Patent Publication Number: US-8118586-B2

Title: Portable conduit bending frame assembly and method of use thereof

Description:
RELATED APPLICATION DATA 
     This application is a continuation in part application of application Ser. No. 11/559,327 filed Nov. 13, 2006, now U.S. Pat. No. 7,766,642. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a portable conduit bending frame assembly and method of bending a conduit utilizing the same. 
     BACKGROUND 
     Conduits requiring a plurality of bends or offsets are preferably fabricated, formed, or bent to a desired configuration at the site where the conduits are to be installed. In order to fabricate the conduit on site, several pre-formed or pre-bent conduit components are fixed together with couplings to form a desired configuration. Because several conduit components having different bends or offsets must be brought to the site in order to fabricate the conduit, this type of fabrication requires transporting a large amount of conduit components to every site. Additionally, the couplings add to the final cost of the conduit. Alternatively, to form or bend the conduit on site, the conduit must be heated to a temperature where the conduit is capable of being formed or bent to a desired configuration. Conventional methods for heating the conduit, however, are bulky and inefficient. It is therefore desirable to provide a portable conduit bending frame assembly that is easy to transport and operate that can economically heat and form or bend a conduit to a desired configuration. 
     SUMMARY 
     The invention provides a portable conduit bending frame assembly has a support member, a shoe and a heating device. The support member has a first alignment end, a second alignment end, and a first conduit measuring device that extends an approximate width of the support member. The support member also has a flat conduit support surface fixed thereto, and extending substantially perpendicular to a top surface of the support member. The top surface has at least a portion of a first attachment strip located thereon. The shoe has a first alignment surface extending substantially perpendicular to a second alignment surface, an arcuate conduit bending surface extending between the first and second alignment surfaces, and a complementary attachment strip extending at least partially on a major surface of the shoe. The conduit bending surface faces the conduit support surface and the shoe is removably attachable to the top surface such that either of its alignment surfaces can be aligned parallel with either alignment end of the support member. The heating device is arranged proximate the conduit support surface for heating a conduit prior to bending the conduit at least partially about the conduit bending surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top perspective view of a portable conduit bending frame assembly according to a first embodiment of the invention. 
         FIG. 2  is a perspective view of a first step in a method of bending a conduit using the portable conduit bending frame assembly of  FIG. 1 . 
         FIG. 3  is a perspective view of a second step in the method of bending the conduit using the portable conduit bending frame assembly of  FIG. 1 . 
         FIG. 4  is a perspective view of a third step in the method of bending the conduit using the portable conduit bending frame assembly of  FIG. 1 . 
         FIG. 5  is a perspective view of a fourth step in the method of bending the conduit using the portable conduit bending frame assembly of  FIG. 1 . 
         FIG. 6  is a perspective view of a second method of bending the conduit using the portable conduit bending frame assembly of  FIG. 1 . 
         FIG. 7  is a top perspective view of a portable conduit bending frame assembly according to a second embodiment of the invention. 
         FIG. 8  is a bottom perspective view of the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 9  is a perspective view of a first step in a method of bending a conduit using the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 10  is a perspective view of a second step in the method of bending the conduit using the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 11  is a perspective view of a third step in the method of bending the conduit using the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 12  is a perspective view of a second method of bending the conduit using the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 13  is a perspective view of a third method of bending the conduit using the portable conduit bending frame assembly of  FIG. 7 . 
         FIG. 14  is an exploded prospective view of a portable conduit bending frame assembly according to a third embodiment of the invention 
         FIG. 15  is a top perspective view of a portable conduit bending frame assembly according to a fourth embodiment of the invention. 
         FIG. 16  is a sectional view taken along the line E-E of  FIG. 15 . 
         FIG. 17  is a sectional view of attachment strips taken along the line F-F of  FIG. 15 . 
         FIG. 18  is a top view of one configuration of the shoes according to a fourth embodiment of the invention. 
         FIG. 19  is a bottom view of one configuration of the shoes according to a fourth embodiment of the invention. 
         FIG. 20  is a sectional view of another configuration of the shoes taken along the line A-A of  FIG. 18 . 
         FIG. 21  is a sectional view of another configuration of the shoes taken along the line B-B of  FIG. 18 . 
         FIG. 22  is a top view of another configuration of the shoes according to a fourth embodiment of the invention. 
         FIG. 23  is a bottom view of another configuration of the shoes according to a fourth embodiment of the invention. 
         FIG. 24  is a bottom view of another configuration of the shoes according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIGS. 1-6  show a portable conduit bending frame assembly  1  according to a first embodiment of the invention. As shown in  FIG. 1 , the portable conduit bending frame assembly  1  includes a support member  2 , a storage container  4 , a plurality of shoes  10 , a plurality of shoe attachment members  16 , a plurality of shims  17 , a plurality of springs  19 , and a heating device  20 . Each of the individual elements of the bending frame assembly  1  will now be described in greater detail. 
     As shown in  FIG. 1 , the support member  2  is substantially rectangular and is provided with a plurality of apertures  3 . The support member  2  may be formed, for example, from a non-conductive material, such as a mineral wool peg board, or a heat tolerant material, such as aluminum. The support member  2  includes first and second alignment ends  14 ,  25 , respectively, and a conduit receiving end  15 . The first and second alignment ends  14 ,  25  extend substantially perpendicular to the conduit receiving end  15 . The first and second alignment ends  14 ,  25  extend in a direction of length of the support member  2 , and the conduit receiving end  15  extends in a direction of width of the support member  2 . The length of the support member  2  may be, for example, about 21 inches and the width of the support member  2  may be, for example, about 24 inches. 
