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JCE Technical Drawing practice questions

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Question 1Geometric Construction

In a standard title block, which item identifies the person who produced the drawing itself?

  1. Checked by
  2. Scale
  3. Drawn by Correct answer.
  4. Approved by

Explanation

A title block normally separates responsibility fields: the drafter's name is entered beside 'Drawn by', the checker signs 'Checked by', and the authorising engineer signs 'Approved by'. Scale is a separate field giving the ratio of drawing to real size, not a person. Recording each role separately allows later tracing of who created and who verified the sheet.

Question 2Geometric Construction

A drawing is marked 'Scale 1:50'. What does this mean?

  1. The object is fifty times smaller than the paper
  2. One unit on the paper represents 50 of the same units on the object Correct answer.
  3. Fifty units on the paper represent one unit on the object
  4. The drawing has been enlarged fifty times

Explanation

A scale of 1:50 is a ratio of drawing length to real length, so one millimetre measured on the sheet corresponds to fifty millimetres on the actual object. This is a reduction scale, typical for building plans. Enlargement scales such as 5:1 work in the opposite sense.

Question 3Geometric Construction

Which line type is used for the visible outlines and edges of an object?

  1. Continuous thick line Correct answer.
  2. Long-dashed thin line
  3. Chain thin line
  4. Continuous thin line

Explanation

Visible outlines and visible edges are drawn with a continuous thick line, the heaviest line on a technical drawing. Thin continuous lines serve dimension, extension and hatching purposes. Dashed and chain lines indicate hidden detail and centre or symmetry axes respectively.

Question 4Geometric Construction

What is the purpose of a centre line drawn as a chain thin line through a circle in orthographic views?

  1. To indicate the axis of symmetry and the centre of the associated features Correct answer.
  2. To mark the cutting plane of a section
  3. To delimit the boundary of a removed detail
  4. To show a visible edge of the hole

Explanation

Chain thin lines are used for axes of symmetry, centre lines of circles and axes of cylinders, and they extend slightly beyond the feature outline. They establish the geometric centre from which radii and diameters are dimensioned. They never represent a physical edge of the part.

Question 5Geometric Construction

Which statement describes the correct use of a T-square on a drawing board?

  1. The blade is used freehand without reference to the board edge
  2. The stock is held against the paper edge to draw inclined lines
  3. The stock is held against the board's working edge so the blade gives horizontal lines Correct answer.
  4. The blade is held against the working edge so the stock gives vertical lines

Explanation

The stock of a T-square registers against the true edge of the drawing board, and the blade then lies horizontal, providing a reference for horizontal lines and for supporting set squares. Vertical and inclined lines are produced by combining the T-square with set squares rather than by re-orienting the stock.

Question 6Geometric Construction

Which set square combination produces an angle of 75 degrees?

  1. Two 45-degree edges added together
  2. 30-degree and 60-degree edges added together
  3. 45-degree and 60-degree edges subtracted
  4. 45-degree and 30-degree edges added together Correct answer.

Explanation

Angles obtainable with set squares come from sums and differences of 30, 45, 60 and 90 degrees. Adding a 45-degree edge to a 30-degree edge gives 75 degrees, which is why 75 degrees is a standard constructible angle. Subtracting 45 from 60 gives 15 degrees, another standard angle.

Question 7Geometric Construction

What does a dimension of 'R25' on a drawing specify?

  1. A spacing of 25 units between centres
  2. A chamfer of 25 units
  3. A diameter of 25 units
  4. A radius of 25 units Correct answer.

Explanation

The prefix R denotes radius, so R25 means an arc or circle of 25 units radius measured from its centre. Diameters are marked with the diameter symbol or the prefix DIA depending on the standard. Chamfers and centre distances use different notations entirely.

Question 8Geometric Construction

Which statement best describes the function of a border and frame on a drawing sheet?

  1. It defines the working area and protects the drawing content from trimming Correct answer.
  2. It gives the scale and units used
  3. It records the revision history of the sheet
  4. It identifies the projection symbol in use

Explanation

The frame is drawn inside the trimmed edge so that no drawn content is lost when the sheet is cut or filed, and it encloses the working area. Revision history, scale and projection symbols are separate title-block entries. The frame is purely a layout control.

Question 9Geometric Construction

A line 84 mm long is to be divided into seven equal parts using the geometric method. What is each part length?

  1. 7 mm
  2. 14 mm
  3. 10.5 mm
  4. 12 mm Correct answer.

