CAD Modelling Questions

An audio technology company are producing a new record player. A CAD technician was tasked with creating the 3D model of the record player tonearm shown below.

a. Describe the 3D CAD modelling techniques used to create the main arm component, shown above. You may use sketches to support your answer. (7 marks)

Answers

a. One mark for each point

Sketch the path to the dimensions shown.
Turn on a perpendicular workplace and sketch a circle to 12mm, ensuring the centre of the circle lines up with the path.
Sweep the circle along the path.
On the front face, create a new circle and dimension it to 15 and extrude by 15.
Shell, removing front face, to 2mm.
On the front face, create a new profile circle to 2mm. Use a radial array to repeat the circle 8 times around 270 degrees
Extrude, Subtract the eight circles by 10mm

Question 2

A CAD technician is asked to change the counterweight 3D model from Design 1 to Design 2.a. Describe, with reference to the modelling tree, how the CAD technician can edit the counterweight 3D model to make the change to the design. You must make reference to the dimensions shown on the opposite page. (2 marks)

Answers

a. One mark for each point

Open workplane two on the modelling tree and edit the sketch.
Change the profile of the ellipse to a hexagon and set the dimension to 24 A/F

Question 3

An orthographic drawing of a cooker hood concept is shown below.

a. Describe the 3D CAD modelling techniques used to model the cooker hood. You must make reference to the dimensions given. You may use sketches to support your answer. (6 marks)

Answers

a. One mark for each point

Sketch a rectangle 700 x 560 and fillet all four corners to R50, extrude the shape 80mm
Sketch another rectangle on the top to 460 x 600
Offset a workplane by 260 mm from the rectangle and sketch a square on it 260 by 260mm
Loft the square to the rectangle
Sketch a rectangle 580 by 185 at 45 degrees and extrude 260mm
Shell removing the top, back and bottom faces with a wall thickness 20

Question 4

A 3D CAD model of a roof tile was produced for the redevelopment. Two stages in the production of this model are shown below.

a. Describe the 2D CAD techniques used to arrive from stage 1 to stage 2. You must make reference to the dimensions given. You may use sketches to support your answer. (3 marks)

Answers

a. One mark for each point

The trim tool is used to remove lines from hexagons
R15 fillet applied to correctly identified edges
Offset shape 12mm

Question 5

The CAD technician created the handle component in several stages. Dimensions for stage 1 of the 3D modelling process are provided on the working drawing below.

a. Describe, using CAD modelling techniques, how to create stage 1. You must refer to the dimensions given in the drawing. You may use sketches to support your answer. (3 marks)

Answers

a. One mark for each point

Draw an ellipse with a major size of 20mm and a minor size of 12mm
On a perpendicular workplane, sketch the path with the dimensions 70, 50, R77 and height of 24
Sweep the profile along the path

Question 6

Graphics for a toy are provided.

a. Describe the 3D CAD modelling techniques used to create the central support of the toy. You must refer to the dimensions given. You may use sketches to support your answer. (8 marks)

Answers

a. Extrude method - One mark for each point

Sketch a Ø16 circle and extrude 12, on top sketch a Ø10 circle and extrude 80 then a Ø16 circle and extrude 6mm
Fillet R3 on the top and bottom where the circles connect
Offset a plane from the bottom profile 4mm and sketched the shape shown on the plan – R12, trimmed to 10mm and extrude 4mm on both sides
Draw a Hexagonal (8 AC) on the very bottom surface and extrude, subtract 8mm
Turn on a centre plane running horizontally down the middle and draw a circle to a diameter of 2.5, 7mm from the edge of the Ø16 extrusion
Using a linear array, repeat seven times with a spacing of 11mm and extrude subtract them symmetrically all the way through.
Turn on a plane running down centre and draw the Profile for the radial array (6mm height, 5mm top line, 7mm bottom line) and extrude a thickness of 2.5 mm
Use of radial array, three repeats

Revolve method - One mark for each point

Draw a half profile with the following dimensions; 8, 12, 5, 80, 6, 8 with fillet R3 x 2
Revolve around centre axis
Offset a plane from the bottom profile 4mm and sketched the shape shown on the plan – R12, trimmed to 10mm and extrude 4mm on both sides
Draw a Hexagonal (8 AC) on the very bottom surface and extrude, subtract 8mm
Turn on a centre plane running horizontally down the middle and draw a circle to a diameter of 2.5, 7mm from the edge of the Ø16 extrusion
Using a linear array, repeat seven times with a spacing of 11mm and extrude subtract them symmetrically all the way through.
Turn on a plane running down centre and draw the Profile for the radial array (6mm height, 5mm top line, 7mm bottom line) and extrude a thickness of 2.5 mm
Use of radial array, three repeats

The top section can be lofted on the extrude or revolved method. Remove the last two points and use the marks below instead:

