Orthographic, Oblique

8/7/2019 Orthographic, Oblique

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Orthographic, ObliqueOrthographic, Oblique

&&

Isometric ProjectionsIsometric Projections

Created byCreated by

Carpentry & Joinery SectionCarpentry & Joinery Section

Granville TAFE.Granville TAFE.


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Statement of ObjectivesStatement of Objectives

The student will be able to:The student will be able to:--

1.1. Reproduce oblique, isometric & orthographic representations ofReproduce oblique, isometric & orthographic representations ofobjectsobjects

2.2. Draw the plan view, front and side elevation of a particularDraw the plan view, front and side elevation of a particularobject given either the isometric or oblique representation.object given either the isometric or oblique representation.

3.3. Draw an isometric or oblique representations of an object givenDraw an isometric or oblique representations of an object giventhe plan, front and side elevation.the plan, front and side elevation.

4.4. State the need for using scales when drawing an object.State the need for using scales when drawing an object.

5.5. Draw the plan of an object at a scale of 1:2 and 1:5Draw the plan of an object at a scale of 1:2 and 1:5

6.6. Find the measurements from a plan when a scale is given but noFind the measurements from a plan when a scale is given but nomeasurements are given on the plan.measurements are given on the plan.


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Any object can be drawn.Any object can be drawn.

The purpose of drawing may be to show the object eitherThe purpose of drawing may be to show the object eitheras a picture or to show it in a way that would enableas a picture or to show it in a way that would enablesomeone to make it.someone to make it.


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In the building Trade drawingsIn the building Trade drawings

serve two purposesserve two purposes

1.1. Cottages can be drawn as a pictorial by an architect.Cottages can be drawn as a pictorial by an architect.

2.2. Or drawn by a builder to show what it will look like whenOr drawn by a builder to show what it will look like whenfinished.finished.


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In the building Trade drawingsIn the building Trade drawings

serve two purposesserve two purposes


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Housing joints can be shown theHousing joints can be shown the

same way for similar reasons.same way for similar reasons.

Through housing jointThrough housing joint


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Cottages can be drawnCottages can be drawn

orthographicallyorthographically This shows internal details such as:This shows internal details such as:--

1.1. Room sizes and spacing.Room sizes and spacing.

2.2. Orthographic projections is from one aspect only.Orthographic projections is from one aspect only.

3.3. This gives the builder the information required to do theThis gives the builder the information required to do the

job.job.


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Cottages can be drawnCottages can be drawn

orthographicallyorthographically


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This also applies to a simpleThis also applies to a simple

housing joint for the same reasonhousing joint for the same reason


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Pictorial drawings most commonly used inPictorial drawings most commonly used in

the building trade are eitherthe building trade are eitherISOMETRIC OR OBLIQUE PROJECTIONISOMETRIC OR OBLIQUE PROJECTION

They are probably used more in freehand sketches on theThey are probably used more in freehand sketches on thejob, than detailed drawings.job, than detailed drawings.


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Pictorial drawings most commonly used inPictorial drawings most commonly used in

the building trade are eitherthe building trade are eitherISOMETRIC OR OBLIQUE PROJECTIONISOMETRIC OR OBLIQUE PROJECTION


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Isometric projection is a methodIsometric projection is a method

used to depict three sides of anused to depict three sides of anobject.object.

( ISO meaning equal, metric meaning measure)( ISO meaning equal, metric meaning measure)

An isometric drawing shows length, width & thickness.An isometric drawing shows length, width & thickness.

However any lines which are not parallel to the length, width &However any lines which are not parallel to the length, width &thickness are not true measurements.thickness are not true measurements.

For example the diagonals of a square or rectangle are equal onFor example the diagonals of a square or rectangle are equal onthe actual object , but do not appear so in isometric.the actual object , but do not appear so in isometric.

The vertical lines are drawn vertically and the angle is 30The vertical lines are drawn vertically and the angle is 30degrees.degrees.


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Isometric projection is a methodIsometric projection is a method

used to depict three sides of anused to depict three sides of anobject.object.


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Oblique projection is anotherOblique projection is another

method of showing three sides ofmethod of showing three sides ofan object in one drawing.an object in one drawing.

An oblique drawing shows one view in true proportion.An oblique drawing shows one view in true proportion.

The sides of an object are drawn full size and at a angle ofThe sides of an object are drawn full size and at a angle of45 degrees.45 degrees.

ToToPROPORTIONPROPORTIONthe drawing we halve the measurementthe drawing we halve the measurement

of the oblique side.of the oblique side.


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Oblique projection is anotherOblique projection is another

method of showing three sides ofmethod of showing three sides ofan object in one drawing.an object in one drawing.


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This can be better illustrated if aThis can be better illustrated if a

cube is drawn in bothcube is drawn in bothisometric & oblique projection.isometric & oblique projection.

The diagonals on the face of the oblique drawing are equalThe diagonals on the face of the oblique drawing are equalbecause this is a true view but not on the isometric.because this is a true view but not on the isometric.


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This can be better illustrated if aThis can be better illustrated if a

cube is drawn in bothcube is drawn in bothisometric & oblique projection.isometric & oblique projection.


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Orthographic projection is theOrthographic projection is the

correct or true shape of an objectcorrect or true shape of an objectdrawn on a flat surface.drawn on a flat surface.

It is the main method used to represent an object in aIt is the main method used to represent an object in a

drawingdrawing..

It gives three views of the object in three separateIt gives three views of the object in three separatedrawings.drawings.

