How to Create a 3D Donut and Other Unusual Shapes in Your PCB Design

It is generally very simple to create realistic 3D mechanical shapes in Altium Designer^® using the included Extruded, Cylinder, and Sphere shape types in the PCB Library editor. However, some shapes can be tricky. A board outline can be extremely helpful and can even produce shapes like the polygon (polygon pour). A 3D donut, however, is what we will be focusing on today. Although a hole cannot be cut out of any of the Altium-created shapes, a donut shape can still be achieved by essentially creating a closed “C” board shape. Let’s take a look at creating shapes in your PCB.

Create the Donut for Use in Your PCB Design

The dimensions for the donut are 1.5-inch outer diameter, 0.8-inch inner diameter, and 0.475-inch size width.

In an open .PcbLib file, set the snap grid (G hotkey) to create something large and easy to work with, in this case, 50 mils. Start the 3D body drawing mode from the Place/3D Body menu. In the 3D Body dialog, set the 3D Model Type to Extruded. The Body Side should default to Top side. The Layer should be any visible mechanical layer. The Overall Height is going to be the same as the width of the donut, 475 mils. Click OK to close the dialog and enter the drawing mode.

Using the (0, 0) point as a reference, click there to start to customize the shape. Use <Shift+space bar> to toggle the drawing mode until the heads-up display shows the “Line 90/90 Vertical (Horizontal) with Arc (Radius: xx)” mode. The <space bar> (without the Shift) will toggle and change the direction of the arc. The <comma> and <period> keys decrease and increase the arc radius while the shape is being drawn (so chosen because the <and> symbols are on the same keys).

Use the <Shift+comma> or <Shift+period> to change the radius in steps of 10. Use these keys to set the radius to 750 mils (for a 1.5-inch diameter donut). Watch the heads-up display and move the cursor down to (750, -750) and click to lock in the first arc.

Continue on to (1500, 0) to add the next arc section.

Continue around the circle by steps of 750 mils to finish the outer diameter. Do NOT end the drawing mode at this point.

Since the outer and inner diameters of the donut are 1500 and 800 mils, the width of the ring is calculated as (1500-800)/2 = 350 mils. Move the cursor 350 mils inside the circle to begin drawing the inner diameter.

Click to lock in the line. The inner diameter of the donut will now be drawn using a 400 mil radius. It is not necessary to adjust the radius setting, since the inner arc will be smaller. Move the cursor back along the same path used for the outer circle. Use the <spacebar> to swap the direction of the arc if it starts off the wrong way. The inner circle has a 400 mil radius, so watch the dx and dy values in the heads-up display to add the arc sections at 400, 400 increments.

Continue until the inner circle is completed.

Click the right-mouse button to complete the shape.

Switch to 3D mode (View/Switch to 3D or 3 hotkey) to view the results.

Even without access to more complicated 3D mechanical editing tools, complex component 3D models can still be created with ease using the flexible and powerful printed circuit board editing capabilities in Altium Designer. Now that you have successfully created a 3D donut shape, the next step will be converting it into a STEP model so that you can utilize it as necessary in your designs.

Interested to find out more about creating 3D donuts and other unusual shapes and converting them into STEP models? Download a free white paper today to learn more.

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