Isometric Projection Drawing -...

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Isometric Projection DrawingCHAPTER 6

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MEMB113 | MANUAL DRAWING | CHAPTER 6MEMB113 | MANUAL DRAWING | CHAPTER 6

ContentContent

•Overview–Pictorial projection–Parallel projection–Axonometric projection

•Isometric projection–Axes and selection–Isometric lines and planes–Isometric scale–Isometric projection & Isometric drawing

•Producing Isometric sketches & drawing–Isometric lines & non-isometric lines–Circles and arcs–Irregular curves

•Oblique projection drawing

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6.16.1 Pictorial projectionPictorial projection

•Pictorial projection:–Not intended to give

exact or true view–Not intended to

transmit dimensions, although sometimes dimension is useful

–Useful when the information and instructions to be given to non-technical and untrained people

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6.16.1 Parallel projection techniqueParallel projection technique

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6.16.1 Axonometric projectionAxonometric projection

•axon = axis; metric = measure, in Greek•Axonometric projection is a parallel

projection technique to create a pictorial drawing of an object by rotating the object on an axis relative to a projection or picture plane

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•Axonometric projection–Trimetric–Dimetric–Isometric

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6.26.2 Isometric projectionIsometric projection

•Isometric projection is a true representation of the isometric view of an object

•Isometric view is created by rotating the object 45 degree about vertical axis, and tilting it forward 35 deg 16’

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6.26.2 Isometric projection: axesIsometric projection: axes

•The 3 axis meet at A,B form equal angles of 120 deg and they are called Isometric Axes

•OA is vertical, OB is inclined at 30deg to the right, OC is inclined at 30deg to the left

•Any lines parallel to these –Isometric Line•Any planes parallel –Isometric Planes

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6.26.2 IsoIso--lines & lines & IsoIso--planesplanes

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6.26.2 Selection of Isometric AxesSelection of Isometric Axes

•Main purpose of isometric view is to provide a pictorial view which reveals as much detail as possible

•Selection of principal edges is important•Figure shows 8 isometric views of the same

block

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6.26.2 Selection of Isometric AxesSelection of Isometric Axes

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6.26.2 Isometric projection: scaleIsometric projection: scale

•The tilt causes the edges & planes to become foreshortened

•The projected length is approximately 80% of the true length

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6.26.2 Isometric projection & drawingIsometric projection & drawing

•Isometric projection & Isometric drawing–Isometric projection: drawn at scale of 0.816–Isometric drawing: drawn at full scale

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6.36.3 Producing Isometric SketchesProducing Isometric Sketches

•Begin with defining isometric axis•Begin sketch by extending axes –vertical

lines, 30deg left & right

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6.36.3 Producing Isometric SketchesProducing Isometric Sketches

•Sketch an isometric ‘box’•Sketch the view on each faces, starting

with isometric lines•Add in non-iso lines and other details•Darken all visible lines.

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6.36.3 Isometric angles & nonIsometric angles & non--isoiso lineslines

•Isometric angles & non-iso lines

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6.36.3 NonNon--isometric linesisometric lines

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6.36.3 IsoIso--circles and arcscircles and arcs

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6.36.3 IsoIso--circles and arcs: sketchcircles and arcs: sketch

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6.36.3 IsoIso--circles and arcs: cylindercircles and arcs: cylinder

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6.36.3 Partial arcsPartial arcs

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6.36.3 Producing isometric drawingProducing isometric drawing

–Draw centre lines AOB and COD, O is centre of circle, AO=OB=CO=OD = radius of circle.

–Draw FCG and EDH parallel to AOB, draw FAE and GBH parallel to COD.

–Draw diagonal FOH, mark points J and K where FJ = HK = radius of circle.

–With centre G and rad. R1 = GA, draw an arc between GJ produced at L and GK produced at M. Similarly with centre E.

–With centres J and K and radius R2 = JL and KM, complete the figure.

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6.36.3 IsoIso--circles and arcs: drawcircles and arcs: draw

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6.36.3 Irregular curves in isometricIrregular curves in isometric

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6.46.4 Producing Isometric drawingProducing Isometric drawing

–Read the orthogonal drawing carefully,–observe the scale, –choose the best point where isometric axes

meet to reveal as much detail as possible–draw an 'isometric box' enclosing the object–draw in light construction lines–draw arc & curves in thick, remove excess..–line in 30°right lines–line in 30°left lines–line in vertical lines to complete the view

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6.46.4 Producing Isometric drawingProducing Isometric drawing

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6.66.6 Oblique projection drawingOblique projection drawing

•Oblique projection –parallel projection where the projectors are parallel to each other but not perpendicular to the projection plane

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•The actual angle that the projectors make with the plane is not fixed, but preferably between 30deg –60deg

•Most common 45 degree

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•3 types:–Cavalier projection: true length along axis–Cabinet projection: half true length–General: any from half to full true length

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•Place complex surfaces (arcs, holes, irregular curve, etc.) parallel to front plane

•The longest dimension should be parallel to frontal plane

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