BT-105 Engineering Graphics - Jun 2025 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
   aCompare diagonal scale and Vernier scale in terms of construction and precision. Provide a situation in engineering where each is used.
   How to answer

   • Principle of diagonal division vs vernier division
   • Comparison of least count and precision
   • Constructional differences (grid vs sliding/auxiliary scale)
   • Practical engineering applications for each
2. 7 Marks
   bA water tank of size $27\text{ m}^3$ was represented in the drawing by $216\text{ cm}^3$ size. Construct a Vernier Scale for the same to measure upto 5 meter. Also show on it the distance of $3.95\text{ meter}$ and $0.042\text{ meter}$.
   How to answer

   • Calculate R.F.: $\sqrt[3]{\frac{216 \text{ cm}^3}{27 \times 10^6 \text{ cm}^3}} = \frac{6}{300} = \frac{1}{50}$
   • Calculate Length of Scale (LOS): $\frac{1}{50} \times 500\text{ cm} = 10\text{ cm}$
   • Determine primary divisions and vernier divisions
   • Draw main scale and vernier scale
   • Mark distances 3.95 m and 0.042 m
3. 7 Marks
   aA coin $30\text{ mm}$ diameter rolls on a straight line on a table. Plot and name the locus of a point lying on the circumference for one complete revolution.
   How to answer

   • Identify curve name: Cycloid
   • Calculate perimeter: $\pi D = \pi \times 30 \approx 94.25\text{ mm}$
   • Draw rolling circle of diameter 30 mm and divide into 8 or 12 equal parts
   • Draw base line equal to $\pi D$ and divide into equal number of parts
   • Construct horizontal locus lines and find points on cycloidal curve, joining them smoothly
4. 7 Marks
   bA line AB $70\text{ mm}$ long is inclined at an angle of $30^\circ$ to HP. Its end A is $10\text{ mm}$ above the HP and $15\text{ mm}$ infront of VP. The front view is $50\text{ mm}$. Draw the projection of line AB.
   How to answer

   • Mark reference line XY, locate front view $a'$ (10 mm above XY) and top view $a$ (15 mm below XY)
   • Draw true inclination line $a'b_1'$ at $30^\circ$ to XY with length 70 mm to find locus of $b'$
   • Cut arc from $a'$ with front view length 50 mm onto the locus of $b'$ to locate $b'$
   • Project $b_1'$ to top view to find apparent/true lengths, and rotate to find $b$
   • Draw final front view $a'b'$ and top view $ab$
5. 7 Marks
   aDraw the projection of a regular hexagonal lamina of $30\text{ mm}$ side having one of its edge in the VP and inclined at $60^\circ$ to HP and the surface making an angle of $40^\circ$ with the VP.
   How to answer

   • Stage 1: Assume lamina in VP with one side perpendicular to HP; draw true shape in front view and line in top view on XY
   • Stage 2: Tilt top view line at $40^\circ$ to XY (surface inclined to VP); project front view
   • Stage 3: Incline the edge lying in VP at $60^\circ$ to HP (XY line) in front view and project the final top view
6. 7 Marks
   bWrite about Dialog boxes and Windows in CAD software.
   How to answer

   • Definition and purpose of dialog boxes in CAD (inputting parameters, settings, layer properties)
   • Key components of dialog boxes (buttons, checkboxes, text fields, drop-down menus)
   • Definition and purpose of windows/drawing windows in CAD (model space, paper space, multi-document interface)
   • Examples in AutoCAD (e.g., Layer Properties Manager, Plot dialog box)
7. 7 Marks
   aDraw the projection of a hexagonal prism base $30\text{ mm}$ and axis $75\text{ mm}$ long when its axis is inclined at $30^\circ$ to the VP and parallel to HP and edge of the base is perpendicular to HP.
   How to answer

   • Stage 1: Simple position - axis perpendicular to VP (or parallel to VP, simple orientation); draw regular hexagon in front view with one edge perpendicular to HP, draw rectangle in top view
   • Stage 2: Incline the top view so that the axis makes $30^\circ$ with XY (VP)
   • Project points vertically upwards from top view and horizontally from stage 1 front view to get final front view
   • Determine visibility of edges (hidden vs continuous lines)
8. 7 Marks
   bWhat is meant by projection? Explain the principle of projection and differentiate between First angle projection and Third angle Projection.
   How to answer

   • Define projection and projector lines
   • Explain principle of orthographic projection using viewing planes and rays of sight
   • Table of differences between First Angle and Third Angle projections (object placement, plane of projection transparency, relative view positions)
   • Draw standard projection symbols for both systems
9. 7 Marks
   aA hexagonal Pyramid side of base $30\text{ mm}$ and axis $60\text{ mm}$ long rest with its base on HP and one of the edge of its base is parallel to VP. It is cut by a horizontal section plane at a distance of $38\text{ mm}$ above the base. Draw its Front view and Sectional Top View.
   How to answer

