Patent Publication Number: US-9902588-B2

Title: Consumable assembly with payout tube for additive manufacturing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a Continuation Application of U.S. patent application Ser. No. 13/334,921, filed Dec. 22, 2011; the contents of which are incorporated by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to additive manufacturing systems for building three-dimensional (3D) parts with layer-based, additive manufacturing techniques. In particular, the present disclosure relates to consumable assemblies for supplying consumable part and support materials to additive manufacturing systems. 
     Additive manufacturing systems are used to print or otherwise build 3D parts from digital representations of the 3D parts (e.g., AMF and STL format files) using one or more additive manufacturing techniques. Examples of commercially available additive manufacturing techniques include extrusion-based techniques, jetting, selective laser sintering, powder/binder jetting, electron-beam melting, and stereolithographic processes. For each of these techniques, the digital representation of the 3D part is initially sliced into multiple horizontal layers. For each sliced layer, a tool path is then generated, which provides instructions for the particular additive manufacturing system to print the given layer. 
     For example, in an extrusion-based additive manufacturing system, a 3D part may be printed from a digital representation of the 3D part in a layer-by-layer manner by extruding a flowable part material. The part material is extruded through an extrusion tip carried by a print head of the system, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded part material fuses to previously deposited part material, and solidifies upon a drop in temperature. The position of the print head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D part resembling the digital representation. 
     In fabricating 3D parts by depositing layers of a part material, supporting layers or structures are typically built underneath overhanging portions or in cavities of 3D parts under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D part being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the printing process. The support material adheres to the part material during fabrication, and is removable from the completed 3D part when the printing process is complete. 
     SUMMARY 
     An aspect of the present disclosure is directed to a payout tube for enabling payout of a consumable filament from a consumable assembly that is configured for use with an additive manufacturing system. The payout tube includes a tip end having an inlet opening, a base end having an outlet opening, and a tube body having an average effective outer diameter that is substantially greater than an effective inner diameter of the inlet opening. 
     Another aspect of the present disclosure is directed to a consumable assembly for use with an additive manufacturing system. The consumable assembly includes a coil of a consumable filament retained in a figure-8 configuration, and having a payout hole extending from an inner layer of the coil to an outer layer of the coil, where the consumable filament has an average cross-sectional area ranging from about 0.5 square millimeters to about 11.3 square millimeters. The consumable assembly also includes a payout tube that has a tip end having an inlet opening, a base end having an outlet opening, and a tube body, where the tube body has an average effective outer diameter that is substantially greater than an effective inner diameter of the inlet opening. 
     Unless otherwise expressly indicated, the terms “effective inner diameter” and “average effective outer diameter” are used herein as defined below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top, front perspective view of an additive manufacturing system in use with consumable assemblies of the present disclosure. 
         FIG. 2  is a top, front perspective view of one of the consumable assemblies. 
         FIG. 3  is a top perspective view of a coil, payout tube, and guide tube of the consumable assembly. 
         FIG. 4  is a side illustration of the coil, payout tube, guide tube, and a liner of the consumable assembly. 
         FIG. 5A  is a bottom, front perspective view of the payout tube. 
         FIG. 5B  is a top perspective view of the payout tube. 
         FIG. 5C  is a sectional view of the payout tube in use with a guide tube, taken along Section 5C-5C in  FIG. 5B . 
         FIG. 5D  is an expanded sectional view of a tip end of the payout tube and the guide tube. 
         FIG. 6A  is a bottom, front perspective view of a first alternative payout tube of the present disclosure, which includes a capture tip, in use with a guide tube. 
         FIG. 6B  is an exploded bottom, front perspective view of the first alternative payout tube in use with the guide tube. 
         FIG. 6C  is a sectional view of a tip end of the first alternative payout tube in use with the guide tube, taken along Section 6C-6C in  FIG. 6A . 
         FIG. 7A  is a bottom, front perspective view of a second alternative payout tube of the present disclosure, which includes a flat tip end. 
         FIG. 7B  is a top perspective view of the second alternative payout tube. 
         FIG. 7C  is a sectional view of the second alternative payout tube, taken along Section 7C-7C in  FIG. 7B . 
