AUTOCAD

1. 1. What is projection, projector and plane of projection?
Ans. Projection is an image or a view. Projectors are the lines drawn from
each and every point of the object. These lines are perpendicular to the plane
of projection & parallel to each other. Plane of projection (POP) is the plane
on which image is drawn.
2. Explain auxiliary plane with sketch.
Ans. The plane which is not at right angle to the reference planes (HP&VP)
and true image in shape and size of the details is drawn on it.
3. Differentiate first and third angle projection.
Ans i.)Object is placed in first and third quadrant in first and third angle
projection respectively. ii.)Object is in between POP and observer in first angle
projection, whereas in third angle projection POP is in between object and
observer. iii.)Plan (Top View) is below the Elevation (Front View). RSV is on
the left of elevation and LSV is on the right of the elevation.
Q5. What are the types of lines?
Ans. Object Line Continuous (FIRM) Thick Line
Construction Line Continuous (FIRM) Thin Line
Hidden Line Dashed Thick Line
Centre Line Chain Dotted Line
Section Line(Hatching) Thin & light at 45
Q6. What is dimensioning? Mention its notations.
Ans. Dimensioning is “ What is what from where”
Dimension Line & Notations
Extension Line
Dimension Line
Arrow Heads
Numerals
Leader
Notes
Q7. What are reference, coordinate and section cutting planes?
Ans. Horizontal Plane (HP) and Vertical Plane (VP) are reference planes. Profile
Plane (PP) is a coordinate plane. Cutting plane is an imaginary plane used for
viewing and showing the sectioned details (cut portion) of an object.

2. Q8. What is an isometric projection? Differentiate it with oblique view.
Ans. When all the faces of an object are equally inclined to the POP.When 2/4
faces in an example of a cube are equally inclined to POP is called Dimetric
Projection. When all the faces are not equally inclined is called Trimetric
Projection.
Oblique View is the projection, when One face to the front of observer is
parallel to POP, but other faces are inclined to POP at an angle of generally 45
(ie between 30 to 60.
Q10. Explain isometric scale and write isometric view of a circle & sphere.
Ans. Isometric scale is used for drawing isometric projection/ view. Practice to
draw as explained.
An ellipse is the isometric projection of a circle and a circle for a sphere.
Q11. What is difference between orthographic and pictorial views?
Ans. Orthographic projection is commonly used because it gives 100% details of an
object by drawing different views e.g. Elevation, Plan, side views, section views
auxiliary views etc. It is 2-D, whereas Pictorial views are 3-D and don’t give
full details. Yes pictorial projection can be understood by a layman easily, but
orthographic projection can be understood by an engineer or concerned person
only.
Q12.What is perspective view and where is it preferably used?
Ans.Perspective view is a pictorial projection and used by Architectural branch
of engineering.
Q13. Why orthographic projection is commonly used to express engineering
details?
Ans. It gives 100% details of an object by drawing many views, as much
required.
Q14. Why it is necessary to use isometric scale for drawing isometric projection?
Explain with sketch
Ans. It is to be explained by sketch as told in the class..
Q15.Under what circumstances hidden lines are to be drawn in an isometric
projection.
Ans.Generally hidden lines are drawn in isometric projection to show blind
details (blind holes etc)
Q16.How do isometric drawing and isometric view differ in projection?

3. Ans. Isometric views are always drawn with isometric scale, whereas isometric
drawings can be drawn in normal scale.
Q17. For which type of an object, oblique view is preferred over an isometric
view.
Ans. Oblique view is preferred over isometric view if circular, irregular & curved
details are more in the object.
Q18. What are the factors to be kept in mind for taking perfect orientation of an
object?
Ans. An object should be kept such that maximum details are visible to
observer in frontand so that minimum dotted lines are there in the views.
Q19. What do you mean by Auto Cad? Give definition & their use.
Ans. CAD-Computer-Aided Drafting. Creating 2D/ 3D drawing by the use of
computer software(Auto Cad) instead of manual drawing. Any modification/
editing in drawing can be done easily and fast by the use of this software.
Q20. What are Co-ordinates systems? Name types of co-ordinate systems and explain
with an example of a polygon for each system.
Ans. Co-ordinates systems are basically three axis X, Y & Z. Any objects drawing
should be prepared by the use of these axes giving dimension such as length,
width & thickness/ height respectively. There are three types of co-ordinate
system i.) Absolute ii.) Relative Rectangular iii.) Relative Polar.
Q21. Explain how an ellipse can be drawn by different ways, if axes are 180x70.
Ans. 1.Axis Endpoint Method- i) full(180), ii) half(35)
2.Centre Method – both dimensions put half(90,35)
Q22. What are the basic object-selection methods? How many types of selection
windows?
Ans. There are three methods of object selection i.) Selection Window ii.) Direct
Clicking on object iii.) Ctrl+A (Through Key-board).
There are two types of Selection Window i.) Regular window ii.) Crossing
Window.
Q23.Explain Move, Copy, Fillet and Chamfer with free hand sketches
Ans. Move- to transfer an object drawing from one place to other, the figure
copied will not remained.

