WEBVTT

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>> This is a tutorial
illustrating how you would do

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the sectioning lab
part b of lab number 8.

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This is the figure
that we're given.

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We are given the top and the
front view of this 3D object.

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Here's the front
and here's the top.

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And we're asked to create a
sectional view corresponding

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to the aligned section AA.

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So first thing you want to do is
to try to visualize the object

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by creating construction lines
by looking at the correspondence

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between features in
the top and front view.

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So for instance, this
construction line here tells me

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that this circle is a protruding
part based on the top view.

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And this construction line here
tells me that there's a shell,

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this part here is empty,
this towards the back here,

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the small circle corresponds

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to a small circular cylindrical
hole towards the back,

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and this is a keyway right
in the middle corresponding

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to those hidden lines
in the top view.

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Now, to show you what
the 3D object is, okay,

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I've created a 3D model on
the left side here a 3D model,

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the isometric of the
solid. If I rotate it,

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there it is.

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Okay, there's a shell
on the sides,

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and there's a protruding
part, and then a key hole

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in the middle and three tiny
little circles towards the back.

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Okay? And we're trying to
create the aligned section

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corresponding to that
cutting plane AA.

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And what that means is, imagine
cutting it along this planes

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and then imagine rotating
or aligning the position

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of this hole so that it's
directly below the center

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of the circles.

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Okay? So that is
an aligned section.

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So what we're going to
do next is we're going

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to start constructing...
Here's the aligned section.

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This, if I cut it
vertically right here, okay,

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it would correspond to
this sectional view, okay.

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And if I join it in order
to see what it looks

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like on the right side
here, as you can see,

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we have the hatch
areas corresponding

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to the solid parts
of the object.

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And both on top and the bottom,
but, so this one is hatched,

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this one is empty, this
is hatched, this is empty

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because of the key hole,
this one is hatched.

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The main problem here is that
we have not aligned the circular

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holes on the actual drawing.

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Here we need to align the
position of the circular hole.

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So going to the construction
layer, okay,

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next thing I'm going to do
is generate a whole bunch

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of horizontal construction
layers and construction lines

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by copying this from its
current location here

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to all the points I see here
in the front view, the quadrant

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of this circle, the quadrant
of this circle, the position

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of the center lines of the
three little holes, the quadrant

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of the circle here, the top
of the keyway, the quadrant

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of the circle corresponding
to the keyway,

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more horizontal construction
lines matching

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to the quadrant here is
the location of the center

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of the aligned circle,
quadrant here and quadrant here.

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And then I'm going to continue
creating horizontal construction

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lines based on all the
positions I see in the top view.

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And then I'm going to create
vertical construction lines

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by copying an existing one
from its current location here

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to all the intersections
we might align in order

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to find depth dimensions
in the right side.

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So I have created all the
necessary construction lines.

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I'm ready to create
object lines.

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So I'm going to go to the object
layer, and I'm going to start

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at the upper part
corresponding to the shell.

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So here in this part
is the back part.

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So I'm going to create a line.

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I'm going to zoom
in a little bit

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so we can see closer the
centers of our screen,

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and then I'm going to
create a line starting

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from the outer shell.

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This is the shell part, okay,
that goes towards the back.

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Okay. And it goes to the top
of the keyway, which is this.

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Okay. And I'm going
to follow the keyway

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that protrudes all
the way to the front.

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Here's the protruding part.

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Okay. And then it's
going to go all the way

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to the solid part
of the back shell.

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There's the shell and
keyway that's protruding.

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Then I'm going to go towards,
I'm going to create the keyway,

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the thin rectangle corresponding
to the upper part of the keyway.

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Then I'm going to go to the
lower part, but before I can do

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that I should probably
make a copy of the position

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of the small circle that I need
to align for the align section.

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So I'm going to zoom in
and copy this circle here,

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which is the actual location
of the cylindrical hole

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from its current position

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to this aligned position here
corresponding to the quadrant

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of that center line
for all the circles.

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Create horizontal construction
lines by copying that to

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that quadrant, the upper and
the lower quadrants of the copy

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of the circle that I just made.

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Now I'm ready to
create the lower part.

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I'm going to start
again with the,

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let's zoom out a little
bit, the shell, okay.

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Let's go all the
way to the front.

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So I start here and go down.

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That's the outer shell.

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Then it's going to go
towards the hole here,

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so where the hole starts in the
back, okay, and then it goes

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down because that's
thickness of the back.

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Okay? That's another part.

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And then I'm going to
create the bottom part

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of the keyway here is solid,
going all the way to the back

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and going down until the top of
the aligned circle and goes back

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and then up and then
there's the protruding part.

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Then, now, I just need to
show this solid lines here.

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This line here corresponds to
the surface of the shell that is

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from the right side be
moving away from me,

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but it's actually visible.

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This is the cylindrical
surface of the keyway.

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I can see it, but
I'm not touching it.

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And here's the other part of the
cylindrical part of the shell.

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And of course, this is
the cylindrical part

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of the tiny little
hole that I align.

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I will see, then,
all those empty.

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Now I'm ready to do my hatching.

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Let me make sure that I got
the correct hatch pattern.

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This is the hatch
pattern for steel.

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And the 32, and start hatching
our solid, by my cuttings there,

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so this is solid,
solid, solid, solid.

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This one is also solid.

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Okay. That empty part
up there is the shell

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that I'm seeing now.

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This is the keyway.

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Those are all hollow.

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Here's solid, solid, solid.

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Okay. That's it.

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And then we have the hole.

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This is solid, and
then solid as well.

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I think I'm done
with my hatching.

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So the only thing we
need to do now is go

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to the center line layers
and create the center lines

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for the key hole and
the hole in the bottom.

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But I will leave this up to you
to do that and finish the lab.