         FIG. 7D  is an expanded sectional view of a tip end of the second alternative payout tube in use with a guide tube. 
         FIG. 7E  is an alternative expanded sectional view of a tip end of the second alternative payout tube, which includes a capture tip, in use with the guide tube. 
         FIG. 8A  is a bottom, front perspective view of a third alternative payout tube of the present disclosure, which includes sharp-sloped outer geometry. 
         FIG. 8B  is a top perspective view of the third alternative payout tube. 
         FIG. 8C  is a sectional view of the third alternative payout tube, taken along Section 8C-8C in  FIG. 8B . 
         FIG. 8D  is an expanded sectional view of a tip end of the third alternative payout tube in use with a guide tube. 
         FIG. 8E  is an alternative expanded sectional view of a tip end of the third alternative payout tube, which includes a capture tip, in use with the guide tube. 
         FIG. 9A  is a bottom, front perspective view of a fourth alternative payout tube of the present disclosure, which includes four opposing flanges in an X-shaped pattern. 
         FIG. 9B  is a top perspective view of the fourth alternative payout tube. 
         FIG. 9C  is a sectional view of the fourth alternative payout tube, taken along Section 9C-9C in  FIG. 9B . 
         FIG. 9D  is a bottom, front perspective view of the fourth alternative payout tube, taken from an opposite lateral side from the view shown in  FIG. 9A , and which illustrates circumscribed circles of a payout tube body. 
         FIG. 9E  is an expanded sectional view of a tip end of the fourth alternative payout tube in use with a guide tube. 
         FIG. 9F  is an alternative expanded sectional view of a tip end of the fourth alternative payout tube, which includes a capture tip, in use with the guide tube. 
         FIG. 10A  is a bottom, front perspective view of a fifth alternative payout tube of the present disclosure, which includes two opposing flanges. 
         FIG. 10B  is a top perspective view of the fifth alternative payout tube. 
         FIG. 10C  is a side view of the fifth alternative payout tube. 
         FIG. 10D  is a sectional view of the fifth alternative payout tube, taken along Section 10D-10D in  FIG. 10B . 
         FIG. 10E  is a sectional view of the fifth alternative payout tube, taken along Section 10E-10E in  FIG. 10C . 
         FIG. 10F  is a bottom, front perspective view of the fifth alternative payout tube, taken from an opposite lateral side from the view shown in  FIG. 10A , and which illustrates circumscribed circles of a payout tube body. 
         FIG. 10G  is an expanded sectional view of a tip end of the fifth alternative payout tube in use with a guide tube. 
         FIG. 10H  is an alternative expanded sectional view of a tip end of the fifth alternative payout tube, which includes a capture tip, in use with the guide tube. 
         FIG. 11A  is a cut bottom, front perspective view of a sixth alternative payout tube of the present disclosure, which includes a filament drive mechanism. 
         FIG. 11B  is a side illustration of the coil, payout tube, guide tube, and liner of an alternative consumable assembly, which also includes a coupling adapter. 
         FIG. 12  is a photograph of a test set up for tested payout tubes of the present disclosure and for tested comparative payout tubes. 
         FIG. 13A  is a photograph of a tested payout tube of Comparative Example A. 
         FIGS. 13B and 13C  are photographs of payout test results for the payout tube of Comparative Example A. 
         FIG. 14A  is a photograph of a tested payout tube of Comparative Example B. 
         FIG. 14B  is a photograph of payout test results for the payout tube of Comparative Example B. 
         FIG. 15A  is top perspective view of a payout tube used for Comparative Examples C-E. 
         FIG. 15B  is side view of the payout tube used for Comparative Examples C-E. 
         FIG. 16A  is a photograph of a tested payout tube of Comparative Example C. 
         FIG. 16B  is a photograph of payout test results for the payout tube of Comparative Example C. 
         FIG. 17A  is a photograph of a tested payout tube of Comparative Example D. 
         FIG. 17B  is a photograph of payout test results for the payout tube of Comparative Example D. 
         FIG. 18A  is a photograph of a tested payout tube of Comparative Example E. 