Top section can be lofted by creating the following sketches: 1 mark for two correct sketches shown below.
1 mark for offset plane (6mm) and loft command

Question 7

A drawing of the toy slide component is shown below.

a. Describe the single 3D CAD modelling technique used to create the slide component. You must refer to the dimensions shown in the orthographic drawing shown above. You may use sketches to support your answer. (4 marks)

Answers

Draw the profile shown on detail A with all dimensions (8, 3, 5 and 14)
Draw a centre axis 32 mm from the centre of the profile and fillet the edges of the profile by R1
Using helix, helix the profile around the axis
Set the pitch to 24mm, length (96mm) and 4 revolutions (any two for 1 mark)

Question 8

3D CAD illustrations and an exploded line drawing of a table lamp are shown below.

a. Describe the 3D CAD modelling techniques used to create the wing mirror component. To answer this question, you must refer to the dimensions shown in the drawings above. You may use sketches to support your answer (6 marks)

Answers

a. One mark for each point

Create a rectangle (200 x 120) and extrude by 30
Revolve the rectangle profile by 90° around the centre axis (60° from the edge)
Apply irregular fillet 60 at front to 30 at extruded side
Shell, removing end surface, with wall thickness 10
Sketch a circle at Ø80 with centre vertical 60 and horizontal 100 on side profile, offset a workplane 100 from the circle and sketch a square 50mm
Loft between profiles

Question 9

A client has requested that a small outdoor workshop is constructed. The graphics shown below were generated by a CAD technician during the planning stages of the project.

a. Explain, giving two reasons, why the CAD technician would use a CAD library when producing construction drawings for this project. (2 marks)

Answers

Reduce time required as symbols are not created repeatedly
Reduce the likelihood of CAD technicians making errors as parts or symbols do not need to be remodelled or redrawn
A library would contain all commonly used symbols, meaning they would be standardised or commonly understood
The library can be used by all CAD technicians in the company, meaning consistency across all drawings

Question 10

A set of production drawings for a stone bench has been produced by the CAD technician, as shown above. a. State the type of array used to produce the repeated feature shown in the elevation. (1 mark)b. Complete the table below to include the correct spacing for the array shown in the elevation. (2 marks)c. State the name of the 2D CAD tool used to ensure that the outer profile is the same shape as the inner profile on DETAIL A. (1 mark)

Answers

Box Array

Offset

Question 11

The production drawing for the stone bench leg is shown.a. Describe the 3D CAD modelling techniques used to create the stone bench leg. You must make reference to the dimensions shown in the 2D production drawing to answer this question. You may use sketches to support your answer. (8 marks)

Answers

Sketch the profile shown.

Extrude profile 480.
Sketch a square 280 shown, extrude subtract 100mm

Loft Subtract (c)

Sketch on top surface 380 x 30 and offset a workplane by 380 and sketch 280 x 30 on bottom
Loft subtract between profiles

Loft Subtract (d)

Sketch a profile 380 at the top, 280 at the bottom, 50 at the sides, and 380 tall.
Extrude subtract 30 from offset workplane 35 from front or back surface

Sketch the profile with all dimensions shown below.

Revolve the profile around the centre axis, ensuring there is a 60-degree gap as shown
Repeat symmetrically on both sides

Question 12

The coffee machine water reservoir component was created using 3D CAD modelling software. Steps in the modelling process are shown below.a. State the name of the modelling edit used between Step 1 and Step 2. (1 mark)

An error was made during the modelling process of the drip tray shown below.

b. Describe the change that needs to be made to the modelling tree to fix the error and achieve the expected end result. (1 mark)

Answers

Intersect

Move the shell before extrude subtract

Question 13

The production drawing for the coffee filter is shown. a. Describe the 3D CAD modelling techniques used to create the coffee filter. You must make reference to the dimensions shown in the 2D production drawing on the opposite page to answer this question. You may use sketches to support your answer. (6 marks)

Answers

a. 1 mark for each point unless otherwise stated

Sketch an ellipse (maj 60 and min 40), offset a plane 20mm and sketch a circle Ø60, offset a plane 30mm and sketch a circle at Ø70, offset another plane to 6mm and draw another circle at Ø70 (1 mark for all four correct profiles and 1 mark for all correct offset planes)
Loft all four profiles together
Shell to a wall thickness 3, removing top face
Sketch a profile on the top surface R40 and 35 wide and extrude it 6mm
On the bottom face, sketch a Ø20 circle and extrude, subtract 3

Question 14

The production drawing for the steam wand is shown below.

a. Describe the 3D CAD modelling techniques used to create the steam wand. You must make reference to the dimensions shown in the 2D production drawing on the opposite page to answer this question. You may use sketches to support your answer. (4 marks)

Answers

a. One mark for each point

Sketch a circle to Ø8 and Ø4, both having the same centre point
On a perpendicular workplane, sketch a path to the dimensions shown

Extrude the profile along the path
Sketch a circle with a Ø4 (R2) 10mm from the bottom and four mm from the centre axis and revolve around the central axis.

