Figure 5-7.Mechanically operated tube bender.
slide bar is moved around until the mark on the
slide bar reaches the desired degree of bend on
the radius block. See figure 5-6 for the six
procedural steps in
tube bending with the
hand-operated tube bender.
MECHANICAL TUBE BENDER. The
tube bender shown in figure 5-7 is issued as a kit.
The kit contains the equipment necessary for
bending tubing from 1/4 inch to 3/4 inch in
This tube bender is designed for use with
aircraft grade, high-strengths stainless-steel
tubing, as well as all other metal tubing. It is
designed to be fastened to a bench or tripod. The
base is formed to provide a secure grip in a vise.
This type of tube bender uses a hand crank
and gears. The forming die is keyed to the drive
gear and is secured by a screw.
The forming die on the mechanical tube
bender is calibrated in degrees, similarly to the
radius block of the hand bender. A length of
replacement tubing may be bent to a specified
number of degrees or it may be bent to duplicate
a bend either in a damaged tube or in a pattern.
Duplicating a bend of a damaged tube or of a
pattern is done by laying the sample or pattern
on top of the tube being bent and slowly bending
the new tube to the required bend.
Tube flaring is a method of forming the end
of a tube into a funnel shape so it can be held by
a threaded fitting. When a flared tube is prepared,
a flare nut is slipped onto the tube and the end
of the tube is flared. During tube installation, the
flare is seated to a fitting with the inside of the
flare against the cone-shaped end of the fitting,
and the flare nut is screwed onto the fitting,
pulling the inside of the flare against the seating
surface of the fitting.
Either of two flaring tools (fig. 5-8) may be
used. One gives a single flare and the other gives
a double flare. The flaring tool consists of a split
die block that has holes for various sizes of tubing,
Figure 5-8.Flaring tools.