4. Copy – preparing the same drawing of an object in multiple number with
reference drawing, the figure copied will remain.
Fillet – to show the corner of an object drawing in an arc shape by giving some
fillet radius i.e.filling of material
Chamfer – to show the sharp corner in taper form by giving some taper angle &
length of taper.
Q24. Name any 10 commands used in drawing orthographic projection.
Ans. Line, Circle, Arc, Rectangle, Polygon, Ellipse, Fillet, Chamfer, Move, Copy,
Erase, Trim, Break, Array, Offset, Mirror, Extend, Stretch.

5.  What Are Different Methods Of Dimensioning?
There are two methods of dimensioning:
 Unidirectional system: All the dimensions are placed in one direction only.
These are normally put from left to right whether written on a
horizontal/vertical/inclined dimension.
 Aligned system: The dimensions are placed perpendicular to the dimension line.
On a horizontal dimension, it is horizontal while on a vertical dimension, it is in
the vertical direction.
Aligned system of dimensioning is more common.
 Name The Principal Planes Of Projection.
The principal planes of projection are three:
 P.—Vertical plane for a front view
 P.—Horizontal plane for the top view of the object.
 P.—Profile plane for left or right side view of an object.
NOTE: All these planes (HP, VP and PP) are at right angles to each other.
 What Is A ? Why Are Sectional Views Used In Drawing?
Sectional view: The object is cut by a vertical plane to see the internal invisible
details in the front view.
The object is cut by a horizontal plane to see the internal invisible details in the
top view.
Sectional views are:
 Front right half in section
 Total front in section
 Total top in section

6. All the sectional views are meant to see and understand the internal invisible
details of the object. It will help in the right manufacturing as well as in repair
and servicing of the object.
 What Do You Understand By The V.t. And H.t. Of A Section Plane?
V.T. of a section plane: It is a line in the vertical plane where the cutting plane
is meeting as well as perpendicular to the vertical plane.
H.T. of a section plane: It is a line in the horizontal plane where the cutting
plane is meeting as well as perpendicular to the horizontal plane.
5. Give the practical applications of intersection of surfaces or interpenetration
of solids.
Practical applications of Intersection of surfaces: Manufacture of tables,
chairs, installation of air conditioning ducts, in the construction of boilers,
furnaces, chimneys.
Practical applications of interpenetration of solids: Connecting pipe to a
cylinder, making a tee joint in a pipe line, arm of a person going into the main
body.
 What Is Difference Between A Plane And A Lamina?
 Plane is a two dimensional figure with limited/ unlimited two dimensions.
 Lamina is also a two dimensional figure with limited two dimensions. For
example a sheet of paper is a lamina.
 What Is Meant By Conventions In Drawings?
There are standard symbols as per national or international codes. There are
standard symbols for types of lines, types of letters, types of materials, types of
sections, types of joints used in industry as well as daily life. These conventions
make the study easy, simple and convenient.
 What Is The Principle Of Development Of Surfaces?

