Cable Routing and Pipe Runs in FreeCAD

Simulating cable routing and pipe runs in FreeCAD involves generating 3D paths between target coordinates and sweeping cross-sectional profiles along those trajectories. Depending on whether you are designing flexible electrical wire harnesses or rigid industrial piping networks, FreeCAD offers several distinct workflows. You can utilize the native Sketcher and Part Design workbenches for basic sweeps, the BIM/Draft workbench for standard architectural piping, or dedicated add-on workbenches such as Curves and Dodo for advanced 3D paths and standard pipe fittings.

Method 1: Flexible Cable Routing Using Curves and Part Design

For electrical harnesses and flexible cables that follow complex 3D paths, the standard 2D sketcher is often insufficient. The combination of the Curves workbench (available via the Addon Manager) and the Part Design workbench is the standard solution.

  1. Establish Anchor Points: In your 3D assembly, identify or create reference datum points or vertices where the cable must attach or pass through (such as clips, connectors, and bulkheads).
  2. Generate the 3D Centerline:
    • Switch to the Curves Workbench.
    • Select your reference points in the sequential order the cable should follow.
    • Click the Interpolated Curve tool (or Parametric Curve) to create a smooth, continuous 3D spline traversing all selected points.
    • Adjust the tangent vectors at the start and end points to ensure the cable enters and exits connectors at perpendicular angles.
  3. Generate the Cable Solid:
    • Switch to the Part Design Workbench and create a new Body.
    • Create a Sketch on a plane perpendicular to the start point of your 3D curve, or create a Datum Plane aligned normally to the curve’s starting vertex.
    • Draw the outer diameter circle representing the cable cross-section (or multiple circles for bundled conductors).
    • Select the profile sketch, click Additive Pipe, and select the 3D spline as the spine path.

Method 2: Rigid Pipe Runs Using the BIM/Arch Workbench

For standard plumbing, pneumatic lines, or process piping with defined bend radii and uniform cross-sections, the BIM workbench provides automated pipe tools.

  1. Draw the Centerline:
    • Switch to the Draft Workbench.
    • Use the Draft Wire (Polyline) tool to draw the center route of the pipe run in 3D space. You can constrain points to existing model geometry using object snapping.
  2. Convert the Wire to a Pipe:
    • Switch to the BIM Workbench (or Arch Workbench in older FreeCAD versions).
    • Select the Draft Wire you created.
    • Click the Pipe tool. FreeCAD automatically converts the 2D wire into a hollow, 3D pipe object.
  3. Configure Pipe Parameters:
    • Select the generated Pipe object in the Tree view and open the Data tab in the Property View.
    • Set the Diameter (outer diameter) and Thickness (wall thickness).
    • Define the Fillet Radius to represent standard sweeping tube bends or elbow radiuses at every joint in the wire.

Method 3: Industrial Piping Systems with the Dodo Workbench

When designing structural piping that requires predefined standard sizes, flanges, valves, and elbows, the Dodo Workbench (formerly Flamingo) is the preferred add-on tool.

  1. Install Dodo from the FreeCAD Tools > Addon Manager.
  2. Define a skeletal framework of lines and intersections in the Draft or Sketcher workbench.
  3. Open the Dodo toolbar to select standard pipe schedules (e.g., DIN, ASME, ISO).
  4. Select the path lines and use Dodo's Pipe Insertion tool. Dodo will generate the pipe geometry and automatically place standardized elbows and fittings at every change of direction.

Checking Clearance and Run Lengths

  • Measure Run Lengths: To obtain the total cut length of a routed cable or pipe, select the underlying centerline curve and inspect the Length property inside the Data panel.
  • Collision Detection: Ensure routed cables do not intersect surrounding components by selecting the finished pipe and adjacent parts, then running Check Geometry from the Part Workbench or inspecting clearances using standard assembly interference tools.