     As shown in  FIG. 1 , the storage container  4  is mounted to the conduit receiving end  15  of the support member  2 . The storage container  4  is substantially rectangular in shape and includes a cover  5  rotatably mounted thereto. The storage container  4  may, for example, have a width of about 5.5 inches and a length substantially similar to the width of the support member  2 . A locking mechanism  6  secures the cover  5  to the storage container  4  in a closed position. One side of the storage container  4  is formed as a conduit support surface  7 . The conduit support surface  7  extends the approximate length of the support member  2  and is positioned substantially parallel thereto. The storage container  4  is provided with a handle (not shown) that facilitates carrying the support member  2 . 
     As shown in  FIG. 1 , a first conduit measuring device  8  is provided on the conduit support surface  7 . The first conduit measuring device  8  extends the approximate width of the support member  2 . The first conduit measuring device  8  may have, for example, units of measurement that measure from the first alignment end  14  to the second alignment end  25  and/or from the second alignment end  25  to the first alignment end  14 . Second conduit measuring devices  9  extend substantially perpendicular to the first conduit measuring device  8  along the first and second alignment ends  14 ,  25 . The second conduit measuring devices  9  extend the approximate length of the support member  2 . The first and second conduit measuring devices  8 ,  9  may be, for example, provided with units of measurement, such as notches, metric units, English units, etc. 
     As shown in  FIG. 1 , each of the shoes  10  has first and second alignment surface  11 ,  12 , respectively. The first alignment surface  11  extends substantially perpendicular to the second alignment surface  12 . A conduit bending surface  13  extends between the first surface  11  and the second surface  13 . The conduit bending surface  13  has a substantially arcuate configuration. The first and second alignment surfaces  11 ,  12  and the conduit bending surface  13  are formed to have a desired dimension. The substantially arcuate configuration of the conduit bending surface  13  may be, for example, the minimum arcuate configuration specified by the national electric code. For example, the shoes  10  may have a radius of between about 5 inches and 17 inches, however, other dimensions are possible. In the illustrated embodiment, a plurality of the shoes  10  are provided, which each have a different dimension. 
     Shoe attachment member receiving openings  26  are formed in the shoes  10  and extend from a bottom surface to a top surface thereof. The shoe attachment member receiving openings  26  are arranged a distance from the first and second alignment surfaces  11 ,  12  and the conduit bending surface  13  of the shoe  10 . The shoe attachment member receiving openings  26  correspond to the apertures  3  of the support member  2 . Each of the shoes  10  may be formed with a plurality of weight reducing openings (not shown) that extend between the top surface and the bottom surface of the shoes  10 . The weight reducing openings (not shown) provide for easier handling when positioning and removing the shoes  10 . The shoes  10  may be formed, for example, from wood, aluminum, fiberglass, etc. 
     As shown in  FIG. 1 , the shoe attachment members  16  are substantially cylindrical and correspond to the shoe attachment member receiving openings  26  of the shoes  10  and the apertures  3  of the support member  2 . The shoe attachment members  16  have a length such that a portion of the shoe attachment members  16  extends from the top and bottom surface of the shoes  10 . It will be appreciated by those skilled in the art that the shoe attachment members  16  may alternatively be formed integrally with the shoes  10  or the support member  2 . The shoe attachment members  16  may be formed, for example, from wood, aluminum, fiberglass, or a heat tolerant material. 
     As shown in  FIG. 1 , the shims  17  are substantially rectangular in shape and have at least one beveled end  18 . The beveled ends  18  are formed to have a desired dimension. In the illustrated embodiment, a plurality of the shims  17  are provided, which each have a different thickness and beveled ends of different angular dimensions. The shims  17  may, for example, have a thickness of between about ⅛ inch and ¾ inch, however other dimensions are possible. The shims  17  may be formed, for example, from wood, aluminum, fiberglass, sheet felt, etc. 
     As shown in  FIG. 1 , the springs  19  are substantially elongated in shape and are formed to have an external dimension and length. In the illustrated embodiment, a plurality of the springs  19  are provided, which each have a different external dimension and length. A tape  22  may be woven through a first end of the spring  19 . A pulling member  27 , such as steel fish tape, may be attached to the tape  22 . In the illustrated embodiment, the pulling member  27  is fed through the spring  19  such that the pulling member  27  extends from the second end of the spring  19 . Alternatively, the pulling member  27  may be directly attached to the first end of the spring  19 . It will be appreciated by those skilled in the art that structures other than springs  19  may also be provided. 
     As shown in  FIG. 1 , the heating device  20  is substantially rectangular in shape and has a length substantially corresponding to the length of the support member  2 . The heating device  20  is provided with a plurality of radiation elements  23  that radiate heat toward a heat emitting surface of the heating device  20 . The radiation elements  23  may be, for example, a plurality of 500 Watt halogen heat strip bulbs. It will be appreciated by those skilled in the art, however, that the wattage of the halogen heat strip bulbs may vary depending of the desired speed of heating. The radiation elements  23  may also be individually controlled. A metal guard (not shown) may be provided between the radiation elements  23  and the heat emitting surface of the heating device  20 . The heating device  20  may be any of a variety of conventional heating devices that is portable and is capable of radiating heat. 
