Peterhead Academy

1
Peterhead Academy
Graphic Communication
Auxiliary Plans
Technology Department
2
Auxiliary Plan

• Two views of a coat hook are shown below.
• The coat hook is made from Ø40mm aluminium bar
  and is fixed to the wall through a Ø4mm hole.
• Draw an Auxiliary Plan showing the True Shape of
  the sloping surface with the hole through it.

3
Positioning the Auxiliary Plan
X

• Project from the Elevation to find the extreme
  edges of the Auxiliary Plan.
• The projection lines should be drawn at right
  angles to the cut surface that is to be drawn as
  a True Shape.

X
X
X

• As the coat hook is cylindrical in shape it is
  best to work with a centre line as a datum. This
  should be added at right angles to the projected
  lines.

4
Drawing Generators
/10
8
/11
7
9
6
/12
5 /
1
X
4 /
2

• Divide the Elevation and Plan into equal parts
  using 30o / 60o lines.

3
9
8
/10
X

• Divide the Auxiliary Plan in the same way.

/11
7
X
X
6
/12

• Number each of the points making sure that the
  numbering sequence is correct. (The numbering on
  the Plan and the Auxiliary Plan should be exactly
  the same)

5 /
1
4 /
2
3
12
1
/11
2
/10
3
/9
4
/8

• Draw generators along each of the views.

5
/7
6
5
Drawing True Shape
X

• Start by drawing the main surface of the
  Auxiliary Plan.
• In this case you have been asked to draw the True
  Shape of the sloping surface, so this is the
  surface to start with.
• Project where each of the generators cut this
  surface on the Elevation onto the Auxiliary Plan.

X
X
X
12

• Mark each of the points with a small dot and draw
  a smooth line through each of the points.

1
/11
2
/10
3
/9

• Add the hole to the Auxiliary Plan.

4
/8
5
/7
6
6
Drawing End Curves
X

• It is usual to draw all of the parts that can be
  seen first and then to concentrate on any hidden
  surfaces.
• Therefore, the next part to be drawn would be the
  right hand end of the coat hook.
• Project the points where the generators cut the
  end points up to the Auxiliary Plan.
• Project any end points of these surfaces even
  though they are not located on generator lines.

X
X
X
12
1
/11
2
/10
3
/9

• Mark each of the points where these lines cross
  the generator lines on the Auxiliary Plan with a
  small dot. (This will not be possible for the
  end points at present)

4
/8
5
/7
6
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Finding End Points - (method 1)
A
B
B
A
X

• To find the end points of these curves it will be
  necessary to add extra generators.
• Draw extra generators along the Elevation OR Plan
  until they reach the half circle construction
  line.
• Identify each of these points on the view used
  in this case A and B have been used.

X
A
B
X
X
B
A

• Transfer these points onto the Auxiliary Plan.
  This is done by using compasses to measure the
  distance on the construction circle from one
  point towards another and transferring this size
  between the appropriate points on the Auxiliary
  Plan.

12
1
/11
B
A
2
/10
3
/9

• Draw generators along the Auxiliary and indicate
  the end points found with a small dot.
• Complete this part of the drawing by adding
  smooth curves through each of the points.

4
/8
5
/7
6
8
Finding End Points - (method 2)
X

• An alternative way to find these points is to use
  compasses and to measure their distance from the
  datum line being used in the case of this
  drawing this is the centre line X-X and X-X.
• Measure the widths to each of the points on the
  plan (A, B, C and D) and transfer these sizes to
  the appropriate generator lines on the Auxiliary
  Plan.
• Care should be taken that the points are being
  transferred to the correct generator.

A
D
X
D
B
A
C
X
X
B
C
12
1
/11
2
/10
3
/9
4
/8
5
/7
6
9
Darkening Outlines
A
B
B
A
X

• Because the drawing is beginning to look a bit
  complicated with so many lines it is a good time
  to darken in the information that we already
  have.
• Remember that some of the lines may be hidden
  from view and should be drawn as hidden lines if
  they have been asked for in the question

X
A
B
X
X
B
A
12
1
/11
B
A
2
/10
3
/9
4
/8
5
/7
6
10
Drawing End Ellipse
A
B
B
A
X

• The plain end of the coat hook can now be
  constructed.
• Project each of the points from the Elevation to
  the Auxiliary Plan indicating any points on the
  end curve with a small dot.
• Draw a smooth curve through each of the points.

X
A
B
X
X
B
A
12
1
/11
B
A
2
/10
3
/9
4
/8
5
/7
6
11
Darkening Finished Drawing
A
B
B
A
X

• The view is now complete and any extra lines
  should now be darkened.
• Remember that some of the lines may need to be
  drawn as hidden detail.

X
A
B
X
X
B
A
12
1
/11
B
A
2
/10
3
/9
4
/8
5
/7
6
12
Final Drawing

• The finished drawing should look like this.

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PowerPoint Presentation 2003