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Segment Bends
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Porcupine Labor Press


Segment bending is a method of bending conduit by making several small bends to produce one larger bend.  The segment bend on this page illustrates producing a 90 bend by making a total of 9 bends at 10 each.

The steps for making a segment bend are:

  1. Determine the radius of the desired bend. 

    There are several factors that can determine what the radius of a bend will be.  A radius larger than the radius of a bender's shoe may be required to meet a job's specifications.  Sometimes the radii of conduit bends on a job are specified to meet a manufacturer's specification, such as cable used for voice, data, or video.  Larger radii bends are also easier to pull, and put less strain on the cable being pulled.  Larger radii may also be used to fit conduit around an object that may be in the way, if the standard bender shoe radius is used.  Larger that normal radii may be required to fit conduit either inside, or around an object, such as a tank, or a barrel-shaped ceiling.
  2. Determine the number of segments desired or required for the completed bend.

    The greater the number of segments in a large radius bend, the smoother the overall bend will be.  Job related factors may determine what radii will be used.  If, for example, small EMT is used on a conveyor system, it is faster to bend with a standard hand bender.  Most hand benders for 1/2" EMT through 1-1/4" EMT have 10 degree marks.  A 90 degree bend for a conduit could then be made with 9, 10 degree bends.
  3. Determine the Developed Length of the bend.

    Developed length (DL) is the length of conduit that is actually bent. The formula to calculate the developed length of a bend is:  Developed length (DL) is equal to the centerline radius (R) of the bend times the angle (A) of the bend times 0.01745. 

    DL = R x A x 0.01745

    The developed length for a 90 degree bend with a 40" radius is 90 x 40 x 0.01745 = 62.82".

    DL = 90 x 40 x 0.01745 = 62.82"


Figure 1.
Segment6.wmf (30434 bytes)

To use the segment bending calculator:

  1. Select the Total angle of the Bend.
  2. Select the number of bends to use to make the segment bend.
  3. Select the centerline radius of the bend.
  4. Select 'Calculate' button.

The angle of the individual segment bends, the distance between bends, and the Total Length , or Developed Length of the bends, will be calculated for you.

Total angle of Bend:  
Select number of bends to make:
Select centerline radius of bend:
Angle of individual segment bends: degrees.
Distance between bends: inches.
Total Length of bends (Developed Length): inches.

The length of the bent portion of conduit = Radius x Degree of bend x 0.0175.

For a 90 bend with a centerline radius of  40",
Length = 90 x 40 x 0.0175 = 62.82".

Notice, that as a matter of practicality, the distance between bends must be greater than the length of each bent segment.  If the distance between bends is not greater than the length of each bent segment, select a lesser number of bends to make, and/or a different centerline radius.

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Copyright 1998-2012 Dennis Lackey -- All Rights Reserved

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