You can buy a manufactured 90 degree bend or make one on a cable tray bending machine but in this video I show you how to make one using a metal bar. more Students trading aid on how best to put an internal 90 degrees bend in steel cable tray. You. Cable trays are essential for supporting our electrical and data cables in modern buildings. But getting them installed without causing harm to the cables requires careful planning and the right approach. Those seem pretty easy, and give room for error, but if there's a trick to it, I'd love to hear it. The first step in preparing the. Sagging and Deflection: Excessive bending occurs when trays carry loads beyond their designed capacity or when support intervals are improperly spaced.