number of equal parts. The first part is further sub-divided into smaller parts. It contains only two units (ones and tens or tens and hundred)

Diagonal Scale

A diagonal scale consists of three units. For example dm, cm, and mm (ones, tens and hundreds).

Q30. What is the principle of a diagonal scale?

 The principle of diagonal scale is to divide a short line into ten equal parts. It has further diagonal division into another ten parts.

Q31. Describe scale in drawing.

Depending on the size of the object, the size taken on drawing (sheet) can be same or different.

 Size on drawing can be = or < or > the actual size.

  1. If size on drawing = the actual size, it is a FULL SCALE. It represents 1:1.

  2. If size on drawing < the actual size, it is a REDUCED SCALE, represented as 1:4

  3. If size on drawing > the actual size, it is a ENLARGED SCALE, represented as 3:1

     Q32. Give applications of scales.

Use of the scale is for the following purposes:

  1. For drawing an object on a full, reduced and enlarged scale.

  2.  Measure distances.

  3. To mark dimensions on the drawing.

       Q33. What are different types of scales?

Different styles of scales are:

  1. Plain scale

  2. In which, one can measure certain units and its one tenth value. For example a scale in cm and mm is a plain scale, m and dm is another plain scale.

  3. Diagonal scale

  4. In which, one can measure certain units, its one tenth value as well as its one hundredth value. For example a scale in m, dm and cm is a diagonal scale.  A scale in dm,  cm and mm is another diagonal scale.

  5. Comparative or Corresponding scale

  6. These are two different scales having same R.F. but different units. Place these side by side.  or over one and another.

For example: in miles and kilometers.

These scales can be plain scales or diagonal scales.

      Vernier scales: It is a scale which is extremely accurate for measurement. It uses a Vernier caliper. Vernier caliper is an instrument to measure a dimension very precisely. Normally its least count is 1/100 of the scale unit. Say a scale is in cm, then a Vernier can measure very accurately up to 1/100 of a cm i.e. 2.12 cm.

      Q34. What are the requirements for the construction of a scale?

(i) to measure maximum distance

(ii) R.F.( representative fraction) of the scale

(iii) Units of scale i.e. mm, cm, m, km

    Q35. Write the procedure for the construction of a scale.

  1. Write the required units i.e. km, m, cm——.
  2.  Find the R.F. of the scale.
  3.  Find the scale length, L
  4. L= (R.F.) x actual distance
  5. Draw a line and mark 0, 1, 2, 3, 4—— at equal distances on the right side of zero.
  6. Sub-divide 1 main part into 10 parts on the left side of zero.
  7. Mention clearly the units and sub units below the scale constructed.

 Example

Construct a scale having 2cm = 1 m.  Show m and dm.  It should be long enough to measure a distance of 10 m.

  1. Units are m and dm.

  2. R.F. = 2/100=1/50

  3. L = (1/50) x 10 x 100=20 cm

  4. Draw a line of 20 cm length. Divide it into 10 equal parts to represent 1 m each.

  5. Mark zero after the first division. Then number it 1, 2, 3, ——up to 9 on the right side of zero.

  6. Divide the first part into ten equal divisions to represent 1 decimeter each.

  7. Mark ten points on the left side of zero.

  8. Represent full meters on the right side and decimeters on the left side of zero. Then it can represent any required length, say 5m 7 dm.

Q36. Why the drawing is called the language of engineers?

It is because drawing helps in conveying one’s ideas in an easy, convenient
and fast manner. It also makes study simple as it uses international standard
conventions as well as symbols.

Q37. What are the standard sizes of drawing sheets and which one more suitable for drawing work?

Table: Standard Sizes of Drawing Sheets

Designation

Trimmed size in mm

Width x Length

Untrimmed size in mm

Width x Length

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
Most commonly used is sheet A1 size.
Size A0 is used by Architects and draftsmen.

Q38. What is dimensioning?

Dimensioning is the art of writing the various sizes on the finished drawing of an object.

Q39. What is the importance of dimensions?

(i) Dimensions conveys all the sizes and other necessary information to draw completely the object.
(ii) Manufacturing processes and inspection requirements need dimensions.
(iii) The dimensions also includes tolerances necessary for the correct functioning of the parts in the component assembly.

Q40.  Describe the various notations used in dimensioning.

The notations of dimensioning consists of dimension lines, extension lines, arrow heads, dimension figures, notes, symbols etc.

Q41. What is a leader or pointer line? How a leader should be drawn?

A leader is a thin continuous line drawn from the drawing. It shows its location. An arrow head is its termination. The arrow head touches the outline. The leader is drawn at some angle, usually 30º, 45º, and 60º. It is not less than 30º.

Q42. Explain with the help of a simple sketch (i) size dimensions (ii) location dimensions.

 Size dimension 

The dimensions indicate length, breadth and diameter. These are size dimensions. Represent these dimensions by letter ‘S’.
Location dimension 

The dimensions which locate the position is the location dimensions. Location dimensions give the distance between the center lines of the two shafts. Mark these dimensions by letter ‘L’.

Q43. What are the different methods of dimensioning?

There are two methods of putting dimensions.
1) Aligned Method

In aligned system, place dimensions parallel to the dimension lines, preferably in the middle. These do not interrupt the dimension lines. Place dimensions as per orientation of all other lines in the drawing.
2) Unidirectional Method

In this system. place dimensions horizontally. It is irrespective of the orientation of the dimension lines in the drawing.

Q44. What are the general rules of putting dimensions?

(i) A drawing should show each and every dimension.
(ii) Do not repeat a dimension.
(iii) Place dimensions outside the views.
(iv) Avoid dimensioning of hidden lines wherever possible.
(v) Dimension lines should not cross any other line.

Q45. Which is the recommended method of writing dimensions?

Recommended Aligned system of dimensions. It is simple and easy.