         FIG. 18B  is a photograph of payout test results for the payout tube of Comparative Example E. 
         FIG. 19A  is top perspective view of a payout tube of Comparative Example F. 
         FIG. 19B  is sectional view of the payout tube of Comparative Example F, taken along Section 19B-19B in  FIG. 19A . 
         FIG. 19C  is a photograph of the tested payout tube of Comparative Example F. 
         FIG. 19D  is a photograph of payout test results for the payout tube of Comparative Example F. 
         FIG. 20A  is a photograph of the tested payout tube of Example 1 of the present disclosure. 
         FIG. 20B  is a photograph of payout test results for the payout tube of Example 1. 
         FIGS. 21A and 21B  are photographs of payout test results for a tested payout tube of Example 2 of the present disclosure. 
         FIG. 22A  is a photograph of the tested payout tube of Example 3 of the present disclosure. 
         FIG. 22B  is a photograph of payout test results for the payout tube of Example 3. 
         FIG. 23A  is a photograph of the tested payout tube of Example 4 of the present disclosure. 
         FIG. 23B  is a photograph of payout test results for the payout tube of Example 4. 
         FIG. 24A  is a photograph of the tested payout tube of Example 5 of the present disclosure. 
         FIG. 24B  is a photograph of payout test results for the payout tube of Example 5. 
         FIG. 25A  is a photograph of the tested payout tube of Example 6 of the present disclosure. 
         FIG. 25B  is a photograph of payout test results for the payout tube of Example 6. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is directed to a consumable assembly having a payout tube for use in an additive manufacturing system, such as an extrusion-based additive manufacturing system. The consumable assembly is an easily loadable, removable, and replaceable container device configured to retain a coil of part or support material consumable filament in a figure-8 configuration. The payout tube enables payout of the consumable filament from the consumable assembly without having the consumable filament become entangled (e.g., knotting up or kinking). As discussed below, this allows successive segments of the consumable filament to be fed from the consumable assembly to the additive manufacturing system without interruption. Additionally, in comparison to spooled filaments, which are limited in size due to excessive pulling forces that otherwise occur with large spools (which could break the filaments), the use of a coil of the consumable filament (in a figure-8 configuration) also effectively allows the consumable assembly to be any desired size (e.g., large coils for large printing runs). 
       FIG. 1  shows system  10  in use with two consumable assemblies  12  of the present disclosure, where each consumable assembly  12  is an easily loadable, removable, and replaceable container device that retains a coil of consumable filament for printing with system  10 . Typically, one of the consumable assemblies  12  contains a coil of part material filament (“part material consumable assembly”), and the other consumable assembly  12  contains a coil of support material filament (“support material consumable assembly”). However, both consumable assemblies  12  may be identical in structure. 
     In the shown embodiment, each consumable assembly  12  includes container portion  14 , guide tube  16 , and print head  18 , where container portion  14  retains a coil of a consumable filament and a payout tube. Guide tube  16  interconnects container portion  14  and print head  18  to supply successive segments of the consumable filament from container portion  14  to print head  18 . In this embodiment, guide tube  16  and print head  18  are subcomponents of consumable assembly  12 , and may be interchanged to and from system  10  with each consumable assembly  12 . As discussed below, in alternative embodiments, guide tube  16  and/or print head  18  may be components of system  10 , rather than subcomponents of consumable assemblies  12 . 
     System  10  is an additive manufacturing system for printing 3D parts or models and corresponding support structures (e.g., 3D part  22  and support structure  24 ) from the part and support material filaments, respectively, of consumable assemblies  12 , using a layer-based, additive manufacturing technique. Suitable additive manufacturing systems for system  10  include extrusion-based systems developed by Stratasys, Inc., Eden Prairie, Minn. under the trademarks “FDM” and “FUSED DEPOSITION MODELING”. As shown, system  10  includes system casing  26 , two bays  28 , build chamber  30 , platen  32 , platen gantry  34 , head carriage  36 , head gantry  38 , z-axis motor  40 , and a pair of x-y motors  42 . 