7. The unfolding of an object on a flat surface is the principle of development. It is
used in sheet metal work for the manufacture of funnels, boilers, chimneys and
furniture of various types.
 Why The Drawing Is Called The Language Of Engineers?
It is because drawing helps in conveying one’s ideas in an easy, convenient and
speedily manner. It also makes study simple as it uses international standard
conventions and symbols.
 What Is The Necessity Of Dimension A Drawing?
It will give the overall size as well as sizes different parts of the object. The
dimensioning is necessary for the manufacture of the object in the industry.
 What Is The Trace Of A Line?
 Trace of a line is the point where line meets the plane on extending the line.
 If the line is inclined to H.P., it will have a H.T., (horizontal trace).
 If the line is inclined to V.P., it will have a V.T., (Vertical trace).
 If the line lies in a horizontal plane, it will have a horizontal trace as a line itself.
 If the line lies in a vertical plane, it will have a vertical trace as a line itself.
 Define Representative Fraction (r.f.)?
 It is a ratio of size taken on drawing sheet to the actual size of the object.
 R.F. < 1 for big objects like airplane, ship, tree, lathe etc.
 R.F. = 1 for objects in common use. May be a book, shoe, pencil, pen, cell
phone, remote etc.
 R.F.>1 for small size objects like a wrist watch, pencil cell, thread needle,
button etc.
 What Are A Single And A Double Stroke Letters?
 A letter written in one stroke of the pencil is a single stroke letter.

8.  A letter written in two strokes of the pencil is a double stroke letter.
 Why Are The Projections Of Objects Not Drawn In Second And Fourth
Angle Of Projections?
Front view and top view will overlap each other and thus there will be no clarity
and it will all be only confusion.
 What Is A Plane?
It is a two dimensional figure which has area only such as a triangle, square,
trapezium, circle, (object of negligible thickness such as sheet of paper, thin
plastic sheet).
 What Is Angle Of Inclination Of Section Lines?
The angle is 450 to the reference line xy. All the section lines are parallel and
equidistant.
 Describe Free Hand Sketching.
It is fast, easy and convenient method of drawing an object.
 What Is Meant By 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.
 If size on drawing = the actual size, it is a FULL SCALE, represented as 1:1
 If size on drawing < the actual size, it is a REDUCED SCALE, represented as
1:4
 If size on drawing > the actual size, it is a ENLARGED SCALE, represented as
3:1
 What Are Applications Of Scales?
Scales can be used for the following purposes:
 To draw an object on a full, reduced and enlarged scale.

9.  To measure distances.
 To mark dimensions on the drawing.
 What Are Different Types Of Scales?
Different styles of scales are:
Plain scale: 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.
Diagonal scale: 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, dm, and cm and mm is another diagonal scale.
Comparative or Corresponding scale: These are two different scales having
same R.F. but different units. These can be placed side by side or placed over
one and another.
For example: in miles and kilometres.
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 calliper. Vernier calliper 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.
 What Are The Requirements For The Construction Of A Scale?
(i) Maximum distance to be measured
(ii) R.F.( representative fraction) of the scale
Units of scale i.e. mm, cm, m, km
 Write The Procedure For The Construction Of A Scale.?
 Note down the units to be measured i.e. km, m, cm——
 Find the R.F. of the scale.

10.  Find the length, L, of the scale
L= (R.F.) x actual distance to be measured
Draw a line and mark 0, 1, 2, 3, 4—— at equal distances on the right side of
zero.
Sub-divide 1 main part into 10 parts on the left side of zero.
Mention clearly the units and sub units below the scale constructed.
Example: Construct a scale having 2cm = 1 m to show m and dm and it should
be long enough to measure a distance of 10 m.
Units are m and dm.
F. = 2/100=1/50
L = (1/50) x 10 x 100=20 cm
Draw a line of 20 cm length. Divide it into 10 equal parts to represent 1 m each.
Mark zero after the first division and then number it 1, 2, 3, ——up to 9 on the
right side of zero.
Divide the first part into ten equal divisions to represent 1 decimetre each.
Mark ten points on the left side of zero.
Represent full meters on the right side and centimeters on the left side of zero to
represent any required length say 5m 7 dm.
 Which Are The Types Of Projections Done In Engineering Drawing?
Orthographic projections are done on HP, VP and PP planes. Since projections
are done on a plane, these projections are 2 dimensional.
 Discuss Some Key Features About The Projection Of Points?
 Distance of the front view is always from the HP.
 Distance of the top view is always from the VP.
If distance above HP, front view is above xy and vice versa.
If distance is in front of VP, top view is below xy and vice versa.