Gives three basic dimensions, Length, Width & ThicknessGives three basic dimensions, Length, Width & Thickness

Gives three views of the object plan, front, & side elevationGives three views of the object plan, front, & side elevation


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Orthographic projection is theOrthographic projection is the

correct or true shape of an objectcorrect or true shape of an objectdrawn on a flat surface.drawn on a flat surface.


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The object shown if surrounded by 3The object shown if surrounded by 3

surfaces or planes (vertical, sidesurfaces or planes (vertical, sidevertical & horizontal) each of the 3vertical & horizontal) each of the 3

views is called projection.views is called projection.

The three surfaces or planes are to be represented onThe three surfaces or planes are to be represented onpaper as one flat surfaces.paper as one flat surfaces.


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The object shown if surrounded by 3The object shown if surrounded by 3

surfaces or planes (vertical, sidesurfaces or planes (vertical, sidevertical & horizontal) each of the 3vertical & horizontal) each of the 3

views is called projection.views is called projection.


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The 3 views of the object on aThe 3 views of the object on a

drawing are obtained by projectingdrawing are obtained by projectingor throwing points of the objector throwing points of the object

onto the drawing.onto the drawing.

These projection lines are at 90 degrees to the surface ofThese projection lines are at 90 degrees to the surface ofthe object. Therefore the view obtained will be a true one.the object. Therefore the view obtained will be a true one.


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The plan is obtained by looking

down on the topof the object.(i.e. projecting onto the horizontal plane.)

The front elevation is projectedonto the vertical plane but

looking from the front.

The side elevation is projected onto the

side vertical plane.

looking from the side


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Drawing paper represents one flatDrawing paper represents one flat

surface, so if the objects drawnsurface, so if the objects drawnwere laid out flat then the threewere laid out flat then the three

views would appear as drawn.views would appear as drawn.

Projections are made from one view to another.Projections are made from one view to another.

Projecting from the plan and front elevation will give theProjecting from the plan and front elevation will give the

side elevation.side elevation.


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Drawing paper represents one flatDrawing paper represents one flat

surface, so if the objects drawnsurface, so if the objects drawnwere laid out flat then the threewere laid out flat then the three

views would appear as drawn.views would appear as drawn.


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Orthographic projection is used forOrthographic projection is used for

working drawings it is essential thatworking drawings it is essential thatthe sizes or dimensions are placedthe sizes or dimensions are placed


Most objects to be drawn are bigger than the drawingMost objects to be drawn are bigger than the drawing

sheet, then it is necessary to fit or scale the object it so itsheet, then it is necessary to fit or scale the object it so it

can be placed onto the paper.can be placed onto the paper.


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Orthographic projection is used forOrthographic projection is used for

working drawings it is essential thatworking drawings it is essential thatthe sizes or dimensions are placedthe sizes or dimensions are placed



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To keep the drawing in proportionTo keep the drawing in proportion

the actual dimensions are reducedthe actual dimensions are reducedin the same ratio. This is calledin the same ratio. This is called

SCALINGSCALING

Although the actual measurements are written on theAlthough the actual measurements are written on the

drawing they dont actually measure that amount on adrawing they dont actually measure that amount on a

SCALEDSCALEDdrawing.drawing.


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To keep the drawing in proportionTo keep the drawing in proportion

the actual dimensions are reducedthe actual dimensions are reducedin the same ratio. This is calledin the same ratio. This is called

SCALINGSCALING


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Drawing to scale is the reducing orDrawing to scale is the reducing or

enlarging by ratio of an object fromenlarging by ratio of an object fromits actual size that can fit onto aits actual size that can fit onto a

working drawing.working drawing.

Scaling is a ratio that can be expressed as:Scaling is a ratio that can be expressed as:

1:2 1:5 1:10 1:50 1:1001:2 1:5 1:10 1:50 1:100

The scale chosen depends on the size of the object and theThe scale chosen depends on the size of the object and the

size of the drawing paper.size of the drawing paper.


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Drawing to scale is the reducing orDrawing to scale is the reducing or

enlarging by ratio of an object fromenlarging by ratio of an object fromits actual size that can fit onto aits actual size that can fit onto a

working drawing.working drawing.


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On a scale of 1:5 the 300On a scale of 1:5 the 300

represents 300mm but to a scalerepresents 300mm but to a scaleof 1:5 in represents 60mmof 1:5 in represents 60mm

(( 300300 = 60= 60 ))5050


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If measurements are indicated on aIf measurements are indicated on a

drawing they should be used indrawing they should be used in

preference to scaling.preference to scaling.

All dimensions are not shown on a drawing as this wouldAll dimensions are not shown on a drawing as this would

clutter the working drawing. If this is the case scaleclutter the working drawing. If this is the case scale

matching the drawing can be done but accuracy can bematching the drawing can be done but accuracy can be

compromised.compromised.


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If measurements are indicated on aIf measurements are indicated on a

drawing they should be used indrawing they should be used in

preference to scaling.preference to scaling.


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At this stage you should be haveAt this stage you should be have

some knowledge of:some knowledge of:--

1.1. 3 different types of drawings.3 different types of drawings.

2.2. How to draw and recognise these types.How to draw and recognise these types.

3.3. The purpose of scales.The purpose of scales.

4.4. How to use scales.How to use scales.


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Carpenters have to do the actual building whichCarpenters have to do the actual building which

involves READING plans and interpretinginvolves READING plans and interpreting

drawings.drawings.

Without this knowledge of drawing any carpenterWithout this knowledge of drawing any carpenter

will find it hard to understand the plans andwill find it hard to understand the plans and

therefore hard to build the job.therefore hard to build the job.


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Orthographic, Oblique