Explanation

Dividing a line into equal parts means each part equals total length divided by the number of parts, so 84 divided by 7 gives 12 mm. The geometric construction using an inclined auxiliary line and parallels achieves exactly this subdivision without measuring each segment. The construction is used when the division is not a convenient decimal.

Question 10Geometric Construction

To bisect a straight line AB with compasses only, where must the arcs be struck?

  1. From A and from B with equal radii greater than half of AB Correct answer.
  2. From A only, with a radius equal to AB
  3. From A and from B with equal radii less than half of AB
  4. From the midpoint of AB with any radius

Explanation

Equal arcs struck from both endpoints intersect above and below the line only when the radius exceeds half the line length. The line joining the two intersections is the perpendicular bisector. Radii smaller than half the line produce arcs that never meet.

Question 11Geometric Construction

Which construction produces a perpendicular to a line at a given point on it?

  1. Draw a 45-degree line through the point and rotate it
  2. Draw a parallel line and offset it by the required distance
  3. Bisect the line and join the midpoint to the point
  4. Strike equal arcs either side of the point, then intersect arcs from those two marks Correct answer.

Explanation

Marking equal distances on both sides of the point creates two symmetric centres, and equal arcs from them intersect on the perpendicular through the point. The method relies on symmetry about the given point. It works for any point lying on the line, including points near the ends.

Question 12Geometric Construction

How is an angle of 60 degrees constructed with compasses from a given line and point?

  1. Divide a semicircle into five equal parts and take two
  2. Add a 30-degree set square angle to a 15-degree angle
  3. Strike an arc from the point, then with the same radius mark from the intersection on the line and join Correct answer.
  4. Bisect a right angle twice

Explanation

An arc of any radius centred at the vertex cuts the line at a point; stepping the same radius from that point onto the arc locates a second point, and the line from the vertex through it makes 60 degrees. The construction works because the resulting triangle is equilateral. It requires no protractor.

Question 13Geometric Construction

A regular hexagon is constructed on a circle of diameter 60 mm. What is the side length of the hexagon?

  1. 42 mm
  2. 60 mm
  3. 30 mm Correct answer.
  4. 15 mm

Explanation

In a regular hexagon the side length equals the circumradius, which is half the diameter, giving 30 mm. This is why stepping the compass radius six times around the circle divides it exactly. The relationship holds for every regular hexagon regardless of size.

Question 14Geometric Construction

Which method correctly constructs a regular pentagon inside a given circle?

  1. Draw five tangents at 72-degree intervals to the circle
  2. Bisect the circle into ten parts and join alternate points
  3. Step the radius around the circumference five times
  4. Divide the vertical diameter into five parts, strike an arc from the top to the horizontal centre line, then step that chord around Correct answer.

Explanation

The standard construction divides a diameter into five equal parts, uses an arc from the upper end of the diameter to locate a point on the horizontal centre line, and the distance from that point to the circle centre gives the pentagon chord. Stepping this chord around the circle locates the five vertices. Simply stepping the radius gives six divisions, not five.

Question 15Geometric Construction

What is the first step in constructing a regular octagon inscribed in a given circle?

  1. Draw two diameters at right angles and bisect the four right angles Correct answer.
  2. Draw one diameter and divide it into eight parts
  3. Draw a square circumscribing the circle
  4. Step the radius around the circle eight times

Explanation

An inscribed octagon is obtained by drawing two perpendicular diameters to fix four vertices and bisecting each right angle at the centre to fix four more. The eight radii thus obtained are 45 degrees apart. Dividing a diameter into eight parts does not locate vertices on the circumference.

Question 16Geometric Construction

An ellipse has a major axis of 100 mm and a minor axis of 60 mm. Which statement about its construction is correct?

  1. The foci lie on the minor axis 40 mm from the centre
  2. The foci lie 50 mm from the centre on the major axis
  3. The foci coincide with the ends of the major axis
  4. The foci lie on the major axis 40 mm from the centre Correct answer.

Explanation

For an ellipse the focal distance from the centre satisfies c squared equals a squared minus b squared, with a equal to 50 mm and b equal to 30 mm. This gives c equal to 40 mm, measured along the major axis. The foci always lie on the major axis, inside the ellipse.

Question 17Geometric Construction

In the concentric-circle method for drawing an ellipse from its axes, what is drawn first?

