Formula for making bends in cable trays

Cable tray bends can be fabricated using proportional formulas based on tray height and width, with specific cutting and bending techniques for 45° and 90° angles.

45° Bend Fabrication

To create a flat 45° bend:

1. Determine the tray height (H).
2. Calculate the base of the isosceles triangle to cut using the formula: L = 2 × (H × sin 22.5°). For example, a 100 mm high tray gives L ≈ 76.5 mm on each side of the center line ( ).
3. Mark the tray along the center line and the calculated distances on either side.
4. Cut and remove the lip along these lines.
5. Bend the tray so the cut edges overlap, forming a 45° angle. This method can be scaled for different tray heights and angles.

90° Bend Fabrication

For a flat 90° bend:

1. Mark the tray along the center line.
2. Remove the tray lip equal to 2/3 of the tray width, split evenly on both sides of the center line ( ).
3. Cut down the center line carefully to avoid tray deformation.
4. Flatten the tray lip at the bend point using a blunt tool.
5. Bend the tray to 90° and secure the two parts together.
6. Add a gusset by cutting a piece of tray to fit the internal edges, removing one lip, and bolting it to reinforce the bend.

General Guidelines

• For 90° bends using two 45° cuts: Apply the 45° formula twice to create a 90° elbow ( ).
• Adjusting for tray width and height: Use proportional calculations to maintain the correct bend ratio.
• Safety and precision: Use hand grinders or files carefully, and test with cardboard or scrap material before cutting the actual tray ( ).
• Custom angles: Halve the desired angle to calculate the triangle base for cutting, then fold accordingly. These formulas and methods allow precise fabrication of bends in cable trays of various sizes while maintaining structural integrity and proper alignment.