WEBVTT

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>> This is a tutorial for
the first part of lab eight,

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sectional views on
paper and pencil,

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and this problem we're
given front and top views.

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There's the top view, and
here's the front view, okay?

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There's another top and
front view, and we're asked

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to sketch full section view
for each of the objects shown.

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For each of the problems here
it's not really given the

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position of the cutting plane
but to expose to the side

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on what position
makes sense based

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on what these hidden lines
are trying to convey.

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So we have a lot of
inner lines here.

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In order to expose
those inner lines,

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we need a cutting section.

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So what I've done, I've created
a three-dimensional model

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of the object.

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It's right here.

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So the hidden lines are coming

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from the internal
features the holes inside.

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So we need a cutting
section that goes right

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through the center because
we want a full section.

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And then slicing it and then
removing the upper part results

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in this figure on
the right side.

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As you can see, okay,
we removed the top part

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and we have certain parts of
the drawing, this part here,

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section, section, and
section indicating parts

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where the cutting plane cut

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through solid parts
of the object.

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Now going back to
the problem itself.

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Here's the top view again.

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And here's the front view.

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Okay, again, the objective
of the sectional view is

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to clarify the internal
details of the object.

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And as you can see,
these details

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that need clarification
are these hidden lines

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in the top view,
which can be exposed

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by taking a cutting section.

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This time we have indicated the
position the cutting section

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and the direction of the
line of sight downwards

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so the top view will
be converted

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into the sectional view
by taking the slice

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and removing the upper
half of the object.

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And as a result, these hidden
lines here will become solid.

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So let's put on solid lines that
are exposed now, visible lines

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as a result of the cutting plane
and removing the upper part

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for this whole section.

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Of course the outline of the
object would also stay solid.

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So I'm creating those solid
over the construction lines.

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So for the lab itself,
you're going

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to do your sketching
on the paper itself.

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Just draw over the
lines that are given.

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This hidden line here
will become solid.

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So it's this other
hidden line here as well

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as this hidden line
here becomes solid.

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And this other hidden line
will become solid as well.

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Then after that, okay,
converting the hidden lines

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to solid lines after the fact.

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We need to indicate areas
that were solid and cut

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through by the cutting
plane with hatches.

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So this area here
would be hatched

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because that part is
solid, so is this part here

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and this part as well.

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And then after that the only
thing that needs to be done is

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to add the centerlines
fashioned to the circles,

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one here and one here, okay?

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Turn this into solid centerlines

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because now they
should be shown.

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And then the sectional view for
the full section is now done.

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For the second problem, we have
the top and the front view,

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and we can see that there
are a lot of hidden lines

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in the front view, so we
take the cutting plane

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through the top fashioned
through the circles

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and that will expose the
features in the front view.

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For the third problem,
similarly,

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we need a cutting plane through
the top right through the middle

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of the circles here in order

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to visualize this
hidden lines here.

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Similar for the fourth one,
cutting through the top view

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to expose the internal
features in the front.