Answers are in brief. Q
19 to 24 are auto-cad question.
Q1. 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.
Q2. 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.
Q3. Classify
projection by making a chart.
Ans.
Q4. 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
Break
Line (Short)
Break
Line (Long)
Cutting Plane Line
Dimension Line &
Notations
Ø
Extension
Line
Ø
Dimension
Line
Ø
Arrow
Heads
Ø
Numerals
Ø
Leader
Ø
Notes
Q6. What
is dimensioning? Mention its notations.
Ans. Dimensioning
is “ What is what from where”
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.
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.
Q9. Why
30° angle is used in isometric projection?
Ans. It
is to be explained by a sketch.
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?
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.
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.
