Tips & Tricks

Create 3D Solids Easily with Sweeps and Lofts

Three-dimensional modeling has gradually become a significant trend in CAD field over the last many years. The ability to model in 3D is now an important standard in judging whether a CAD program is feature-complete. Furthermore, the modern CAD program must offer convenient methods for creating 3D solid models. So we`d like to share with you something new and useful in ZWCAD: Sweep and Loft.

Both of these functions appear in the newly released ZWCAD 2010 Update Patch. They offer you quick ways to create 3D solids, yet provide you with a great deal of control over the final result.

Sweeping Solids

First, let`s try Sweep command. It creates 3D solids by sweeping 2D objects along a specified path. This means that a 2D object defines the cross section of the final 3D solid.

This command creates 3D objects with uniform cross sections. For example, the cross section of a torus (donut shape) is made from a circle, swept along a path that is also a circle. To use the Sweep command to draw a torus, following these steps:
In 2D plan view, first draw a larger circle as the path.

Next, draw a smaller circle as the cross section of the torus. See figure below.

 Run the Sweep command by entering sweep at the ‘Command:’ prompt in the command line, or by selecting from the menu, Draw -> Solid -> Sweep.

Following the prompts, select the smaller circle (as the object to sweep), and then select the larger circle (as the sweep path).

After you press Enter to end the command, notice that ZWCAD instantly draws the 3D torus. If you wish, use the Shade command to see it better, as illustrated below. 

 Creating Lofts

You might be asking, “How can I create solids with varied cross sections?” Good question! Another new command, Loft, provides the answer. It supports the use of at least two objects to define cross sections; in addition, it provides you with a dialog box to configure the shape of the loft.

Let’s use the command to an umbrella shape. Follow these steps:

In 2D plan view, first draw a small circle as the top of the umbrella.
Next, use the Polygon command to draw the outer edge of the umbrella as a large decagon (10-sided polygon). Ensure that the circle and polygon share the same center point, as illustrated below (left). 

 Change the 3D viewpoint to the left side.

Move the circle above the polygon, the distance being the height of the umbrella. See figure above (right). Remember to keep their centers on the same axis!

Now use the Loft command just like Sweep: Select the top circle as the first cross section, and the decagon as the second.

Specify the “Cross sections only” option, and then press Enter. Notice the Loft Settings dialog box, where you can adjust parameters to control the loft. 

The “Ruled” and “Smooth Fit” options are simple, because they have no parameters, creating solid surface directly.

The “Normal to” option means that the solid surface will be normal (at right angles) to certain cross section you choose.

The “Draft angle” option lets you control the start and end angles and magnitudes. (When you set both angles to 90 degrees, it is the same as choosing Normal to start and end the sections.)

Choose the “Draft angles” option, and then enter the values shown above. This will produce a shape like an umbrella.

Click OK, and then use Shade to render the simple umbrella that shows up before your eyes. 

So easy, isn’t it? This command can also produce lofts by path or guides -- similar to the Sweep command’s path. You can try it yourself in ZWCAD 2010 Update Patch.