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Isometric ProjectionDrawing
GROUP V
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MEMB113 | MANUAL DRAWING | CHAPTER 6
GROUP MEMBERS
Sebastian Bubiru Kevin Kiplangat
Bruno Kisia Emanuel Ogada Dennis Mworia Peter Wanyoike
Gilbert Kamau Samuel Gateru
David Chipinde Ivy Wairimu Josphat Gacheru Abdirahman Abdi
Steve Omondy Esther Macharia
Samuel Maina Eunice Wahome
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MEMB113 | MANUAL DRAWING | CHAPTER 6
Content
Overview
Pictorial projection Parallel projection
projection
Principles of 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
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Axonometric projection
Axonometric projection
Trimetric Dimetric
Isometric
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Principle of Isometric Projections
It is a pictorial orthographic projection ofan object in which a transparent cubecontaining the object is tilted until one ofthe solid diagonals of the cube becomes
perpendicular to the vertical plane and thethree axes are equally inclined to thisvertical plane
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Important Terms
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Lines in Isometric Projection
The following are the relations between the lines in
isometric projection;
The lines that are parallel on the object are parallel inthe isometric projection.
Vertical lines on the object appear vertical in the
isometric projection. Horizontal lines on the object are drawn at an angle of
3 0with the horizontal in the isometric projection.
A line parallel to an isometric axis is called anisometric line and it is fore-shortened to 82%.
A line which is not parallel to any isometric axis iscalled non-isometric line and the extent of Fore-shortening of non-isometric lines are different if theirinclinations with the vertical planes are different.
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Isometric projection
Isometric projection is a true representation of theisometric view of an object
Isometric view is created by rotating the object 45degree about vertical axis, and tilting it forward 35deg 16
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Isometric 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 theseIsometric Line
Any planes parallelIsometric Planes
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Selection 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 different isometric views of the same block
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Isometric 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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Isometric projection & drawing
Isometric projection & Isometric drawing
Isometric projection: drawn at scale of 0.816 Isometric drawing: drawn at full scale
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MEMB113 | MANUAL DRAWING | CHAPTER 6
Methods of Constructing IsometricDrawing
Box method.
Off-set method.
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MEMB113 | MANUAL DRAWING | CHAPTER 6
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Off-set Method
Off-set method of making an isometric
drawing is preferred when the objectcontains irregular curved surfaces. In theoff-set method, the curved feature may beobtained by plotting the points on the
curve, located by the measurements alongIsometric lines. The figure in the next slideillustrates.
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MEMB113 | MANUAL DRAWING | CHAPTER 6
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Draw the isometric projection of a rectangle of
100mm and 70mm sides if its plane is (a) Verticaland (b) Horizontal.
To draw the isometric projection of a square plane
Construction
Case
Vertical plane
Draw a line at 30to the horizontal and mark the isometric
length on it.
Draw verticals at the ends of the line and mark the isometriclength on these parallel lines.
Join the ends by a straight line which is also inclined at 30tothe horizontal.
There are two possible positions for the plane.
Isometric Projection of Planes
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Case
Horizontal plane Draw two lines at 30to the horizontal and mark
the isometric length along the line.
Complete the figure by drawing 30inclined lines
at the ends till the lines intersect.Note
(i) The shape of the isometric projection ordrawing of a square is a Rhombus.
(ii) While dimensioning an isometric projection orisometric drawing true dimensional values onlymust be used.
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The figure below shows how the cases canbe executed;
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Non-isometric lines
Non-isometric lines are the lines that are not parallel to any
of the iso-lines.
They are drawn by transferring the distance of X or Y frommulti-view to iso-view, not the actual length itself.
L is orthogonalnot equal to Lin isometric
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Isometric angles & non-iso lines
Example of producingnon-isometric lines.
The position of point Z isobtained in the isometricview, by transferring the
distance of X and Y.
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Iso-circles and arcs: draw
Drawing isometric circles and arcs using
four-centre method
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| |
Iso-circles and arcs: draw
Drawing isometric circles using ordinate
method.
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Drawing iso-circles
To draw an iso-circle,on left plane, Diameter
20mm
(a) Draw centre lines,vertical & 30deg to left.
(b) Draw (construction line)20mm square box.The centre lines shoulddivide each side by half.
(c) Draw straight lines; 1-2 & 1-3 and 2-5 & 2-6.(d) Point 7 is the intersection between line 1-2 & 2-5, and similarly point 8, 1-3 & 2-6 on
the other side.(e) Set your compass to the distance 7-2, draw an arc with centre at point 7, from point 2
to point 5. Do the same on the other side.
(f) Set your compass to the distance 1-2, draw an arc with centre (1), from (2) to (3).
(a)
12
3
4
5
6
7
8
2
5
4
5
6
(b) (c)
(d)(e) (f)
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Irregular curves in isometric Irregular curves in
isometric are
produced bytransferring thecoordinates fromorthogonal view.
A fixed distance is set,
A, and the distance inB direction areobtained.
These values are thentransferred to the
isometric view.
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Producing Isometric Sketches
Isometric drawing starts with isometric
sketches. Begin with defining isometric axis.
Begin sketch by extending axesverticallines, 30deg left & right.
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Producing Isometric Sketches
Sketch an isometric box.
Sketch the view on each faces, startingwith isometric lines.
Add in non-iso lines and other details
Darken all visible lines.
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Iso-circles and arcs: sketch
Sketching iso-circle is simpler than drawing.
Create isometric square, each side=diameter.
Find the centre point and midpoints of each side.
Use the construction lines and point to sketch each quarter of thecircle.
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Sketching isometric cylinder Start by drawing the bounding box.
The front end of the cylinder is sketched using the previous
technique. The far end of the cylinder is a partial iso-circle. Sketch until
meeting the tangent with the two straight lines.
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Producing 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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Examples of isometric drawings ofdifferent shapes
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Producing Isometric drawing Read multi-view dwg
given.
Observe scale,dimension, proj. angle
Determine front, side &top view.
Try to visualise how the
object looks like.
Start with sketching, donot draw straight away.
If not sure, start withsketching an isometricbox, enclosing thewhole object.
You can label points,lines and surfaces onmulti-view to help
visualisation.
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Isometric assembly: 3D render
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The EndTHANK YOU