436-105 Engineering Communications GL5:1 GL5: Visualisation and reading drawings Being able to both: represent a 3D object in multiview drawings interpret a multiview drawing to visualise a 3D object is important for all engineers, in: developing design ideas communicating design intentions to others understanding communications from other engineers
Graphical representation When we look at an object we see variations of texture, colour and brightness, not lines! GL5:2 limiting element edge Visual features (edges, limiting elements) are associated with discontinuities in these attributes we draw lines to represent these features
GL5:3 Geometric and visual features of solids Face Geometric: surface boundary of object between discontinuities of curvature Visual: continuous attribute, represented by plane Edge: Geometric: boundary between two faces Visual: discontinuity, represented by line Vertex Face Edge Face Vertex: Geometric: common termination of three or more edges Visual: meeting of edge discontinuities, represented by point Edge No vertices!
Fundamental views GL5:4 Lines seen in true length (TL) if parallel to projection plane seen as a point if perpendicular to projection plane an inclined line is seen in TL in one standard view an oblique line is foreshortened in all standard views TL TL
Fundamental views GL5:5 Planes seen in true shape (TS) if parallel to projection plane seen as a line if perpendicular to projection plane an inclined plane is seen as a line (edge view) in one standard view an oblique plane is similar in all standard views TS edge view
Views of lines and planes B is // to horiz. plane E is an oblique plane E is a triangle in all views TS view of B Edge view of D GL5:6 Foreshortened view of D Bertoline Fig. 8.78 D is inclined to horiz. plane A is // to frontal plane TS True Shape/Size (TS) view of A
GL5:7 Solid primitives Most engineered objects can be contructed using simple shapes, which have familiar multiviews
Further examples GL5:8 See Bertoline fig. 8.47 for more examples inclined face seen on edge
Intersecting planes GL5:9 Lockhart & Johnson, fig. 4.40, 41
Tangent planes GL5:10 No visible line Lockhart & Johnson, fig. 4.40, 41
More tangent planes GL5:11 No line No lines Lockhart & Johnson, fig. 4.41
Fillets and rounds GL5:12 fillet round fillet round Lockhart & Johnson, fig. 4.46
Lockhart & Johnson, fig. 4.44 But, tangency lines may be required for clarity... GL5:13
GL5:14 Intersecting cylinders Lockhart & Johnson, fig. 4.42
GL5:15 Intersecting cylinders... Intersection lines are straight if diameters are equal Lockhart & Johnson, fig. 4.42
Aids to interpretation: surface labelling Label surfaces on pictorial view before drawing multiviews Then label projections of surfaces to check for consistency of representation GL5:16 Bertoline Fig. 8.75
Visualisation by solids Technique for interpreting multiview drawings. Identify and label solid primitives A, B,... Label planes P, holes H, cylinders C Draw projection lines connecting features Check hypotheses about solid primitives GL5:17 Bertoline Fig. 8.78
See Bertoline 8.8.8 for detailed case study GL5:18
Summary: Bertoline's principles of orthographic projection GL5:19 Alignment of features Every point or feature in one view must be aligned on a parallel projector in any adjacent view Vertical parallel projectors Horizontal parallel projectors
Distances in related views Distances between any two points of a feature in related views must be equal GL5:20 2 2
True length and size Features are true length or true size when the lines of sight are perpendicular to the feature GL5:21 TL TL TS edge view
Foreshortening Features are foreshortened when the lines of sight are not perpendicular to the feature GL5:22 TS edge view
Configuration of planes Areas that are the same feature will always be similar in configuration from one view to the next, unless viewed on edge GL5:23 TS edge view
Parallel features Parallel features will always appear parallel in all views Edge views Surfaces that are parallel to the lines of sight will appear as lines or edge views GL5:24 TS edge view
Exercise: Bertoline prob 8.5(13) Given incomplete multiviews, add missing lines and sketch pictorial view GL5:25
Exercise: Bertoline prob 8.5(13) GL5:26 1. Form initial hypotheses about surfaces 2. Check alignment of features 3. Insert missing lines in side view
Exercise: Bertoline prob 8.5(13) GL5:27 4. Block in pictorial of prismatic billet 5. Cut slot through billet
Exercise: Bertoline prob 8.5(13) GL5:28 6. Identify and draw in top horizontal, and front & side vertical faces 7. Draw in outer edges of top inclined face
Exercise: Bertoline prob 8.5(13) GL5:29 8. Find intersection of vertical slot and top inclined face
Exercise: Bertoline prob 8.5(13) GL5:30 9. Complete edges of top inclined face 10. Draw edges of vertical slot faces
GL5:31 Follow up Read Bertoline: Chapter 5, 8.8 Do problems from Bertoline: Probs 5.15-17, 8.3, 8.5(1)(9)