Basics of Different views, first and third angle projection in detail, examples of orthographic views, basics and rules of sectional views, types of sectional views, solved examples and to solve problems for sectional views.

1. Mechanical Drafting
Sectional Orthographic
Gaurav Mistry
AssistantProfessor
Diwaliba Polytechnic, UTU.

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 Sectional Orthography MechanicalDrafting
Basics of Multi views
It is a technical drawing in which different views of an object are projected on
different reference planes observing perpendicularto respective reference plane
DifferentReferenceplanes are
Horizontal Plane (HP),
Vertical Frontal Plane ( VP )
Side Or Profile Plane ( PP)
Different Views are Front View (FV), Top View (TV) and Side View (SV)
FV is a view projected on VP.
TV is a view projected on HP.
SV is a view projected on PP.

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Basics of Multi views

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 Sectional Orthography MechanicalDrafting
Introduction to Sectional Orthography
Why sectional Orthographic
projections are used?
I. To understand inner details of complex
object:
When the object is complex from inside,
there will be many hidden lines in the
projections and it will be difficult to
understand the orthographic projections.
Therefore, to understand the details of the
complex object, sectional orthographic
Projectionsare used.
II. To understandthe materialsof object :
If object is made of two or more materials,
then it can be understood clearly by sectional
orthographic projections.

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 Sectional Orthography MechanicalDrafting
Introduction to Sectional Orthography
 A sectional view is obtained by
imagining the object, as if cut by a
cutting plane and the portion between
the observer and the section plane
being removed.
 In order to obtain a sectional view,
only one half of the object is imagined
to be removed, but is not actually
shown removed anywhere except in
the sectional view.
 Further, in a sectional view, the
portions of the object that have been
cut by the plane are represented by
section lining or hatching.

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 Sectional Orthography MechanicalDrafting
Introduction to Sectional Orthography
 Projection of cut object is known as sectionalview or sectional projection.
 Generally hidden lines are not drawn in sectional view.
 In sectional views, the Shape of the section, visible edges and contours of object
behind the section plane are drawn.
 When one view is drawn sectional, other views are drawn as if the object is not
cut and the object exists as a whole.
 It means other views are not affected by taking section in one view, but Cutting
plane line is shown in non sectioned view to locate the section plane and arrows
are drawn to show the direction of sight. Cutting plane line is also known as line
of section or trace of the cutting plane.

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 Sectional Orthography MechanicalDrafting
 Various Cutting Planes / Sectional Planes.
 Cutting plane Parallelto Principalverticalplane.
o When an object is cut by a plane parallel to Principal vertical plane then:
a) The real or true shape of the section is observed in F.V.
b) Section plane will be seen as a cuttingplane line in T.V.
 Cutting plane Parallelto Principalhorizontalplane.
o When an object is cut by a plane parallel to Principal horizontal plane then:
a) The real or true shape of the section is observed in T.V.
b) Section plane will be seen as a cuttingplane line in F.V.
 Cutting plane Parallelto profile plane.
o When an object is cut by a plane parallel to profile plane then:
a) The real or true shape of the section is observed in side view.
b) Section plane will be seen as a cuttingplane line in T.V. and in F.V.

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 Sectional Orthography MechanicalDrafting
 Various Cutting Planes / Sectional Planes.
 Cutting plane Parallelto Principalverticalplane.

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 Sectional Orthography MechanicalDrafting
 Various Cutting Planes / Sectional Planes.
 Cutting plane Parallelto Principalhorizontalplane.

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 Sectional Orthography MechanicalDrafting
 Various Cutting Planes / Sectional Planes.
 Cutting plane Parallelto profile plane.

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 Sectional Orthography MechanicalDrafting
 Various Cutting Planes / Sectional Planes.

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 Sectional Orthography MechanicalDrafting
 Rules for Sectional Orthography.
 The portion of the object cut by cutting plane and
touching the cutting plane is shown by drawing
hatching or section lines in them.
 Hatching or section lines are drawn thinner than
object lines.
 Normally hatchingor section lines are drawn at 45°.
 Hatching lines are evenly spaced at about 2 to 3 mm
apart.

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 Sectional Orthography MechanicalDrafting
 Rules for Sectional Orthography.
 If the axis of the boundary of section is at
45°then the vertical or horizontal hatching
lines are drawn.
 Separate area of a section of a single
component are hatched in the same
manner.
 Hatching lines on a second part, adjacent to
the first are at an angle of 45° but in the
opposite direction. Hatching lines on a
third part adjacent to first two are drawn at
an angle of 30° or 60° Sometime spacing
or pitch of the hatching lines is varied to
separate it from the adjacent parts.

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 Sectional Orthography MechanicalDrafting
 Rules for Sectional Orthography.
 If hatching is required on a large section
area, it is avoided. It is limited to a zone
following the contour of the sectioned area
required to be hatched.
 If hatching is required on a very thin
section area, it is avoided. Complete
section is shown entirely black. Thin space
is left between adjacent section of the same
type.
 As far as possible avoid dimensioning
inside hatched area, but, if not possible,
hatching lines may be interrupted for the
dimensioning.
 Hatched area can never have dashed or
dottedboundary.

