The objective in tube bending is to obtain a smooth bend without flattening the tube. Acceptable and unacceptable bends are shown in figure 6-9. Tube bending is usually done by using a mechanical or hand-operated tube bender. In an emergency, soft, nonheat-treated aluminum tubing smaller than 1/4 inch in diameter may be bent by hand to form the desired radius.

Figure 6-9.Tubing bends.



Figure 6-10.Bending tubing with hand-operated tube bender.

Hand Tube Bender 

The hand-operated tube bender, shown in figure 6-10, consists of a handle, radius block, clip, and a slide bar. The handle and slide bar are used as levers to provide the mechanical advantage necessary to bend tubing. The radius block is marked on degrees of bend ranging from 0 to 180 degrees. The slide bar has a mark that is lined up with the zero mark on the radius block. The tube is inserted in the tube bender, and after lining up the marks, the slide bar is moved around until the mark on the slide bar reaches the desired degree of bend on the radius block. See figure 6-10 for the six procedural steps in tube bending with the hand-operated tube bender.