Bottom Up Modelling
Process of creating individual components and assemblies, using appropriate constrains.
- Can be simpler to follow and ensure that the components are made to the production drawings
Top Down Modelling
Process of editing or building around existing components. You end up with a single CAD file rather than one for each part.
- You can use the geometry of other parts to create a new part without having to add lots of dimensions
- When you resize or change one part, the software automatically makes the necessary changes to the other parts too, saving time
- Ensures that components fir together without dimensioning
- It is quicker as you don’t need to individually model then assemble as it is being assembled while build built
Changes to one component will update other components.
Extrude
When a 2D profile is pulled into 3D form
Subtract (cut)
Same as extrude, but this time we remove material
Revolve
- Created by taking a 2D sketch and rotating it around a central axis
- Can be revolved around at any angle
Shell
Used to hollow out an object
Faces can be removed if required
Chamfer
Straight edge applied to a corner. 45 degree angle fillet
Fillet
Round edge applied to corner or edge
Array
- Allows you to repeat a feature or part several times
- Direction and number of repetitions and spacing can be changed
- Can be done in a 2D sketch or 3D feature
Mirror
Duplicates and reverses existing features through line of symmetry (axis)
Purpose of a detail view?
Gives a larger view of an area of a part allowing for greater clarity in the view.
Purpose of an exploded isometric view?
- Shows how the parts fit together
- Shows how many parts there are
- Allows someone to see how to assemble the object
- Allows someone to see the order of assembly
