BT-105 Engineering Graphics - Jun 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aFill in the blanks.

   1. i)The number of mutually perpendicular planes that may surround an object in space is _______.
   2. ii)In the third angle projection, the object is imagined to be placed _______.
   3. iii)In half sectional view, _______ of the object is imagined to be removed.
   4. iv)In the orthographic projection, the projectors are _______ to the plane of projection.
   5. v)Hatching lines are drawn at an angle of _______ to the axis or to the main outline of the sections.
   6. vi)Graphics can be converted into hard copy with a _______.
   7. vii)Mass prop provides _______ for solid.
   How to answer

   • i) 3 (or 6)
   • ii) in the third quadrant / below HP and behind VP
   • iii) one-fourth (1/4th)
   • iv) perpendicular / normal
   • v) 45°
   • vi) plotter / printer
   • vii) mass / volume / geometric properties / mass properties
2. 7 Marks
   bWhat are Scale? Classify its different types, also describe how RF is calculated.
   How to answer

   • Definition of Scale in engineering drawing
   • Classification: Plain, Diagonal, Vernier, Comparative, Scale of chords
   • Formula for Representative Fraction (RF = Drawing size / Actual size)
   • Example calculation of RF with uniform units
3. 7 Marks
   aA rectangular plot of land area 0.45 hectare, is represented on a map by a similar rectangle of 5 sq. cm. Calculate the RF of the map, Also draw a scale to read up to single metre from the map, the scale should be long enough to measure up to 400 metres.
   How to answer

   • Calculate RF: 0.45 hectare = 4500 m^2 = 4500 * 10^4 cm^2; RF = sqrt(5 / 4.5*10^7) = 1/3000
   • Calculate Length of Scale (LOS): LOS = RF * 400 m = (1/3000) * 40000 cm = 13.33 cm
   • Divide 13.33 cm into 4 equal parts (each representing 100 m)
   • Construct diagonal scale to read single metres
   • Label RF and units clearly
4. 7 Marks
   bAn inelastic string is unwound to a length of 122 mm from a drum of $\phi\ 30\text{ mm}$. Draw the locus of free end of the string which is held taut during unwinding.
   How to answer

   • Identify curve as an involute of a circle of diameter 30 mm
   • Calculate circumference: $\pi D \approx 94.25\text{ mm}$, noting unwound length is 122 mm (> 1 turn)
   • Draw circle of $\phi\ 30\text{ mm}$ and divide circumference into equal parts (e.g., 8 or 12)
   • Draw tangents at division points and mark lengths proportional to unwound arc length
   • Connect points with a smooth curve to get the locus
5. 7 Marks
   aThe projections a'b' and ab of a line AB are 65 mm and 50 mm long, respectively. The midpoint of the line is 38 mm in front of VP and 30 mm above HP. End A is 10 mm in front of the VP and nearer to it. End B is nearer to the HP. Draw the projections of the line, find its true length.
   How to answer

   • Locate midpoint projections: $m'$ at 30 mm above XY and $m$ at 38 mm below XY
   • Since end A is 10 mm in front of VP, point $a$ is at distance 10 mm from XY; find $b$ using midpoint property ($d_b = 2 \times 38 - 10 = 66\text{ mm}$)
   • Construct top view $ab = 50\text{ mm}$ between loci of $a$ and $b$
   • Project to find elevation $a'b' = 65\text{ mm}$ with $m'$ as midpoint and B nearer to HP
   • Rotate line to parallel position to determine true length (TL) and inclinations $\theta, \phi$
6. 7 Marks
   bA regular hexagonal lamina 40 mm side has a square hole of 25 mm side centrally cut through it. Draw its projections when it is resting on one of its sides on HP with its surface inclined at $60^\circ$ to VP and its corner nearest to VP is 24 mm from VP.
   How to answer

   • Stage 1: Assume lamina in HP or parallel to reference plane; draw true shape of regular hexagon (side 40 mm) with concentric square hole (side 25 mm)
   • Project the initial front view onto XY line
   • Stage 2: Incline the lamina surface at 60° to VP
   • Set the corner nearest to VP at 24 mm from the VP / XY line
   • Project corresponding front and top views showing foreshortened hexagonal boundary and square hole
7. 14 Marks
   A triangular prism of side of base 30 mm and axis 55 mm long lies on one of its rectangular faces in HP with its axis parallel to VP. Draw its Projection.
   How to answer

