CAD cable trays cannot form bends automatically because the software requires explicit fittings to connect straight segments, unlike conduits with round cross-sections.

Understanding the Limitation

In CAD and BIM software like AutoCAD and Revit, cable trays are modeled as straight segments with rectangular cross-sections, which makes automatic bending more complex than for round conduits. Unlike conduits, which can rotate and connect more flexibly, cable trays require fittings such as elbows, tees, and transitions to create corners or changes in direction . Without these fittings, the software cannot generate a bend automatically.

How to Implement Bends

1. Use Cable Tray Fittings: To create a bend, you must insert an elbow fitting between two straight segments. Each segment has connectors at its ends, and the fitting aligns these connectors to form the desired angle .

2. Manual Placement: In AutoCAD, you can use predefined blocks for angled cable trays or elbows to represent bends in 2D or 3D layouts . These blocks must be positioned and rotated manually to match the tray run.

3. Programmatic Creation: In Revit, you can use the API methods such as NewElbowFitting, NewTeeFitting, or NewTransitionFitting to join two cable tray connectors programmatically. This requires retrieving the connectors from each tray segment and explicitly creating the fitting between them .

Practical Tips

• Transfer Project Standards: If your template lacks certain cable tray types or fittings, you can copy them from another project using the Transfer Project Standards tool in Revit .
• Plan Layouts with Fittings: Always design cable tray runs with the necessary fittings in mind, as straight segments alone cannot form bends.
• Check Orientation: Ensure that each segment is correctly oriented so that the fitting aligns properly, especially when connecting horizontal and vertical segments . By understanding that bends require explicit fittings and cannot be auto-generated, you can plan and model cable tray systems accurately in CAD and BIM environments.