Wire Harnesses: The Ultimate 3D Nemesis

Most designers will groan when asked to create a wire harness in 3D. It can be tedious and time consuming to create a 3D wire harness that will not only look natural but will also be useful in creating a BOM.

If you have the SOLIDWORKS Electrical add-in, you have the ability to route cables. However, I have found that I spend more time trouble-shooting the auto-route placement than it takes me to create a wire or cable using my basic methods. The auto-route has an annoying habit of passing cable/wire through solid objects. This means I end up having to modify the placed wire or delete it and start over. Additionally, if objects that the cable/wire is connected to move, the cable/wire can show an error as the in-place mates are no longer viable.

The method I have developed ensures that your wire/cable avoids any components that are between connections and allows you to easily edit the wire/cable if one of the end connections move. It also allows you to easily determine the length of cable/wire needed so you can have that information for your bill of materials and 2D drawing.

Start by placing all relevant sub-assemblies and components, including components which may lie in the path of the wire harness.

Add the connectors that will be used in the wire harness. Mate them to the desired position in the assembly.

I have three connectors placed for my wire harness.

In the Assembly Browser, organize the parts that will be used for the wire harness, so they are next to each other. That allows you to form a sub-assembly.

Highlight the connectors in the Assembly Browser. Right click and select Form New Subassembly.

Move the connectors into the new sub-assembly.

Suppress any over-defining mates.

Open the new sub-assembly and save with the wire harness part number and description.

Fix the location for all the connectors. The connectors will not be moving, as their positions have already been determined in the top assembly.

Use the Measure tool to determine the X/Y/Z distances between the pin connections. Make a note of each distance.

In the connector model, add reference planes that align to the center of each pin.

Create planes to use for sketches for the wire. Turn on the visibility of the planes to be used, and use the offset distances provided by the Measure tool to help you place the reference planes. If you constrain the wire sketches to the reference planes, you can use the reference planes to control the route of the wires.

It’s time to place the first wire. Use Insert Components > New Part.

Place a 2D sketch from the first pin and exit the sketch.

Place a 2D sketch at the termination pin. Exit the sketch.

Open the in-context part. Save As to a wire name. Edit each sketch and remove any external references. Right click and Fully Define each sketch, then save and close.

Return to the main assembly. You should see the sketches that reside in the wire part. If you do not see the sketches, use Hide/Show to turn on visibility of sketches.

You want to modify the wire part in the main assembly so you can route the wire to avoid any collisions.

Edit the wire component.

Select the 3D Sketch tool.

Use the 2D sketches as guidelines to place the start and end of the wire so they connect with the proper pins. Perform a 3D rotate to verify that the wire has routed correctly. Be careful not to inadvertently add any constraints that might negatively affect the routing.

Use the Fillet tool to create clean curves at the intersections. Keep in mind the wire diameter that is going to be placed and use a Fillet radius at least 2.5 times the wire diameter.

Use the Sweep tool to create the wire. Enable the circular profile option, set the wire diameter, and select the 3D Sketch. Click on the green checkmark.

Turn off the visibility of the 2D sketches that were used as guides.

Apply a color to the wire if desired.

The completed wire is easy to edit by modifying the distances applied between the reference planes or adjusting the 2D guide sketches.

Open the wire part.

Edit the 3D Sketch.

Using the Measure tool, carefully select each arc and line. The Measure tool will display a running total of the segments. Make a note of the total length.

Go to File Properties.

Add a parameter for wire diameter and wire length. If you want to be able to calculate the total wire length used in your wire harness, set the parameters to use Number. You may also want to have a parameter for wire type for inventory purposes.

Repeat the process until you have all the desired wires placed.

If you want to add a split loom, create a shelled cylinder or ellipse around the wires to be gathered. Add the chain link material under Steel and modify the scale to make it appear as a mesh.

To create the 2D drawing, add a configuration where you suppress the wires and all but the main connector in the assembly.

It’s a bit of smoke and mirrors. Place the configuration to be used for the 2D drawing on the sheet. Place the 3D configuration off the sheet. Create a parts list using the view of the 3D configuration that is not seen on the sheet. This allows you to use the wire information for the wires in the 3D configuration.

Keep in mind you can export the parts list to a CSV file to make it easy to perform calculations for the different wire lengths for each wire type.

With a bit of practice, you will be creating 3D wire harnesses along with the 2D drawings in a couple of hours or less, depending on the complexity of the wire harness.

Being able to add a 3D wire harness into your assembly is helpful in visualizing wire routing as well as for assembly instructions. It’s a useful skill and worth cultivating. Because so many designers find it challenging, your ability to demonstrate proficiency will put you ahead of those who groan when asked to tackle this challenge.

About the Author

Elise Moss is a mechanical design engineer, currently working in Silicon Valley. She has been using SOLIDWORKS since 1998 and uses it daily in her current work. She holds a BSME from San Jose State University. She has written articles for Autodesk’s Toplines magazine, AUGI’s PaperSpace, DigitalCAD.com, Tenlinks.com and EngineersRule.com. She has taught CAD classes at Laney College, DeAnza College, Silicon Valley College, San Francisco State Universi

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