   • Draw side view or end view showing equilateral triangle of side 30 mm resting on base in HP
   • Draw front view: rectangle of 55 mm length and height equal to altitude of triangle ($30 \times \frac{\sqrt{3}}{2} \approx 26\text{ mm}$)
   • Draw top view: rectangle of length 55 mm and width 30 mm
   • Ensure axis is parallel to VP (parallel to XY in top view)
8. 14 Marks
   A right regular square pyramid, edge of base 35 mm and height 50 mm, rest on its base on HP with its base edges equally inclined to VP. A section plane perpendicular to VP and inclined to HP on $32^\circ$, cuts the pyramid bisecting its axis, Draw the projections and true shape of the section of truncated pyramid.
   How to answer

   • Draw top view: square of side 35 mm with edges inclined at 45° to XY
   • Draw front view: triangular elevation with base 35*sqrt(2) across corners, height 50 mm
   • Draw cutting plane line (cutting-plane line) at 32° to HP bisecting the axis at 25 mm from base
   • Identify intersection points on slant edges and project to top view to draw sectional top view with hatching
   • Draw auxiliary plane parallel to cutting plane and project true shape of the section
9. 7 Marks
   aDevelop the lateral surface of an oblique cone, diameter of the base 40mm and height 40 mm having its axis inclined at $60^\circ$ to its base.
   How to answer

   • Draw projections of the oblique cone (circular base in TV, tilted apex in FV with axis at 60° to base)
   • Divide base circle into 12 equal parts and draw generators to the apex
   • Find true length of each generator using rotation method
   • Develop lateral surface by triangulating adjacent generator true lengths with base chord lengths
   • Join the points with a smooth continuous curve
10. 7 Marks
    bA right circular cone, diameter of base 50 mm and axis 62 mm long, rest on its base rim on HP with its axis parallel to VP and one of the elements perpendicular to HP. Draw the projections.
    How to answer

    • Stage 1: Draw simple position with base on HP: top view is circle of $\phi 50\text{ mm}$, front view is isosceles triangle of base 50 mm and height 62 mm
    • Calculate semi-apex angle $\alpha = \tan^{-1}(25/62) \approx 22^\circ$
    • Stage 2: Tilt the front view so that one end generator becomes vertical (perpendicular to XY / HP)
    • The base rim rests on XY line at one point
    • Project downward from tilted front view to get the final top view (elliptical base with apex)
11. 9 Marks
    aA cube 30 mm edge is placed centrally on the top of a cylindrical block of $\phi\ 52\text{ mm}$ and 20 mm height. Draw the isometric drawing of the solid.
    How to answer

    • Set up isometric axes at 30° to horizontal
    • Draw bottom and top isometric ellipses of cylindrical block ($\phi\ 52\text{ mm}$, height 20 mm) using four-centre method
    • Locate center of top face of cylinder
    • Construct 30 mm square centrally on top face along isometric axes
    • Project vertical edges of 30 mm upward to complete isometric view of the cube
    • Outline visible lines in bold and remove or dash hidden details
12. 5 Marks
    bExplain the purpose of Zoom Command.
    How to answer

    • Definition and primary purpose: changing magnification/display scale without altering actual object dimensions
    • Key options: Zoom All, Zoom Extents, Zoom Window, Zoom Dynamic, Zoom Previous
    • Importance in viewing fine details and overall drawing navigation in CAD
13. 14 Marks
    Write short note on : (any two)

    1. i)View ports
    2. ii)Layering concept
    3. iii)Type of projections
    How to answer

    • i) Viewports: Model space vs paper space viewports, displaying multiple views simultaneously, setting scales for printing
    • ii) Layering concept: Organizing drawing elements by color, linetype, lineweight; toggling visibility (freeze/thaw, lock/unlock), standard layer management
    • iii) Types of projections: Classification into parallel (orthographic, oblique, axonometric/isometric) and perspective projections with characteristics