  1. A rectangle enclosing the axes
  2. Two equal circles tangent to each other
  3. Two concentric circles with diameters equal to the major and minor axes Correct answer.
  4. A parabola through the axis ends

Explanation

The concentric-circle method starts with two circles centred on the axes crossing, with diameters equal to the major and minor axes. Radii are drawn at intervals and horizontal and vertical projectors from the circle intersections give points on the ellipse. The points are then joined with a smooth curve.

Question 18Geometric Construction

A parabola is constructed from a directrix and a focus 40 mm apart. Which property defines every point on the curve?

  1. Its distance from the directrix is always 40 mm
  2. Its distance from the focus plus its distance from the directrix is constant
  3. Its distance from the focus equals its distance from the directrix Correct answer.
  4. Its distance from the focus equals twice its distance from the directrix

Explanation

A parabola is the locus of points equidistant from the focus and the directrix, and this definition underlies the construction using a series of parallel lines and arcs. The constant-sum property belongs to the ellipse, and the constant-difference property to the hyperbola. The 40 mm separation fixes the focal parameter, not the locus distances.

Question 19Geometric Construction

A line is to be divided in the ratio 3:5 by geometric construction. How many equal divisions are marked on the auxiliary line?

  1. 5
  2. 15
  3. 3
  4. 8 Correct answer.

Explanation

Ratio division uses an auxiliary line divided into a number of equal parts equal to the sum of the ratio terms, here 3 plus 5 giving 8. The parallel through the eighth division closes the construction, and the parallel through the third division cuts the line in the required ratio. Marking only 5 parts would give a different subdivision.

Question 20Geometric Construction

Two circles of radii 25 mm and 15 mm have centres 50 mm apart. Which statement about their common tangents is correct?

  1. No common tangent can be drawn
  2. Only one common tangent exists in total
  3. The external tangents intersect between the two circles
  4. Two external tangents exist and the internal tangents also exist because the circles are separate Correct answer.

Explanation

Because the centre distance of 50 mm exceeds the sum of the radii, 40 mm, the circles are external to each other and both pairs of common tangents exist. External tangents meet outside the circles on the side of the smaller circle, while internal tangents cross the line of centres between the circles. Tangent construction depends on this distance comparison.

Question 21Geometric Construction

An arc of radius 40 mm is to be drawn tangent internally to two straight lines meeting at 90 degrees. Where does its centre lie?

  1. On one of the lines, 40 mm from the vertex
  2. On the bisector of the angle, 40 mm measured perpendicular to each line Correct answer.
  3. On the bisector of the angle, 40 mm from the vertex
  4. At the vertex of the angle

Explanation

A circle tangent to both sides of an angle has its centre on the angle bisector, at a perpendicular distance equal to the radius from each line. Along the bisector that distance corresponds to a greater distance from the vertex, namely 40 mm multiplied by the square root of two for a right angle. Placing the centre 40 mm from the vertex would make the arc cut the lines rather than touch them.

Question 22Geometric Construction

A regular polygon is constructed on a given side using the general method based on a semicircle. What does the semicircle provide?

  1. The centres from which the circumscribing circle of each polygon is drawn Correct answer.
  2. The apothem of each polygon
  3. The interior angles of each polygon directly
  4. The side lengths of each polygon

Explanation

In the general method a semicircle is erected on the given side and divided into a number of equal parts matching the polygon, and lines from the division points locate the centres of the circumscribing circles for polygons of increasing numbers of sides. Each centre then gives the circle in which the polygon is completed from the given side. The semicircle does not itself give side lengths or angles.

Question 23Geometric Construction

A cycloid is to be drawn for a generating circle of diameter 50 mm rolling on a straight line. What is the length of the straight line over one complete revolution?

  1. 100 mm
  2. Approximately 157 mm Correct answer.
  3. Approximately 79 mm
  4. 50 mm

Explanation

One revolution of a rolling circle traces a path whose base length equals the circumference, given by pi times the diameter, so about 157 mm for a 50 mm diameter. The construction divides both the circle and this base line into the same number of equal parts. Using the diameter or twice the diameter as the base is a common error.

Question 24Geometric Construction

When constructing tangents from an external point to a circle, why is the midpoint of the line joining the point to the circle centre used?

  1. It gives the radius of the given circle
  2. It marks the point of tangency itself
  3. It locates the intersection of the two tangents
  4. It is the centre of the circle whose diameter is that line, which passes through the tangent points Correct answer.

Explanation

The angle between the radius to a tangent point and the tangent line is a right angle, so the tangent points lie on the circle with the external point and the centre as a diameter. Thales' theorem then places them on that circle. The midpoint of the joining line is therefore the centre of the auxiliary circle used to find the tangent points.