     A method of bending a conduit  21  using the portable conduit bending frame assembly  1  according to the first embodiment of the invention will now be described with reference to  FIGS. 2-6 . It will be appreciated by those skilled in the art that the conduit  21  may include a pipe or other tubular member formed, for example, from a non-metallic material, such as a schedule  40  pipe, water conduit, elect conduit, etc. 
     As shown in  FIG. 2 , one of the springs  19  is inserted into the conduit  21  such that the pulling member  27  protrudes from an end of the conduit  21  opposite from the tape  22 . A lubricant (not shown), such as liquid soap or a non-stick spray, may be applied to the spring  19  and/or the conduit  21  before insertion of the spring  19  into the conduit  21 . The external dimension of the spring  19  substantially corresponds to an internal dimension of the conduit  21 . The conduit  21  is positioned on the conduit receiving end  15  of the support member  2  against the support surface  7  of the storage container  4  such that the conduit  21  extends in the direction of length of the support member  2 . The heat emitting surface of the heating device  20  is positioned proximate the conduit  21  such that the radiation elements  23  radiate heat toward the conduit  21 . The metal guard (not shown) of the heating device  20  may optionally be positioned such that the metal guard (not shown) is in contact with the conduit  21 . As the conduit  21  is heated, the conduit  21  is periodically rotated in a direction of the arrows shown in  FIG. 2  until the conduit  21  is heated to a temperature where it is substantially rubbery and/or capable of being bent with no or minimal resistance. Because the spring  19  is provided inside the conduit  21 , the spring  19 , which conducts heat, contributes to heating the conduit  21 . Once the conduit  21  has been heated, the heating device  20  is removed from the support member  2 . 
     As shown in  FIG. 3 , at least one of the shoes  10  is attached to the support member  2 . The shoe attachment members  16  are inserted into a plurality of the apertures  3  of the support member  2 . The shoe  10  is attached to the support member  2  by aligning the first alignment surface  11  of the shoe  10  substantially parallel to the first alignment end  14  of the support member  2  such that the conduit  21  is sandwiched between the conduit bending surface  13  of the shoe  10  and the support surface  7  of the storage container  4 . Alternatively, the shoe  10  may be attached to the support member  2  by aligning the first alignment surface  11  of the shoe  10  substantially parallel to the second alignment end  25  of the support member  2  such that the conduit  21  is sandwiched between the conduit bending surface  13  of the shoe  10  and the support surface  7  of the storage container  4 , as shown in phantom in  FIG. 3 . The shoe attachment members  16  are received in the shoe attachment member receiving openings  26  of the shoe  10  to fix the shoe  10  relative to the support member  2 . 
     As shown in  FIG. 4 , an end of the conduit  21  positioned farthest from the shoe  10  is pulled away from the support surface  7  such that the conduit  21  is bent about the conduit bending surface  13  with no or minimal resistance. The conduit  21  is bent until the conduit  21  concentrically embraces the substantially arcuate configuration of the conduit bending surface  13  of the shoe  10 . Because the spring  19  is provided inside the conduit  21 , the spring  19  prevents the internal dimension of the conduit  21  from constricting or deforming when the conduit  21  is bent about the conduit bending surface  13  of the shoe  10 . Once the conduit  21  is bent to the desired configuration, the conduit  21  is allowed to cool and is then removed from the support member  2 . 
     The spring  19  is removed from the conduit  21  by pulling on the pulling member  27  protruding from the end of the conduit  21 , as shown in  FIG. 5 . Because the tape  22  is attached to the first end of the spring  19  and the pulling member  27 , which is attached to the tape  22 , extends from the second end of the spring  19 , the spring  19  is prevented from stretching when the spring  19  is pulled from the conduit  21 . 
       FIG. 6  shows a second method of bending the conduit  21 . As shown in  FIG. 6 , after the conduit  21  is heated to a temperature where it is substantially rubbery and/or capable of being bent with no or minimal resistance, at least one of the shims  17  may be positioned substantially parallel to and against the support surface  7  of the storage container  4  such that the beveled edges  18  extend in a direction of a desired offset d in the conduit  21 . In the illustrated embodiment two of the shims  17  are positioned substantially parallel to and against the support surface  7  of the storage container  4 . The conduit  21  is re-positioned against the support surface  7  such that the conduit  21  extends in the direction of width of the support member  2  and is positioned against the shims  17 . 
     The shoe  10  is attached to the support member  2  by aligning the first alignment surface  11  of the shoe  10  substantially parallel to the first alignment end  14  of the support member  2  such that the conduit  21  is sandwiched between the conduit bending surface  13  of the shoe  10  and the support surface  7 . The shoe attachment members  16  are received in the shoe attachment member receiving openings  26  of the shoe  10  to fix the shoe  10  relative to the support member  2 . As a result of the conduit  21  being partially bent about the conduit bending surface  13  and engaging with the beveled edges  18  of the shims  17 , the offset d is formed in the conduit  21 . 