11.  How Are The Projections Of A Point Marked For Its Front View And Top
View?
 Front view is marked by a small alphabet with a dash. The front view of point H
will be h’.
 Top view is marked by a small alphabet without a dash. The front view of point
H will be h.
Point as such is written by a capital alphabet.
 Define A Line In General. Also Define It From The Drawing Point Of
View?
0. A line is the shortest distance between two points.
1. A line in drawing can be defined in a number of ways.
It is defined by the location of its two ends with respect to the principal planes
of projections and its true length.
Location of its two ends with respect to the principal planes and the distance
between their projectors.
One end is defined with respect to the principal planes of projections and its
inclination given with one of the principal plane along with true length.
 Define The Trace Of A Line. What Are Various Types Of The Trace Of A
Line?
Trace of a line is a point where the line meets if produced the HP or VP.
Types of trace of a line:
 Horizontal trace (H.T.) When the line when produced meets at some point to
HP.
 Vertical trace (V.T.) When the line when produced meets at some point to VP.
NOTE: When a line lies in a plane (HP or VP) its trace is a line and it is the line
itself.

12.  What Are The Various Methods To Find The True Length And True
Inclinations Of A Line When Its Projections Are Given?
Various methods to find the true length and inclinations are:
 Rotation method
 Trapezoidal method
 Auxiliary plane method
 What Are The Positions Of A Line With Respect To Hp And Vp?
 Line parallel to both HP and VP
 Line inclined to one plane and parallel to the other plane
 Line inclined to both HP and VP
Write some important observations regarding projections of a straight line.
3. Projection on a plane will be the true length to which plane line is
parallel.
4. Projection on a plane to which it is inclined will be less than the true
length. If the line is inclined to HP, its top view on HP will be shorter
than the true length.
5. Projection will be a point on the plane to which line is perpendicular.
 What Is The Most Important Type Of Problems On The Projections Of A
Straight Line?
There are two main types of problems on the projections of a straight line:
 The projections of a line are given. Find the true length and its true inclinations
with HP and VP.
 The true length and its true inclinations with HP and VP are given. Draw its
projections.
 Define Engineering Drawing. Why Drawing Is Called Universal Language
Of Engineers?

13.  Engineering drawing is a graphical language of an engineer to convey one’s
ideas most effectively, easily, conveniently and with high speed.
 So Engineering drawing is a starting point of all engineering branches such as
Mechanical, Production, Civil, Electrical, Electronics, Computer science,
Chemical etc.
 It is spoken, read, and written in its own way. Engineering drawing has its own
grammar in terms of projections, conventional representations, types of lines,
abbreviations, symbols and various geometric constructions.
 Name Different Drawing Instruments.?
Drawing board, drawing sheet, mini-drafter, scale, pencil and sand paper block,
cello-tape, eraser and compass.
 What Are The Standard Sizes Of Drawing Sheets According To I.s.i. And
Which Is Suitable For Drawing Work?
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.
 What Are The Ways Of Sharpening A Pencil For Good And Accurate
Work And Which Type Of Pencil Is More Suitable For Drawing Work?
There are two ways of sharpening a pencil:
 A small piece of sand paper of zero grade, pasted upon a piece of wood.
 Sharpener.

14.  Why Cello-tape Is Used Instead Of Drawing Pins, Nowadays?
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.
 What Is Layout Of Drawing Sheet?
(i) Leave the following margins
1cm on top
1cm on bottom
1cm on right
3cm on left
(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
 Why Is The Layout Of Sheet Is Necessary?
Layout of the drawing on the drawing sheet is necessary in order to make its
reading easy and fast. The title blocks, parts list etc will provide all the required
information.
 List Out The Contents Of Title Block.
The title block should contain the following information:
0. Name of the institution
1. Title of drawing
2. Name, Branch, section and Roll no. of the student
3. Type of scale used
4. Drawing number
5. Type of symbol for the method of projection
 What Do You Mean By Convention/ Code?

15. 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.
 What Do You Understand By Thickness Of Lines?
There are three distinct thickness of lines used in engineering drawing. These
lines are specified as thick, medium and thin lines. The line specified as thick is
usually 3 times thicker and the line specified as medium is 2 times thicker than
a thin line.