     System casing  26  is a structural component of system  10  and may include multiple structural sub-components such as support frames, housing walls, and the like. In the shown embodiment, system casing  26  defines the dimensions of bays  28 , and of build chamber  30 . Bays  28  are container bays configured to respectively receive container portions  14  of consumable assemblies  12 . Typically, each of bays  28  may be intended to receive either a part material consumable assembly  12  or a support material consumable assembly  12 . 
     In an alternative embodiment, bays  28  may be omitted to reduce the overall footprint of system  10 . In this embodiment, container portions  14  may stand adjacent to system casing  26 , while providing sufficient ranges of movement for guide tubes  16  and print heads  18 . Bays  28 , however, provide convenient locations for loading spool assemblies  12 . 
     Build chamber  30  is an enclosed environment that contains platen  32  for printing 3D part  22  and support structure  24 . Build chamber  30  may be heated (e.g., with circulating heated air) to reduce the rate at which the part and support materials solidify after being extruded and deposited (e.g., to reduce distortions and curling). In alternative embodiments, build chamber  30  may be omitted and/or replaced with different types of build environments. For example, 3D part  22  and support structure  24  may be built in a build environment that is open to ambient conditions or may be enclosed with alternative structures (e.g., flexible curtains). 
     Platen  32  is a platform on which 3D part  22  and support structure  24  are printed in a layer-by-layer manner, and is supported by platen gantry  34 . In some embodiments, platen  32  may also include a flexible polymeric film or liner on which 3D part  22  and support structure  24  are printed. Platen gantry  34  is a gantry assembly configured to move platen  32  along (or substantially along) the vertical z-axis and is powered by z-axis motor  40 . 
     Head carriage  36  is a unit configured to receive one or more removable print heads, such as print heads  18 , and is supported by head gantry  38 . Examples of suitable devices for head carriage  36 , and techniques for retaining print heads  18  in head carriage  36 , include those disclosed in Swanson et al., U.S. patent application Ser. No. 12/976,111; Swanson, U.S. Patent Application Publication No. 2010/0283172; and Swanson, International Publication No. WO2009/088995. 
     Head gantry  38  is a belt-driven gantry assembly configured to move head carriage  36  (and the retained print heads  18 ) in (or substantially in) a horizontal x-y plane above build chamber  30 , and is powered by x-y motors  42 . Examples of suitable gantry assemblies for head gantry  38  include those disclosed in Comb et al., U.S. patent Ser. No. 13/242,561. 
     As further shown in  FIG. 1 , system  10  may also include a pair of sensor assemblies  44 , which, in the shown embodiment, are located adjacent to bays  28 . Sensor assemblies  44  are configured to receive and retain guide tubes  16 , while also providing sufficient ranges of movement for guide tubes  16  and print heads  18 . Sensor assemblies  44  are also configured to read encoded markings from successive segments of the consumable filaments moving through guide tubes  16 . Examples of suitable devices for sensor assemblies  44  include those disclosed in Batchelder et al., U.S. Patent Application Publication Nos. 2011/0117268, 2011/0121476, and 2011/0233804. 
     System  10  also includes controller  46 , which is one or more processor-based controllers that may communicate over communication line  47  with print heads  18 , build chamber  30  (e.g., with a heating unit for build chamber  30 ), head carriage  36 , motors  40  and  42 , sensor assemblies  44 , and various sensors, calibration devices, display devices, and/or user input devices. In some embodiments, controller  46  may also communicate with one or more of bays  28 , platen  32 , platen gantry  34 , head gantry  38 , and any other suitable component of system  10 . 
     While illustrated as a single signal line, communication line  47  may include one or more electrical, optical, and/or wireless signal lines, allowing controller  46  to communicate with various components of system  10 . Furthermore, while illustrated outside of system  10 , controller  46  and communication line  47  may be internal components to system  10 . 
     During operation, controller  46  directs z-axis motor  40  and platen gantry  34  to move platen  32  to a predetermined height within build chamber  30 . Controller  46  then directs motors  42  and head gantry  38  to move head carriage  36  (and the retained print heads  18 ) around in the horizontal x-y plane above build chamber  30 . Controller  46  may also direct print heads  18  to selectively draw successive segments of the consumable filaments from container portions  14  and through guide tubes  16 , respectively. 