     Alternatively, at least one of the shims  17  may be positioned against the support surface  7  and substantially above the shoe  10 . The conduit  21  is positioned between the conduit bending surface  13  of the shoe  10  and the shim  17 . The conduit  21  is then bent about the bending surface  13  to form a bend in the conduit  21  when the shoe  10  provided to bend the conduit  21  is configured for a conduit having a larger diameter than the diameter of the conduit  21  desired to be bent. As a result, each of the shoes  10  can be used to bend the conduits  21  regardless of their diameters. 
     Although the conduit  21  is only illustrated as being formed with a single bend or offset d, it will be appreciated by those skilled in the art that the conduit  21  may be formed to have a plurality of bends and/or offsets d. Additionally, because the first conduit measuring device  8  may have, for example, units of measurement that measure from the first alignment end  14  to the second alignment end  25  and from the second alignment end  25  to the first alignment end  14 , the conduit  21  may be easily arranged on the support member  2  to accommodate the direction of the desired subsequent bends and/or offsets d in view of the previously made bends and/or offsets d in the conduit  21 . 
     After use, the shoes  10 , the shoe attachment members  16 , the shims  17 , and the plurality of springs  19  may be stored in the storage container  4 . 
       FIGS. 7-12  show a portable conduit bending frame assembly  30  according to a second embodiment of the invention. As shown in  FIGS. 7-8 , the portable conduit bending frame assembly  30  includes a support member  31 , a conduit holder  35 , a plurality of shoes  40 , a plurality of shoe attachment members  44 , a plurality of shims  45 , a plurality of springs  47 , a pre-heating device  50 , and a heating device  59 . Each of the individual elements of the bending frame assembly  30  will now be described in greater detail. 
     As shown in  FIG. 7 , the support member  31  is substantially rectangular and is provided with a plurality of apertures  32 . The support member  31  may be formed, for example, from a conductive material, such as aluminum, aluminum cast, or plate. The support member  31  includes a top surface  33 , a bottom surface  34 , first and second alignment ends  37 ,  55 , respectively, and a conduit receiving end  38 . The first and second alignment ends  37 ,  55  extend substantially perpendicular to the conduit receiving end  38 . The first and second alignment ends  37 ,  55  extend in a direction of length of the support member  31 , and the conduit receiving end  38  extends in a direction of width of the support member  31 . The length of the support member  31  may be, for example, about 24 inches and the width of the support member  31  may be, for example, about 24 inches. Support legs  53  extend from the bottom surface  34  of the support member  31 , as shown in  FIG. 8 . 
     As shown in  FIG. 7 , the conduit holder  35  is mounted to the top surface  33  of the conduit receiving end  38  of the support member  31 . The conduit holder  35  is substantially U-shaped and extends the approximate width of the support member  31 . One side of the conduit holder  35  is formed as a conduit support surface  36 . The conduit support surface  36  extends the approximate length of the support member  31  and is positioned substantially parallel thereto. The conduit holder  35  may be formed, for example, from a conductive material, such as aluminum. 
     As shown in  FIG. 7 , a first conduit measuring device  39  is provided on the conduit support surface  36 . The first conduit measuring device  39  extends the approximate width of the support member  31 . The first conduit measuring device  39  may have, for example, units of measurement that measure from the first alignment end  37  to the second alignment end  55  and/or from the second alignment end  55  to the first alignment end  37 . Second conduit measuring devices  49  extend substantially perpendicular to the first conduit measuring device  39  along an edge of the support member  31  along the first and second alignment ends  37 ,  55 . The second conduit measuring devices  49  extend the approximate length of the support member  31 . The first and second conduit measuring devices  39 ,  49  may be, for example, be provided with units if measurement, such as notches, metric units, English units, etc. 
     As shown in  FIG. 7 , each of the shoes  40  has first and second alignment surface  41 ,  42 , respectively. The first alignment surface  41  extends substantially perpendicular to the second alignment surface  42 . A conduit bending surface  43  extends between the first surface  41  and the second surface  43 . The conduit bending surface  43  has a substantially arcuate configuration. The first and second alignment surfaces  41 ,  42  and the conduit bending surface  43  are formed to have a desired dimension. The substantially arcuate configuration of the conduit bending surface  43  may be, for example, the minimum arcuate configuration specified by the national electric code. For example, the shoes  40  may have a radius of between about 5 inches and 17 inches, however, other dimensions are possible. In the illustrated embodiment, a plurality of the shoes  40  are provided, which each have a different dimension. 
     Shoe attachment member receiving openings  56  are formed in the shoes  40  and extend from a bottom surface to a top surface thereof. The shoe attachment member receiving openings  56  are arranged a distance from the first and second alignment surfaces  41 ,  42  and the conduit bending surface  43  of the shoe  10 . The shoe attachment member receiving openings  56  correspond to the apertures  32  of the support member  31 . Each of the shoes  40  may be formed with a plurality of weight reducing openings (not shown) that extend between the top surface and the bottom surface of the shoes  40 . The weight reducing openings (not shown) provide for easier handling when positioning and removing the shoes  10 . The shoes  40  may be formed, for example, from wood, aluminum, fiberglass, etc. 
