Simple CAD Extrusion Example
In this page, I will be sowing some basic examples of extrusions used in CAD, a real-world use of planes to provide a stronger foundation on the topics mentioned recently .
The examples shown in this page were produced using the application Autodesk Fusion 360.
As mentioned in the previous page, a 3D object produced in CAD is commonly comprised of extruded 2D profiles.
In order to create a profile, you first have to choose a plane to draw on. The image below shows some of the plane options available in a blank Fusion 360 project.
In this case, the XY plane was chosen, this likely the most common 2D plane in use with other applications, such as making graphs.
In the middle you can see a small circle where the two axes intersect, this is a datum point for the origin, the centre point for the "world" within Fusion of which all positions relate to.
In the top right you can see what is called the "View Cube". This tool is used to show what planes you are looking at in relation to the axes, as well as being able to be clicked or dragged to change the viewpoint of the planes/object in the world.
In this case, it is visible we are in the "TOP" view, looking down on the origin, on the XY plane as describes by the X and Y axes visible in the far corners.
Using some of the drawing tools within Fusion, it is easy to create a simple profile. Some of the basic tools include drawing circles, squares, rectangles and arcs. The image below shows a circle with some rectangles drawn on the surface of the plane.
Finishing the sketch, exiting the 2D view of the frame to the 3D view of the whole environment, we can now view the 2D profile in three dimensions. It can be seen that the plane has no actual thickness in the third dimension Z.
Using the extrusion tool you can select what profile to extrude, in what direction and how far and the type of extrusion. There are additional settings for more complex extrusions but they will not be covered in the current page.
The image below shows the newly created profile being selected.
In the image below it can be seen that the profile will be extruded into a new 3D body, with a thickness on the Z-axis of 25mm.
After this, a 3D object, or Body, is created. This is by having a virtual mesh link material wrapped around the profiles used. The other newly creates surfaces, such as those of the sides of the object, are also newly created profiles that can be manipulated and built on.
The image below shows another example of planes and bodies, where a plane can copy, offset and rotated, where an object on the origin frame can also be copied.
Bodies can also be used to create separate Components, for use in more complex objects and even moving parts.
Otherways to manipulate Bodies and Components includes those included in the "Modify" tool selection in Fusion. The fillet tool can be used to give edges a curved effect.
Take for example the object created previously. By giving a filet on an edge with a large radius, it can manipulate the body to create a large curved surface.
Using a 3D enviroment it also means you can rotate on abojec using different view points, as mentioned previously.
The images below show the object created previously other viewpoints.
They also shows the extrusion tool used again. Rather than creating a new body, this example is using a random shape such as this hexagon to "Cut" into an existing body. This allows for creating more interesting shapes including creating holes, such as for screws.
From the image above it can also be seen that the extrusion also took into consideration the curved surface made before. This is only just touching the surface of the capabilities of this type of application.
The image below shows an example of a body created, used in some later pages in this series.
In the next lectures, i will be using the knowledge presented on Planes and Axis to introduce Frames within Robot Kinematics.