Mesh objects are often used in product design or for 3D printing. After creating an organic 3D mesh object in Autocad’s 3D interface we wish to modify and manipulate its shape. This is quite a different process from other more geometrical modifications which we might undertake in Autocad 3D. We demonstrate various options open to themodeler in our Autocad 3D training courses.

The first method is by selecting and manipulating the individual vertices which define the boundary surfaces of the object. To do this we first switch to the wireframe viewing mode either via the View drop-down menu, or by typing VS (for Visual Style) into the Command line. We then type 3 to represent the wireframe mode.

Wireframe, as the name suggests, represents the object as if it were made of wire segments. These virtual wires are made up of straight edges and points in space known as vertices. The singular is vertex. Each vertex point is defined by its position relative to Autocad’s zero-zero (or origin) point; where the three major axes of x, y and z meet. Each vertex thus has an x, y and z coordinate.

The next step in manipulating these is to go to the Sub-object tab. Press down on No Filter to see the drop down list; note that we have here Vertex, Edge and Face, which denote the various parameters of the 3D shape. Here we select Vertex and press the Control key on the keyboard (PC; Macintosh: Command) to add to our selection of vertices. These will change colour, indicating that they are selected and any changes will only affect these points. Next highlight the Z-axis of the Gizmo and pull upwards in the Z direction. We may then type in a numerical value. The adjacent vertices will  also modify with our selection.

In some cases we may wish to split some of the faces in order to add detail to the existing mesh faces. Note there is a Split Mesh Face tool – select this, then choose No Filter from the Sub-object menu. Again we press the Control key and click on a face. Now click on two opposite edges and extrude a face outwards.

In the illustration shown here we have a cross-section of a 3D mesh object. To create a section like this first use the standard 2D Line tool to draw a temporary guide line from the midpoints of two opposite edges on the object’s base. This is simply a guide for creating our section which we can delete later. Then go to the Mesh Modeling tab at the top of the interface, and select Section, followed by the Section Plane tool. Next click on the end points of the guide line, followed by a click on other side of the object to create the vertical plane. Note the Live Section tool in same tab. Select this then the plane itself, and after a second or two half of the 3D object should disappear from view, revealing a flat section surface.

To view this as a cross-section on paper go into one of your Paper layouts and double-click inside view-port window to enter Model space. Next double-click on the top right View Cube icon to specify the view. Then right-click on the View Cube to select Parallel. Change the visual style to Realistic (type VS then R). Then change the view-port’s scale. Note that dimensions may also be added at this point, either in the Model or Paper space. In this way we can send the client several useful perspectives in a PDF format. See other blog posts for how to create PDFs from Autocad’s workspace.

The 3d interface in Autocad is user-friendly and easy to learn, and we take time to teach a broad range of applications in our classes including modeling, materials, lighting and animation. See many examples of our clients’ work on our Facebook page. For more information there are lots of resources on the web, but try the Autodesk site to begin with: www.autodesk.com. Support options and user forums are also available from the home page.