     As shown in  FIG. 7 , the shoe attachment members  44  are substantially cylindrical and correspond to the shoe attachment member receiving openings  56  of the shoes  40  and the apertures  32  of the support member  31 . The shoe attachment members  44  have a length such that a portion of the shoe attachment members  44  extends from the top and the bottom surface of the shoes  40 . It will be appreciated by those skilled in the art that the shoe attachment members  44  may alternatively be formed integrally with the shoes  40  or the support member  31 . The shoe attachment members  44  may be formed, for example, from wood, aluminum, fiberglass, or a heat tolerant material. 
     As shown in  FIG. 8 , the shims  45  are substantially rectangular in shape and have at least one beveled end  46 . The beveled ends  46  are formed to have a desired dimension. In the illustrated embodiment, a plurality of the shims  45  are provided, which each have a different thickness and beveled ends of different angular dimensions. The shim  45  may, for example, have a thickness of between about ⅛ inch and ¾ inch, however, other dimensions are possible. The shims  45  may be attached to the bottom surface  34  of the support member  31  by an attachment mechanism  54  that extends through the apertures  32 . The shims  45  may be formed, for example, from wood, aluminum, fiberglass, sheet felt, etc. 
     As shown in  FIG. 7 , the springs  47  are substantially elongated in shape and are formed to have an external dimension and length. In the illustrated embodiment, a plurality of the springs  47  are provided, which each have a different external dimension and length. A tape  48  may be woven through a first end of the spring  47 . A pulling member  57 , such as a steel fish tape, may be attached to the tape  48 . In the illustrated embodiment, the pulling member  57  is fed through the spring  47  such that the pulling member  57  extends from the second end of the spring  47 . Alternatively, the pulling member  57  may be directly attached to the first end of the spring  47 . It will be appreciated by those skilled in the art that structures other than springs  47  may also be provided. 
     As shown in  FIG. 7 , the heating device  59  is substantially rectangular in shape and has a length substantially corresponding to the width of the support member  31 . The heating device  59  is provided with a plurality of radiation elements  60  that radiate heat toward a heat emitting surface of the heating device  59 . The radiation elements  60  may be, for example, a plurality of 500 Watt halogen heat strip bulbs. It will be appreciated by those skilled in the art, however, that the wattage of the halogen heat strip bulbs may vary depending of the desired speed of heating. The radiation elements  60  may also be individually controlled. A metal guard (not shown) may be provided between the radiation elements  60  and the heat emitting surface of the heating device  59 . The heating device  59  may be any of a variety of conventional heating devices that is portable and is capable of radiating heat. 
     As shown in  FIG. 8 , the pre-heating device  50  is mounted to the bottom surface  34  of the conduit receiving end  38  of the support member  31 . The pre-heating device  50  includes an elongated heating strip or contact heater  51  and an electrical box  52 . The heating strip  51  extends substantially the width of the support member  31  and is mounted directly beneath the conduit holder  35  and in contact with the support member  31 , which prevents the support member  31  from warping when the support member  31  is heated. A bracket  61  may be mounted over the heating strip  51  to prevent sagging of the heating strip  51 . The heating strip  51  may be, for example, a 300 Wattflat coil operating at about 175-190 degrees Fahreheit, which may or may not be individually controlled by a contact thermostat  58 . The heating strip  51  may be, for example, a CHROMALOX strip heater. The pre-heating device  50  may be any of a variety of conventional heating devices that is capable of radiating heat. 
     A method of bending the conduit  21  using the portable conduit bending frame assembly  30  according to the second embodiment of the invention will now be described with reference to  FIGS. 9-12 . 
     As shown in  FIGS. 9-10 , one of the springs  47  is inserted into the conduit  21  such that the pulling member  57  protrudes from an end of the conduit  21  opposite from the tape  48 . A lubricant (not shown), such as liquid soap or a non-stick spray, may be applied to the spring  47  and/or the conduit  21  before insertion of the spring  47  into the conduit  21 . The external dimension and length of the spring  47  substantially corresponds to an internal dimension and length of the conduit  21 . The conduit  21  is positioned on the conduit receiving end  38  of the support member  31  inside the conduit holder  35  such that the conduit  21  extends in the direction of length of the support member  31 . The heating strip  51  of the pre-heating device  50  applies heat to the conduit  21  to pre-heat the conduit  21 . The pre-heating device  50  is particularly useful in cold environments to pre-heat the conduit  21  prior to heating with the heating device  59 . As the conduit  21  is pre-heated, the conduit  21  may be periodically rotated in a direction of the arrows shown in  FIG. 9 . Because the spring  47  is provided inside the conduit  21 , the spring  47 , which conducts heat, contributes to heating the conduit  21 . When it is time to form or bend the conduit  21 , the pre-heated conduit  21  is removed from the holder  35  of the support member  31  and is positioned against the support surface  36  of the holder  35  such that the conduit  21  extends in the direction of length of the support member  31 , as shown in  FIG. 10 . 
     Similar to the heating device  20  of the first embodiment shown in  FIG. 2 , the heat emitting surface of the heating device  59  is positioned proximate the conduit  21  such that the radiation elements  60  radiate heat toward the conduit  21 . The metal guard (not shown) of the heating device  59  may optionally be positioned such that the metal guard (not shown) is in contact with the conduit  21 . As the conduit  21  is heated, the conduit  21  is periodically rotated in a direction of the arrows shown in  FIG. 2  until the conduit  21  is heated to a temperature where it is substantially rubbery and/or capable of being bent with no or minimal resistance. Because the spring  47  is provided inside the conduit  21 , the spring  47 , which conducts heat, contributes to heating the conduit  21 . Once the conduit  21  has been heated, the heating device  59  is removed from the support member  31 . It will be appreciated by those skilled in the art that the pre-heating device  50  may alternatively be used to heat the conduit  21  to a temperature where it is substantially rubbery and/or capable of being bent with no or minimal resistance if so configured without the assistance of the heating device  59 . 