   • Draw top view (regular hexagon with two edges parallel to XY) and apex at center
   • Project front view (triangle of base width and height 60 mm)
   • Draw a horizontal section line (parallel to XY) in front view at 38 mm above base line
   • Project intersection points of cutting plane with slant edges down to the corresponding edges in top view
   • Join the points to show the cut section and hatch at $45^\circ$ to complete sectional top view
10. 7 Marks
    bA cone of base diameter $55\text{ mm}$ and axis $65\text{ mm}$ is lying on one of its generator on the horizontal plane with its axis parallel to VP. It is cut by a vertical plane section parallel to one of the generator and bisecting the axis. Draw its sectional front view and True shape of section.
    How to answer

    • Draw simple front view and top view of cone, then tilt cone onto its generator in HP
    • Draw cutting plane line in top view that is parallel to the generator and passes through midpoint of axis
    • Locate points where section plane cuts base circle and various generators
    • Project these points to front view to obtain sectional front view
    • Construct true shape of section (parabola) by plotting perpendicular ordinates from the section line
11. 7 Marks
    aDiscuss how CAD software supports the visualization and creation of complex 3D objects such as compound solids. Include references to specific tools or features.
    How to answer

    • Overview of 3D modeling in CAD (solid, surface, and wireframe modeling)
    • Creation tools: Extrude, Revolve, Sweep, Loft
    • Boolean operations: Union, Subtract, Intersect used to form compound solids
    • Visualization features: 3D Orbit, visual styles (wireframe, realistic, shaded), perspective views, viewports
    • Advantages: accurate mass properties, collision detection, and rapid rendering
12. 7 Marks
    bDraw the Floor plan of a single BHK house showing all details like window, doors and other fixtures. Assume suitable dimension for plan.
    How to answer

    • Layout configuration: Living room, Bedroom, Kitchen, Bath/WC, and Balcony/Verandah
    • Appropriate assumed dimensions (e.g., Living: $3.5\text{ m} \times 4.0\text{ m}$, Bedroom: $3.0\text{ m} \times 3.5\text{ m}$, Kitchen: $2.5\text{ m} \times 3.0\text{ m}$, Bath/WC: $1.5\text{ m} \times 2.0\text{ m}$)
    • Wall thickness (e.g., external 200/300 mm, internal 100/150 mm)
    • Standard symbols for doors ($D_1, D_2$), windows ($W_1, W_2$), ventilators ($V$), kitchen slab, and sanitary fittings
    • Proper dimensioning lines and room labelling
13. 7 Marks
    aDiscuss the construction and use of an Isometric Scale.
    How to answer

    • Purpose of Isometric Scale in isometric projections to compensate for foreshortening
    • Geometric construction: horizontal baseline, line at $45^\circ$ for true scale, line at $30^\circ$ for isometric scale
    • Mathematical relation: Isometric Length / True Length = $\cos 45^\circ / \cos 30^\circ = \sqrt{2/3} \approx 0.816$
    • Sketch of isometric scale showing division transfer from true line to isometric line vertically
14. 7 Marks
    bDraw the Isometric view of given figure.

    

    How to answer

    • Create isometric box of dimensions $72\text{ mm} \times 48\text{ mm} \times 48\text{ mm}$ along $30^\circ$ isometric axes
    • Draw base prism of $72 \times 48 \times 12\text{ mm}$
    • Plot tapered upper part reaching top surface dimensions
    • Incorporate the central top notch of width $12\text{ mm}$ and depth $9\text{ mm}$ running through or as indicated
    • Darken visible edges and erase/dim construction lines
15. 14 Marks
    Write short notes on any three of the following: i) Epicycloid ii) Traces of a line iii) Tool bar iv) View ports
    How to answer

    • Epicycloid: Locus traced by a point on the circumference of a circle rolling outside a directing circle without slipping; include formula for subtended angle $\theta = (r/R) \times 360^\circ$ and sketch
    • Traces of a line: Points where the line (or its extension) intersects the reference planes: Horizontal Trace (HT) where it pierces HP, Vertical Trace (VT) where it pierces VP
    • Tool bar: GUI element in CAD containing icons for quick access to drawing, editing, dimensioning commands (e.g., Draw, Modify, Standard toolbars)
    • View ports: Bounded display areas in CAD allowing users to view a model from different angles/perspectives simultaneously (top, front, isometric) in model space or paper space