Cut Cylinder

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Graphic Communication
Department of Technological Education
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Isometric Circle 30o/60o generators method
Department of Technological Education

• Start the isometric circle by drawing the front
  elevation and the plan of the cylinder to be
  drawn.

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Locating Lowest Corner Drawing Isometric Crate
Department of Technological Education

• Choose a suitable point X on the elevation and
  plan and a suitable position to start the
  isometric view.

x

• Draw an isometric crate to fit the isometric view
  into. Use 30o and vertical lines for the angles
  of the lines. The overall size of the crate
  should be the exact size of the isometric view to
  be drawn.

x
x
4
Finding Centre for Isometric Circle
Department of Technological Education

• Draw centre lines on the isometric view. Use 30o
  and vertical lines for this.

x
5
Finding Points on Circumference of Circle
Department of Technological Education

• Divide the orthographic circle into 12 equal
  parts using 30o and 60o lines generated out from
  the centre.

1
2

• Number each of the points where the generators
  cut the circumference of the circle usually
  done in the same format as a clock.

9
3
8
4
7
5
6
x
6
Transferring Circumference Points to Isometric (1)
Department of Technological Education

• Project points where generator lines cut
  circumference of circle down and up to horizontal
  centre line of circle.

1

• Measure horizontal sizes of projected points
  along centre line with compasses and transfer
  these sizes onto 30o isometric centre line.

2
9
3
8
4

• Project vertical lines through these points so
  that circumference points can be found.

7
5
6
x
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Transferring Circumference Points to Isometric (2)
Department of Technological Education

• Using compasses, measure the vertical distances
  from the centre line up and down to each of the
  points on the circumference in turn.
• Transfer each of these dimensions onto the
  isometric view.
• Number each of the points.

1
9
2
8
3
7
4
6
5
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Drawing Isometric Curve
Department of Technological Education

• Draw a smooth curve through each of the points to
  show the circumference of the isometric circle.

1
9
2
8
3
7
4
6
5
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Determining Thickness of Cylinder
Department of Technological Education

• To show the thickness of the cylinder in the
  isometric view it is necessary to project each of
  the points found back at 30o.

• Measure the thickness of the cylinder on the plan
  using compasses and transfer these sizes onto the
  isometric. (In this case all of the sizes are
  the same but this may not always be the case).
• It is not necessary to transfer all of the
  dimensions as all of the points will not be seen
  at the end however if in doubt it is better to
  transfer all and then only use the required ones.

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Drawing Back Curve of Cylinder
Department of Technological Education

• It is necessary to find two final points the
  tangent points - to indicate how far out past
  points 4 and 5 and points 10 and 11 that the
  curve passes.
• This can be done in two ways by finding points
  A and B on the elevation and transferring these
  points to the isometric in the same way as points
  1 to 12.

A
A

• or by drawing diagonal lines on the isometric
  to find where the corresponding points occur on
  the front curve in the isometric.

• These points can then be projected back and
  measured as before to find the final positions.

B
B

• Finally, draw a smooth curve through each of the
  points found.

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Finishing Isometric View
Department of Technological Education

• To finish the drawing darken the required part of
  the outline of the curve.

• Complete the two edges to join the two curves
  together.

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The Final Drawing
Department of Technological Education

• This is the final Isometric View of the cylinder.

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PowerPoint Presentation produced by John McRae,
Nairn Academy 2003