     As shown in  FIG. 10 , at least one of the shoes  40  is attached to the support member  31 . The shoe attachment members  44  are inserted into a plurality of the apertures  32  of the support member  31 . The shoe  40  is attached to the support member  31  by aligning the first alignment surface  41  of the shoe  40  substantially parallel to the alignment end  37  of the support member  31  such that the conduit  21  is sandwiched between the conduit bending surface  43  of the shoe  40  and the support surface  36  of the holder  35 . Alternatively, the shoe  40  may be attached to the support member  31  by aligning the first alignment surface  41  of the shoe  40  substantially parallel to the second alignment end  55  of the support member  31  such that the conduit  21  is sandwiched between the conduit bending surface  43  of the shoe  40  and the support surface  36  of the holder  35 , as shown in phantom in  FIG. 10 . The shoe attachment members  44  are received in the shoe attachment member receiving openings  56  of the shoe  40  to fix the shoe  40  relative to the support member  31 . 
     As shown in  FIG. 11 , an end of the conduit  21  positioned farthest from the shoe  40  is pulled away from the support surface  36  such that the conduit  21  is bent about the conduit bending surface  43 . The conduit  21  is bent until the conduit  21  concentrically embraces the substantially arcuate configuration of the conduit bending surface  43  of the shoe  40 . Because the spring  47  is provided inside the conduit  21 , the spring  47  prevents the internal dimension of the conduit  21  from constricting or deforming when the conduit  21  is bent about the conduit bending surface  43  of the shoe  40 . Once the conduit  21  is bent to the desired configuration, the conduit  21  is allowed to cool and is then removed from the support member  31 . 
     The spring  47  is removed from the conduit  21  by pulling on the pulling member  57  protruding from the end of the conduit  21 . Because the tape  48  is attached to the first end of the spring  47  and the pulling member  57 , which is attached to the tape  48 , extends from the second end of the spring  47 , the spring  47  is prevented from stretching when the spring  47  is pulled from the conduit  21 . 
       FIG. 12  shows a second method of bending the conduit  21 . As shown in  FIG. 12 , after the conduit  21  is heated to a temperature where it is substantially rubbery and/or capable of being bent with no or minimal resistance, at least one of the shims  45  may be positioned substantially parallel to and against the support surface  36  of the holder  35  such that the beveled edges  46  extend in a direction of a desired offset d in the conduit  21 . In the illustrated embodiment two of the shims  45  are positioned substantially parallel to and against the support surface  36  of the holder  35 . The conduit  21  is removed from the holder  35  of the support member  31  and is positioned against the support surface  36  of the holder  35  such that the conduit  21  extends in the direction of width of the support member  31  and is positioned against the shims  45 . 
     The shoe  40  is attached to the support member  31  by aligning the first alignment surface  41  of the shoe  40  substantially parallel to the first alignment end  37  of the support member  31  such that the conduit  21  is sandwiched between the conduit bending surface  43  of the shoe  40  and the support surface  36  of the holder  35 . The shoe attachment members  44  are received in the shoe attachment member receiving openings  56  of the shoe  40  to fix the shoe  40  relative to the support member  31 . As a result of the conduit  21  being partially bent about the conduit bending surface  43  and engaging with the beveled edges  46  of the shims  45 , the offset d is formed in the conduit  21 . 
       FIG. 13  shows a third method of bending the conduit  21 . As shown in  FIG. 13 , at least one of the shims  45  may be positioned against the support surface  36  and substantially above the shoe  40 . The conduit  21  is positioned between the conduit bending surface  43  of the shoe  40  and the shim  45 . The conduit  21  is then bent to form a bend in the conduit  21  when the shoe  40  provided to bend the conduit  21  is configured for a conduit having a larger diameter than the diameter of the conduit  21  desired to be bent. As a result, each of the shoes  40  can be used to bend the conduits  21  regardless of their diameters. 
     Although the conduit  21  is only illustrated as being formed with a single bend or offset d, it will be appreciated by those skilled in the art that the conduit  21  may be formed to have a plurality of bends and/or offsets d. Additionally, because the first conduit measuring device  39  may have, for example, units of measurement that measure from the first alignment end  37  to the second alignment end  55  and from the second alignment end  55  to the first alignment end  37 , the conduit  21  may be easily arranged on the support member  31  to accommodate the direction of the desired subsequent bends and/or offsets d in view of the previously made bends and/or offsets d in the conduit  21 . 