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 Sectional Orthography MechanicalDrafting
 Rules for Sectional Orthography.
 Sectioning rule for machine elements
like : Ribs, rivets, webs, shafts, pins,
nuts, bolts, washers, keys and cotter.
1. Whenever, the cutting plane is passing
through above machine elements and if
cutting plane contains the axis of above
machine elements, then they are not
sectioned.
2. However, when the cutting plane is
cutting, Elements perpendicular to the axis
of the Above Machine elements, section is
taken and in the projection hatching lines
are drawn. If cutting plane does not
include axis then These elements are
hatched.

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Full Sectional View
 Half Sectional View
 Offset Sectional View
 Revolved and Removed Sectional View and
 Partial/ Broken/ Local/ Zonal Sectional View

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Full Sectional View
 The sectional view obtained after
removing one half portion of the object
through its centre line by an imaginary
cutting plane is known as full sectional
view.
 If it happens to be elevation (front
view), it is known as Full sectional
elevation or Full sectional front view.
Normally the word ‘full’ is omitted.
 If it happens to be plan (top view), it is
known as full Sectional plan or full
sectional top view. Similarly there can
be full sectional side view. Normally
the word ‘full’is omitted.

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Half SectionalView
 When the object is symmetrical about its centre
line, from outside as well as from inside, half
sectional view is preferred.
 The main usefulness of the half section is in
assembly drawing where it is often required to show
both internal and external construction of the object
on the same view.

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Half SectionalView
 The sectional view obtained
after removing the front quarter
portion of the object by two
imaginary cutting planes at right
angles to each other is known as
half sectional elevation or half
sectional front view.
 The sectional view obtained
after removing the top quarter
portion of the object by two
imaginary cutting planes at right
angles to each other is known as
half sectional plan or half

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Offset SectionalView
 The path of the cutting plane is bent to pass through features not located in a straight
line, i.e. it is offset to pass through both principle features of the object. Example is
shown.
 Section lines are to be staggered R as shown at R

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Revolved SectionalView

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Removed Sectional View

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Difference Between Revolved and Removed Sectional View

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 Sectional Orthography MechanicalDrafting
 Types of Sectional Orthography.
 Partial/ Broken/ Local/Zonal Sectional View

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 Sectional Orthography Views MechanicalDrafting

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 Sectional Orthography Problem 1 MechanicalDrafting
For the given isometric view. If the vertical cutting plane cuts the object from the center.
Draw its (a) SectionalF.V, (b) T.V and (c) RHSV using 1st angle projection

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 Sectional Orthography Solution 1 MechanicalDrafting
For the given isometric view. If the vertical cutting plane cuts the object from the center.
Draw its (a) SectionalF.V, (b) T.V and (c) RHSV using 1st angle projection

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 Sectional Orthography Problem 2 MechanicalDrafting
For the given isometric view. If the vertical cutting plane cuts the object from the center.
Draw its (a) SectionalF.V, (b) T.V and (c) LHSV using 1st angle projection

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 Sectional Orthography Solution 2 MechanicalDrafting
For the given isometric view. If the vertical cutting plane cuts the object from the center.
Draw its (a) SectionalF.V, (b) T.V and (c) LHSV using 1st angle projection

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 Sectional Orthography Problem 3 MechanicalDrafting
For the given isometric view. If the Side cutting plane (Perpendicularto HP and VP) cuts the
object from the center. Draw its (a) SectionalRHSV, (b) F.V and (c) T.V using 1st angle projection

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 Sectional Orthography Solution 3 MechanicalDrafting
For the given isometric view. If the Side cutting plane (Perpendicularto HP and VP) cuts the
object from the center. Draw its (a) SectionalRHSV, (b) F.V and (c) T.V using 1st angle projection

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 Sectional Orthography Problem 4 MechanicalDrafting
For the given isometric view. If the Vertical cutting planecuts the object from the center. Draw
its (a) SectionalFV, (b) T.V and (c) RHSV using 1st angle projection

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 Sectional Orthography Solution 4 MechanicalDrafting
For the given isometric view. If the Vertical cutting planecuts the object from the center. Draw
its (a) SectionalFV, (b) T.V and (c) RHSV using 1st angle projection

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 Sectional Orthography Problem 5 MechanicalDrafting
For the given isometric view. If the Side cutting plane (Perpendicularto HP and VP) cuts the
object from the center. Draw its (a) SectionalLHSV, (b) F.V and (c) T using 3rd angle projection

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 Sectional Orthography Solution 5 MechanicalDrafting
For the given isometric view. If the Side cutting plane (Perpendicularto HP and VP) cuts the
object from the center. Draw its (a) SectionalLHSV, (b) F.V and (c) T using 3rd angle projection

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REFERENCES:
1. Machine Drawing, K. L. Narayan, NewAge Int. Pub.
2. Engineering Drawing, M. B. Shah and B. C. Rana, Pearson.
3. 4. https://www.slideshare.net
MechanicalDrafting
For Video related to sectional orthographyclick on link below:
https://www.youtube.com/watch?v=4PyKeFGjHOE&list=WL&index=45&t=1030s