CAD & technology · National 5
3D CAD modelling
4 cards · 3 quiz · 0 exam
Graphic Communication · National 5 · mrkellydt.co.uk
What you're learning in this topic
Learning intention WALT
We are learning about 3D CAD modelling, specifically to understand:
- how to model a component with extrude and revolve, giving all dimensions
- shell, subtract, fillet and chamfer edits in the right order
Success criteria WILF
- I can describe how to model a component with extrude and revolve, giving all dimensions
- I can describe shell, subtract, fillet and chamfer edits in the right order
Modelling features
- Extrude: a 2D profile pulled out to a set distance to make a solid.
- Revolve: a profile rotated around an axis. State the axis and the angle: 360° for a full solid, or e.g. 90° for a quarter.
Modelling edits
- Subtract (extrude subtract / cut): removes material, e.g. a hole or slot.
- Add (union): joins solids.
- Shell: hollows a solid to a wall thickness, removing chosen faces. State the thickness and the faces removed.
- Fillet: rounds edges to a radius. Chamfer: bevels edges.
How to answer a "describe how to model" question
These are worth 4–7 marks and are where most of the marks are awarded. For each stage, write:
- the 2D profile (sketch) with its key sizes, and where it is drawn (which face or work plane);
- the feature command (extrude, revolve…) with the distance, angle or axis;
- any edit (subtract, shell, fillet, chamfer) with the size and which edges or faces.
Example: "Sketch a Ø50 circle and extrude 50. On the top face sketch a Ø35 circle and extrude-subtract 40. Fillet the bottom edge R2 and chamfer the top edge 2.5 × 45°."
- Use the correct terms from the course specification: "cut out" or "pull up" are not awarded marks.
- Include every relevant dimension; read them carefully off the drawing.
- Get the order right: shell before adding internal features (in 2025 N5, shelling at the end was not awarded marks).
- For a revolve, name the centre axis and the angle: both carry marks.
Key terms
| Extrude | Pull a 2D profile out to a set distance to make a solid. |
|---|---|
| Revolve | Rotate a profile around an axis; state axis and angle. |
| Shell | Hollow a solid to a wall thickness, removing chosen faces. |
| Extrude subtract | Remove material using a profile, e.g. for a hole or slot. |
Quick check
1. A wine glass stem with a curved profile is best made with…
- Extrude
- Chamfer
- Shell
- Revolve
Show answer
D: Revolve. Revolve the profile 360° around the centre axis.
2. Which hollows out a solid to a wall thickness?
- Shell
- Fillet
- Chamfer
- Revolve
Show answer
A: Shell. Shell, removing chosen faces.
3. For a revolve, which TWO things carry marks?
- Colour and material
- Fillet and chamfer
- Centre axis and angle
- Work plane and zoom
Show answer
C: Centre axis and angle. Both are needed.
Printable worksheet
An I do, we do, you do worksheet for this topic, with a separate answer sheet.