Question 25Geometric Construction

In third-angle projection, where is the view from above placed relative to the front view?

  1. To the right of the front view
  2. Above the front view Correct answer.
  3. Below the front view
  4. To the left of the front view

Explanation

Third-angle projection places each view on the same side as the direction from which it is seen, so the top view sits above the front view and the left-side view sits on the left. First-angle projection reverses this arrangement. The projection symbol in the title block distinguishes the two systems.

Question 26Geometric Construction

A drawing sheet is described as A2. Which statement gives its standard trimmed size?

  1. 594 mm × 841 mm
  2. 210 mm × 297 mm
  3. 297 mm × 420 mm
  4. 420 mm × 594 mm Correct answer.

Explanation

The A series is based on a root sheet of 1 m² with sides in the ratio 1:√2, and each size is obtained by halving the preceding longer side. A0 is 841 mm × 1189 mm, so A1 is 594 mm × 841 mm and A2 is 420 mm × 594 mm.

Question 27Geometric Construction

A line 96 mm long is to be divided into twelve equal parts by the geometric method. What is the length of each part?

  1. 9.6 mm
  2. 6 mm
  3. 12 mm
  4. 8 mm Correct answer.

Explanation

Dividing a line geometrically into twelve equal parts means the total length is shared equally between twelve divisions. 96 mm divided by 12 gives 8 mm per part, and this equals the spacing between consecutive division points.

Question 28Geometric Construction

Which pencil grade is most suitable for drawing the final visible outlines on a technical drawing?

  1. 2B
  2. HB
  3. 2H Correct answer.
  4. 6H

Explanation

Final outlines must be dark, uniform and easy to reproduce, so a moderately hard pencil is used and sharpened to a fine cone. A 2H grade gives a crisp, dense line without smudging, which is why it is the conventional choice for visible outlines.

Question 29Geometric Construction

A drawing is to be produced at a scale of 1:20. A feature measuring 150 mm on the actual object should be drawn at what length?

  1. 3000 mm
  2. 300 mm
  3. 75 mm
  4. 7.5 mm Correct answer.

Explanation

A scale of 1:20 means one unit on the drawing represents twenty units on the object, so the drawing length equals the true length divided by 20. Dividing 150 mm by 20 gives 7.5 mm, a reducing scale drawing.

Question 30Geometric Construction

What does the abbreviation 'AF' in a dimension such as '25 AF' specify?

  1. The dimension is taken from the front view only
  2. The dimension is given across flats of a hexagonal or square feature Correct answer.
  3. The dimension is an allowable finishing tolerance
  4. The dimension is measured along the axis of the feature

Explanation

Across flats denotes the distance between two opposite parallel faces of a square or hexagonal feature, such as a nut or a machined hexagon. It is quoted because the spanner size is governed by this distance rather than by the corner-to-corner dimension.

Question 31Geometric Construction

A straight line AB is 70 mm long. Using the geometric method, where is the perpendicular bisector located?

  1. At 45 degrees to AB through its midpoint
  2. Through B, at 90 degrees to AB
  3. Through the midpoint of AB, at 90 degrees to AB Correct answer.
  4. Through A, at 90 degrees to AB

Explanation

The perpendicular bisector is the locus of points equidistant from A and B, so it must pass through the midpoint of AB and meet it at a right angle. Equal-radius arcs struck from A and B intersect above and below the line, and the line joining those intersections is the bisector.

Question 32Geometric Construction

An angle of 45 degrees is required with compasses only, starting from a straight line. Which construction sequence achieves it?

  1. Add a 30-degree and a 60-degree angle at the vertex
  2. Bisect a 60-degree angle constructed at the vertex
  3. Bisect a 90-degree angle erected at the vertex Correct answer.
  4. Trisect a 90-degree angle erected at the vertex

Explanation

A right angle can be erected at a point on a line with compasses, and bisecting that 90-degree angle gives two equal angles of 45 degrees. Trisecting an angle is not a compass-and-straightedge construction, so the bisection route is the valid one.

Question 33Geometric Construction

A regular hexagon is to be constructed on a given side AB using the compasses-only method. What radius is used for the arcs that locate the remaining vertices?

