HigherQuestions

GraphicCommunication

CADKnowledge and understanding of the use ofcomputer programs to create two- or three-

dimensional (2D or 3D) graphical representations ofphysical objects

5.

Preliminary sketches of a tap body and an assembled 3D CAD model of thetap are shown above.

(a) Describe, with reference to 3D CAD modelling techniques, how the tapbody can be modelled. You should make references to the dimensionsshown above. 3

5. (continued)

Preliminary sketches of the neck of the tap are shown above.

(b) Describe, with reference to 3D CAD modelling techniques, how the neckof the tap can be created and hollowed to allow water to flow throughit. 2

5. (continued)

A partially assembled 3D model of the tap is shown in Fig 1 above.

The tap components shown in Fig 2 above were created using a “bottom up”approach.

(c) Describe “bottom-up” CAD modelling. 2

Fig 1

Fig 2

5. (continued)

(d) (i) Describe, with reference to constraints, how the neck and bodycomponents of the tap will be assembled.

(ii) Describe, with reference to constraints, how the control lever andbody components of the tap will be assembled.

2

2

Threaded bolt

Elevation

a) Describe, with reference to 3D CAD modelling techniques, how the boltcan be modelled. You should make references to the dimensions

shown above.

Pictorial view

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2. The sketches below were used by a CAD technician to create a 3D model of aportable speaker casing. The 3D model will be used to make productiondrawings and a promotional illustration.

Orthographic sketch

The CAD technician sketched a modelling plan before creating the 3D model.The first two stages of the modelling plan are shown below.

(a) Describe the 3D modelling techniques proposed for each stage, makingreference to all relevant dimensions from the orthographic sketch. Youcan sketch, annotate the sketches provided and/or use text in youranswer.

(i)

(ii)

22

22

2. (continued)

Component parts of theportable speaker casing

Solid model of theportable speaker casing

A solid model of the portable speaker casing and the two componentsgenerated from it are shown above.

(b) Describe, using a “top-down” approach, the techniques used to createthe two component parts from the solid model. You can sketch,annotate and/or use text in your answer. 4

2. (continued)

Speakergrills

Front caseRear case

Fixing screws

Rings

The components of the speaker casing are shown above.

The fixing screws were imported from a CAD library.

(c) Explain why this type of component would be included in a CAD library. 2

2. (continued)

The two component parts of the portable speaker casing need to beassembled within the CAD software.

(d) Outline the 3D modelling techniques used to fully constrain the twocomponent parts. You may use annotated sketches to support youranswer if you wish. 2

5 (a) Descriptions will make references to appropriate modellingtechniques and will be correctly (and sequentially) ordered.

Either:1. Three profiles — 40 mm square, diameter 60mm, diameter

60 mm (1 mark)2. Loft (1 mark)3. Offset work planes — 240 mm with middle plane at 120 mm

(1 mark)or:

1. Two profiles — 40 mm square, diameter 60 mm (1 mark)2. Loft (1 mark)3. Offset work plane — 120 mm and mirror feature (1 mark)

3 Three correct techniques and all in correct order,3 marks.

Two correct techniques and both in correct order,2 marks.

One correct technique and in correct order,1 mark.

Three correct techniques, with any out of order,2 marks.

Two correct techniques, with either out of order,1 mark.

5 (b) Descriptions will make references to:

“Sweep along a path” and “shell.”

2 Two references at 1 mark each.

5 (c) The description will be similar to:

“Bottom-up CAD modelling involves the creation of individualcomponents and subsequent assembly, using appropriatecontraints.”

2 1 mark for the reference to creating individualcomponents.

1 mark for the reference to assembling thesecomponents and the use of constraints.

5 (d) (i) The description will include references to:

align, align, mate

or

mate, mate, mate

or

centre axis, centre axis, mate

2 In each case, 1 mark for referencing the correctsurfaces of components and 1 mark forreferencing the constraints.

5 (d) (ii) Centre axis (1 mark) and mate (1 mark).