>> This is a tutorial for the first part of lab eight,
sectional views on paper and pencil,
and this problem we're given front and top views.
There's the top view, and here's the front view, okay?
There's another top and front view, and we're asked
to sketch full section view for each of the objects shown.
For each of the problems here it's not really given the
position of the cutting plane but to expose to the side
on what position makes sense based
on what these hidden lines are trying to convey.
So we have a lot of inner lines here.
In order to expose those inner lines,
we need a cutting section.
So what I've done, I've created a three-dimensional model
of the object.
It's right here.
So the hidden lines are coming
from the internal features the holes inside.
So we need a cutting section that goes right
through the center because we want a full section.
And then slicing it and then removing the upper part results
in this figure on the right side.
As you can see, okay, we removed the top part
and we have certain parts of the drawing, this part here,
section, section, and section indicating parts
where the cutting plane cut
through solid parts of the object.
Now going back to the problem itself.
Here's the top view again.
And here's the front view.
Okay, again, the objective of the sectional view is
to clarify the internal details of the object.
And as you can see, these details
that need clarification are these hidden lines
in the top view, which can be exposed
by taking a cutting section.
This time we have indicated the position the cutting section
and the direction of the line of sight downwards
so the top view will be converted
into the sectional view by taking the slice
and removing the upper half of the object.
And as a result, these hidden lines here will become solid.
So let's put on solid lines that are exposed now, visible lines
as a result of the cutting plane and removing the upper part
for this whole section.
Of course the outline of the object would also stay solid.
So I'm creating those solid over the construction lines.
So for the lab itself, you're going
to do your sketching on the paper itself.
Just draw over the lines that are given.
This hidden line here will become solid.
So it's this other hidden line here as well
as this hidden line here becomes solid.
And this other hidden line will become solid as well.
Then after that, okay, converting the hidden lines
to solid lines after the fact.
We need to indicate areas that were solid and cut
through by the cutting plane with hatches.
So this area here would be hatched
because that part is solid, so is this part here
and this part as well.
And then after that the only thing that needs to be done is
to add the centerlines fashioned to the circles,
one here and one here, okay?
Turn this into solid centerlines
because now they should be shown.
And then the sectional view for the full section is now done.
For the second problem, we have the top and the front view,
and we can see that there are a lot of hidden lines
in the front view, so we take the cutting plane
through the top fashioned through the circles
and that will expose the features in the front view.
For the third problem, similarly,
we need a cutting plane through the top right through the middle
of the circles here in order
to visualize this hidden lines here.
Similar for the fourth one, cutting through the top view
to expose the internal features in the front.