Standard Grade Graphic Communication

Transcription

1 Standard Grade Graphic Communication This is an assessment guide for the use of 3D CAD modelling software in of the Illustration & Presentation element Rationale It is important to recognise that, while the use of 3D CAD modelling software is now permitted in the Illustration & Presentation element of the Standard Grade Course, it is not compulsory. Centres may decide to continue using 2D CAD software, move to 3D software or use both types of package. There is no advantage in using one type over the other at Standard Grade. Those centres who already use 3D modelling software with Higher or Advanced Higher students may wish to move to a single CAD platform and introduce students to 3D software earlier. This assessment guide will support teachers who intend moving to a 3D CAD platform and will provide advice for those considering the move. 3D CAD Modelling software The drawings of a clock on the left hand side of the page were produced by students using 3D modelling software. The CAD commands used have been listed along with a description of the degree of difficulty and the grade achieved. A comparison with existing 2D CAD software is also provided; this is shown on the right hand side of the page and comprises drawings of a similar clock. Assessment criteria Please note that the criteria for assessment at each level have not changed and the rules of thumb are as follows: Foundation level - General level - Credit level - Isolated orthographic (2D) view of a simple artefact, showing main dimensions. Related orthographic views with dimensions or a pictorial drawing of a simple artefact. Including dimensions. Related orthographic views or a pictorial drawing of a complex artefact. Including dimensions and textual information. The two crucial factors when assessing within levels are the complexity of the drawings and the quality of production. This includes adherence to British Standards. Please consider these factors after studying the EGRC when you assess work in all elements of the Illustration & Presentation portfolio. Note also that either orthographic drawings or pictorial drawings confirm the grade; though it is good practice to encourage students to complete both. 2D Draughting software The drawings of a clock on the right hand side of the page were produced using 2D CAD software. These provide a comparison to the 3D examples on the left hand page. In each case the time taken to produce the drawings is almost the same for both methods (3D and 2D). The degree of difficulty, using 2D or 3D software, is also very similar as are the CAD commands used to complete the drawings; these have been listed beside each step. Foundation level grade 5 The student has completed one 2D sketch/drawing and part-completed another. The completed drawing is accurate and construction lines have been used to draw it. The accuracy and this level of complexity points to a grade 5 assessment. Dimensions have also been added. These dimensions are not for viewing but are required in order to draw the shape accurately. They do not conform to BS in terms of position but they don't need to at this stage. The student is given credit for having used dimensions and is not penalised for the lack of conformity. CAD commands used include: select workplane, draw line, draw box, draw circle, construction line, trim, attach and dimensioning. Foundation level grade 6 The second 2D drawing is part of the clock face that remained incomplete. It is simplistic and while it provides supporting evidence it does not enhance the grade. On it s own this second drawing would be assessed at grade 6. The student failed to progress his work any further than these two drawings. The teacher took screen prints to provide evidence for verification mm mm mm Foundation level grade 6 Single orthographic view with dimensions. It has several errors and represents the bare minimum required at grade 6. grid, snap, line, circle, auto- CAD Commands used: dimension. Foundation level grade 5 The single view is almost complete and has only a few minor errors. Complexity and quality is appropriate at grade 5. Additional CAD Commands used: none, but the accuracy is better than the previous example and there are fewer errors.

2 At this stage components have been created and are now solid 3D models. No orthographic views have been projected but the 3D models can be printed and would be assessed at General level grade 4. The 2D example introduces related orthographic views at a non-complex level. Dimensions have been added but these are not configured to BS and there are no centre lines or hidden detail in this example. Additional CAD commands used: none, but a related view is added. Note that in this example the initial drawings for each 3D model are relatively simple. This project is differentiated and the example here is targeted towards students hoping to do well at general level. Additional CAD commands include: select face, new sketch, extrude. Degree of complexity is crucial to the assessment. If any of these single components was more complex, the assessment may be enhanced. Here the single component clock body has been projected as related orthographic views and an isometric drawing. Very little additional work has been done by the student. There are no centre lines, hidden detail or view titles and the default sheet settings remain. Dimensions are required at all levels and there are none in evidence here. However, the teacher can determine whether the student has made use of dimensions to create the initial 2D sketches/drawings. project orthographic views. This pictorial drawing has a degree of complexity that would gain a grade 3 if it is completed correctly and accurately, the addition of hands and a recessed base point to this, but there are obvious errors in this example that confirm a grade 4. Additional CAD commands used: grid, snap, fillet. isometric