Question 15

An alternative design for the plastic cup component is shown below. The CAD technician decides to produce this component in two stages.

a. Describe the 3D CAD modelling techniques used to create the steam wand. You must make reference to the dimensions shown in the 2D production drawing above to answer this question. You may use sketches to support your answer. (4 marks)

b. The CAD technician adds additional features to allow the lid to lock into position, shown in red in Stage 2. Describe how, using only the ‘revolve’ 3D modelling technique, the CAD technician created the additional features. (4 marks)

Answers

a. One mark for each point

Create a 105mm, 10mm thick cylinder (extruded, revolved or lofted)
Sketch a 105mm circle, sketch a square 50mm
Workplane 110mm between the 105 mm diameter circle and the 50 mm square
Loft between a 105mm circle and a 50mm square
Shell to 4mm wall thickness, remove bottom face
Add ring to base, OD 113mm & ID 97mm, extruded 4mm Or loft between planes 4mm apart with OD113 & ID97 circles on both planes.

b. One mark for each point

Sketch the centre axis and a 14mm x 4mm rectangle in the correct position and revolve around the centre axis
The vertical workplane mentioned or profile sketch is shown on an elevation
Sketch R2 semi-circle 9mm from base (or 1mm from lip)
Revolve R2 semi-circle 30 degrees around the centre axis
Repeat sketch on the other side and 30 degrees in the opposite direction.

Question 16

The spring was modelled as a separate component using 3D CAD.

a. Describe the 3D CAD modelling technique used to model the spring. You must make reference to the dimensions given. (3 marks)

The leg was 3D CAD modelled as a single component.

The foot was 3D CAD modelled using the revolve command.

b. Describe the modelling edit used to complete the component from Stage 1 to Stage 2. (3 marks)

Answers

a. One mark for each point

Draw a circle with a diameter of 2.5 (radius 1.25), 8.75mm from the circle's centre to the axis line
Select Helix to coil the circle around the axis
Set the length of the spring to 50mm, with 5 revolutions at a pitch of 10mm.

b. One mark for each point

Draw profile with correct dimensions shown below.

Extrude subtract profile 10mm
Radial Array 12 times over 270 degrees.

Question 17

A clock has been 3D modelled using CAD software.

a. State the command used to produce the repeated feature shown in the elevation. (1 mark)

b. State what PCD stands for in the drawing above. (1 mark)The clock base component was created using 3D CAD modelling software. The initial steps in the modelling process are shown below.

c. State the name of the modelling edit used between Step 1 and Step 2. (1 mark)Two stages of the clock hand modelling process are shown below.d. Describe the 2D CAD techniques used to arrive from Stage 1 to Stage 2.

Answers

Radial Array

Pitch Circle Diameter

Intersect

Correctly identify where to trim
Mirror on a horizontal line
Offset of 2mm

Question 18

A CAD technician created 3D CAD components for the stationery holder. The drawing for the stationery holder top component is shown below.

a. Describe, using CAD modelling techniques, how to create the stationery holder top. You must refer to the dimensions given in the drawing. You may use sketches to support your answer. (6 mark)

Answers

Draw a circle with a diameter of 6, 30mm away from the centre axis (see sketch below). (1 mark)
Use the helix command (1 mark)
Set the revolutions to 12, pitch 10 or length to 120 (any two of three) (1 mark)
Project the geometry of the 6mm circle (1 mark)
Turn on a perpendicular plane and draw the path to the dimensions shown below. (1 mark)
Extrude sweep the circle along the path (1 mark)

Question 19

A drawing for the stationery holder base component was also produced. This is shown below.

a. Describe, using CAD modelling techniques, how to create the stationery holder base. You must refer to the dimensions given in the drawing. You may use sketches to support your answer. (7 marks)An additional 3D CAD edit was added to the base of the stationery holder. This is shown below at Stage 2.b. Describe, using CAD modelling techniques, how to create Stage 2. You must refer to the dimension given in the graphic. You may use sketches to support your answer (2 marks)

Answers

Sketch an ellipse (280 x 180) and extrude it 10mm (1 mark)
Offset a workplane 105 (1 mark)
Turn on a plane and offset it 85 from the back edge of the ellipse and sketch a 130mm circle (1 mark)
Loft the ellipse and circle together (1 mark)
Sketch a 104mm circle 121 from the centre of the 130 circle and extrude 62.3mm (1 mark)
Sketch a circle with a diameter 88 in the correct location and extrude, subtracting 45mm (1 mark)
Sketch a 6mm circle, including correct location (30, 26) and extrude subtract 30 (1 mark)

Shell with wall thickness 10 (1 mark)
Remove bottom face (1 mark)

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