       FIG. 14  shows a portable conduit bending frame assembly  70  according to a third embodiment of the invention which illustrates schedule spacers  82 ,  83  and method for correcting the space between the support surface  107  and the conduit  21  for different schedules of the conduit  21 . The support member  102  with a plurality of the apertures  103  is set up for schedule  80  conduit in this embodiment. Two schedule spacers  82 ,  83  are provided, which each have a different thickness. One schedule spacer  82 , when inserted, configures the assembly  70  for schedule  40  conduit, the other schedule spacer  83 , when inserted, configures the assembly  70  for schedule  20  conduit. However, other dimensions of the schedule spacers  82 ,  83  are possible to configure the assembly  70  for any schedule conduit or any conduit having a different wall thickness. As shown in  FIG. 14 , the schedule spacers  82 ,  83  are substantially rectangular in shape and are provided with the holes  84   a ,  84   b ,  85   a ,  85   b  in the schedule spacer  82  and  86   a ,  86   b ,  87   a ,  87   b  in the schedule spacer  83 , respectively. The schedule spacers  82 ,  83  may be attached to the cover  105  of the storage container  104 . The cover  105  includes holes  84   d ,  85   d ,  86   d ,  87   d  (not shown) which are positioned in the cover  105  in a similar way to the holes  84   c ,  85   c ,  86   c ,  87   c  in the support surface  107 . The holes  84   a ,  85   a  in the schedule spacer  82  or the holes  86   a  and  87   a  in the schedule spacer  83  are arranged to anchor the schedule spacers  82 ,  83 , respectively, to the cover  105  for carrying if both spacer plates  82 ,  83  are not needed.  FIG. 14  also shows mounting studs  88  fixed in the holes  84   b ,  85   b  in the schedule spacer  82  by welding or other suitable attachment means. Wing-nuts  89  secure the schedule spacer  82  for the schedule  40  to the conduit support surface  107  through the hole  84   c ,  85   c  on the supporting surface  107  as well as anchor the schedule spacer  82  on the cover  105  in carrying position through the holes  84   d ,  85   d  in the cover  105 . Similarly, the schedule spacer  83  is secured on the support surface  107  with mounting studs  88  fixed in the holes  86   b ,  87   b  in the schedule spacer  83  by welding or other suitable attachment means. Wing-nuts  89  behind the support surface  107 , anchor the schedule spacer  83 . Each schedule spacer  82 ,  83  therefore has studs  88  fixed thereto in the holes  84   b ,  85   b ,  86   b ,  87   b  and holes  84   a ,  85   a ,  86   a ,  87   a  positioned adjacent to each stud  88  in order to allow studs  88  of the other schedule spacer  82 ,  83  to pass through holes  84   a ,  85   a ,  86   a ,  87   a  when they are stacked on the cover  105  in carrying position regardless of which schedule spacer is on the top of the other one. It should be noted here that the holes  84   a ,  85   a ,  86   a ,  87   a  should be sufficiently spaced from the holes  84   b ,  85   b ,  86   b ,  87   b  where the studs  88  are mounted to allow clearance for the wing-nuts  89 . In addition, the schedule spacers  82 ,  83  may be formed, for example, from wood, aluminum, fiberglass, etc. 
     Two measuring devices  108  are on the top portion of the conduit support surface  107  and shown on the top of the schedule spacers  82 ,  83  when they are is in use. Sliding scales  109  extend substantially perpendicular to the measuring devices  108  along the first and the second alignment ends  114 ,  125  and correct for schedule spacers  82 ,  83  when in use. It should be understood that there are variations of sliding scales  109  on the surface member  102 . Sliding scale  109  can be combined with multiple different scales aggregated together for different schedules, or a different scale attached, for example, with tacky chemical materials, on the top of the other scale for a different schedule, or a scale defined with different units of measurements, or any other possible means of adjusting the scale. When a conduit with schedule  40  is presented on the support member  102 , the schedule spacer  82  is attached to the support surface  107 , similarly, when a conduit with schedule  20  is presented on the support member  102 , the schedule spacer  83  is attached to the support surface  107 . Other elements in this illustrated embodiment and a method of bending a conduit are the same as those of the bending frame assembly  1  and their descriptions can be referred to in the description of the bending frame assembly  1  above. 