3 Here the clock is complete and the 3D model is assessed at. A single component or a simple assembly is adequate. Note the pictorial view can be printed as a solid model or a wire frame model. Or, as most centres do, added as a line drawing to the layout on related orthographic drawings (below). The orthographic views below are more complex that those at grade 4 and include one hidden detail line and more dimensions. There are errors in applying BS to dimensions. It is always good practice to print models in the form of line drawings for assessment in topic (g) CAD. Orthographic & Pictorial line drawings This represents two assessable drawings. The grade can come from either the pictorial view or from the orthographic views. Orthographic views and an isometric line drawing are projected. Some centre lines have been added but dimensions do not conform to BS and there is no hidden detail. The minimum use of text is evident and the default page border and title block remain unchanged. Note that this version of the clock is a less complex than the credit level version on the next page. Worksheets have been used and these have been differentiated. This clock has simpler hands than are used in the Credit level version and lacks detail such as a raised rim and an array on the clock face. component, centre axis, mate, align, project orthographic views, centre line, auto dimensioning, text. fix This pictorial drawing has been tackled in a more methodical way than the previous example. It is still relatively simple in construction (the flat face etc) and is incomplete but it is certainly worthy of assessment at grade 3. Additional CAD commands used: none but the commands employed have been used effectively and accuracy has improved.

4 Credit level grade 1 The clock here targets credit level students and is a little more complex than the previous version. It features a circular array and a raised rim on the clock face and the hands are more complex. Some student design modifications may be included but none have been added here. Rounds and chamfers could also be added. The components have been accurately drawn and constructed using simple extrusion modelling techniques. Rotational modelling may also be used but there is no need to carry out a variety of modelling techniques. Credit level grade 1 The evidence below represents two assessable pieces of work: Related orthographic views and a pictorial view. Each is assessed at grade 1. The clock design is more complex that those presented at general level. The complexity is appropriate to this level and British Standards are applied correctly. Also, the quality and accuracy of work are excellent. Additional CAD commands used: add text, radial and diametric dimensions, centre line, chamfer, fillet, ring array. Datum lines are identified and used in dimensioning. Hidden detail is correct and complete. Orthographic & Pictorial line drawings This represents two assessable drawings. The top grade can come from either the pictorial view or from the orthographic views. Features that confirm grade 1 are as follows: Orthographic views Complexity of the drawing (including a ring array and more complex clock hands on this example). Accuracy in drawing and assembly. Correct use of British Standards in dimensioning. Centre lines added. Hidden detail added. Titles and textual information included. Customised border and title block created. The isometric drawing can also be assessed at the top grade. Again the complexity of the components and the accurate construction are crucial indicators. Note: the clock may be drawn as a single component or a simple assembly. circular array, set sheet scale, set to British Standards, centre lines, hidden detail, use of datum line, dimensioning radius, diameter and linear, add text, as well as adding a customised title block and border.

5 CAG Illustration CAG Illustration Using 3D CAD software in a CAD Library drawing. Topic (h) Use of a CAD Library. Most 3D modelling packages provide the capacity to render or attach materials to 3D models. This is not a requirement at Standard Grade. However, in preparing students for Intermediate and Higher Courses, centres can offer this extension to the work and include the resulting illustration in a display that can be used in topics: (a) 2D & 3D Graphs & Charts (d) Layout & Lettering (e) Display (i) CAG for display The clock on the right was rendered in a 3D modelling package and exported to a DTP package where it was incorporated into the display below. This will be used in the portfolio to provide evidence for topics: (d) Layout & Lettering (e) Display (i) CAG for display. CRAFTED CLOCKS Our quality hand crafted clocks are made from locally sourced timber. The mechanism keeps perfect time. It is not possible to determine the student s input from looking at a hard copy of a library drawing. The EGRC guidance is as follows: Foundation level: The student should use a CAD Library of standard symbols and components. General level: The student should manipulate a CAD Library of standard components to produce a simple drawing or diagram. Credit level: The student should create additional symbols or icons for a CAD Library and manipulate them to produce a drawing or diagram. Accordingly, the composite library drawing shown here could be assessed at General or Credit levels depending on the student s input; in fact a Credit grade 1 has been achieved. Assessment The teacher should first determine the level that the drawing falls in. Thereafter, the quality and complexity of the drawing fix the assessment within the level. The teachers should explain the student s input by recording notes in the space provided on the Internal Assessment Flyleaf. The drawing here was produced using 3D modelling software. Some of the icons were predrawn (walls, windows and doors) and stored in a library file by the teacher for students to access. Students then completed the composite drawing by creating several icons of their own. These were drawn to scale and stored in their own library file before being dropped onto the floor plan to be rotated and positioned. Recommendations 1. When creating a folder to store their work in, instruct the students to call it CAD Library. Icons can then be stored in this folder and pulled in as required to a composite (library) drawing. This will help students to understand the term CAD Library. 2. Select a suitable project for CAD Library drawings. Keep it separate from the material produced for topic (g) Computer-aided Draughting. 3. Tackled early in the Course it can be a useful way of introducing students to simple 3D modelling techniques.