  1. Half the length of AB
  2. Twice the length of AB
  3. The length of AB Correct answer.
  4. The length of AB multiplied by √2

Explanation

In a regular hexagon the side length equals the circumradius, so the distance from the centre to each vertex equals AB. Striking arcs of radius AB from A and B locates the centre, and stepping the same radius around the circle gives all six vertices.

Question 34Geometric Construction

In the general method of constructing a regular polygon on a given side, a semicircle is drawn on the side and divided into equal parts. What is the purpose of the radial lines drawn from the division points?

  1. They locate the centre of the polygon by intersection with the perpendicular bisector Correct answer.
  2. They set the length of each side of the polygon
  3. They divide the polygon into equal-area triangles
  4. They establish the line of centres for the inscribed circles

Explanation

The semicircle is divided into as many equal parts as the polygon has sides, and radial lines are drawn to the numbered division points. The line from the second division point, extended to meet the perpendicular bisector of the given side, fixes the circumcentre, and the remaining vertices are stepped off from it.

Question 35Geometric Construction

Two circles have radii of 30 mm and 20 mm with centres 70 mm apart. How many common tangents can be drawn to them?

  1. Two
  2. Four Correct answer.
  3. One
  4. Three

Explanation

The circles are separate because the distance between centres, 70 mm, exceeds the sum of the radii, 50 mm. Separate circles always have four common tangents: two direct tangents that do not cross the line of centres and two transverse tangents that do.

Question 36Geometric Construction

An arc of radius 30 mm is to be drawn tangent internally to a circle of radius 50 mm. How far from the circle's centre must the arc's centre be placed?

  1. 80 mm
  2. 20 mm Correct answer.
  3. 30 mm
  4. 50 mm

Explanation

For internal tangency the distance between centres equals the difference of the radii, because the smaller arc lies inside the larger circle and touches it from within. Subtracting 30 mm from 50 mm gives a centre distance of 20 mm.

Question 37Geometric Construction

A cycloid is generated by a circle of diameter 40 mm rolling without slipping along a straight line. What is the length of the base line of the cycloid?

  1. 160 mm
  2. 80 mm
  3. 125.7 mm Correct answer.
  4. 40 mm

Explanation

One complete arch of a cycloid spans the circumference of the generating circle, since the circle makes one full revolution along the line. The circumference is π times the diameter, so π × 40 mm gives approximately 125.7 mm.

Question 38Geometric Construction

Which statement correctly describes the involute of a circle?

  1. It is the path traced by a point fixed to a circle rolling around a fixed circle
  2. It is the locus of points equidistant from a fixed point and a fixed straight line
  3. It is the path traced by a point on a straight line rolling without slipping on the circle Correct answer.
  4. It is the path traced by a point on a circle rolling without slipping along a straight line

Explanation

The involute is generated by unwinding a taut string from a circle, which is equivalent to a straight line rolling without slipping on the circle while a point on that line traces the curve. It is used for gear tooth profiles because the involute form gives a constant pressure angle.

Question 39Geometric Construction

A hyperbola is constructed from two foci 80 mm apart with a constant difference of focal distances of 30 mm. What is the distance between its vertices?

  1. 30 mm Correct answer.
  2. 15 mm
  3. 40 mm
  4. 80 mm

Explanation

For a hyperbola the constant difference of the distances from any point to the two foci equals the transverse axis, that is, the distance between the vertices. The given constant difference of 30 mm is therefore the vertex-to-vertex distance, while the focal distance of 80 mm fixes the foci.

Question 40Geometric Construction

A line 90 mm long is to be divided geometrically in the ratio 4:5. How is the auxiliary line used to achieve this?

  1. Nine equal divisions are marked on it and the ninth point is joined to the end of the given line
  2. Four equal divisions are marked on it and the fourth point is joined to the end of the given line
  3. Five equal divisions are marked on it and the fifth point is joined to the end of the given line
  4. Nine equal divisions are marked and the fourth is joined to the end of the given line Correct answer.

Explanation

The number of equal parts marked on the auxiliary line is the sum of the ratio terms, here 4 + 5 = 9. Joining the fourth division point to the far end of the given line and drawing parallels through the remaining points divides the line into parts in the ratio 4:5, giving 40 mm and 50 mm.

Question 41Orthographic Projection (First and Third Angle)

In a first-angle orthographic projection, where is the top view placed relative to the front view?

  1. To the right of the front view
  2. To the left of the front view
  3. Below the front view Correct answer.
  4. Above the front view

Explanation

First-angle projection places the object between the observer and the plane, so the view seen from above is projected onto the plane below the object. The top view therefore sits directly below the front view. This is the standard European arrangement.