       FIGS. 15-17  show a portable conduit bending frame assembly  90  according to a fourth embodiment of the invention which illustrates a second method of attaching the shoes  210  on the support member  202 . As shown in  FIG. 15 , the support member  202  is modified to remove the apertures  3  in the bending frame assembly  1  and provided with attachment strips  71  fixed in a direction parallel to the second conduit measuring device  209  through a plurality of slits  203 , where the first two attachment strips  71  are fixed on the support member  202  close to the side of the first alignment end  214  of the support member  202  and the second two attachment strips are fixed on the support member  202  close to the side of the second alignment end  225 . It should be noted that the spacing of the attachment strip  71  to the alignment ends  214 ,  225  should be such that the attachment strips  71  mate with all of the various size shoes  210  as shown in  FIG. 18 . It should also be noted that it is not necessary for the entire surface area of shoe attachment strips  75  shown in  FIG. 18  to engage the attachment strips  71  on the support member  202 . A partial engagement of attachment strips  71 ,  75  is sufficient to hold the shoe in place on the support member  202 .  FIGS. 16 and 17  show how the attachment strips  71  attach to the support member  202 , which includes a plurality of slits  203  in the support member  202  and a plurality of the attachment strips  71  on the support member  202 . In the illustration of the embodiment, the slits  203  formed in the support member  202  are substantially rectangular narrow slits that fit the thickness of the attachment strips  71  and extended from the top surface  73  of the support member  202  to the bottom surface  74  of the support member  202 . The longer side of the slits  203  are substantially perpendicular to the first and second alignment ends  214 ,  215 . As shown in  FIG. 16 , slit  203   a  is formed in the right side of the sectional view taken along the line E-E of the embodiment, slit  203   b  is formed in a short distance away on the left side of slit  203   a  and slit  203   c  is formed in a longer distance than the distance between  203   a  and  203   b  away on the left side of the slit  203   b . Each attachment strips  71  includes tail portions  711 , insertion portions  712 , top portion  713  and bottom portion  714 . The attachment strips  71   a ,  71   b  are formed on the support member  202  in a same means that the tail portions  711  of the attachment strips  71   a ,  71   b  are on the bottom surface  74  of the support member  202 , while the attachment strip  71   c  is configured with one more slit  203   d  formed in a short distance in the left side of a slit  203   c , which results in the tail potions  711  of the attachment strip  71   c  being located on the top surface  73  of the support member  202 . As shown in  FIG. 16 , the tail portions  711  of the attachment strips  71  are clamped with the clamp  72  in the left side of the sectional view taken along the line E-E of the embodiment. It should be understood that clamp  72  can be a stainless steel clamp or any other clamps or fastener which can fix the attachment strips  71  on the top surface  73  and the bottom surface  74  of the support member  202 . With this arrangement, each attachment strip  71  passes through the support member  202  multiple times as shown to facilitate securing it to the support member  202 . The top portion  713  of each attachment strip  71  on the support member  202  is substantially longer than the bottom portion  714  on the bottom surface  74  of the support member  202  to increase the surface area which will contact the complementary attachment strip  75  as will be described below. Attachment strips  71  may be provided with the strips mechanically or chemically formed to temporally fix the shoe  210  on the support member  202 , for example, Velcro strips, tacky adhesive strips, magnetic strips, etc. It should be understood that the attachment strips  71 , while show here to have certain dimensions, may be alternatively formed in other dimensions up to and including dimensions which would cover the entire top surface  73 . It should also be noted here that while the attachment strips  71  are, in this embodiment, secured to the support member  202  in a certain undulating pattern over the top and bottom  73 , 74 , other patterns and methods of securing the attachment strips  71  are anticipated by the invention. Such patterns may extend longer or shorter distances from the conduit support surface  207 . 
       FIGS. 18-24  show different arrangements of attachment strips on the shoe of a portable conduit bending frame assembly  90  according to a fourth embodiment of the invention which illustrates a second method of attaching the shoe on the support member  202 . As shown in  FIGS. 18-21 , the shoe  210  includes a plurality of slits  256  extended from a top surface to a bottom surface of the shoe  210  and formed as rows with substantial even space in a direction parallel to a alignment surface  211  and a plurality of the attachment strips  75  on the top and bottom surfaces of the shoes  210 . As shown in  FIG. 20 , the top and bottom surfaces are each a major surface of the shoe  210 . Attachment strips  75  include tail portions  751 , insertion portions  752 , bottom portions  753  and top portion  754 . The top portion  754  of the attachment strips  75  on the shoe  210  are substantially equal to the bottom portion  753  of the shoe  210  on the bottom surface. Attachment strips  75  may be provided with the strips mechanically or chemically formed that can temporally fix the shoe  210  on the support member  202 , for example, Velcro strips, tacky adhesive strips, magnetic strips, etc. are a few non-exclusive examples. The attachment strips  75  are double sided and undulate through the shoe  210  and the two ends of the double side attachment strips  75  are clamped on the shoe  210  with clamps  76 . It should be understood that clamp  76  can be a stainless steel counter-top clamp or any other clamp which can fix the attachment strip  75  on the surface of the shoe  210  and maintain the surface flat. It should be understood that in all embodiments of the shoe, a single clamp could be utilized instead of two clamps. In the single clamp embodiment, the attachment strip may be wrapped around the edge of the shoe of otherwise woven back to the single clamp. In this illustrated embodiment,  FIGS. 22-23  show the attachment strips  77 ,  78  fixed on the top and the bottom surfaces of the shoe  310 , respectively, for bending and inverse bending. The attachment strips  77 ,  78  can also be glued on the surface of the shoe  310  or attached by other surface means. Note also that the strips  77 , 78  may take other shapes and dimensions.  FIG. 24  shows attachment strips  79  crossly fixed on either top or bottom surface of the shoe  410  for bending and inverse bending. Other arrangements of the attachment strips are possible. 
     With the fourth embodiment of the claimed invention, at least one of the shoes  210 , or  310 , or  410  is attached to the support member  202 . The attachment strips  75  or  77 , or  78 , or  79  of the shoe temporarily attached to the attachment strips  71  on the support member  202 . A method of bending or inverse bending a conduit is the same as those of the bending frame assembly  1  and their descriptions can be referred to in the description of the bending frame assembly  1  above. In this embodiment, the shoe  210 ,  310 ,  410  is advantageously more flexibly and finely adjustable along the scale  209 . 
     The portable conduit bending frame assemblies  1 ,  30 ,  70  and  90  according to the first, second, third and fourth embodiments of the invention are therefore easy to transport and operate and can economically heat and form or bend the conduit  21  to a desired configuration to obtain a conduit with a desired configuration without the use of couplings. 
     The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments are possible within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting, and that the scope of the invention is given by the appended claims together with their full range of equivalents.