Lesson video

Hello, I'm Mrs. Taylor and I'm really pleased you can join me for our lesson today.

Our lesson today is cross-sectional drawings and this is from the communication unit.

The outcome: I can produce cross-sectional drawings to show internal details.

There are three key words in this lesson.

Cross-section: An internal view of a 3D object when cut through a plane.

Cutting plane: Indicates where a sectional view is taken from, represented by a dashed line with arrows.

Internal details: The features inside an object only visible in a cross-sectional drawing.

There are two parts to our lesson, cross-sectional drawing and interpret cross-sectional drawings.

Let's begin.

Cross-sectional drawings are used to show the hidden internal parts of an object.

In design and technology, cross-sectional diagrams are used for engineering and manufacturing.

For example: designing machines, engines, and electronics.

Also in product design, displaying internal components of items like smartphones, shoes, or appliances.

They are only necessary when internal parts are hidden.

Have a look around the room and identify some products that may have hidden detail that you can't see from the outside.

Share this with your talk partner.

When would you need to have a cross-sectional drawing? If all the details are visible externally, like in image A, a cross sectional drawing isn't needed.

If your design appears solid but has hidden details like image B, a cross-sectional diagram is needed.

Imagine you were tasked with making part A or part B.

If you had only one drawing with the information from the outside, you would make two identical products, but actually part B has an internal hidden detail that cannot be seen from the outside.

Here we have a check for understanding.

What does a cross-sectional drawing show? Is it A, an isometric view of a design? B, a small section of a design? C, hidden internal details of a design? Or D, the design across a number of pages? Pause the video and have a go.

Wonderful.

Let's check.

That's right, it's C, hidden internal details of a design.

Well done.

A cross sectional drawing must include a cutting plane indicating where the design is cut to reveal internal details.

It is always shown in the same way.

Here we can see the cutting plane around a cube.

A cutting plane is shown as a thick dashed or chain-dashed line with arrows indicating the view direction.

A good way to remember a cutting plane is imagine if you had a knife and you were to cut the item in half with that knife exactly along the line.

A cross-sectional view of an orange may look like this.

You can see the cutting plane and then the cross-sectional view.

Imagine if you had a knife and you were able to cut through the orange, you would see the image like the cross section here.

Let's have a check for understanding.

What does the cutting plane show? Is it A, where the design is being cut to reveal internal parts of the design? B, the external surface details of a design? Or C, the final assembled appearance of a product? Pause the video and have a go.

Wonderful.

Let's check.

That's right, it's A, where the design is being cut to reveal internal parts of the design.

Well done.

Internal means inside.

Here we have task A: Draw the cross-sectional view of the fruit pieces below, noting the position of the cutting plane.

So much like the orange, imagine cutting the apple and then cutting the strawberry and what the image would look like.

Notice that the cutting plane on the apple is horizontal and the cutting plane on the strawberry is vertical.

Pause the video and have a go.

Great.

How did you get on? Let's have a look at some of the answers you may have come up with.

Do your images look similar to these? We are now going to move on to the second part of our lesson, interpret cross-sectional drawings.

Cross sectional view drawings are produced to help a manufacturer understand any hidden details.

Here we can see A is the solid shape, B has the cutting plane marked on with a dash line with arrows, and C is a three dimensional shape that has been cut along that cutting plane.

In the cross-sectional view, any material that has been cut through is indicated with hatched lines.

Hatched lines are diagonal lines.

Here we have a check for understanding.

True or false? The hatched marks on a cross-sectional drawing indicate that material has been cut through.

Pause the video.

Well done.

Let's check.

That's right, it's true.

The hatched line gives the viewer more information about the object.

And if we think back to the orange in the first part of our lesson, this shows where the item has been cut.

Well done.

Here we have task B, part 1: Draw a cross-sectional view of a pencil.

You can choose to draw your cross-sectional view vertically or horizontally.

Option A is vertically and option B is horizontally.

We can see both examples have the cutting plane indicated with that dashed line with arrows.

Make sure to add the hatched lines to show that it is a cross-sectional view on your drawing.

Pause the video and have a go.

Wonderful.

Let's have a look at some of the answers you may have come up with.

Option A is vertically and we can see the wooden outside of the pencil and the graphite inside.

And option B is horizontally.

We can see the graphite in the centre and the wooden outer of the pencil.

Well done.

Task B, part 2 is to annotate this cross-sectional view to explain what it is showing.

The three dimensional drawing on the right shows what looks like a tube and inside the tube we can see a wire frame diagram indicating that there are two different holes going in different directions, and then we can see that information translated onto the cross sectional view.

Pause the video and have a go.

Great.

Let's have a look at some of the answers you may have come up with.

The drawing reveals an internal hole that connects to a second hole in the design.

The hatched area indicates that material has been cut through.

The area with no hatching indicates a hole.

Well done.

Here we have a summary of our lesson today.

Cross-sectional drawings: Cross-sectional drawings help see inside objects by cutting them open on paper.

Cross-sectional drawings are used when important details are hidden inside and can't be seen from the outside.

A cutting plane is a dashed line with arrows that shows where the object is cut to reveal the inside.

Hatching indicates a cut section showing internal details and clarifying it's not the full design.

I'm so pleased you could join me today.

Well done.