Question 42Orthographic Projection (First and Third Angle)

In third-angle projection, the symbol that identifies the convention shows a truncated cone with the smaller circle nearer which element?

  1. The projection plane
  2. The ground line
  3. The observer Correct answer.
  4. The object

Explanation

The third-angle symbol depicts the cone as seen when the plane lies between observer and object, so the small end of the cone points toward the observer. The first-angle symbol reverses this orientation. Recognizing the taper direction identifies the convention quickly.

Question 43Orthographic Projection (First and Third Angle)

A drawing shows the side view placed on the left of the front view and the top view placed below the front view. Which convention is being used?

  1. Isometric projection
  2. First-angle projection Correct answer.
  3. Third-angle projection
  4. Oblique projection

Explanation

In first-angle projection the left-side view appears on the right and the right-side view on the left, while the top view falls below the front view. The combination of a side view on the left with the top view below is therefore first-angle. Third-angle would place the top view above and the side view on the side from which it is viewed.

Question 44Orthographic Projection (First and Third Angle)

What does the term 'front view' designate in an orthographic drawing set?

  1. The view showing the greatest overall length
  2. The principal view chosen to show the most characteristic shape Correct answer.
  3. The view drawn last in the sequence
  4. The view taken from directly above the object

Explanation

The front view is the principal elevation selected to display the most descriptive shape and the fewest hidden features. Other views are then projected from it. It is a choice of orientation, not a fixed geometric direction.

Question 45Orthographic Projection (First and Third Angle)

In first-angle projection, a hidden edge in a view is represented by which line type?

  1. A continuous thin line
  2. A chain line of short dashes
  3. A continuous thick line
  4. A dashed line of short evenly spaced strokes Correct answer.

Explanation

Hidden outlines and edges are drawn with dashed lines made of short strokes of equal length and spacing. Continuous thick lines are reserved for visible outlines. The convention is identical in first- and third-angle drawings.

Question 46Orthographic Projection (First and Third Angle)

Which statement correctly describes the position of the object relative to the projection plane in third-angle projection?

  1. The projection plane lies between the observer and the object Correct answer.
  2. The object lies between the observer and the projection plane
  3. The projection plane passes through the centre of the object
  4. The observer lies between the object and the projection plane

Explanation

Third-angle projection assumes a transparent plane placed between the observer and the object, so the view is projected onto the near face. This is why the top view appears above the front view. First-angle reverses this arrangement.

Question 47Orthographic Projection (First and Third Angle)

A drawing uses third-angle projection. A feature is visible when the object is viewed from the right side. On which side of the front view must this right-side view be placed?

  1. On the left of the front view
  2. On the right of the front view Correct answer.
  3. Above the front view
  4. Below the front view

Explanation

In third-angle projection each view is placed on the same side as the direction from which it is observed, because the plane lies between observer and object. A view seen from the right therefore appears to the right of the front view. First-angle would place it on the left.

Question 48Orthographic Projection (First and Third Angle)

In an orthographic layout, what is the purpose of the mitre line used with three views?

  1. To indicate the axis of symmetry of the object
  2. To mark the cutting plane of a section
  3. To transfer depths from the top view to the side view Correct answer.
  4. To separate the views with a border

Explanation

A mitre line drawn at 45 degrees at the corner between the top and side views lets a draughtsman project a depth from one view across to the other. It is a construction aid, drawn thin and often omitted from the finished drawing. It ensures the two views agree in depth.

Question 49Orthographic Projection (First and Third Angle)

A cylindrical hole passes vertically through a rectangular block shown in first-angle projection. How does the hole appear in the top view?

  1. As a rectangle of the hole diameter
  2. As a single centre line
  3. As a circle of the hole diameter Correct answer.
  4. As two parallel hidden lines

Explanation

Looking from above along the axis of a vertical hole, the opening is seen as a true circle at the hole diameter. The circle is drawn continuous if the rim is visible and dashed if obscured. The side views would show the hole as parallel hidden lines.

Question 50Orthographic Projection (First and Third Angle)

In a first-angle drawing, the view placed to the right of the front view represents which direction of observation?

  1. From above the object
  2. From the right side of the object
  3. From the left side of the object Correct answer.
  4. From below the object

Explanation

First-angle projection places each view on the far side of the object from the observer, so the view seen from the left is projected to the right of the front view. The view to the right is therefore the left-side view. This reversal is the key difference from third-angle layout.