     Each print head  18  thermally melts the successive segments of the received consumable filament such that it becomes a molten material, thereby allowing the molten material to be extruded and deposited onto platen  32  for printing 3D part  22  and support structure  24  in a layer-by-layer manner. After the print operation is complete, the resulting 3D part  32  and support structure  24  may be removed from build chamber  30 , and support structure  24  may be removed from 3D part  22 . 3D part  22  may then undergo one or more additional post-processing steps. 
     As discussed above, consumable assemblies  12  are removable and replaceable container devices. As shown in  FIG. 2 , consumable assembly  12  also includes box  48 , liner  50 , payout tube  52 , and coil  54  of a consumable filament for use in system  10  (e.g., a part or support material filament). In the shown example, box  48  is a rigid or semi-rigid container for consumable assembly  14 , and may include a variety of indicia and graphics for identifying the material type for coil  54 . Box  48  may also include a compartment to retain guide tube  16  and print head  18  during transportation and storage. 
     Liner  50  encases payout tube  52  and coil  54  within box  48 , and may be one or more polymeric bags, wrappings (e.g., shrink wrap liner), metallic foil casings, and the like, which desirably prevent or substantially prevent ambient conditions from reaching coil  54 . For example, liner  50  may be a moisture-impermeable liner or sheath to provide a moisture barrier, a gas-impermeable liner or sheath to provide a gas barrier, a particulate-impermeable liner or sheath to provide a dust barrier, and the like. Liner  50  may also be opaque to reduce light exposure (e.g., ultraviolet light exposure), to reduce the risk of degrading the consumable filament of coil  54  over extended periods of storage. 
     In the case of moisture-sensitive materials, consumable filament of coil  54  is desirably provided to print head  18  in a dry state (e.g., less than 300 parts-per-million by weight of water) to prevent moisture from negatively affecting the extrusion process. As such, liner  50  may provide a moisture barrier for the consumable filament during transportation, storage, and use in system  10 . 
     In an alternative embodiment, liner  50  may be omitted and box  48  may provide the barrier against ambient conditions (e.g., moisture resistance). In this embodiment, guide tube  16  may extend through a sealed opening in box  48 , adjacent to payout tube  52 , to allow print head  18  to be loaded to head carriage  36  of system  10 . In another alternative embodiment, box  48  may be omitted, and payout tube  52  and coil  54  may be retained solely within liner  54 . In this embodiment, the consumable assembly within liner  54  may be directly loaded to bay  28  or otherwise made available for use with system  10 . 
     Payout tube  52  is a rigid component that extends through coil  54  and is configured to receive guide tube  16 , as shown. In particular, guide tube  16  desirably extends through liner  50  in a sealed arrangement to maintain the barrier from ambient conditions. For example, guide tube  16  may be secured to an opening through liner  50  with a sealing adhesive. 
     As discussed below, payout tube  52  enables the consumable filament of coil  54  to unwind from coil  54  without becoming entangled. As can be appreciated, if the consumable filament of coil  54  becomes entangled during payout, the resulting knot or kink will be caught in guide tube  16  or print head  18  (or fail to even enter guide tube  16 ), preventing the filament from reaching a liquefier of print head  18 . This would disrupt the printing operation in system  10 , which relies on accurate timings of the deposited part and support materials, thereby impeding the printing operation. 
     Prior to use in system  10 , the user may open box  48  and remove guide tube  16  and print head  18 , and engage guide tube  16  through sensor assembly  44 . The user may then insert print head  18  into head carriage  36  as discussed in Swanson et al., U.S. patent application Ser. No. 12/976,111. As discussed in Swanson et al., U.S. patent application Ser. No. 12/976,111; Swanson, U.S. Patent Application Publication No. 2010/0283172; and Swanson, International Publication No. WO2009/088995, the consumable filament in the consumable assembly  12  may be pre-fed through guide tube  16 , and into print head  18 . 
     In this embodiment, print head  18  includes a filament drive mechanism for drawing successive segments of the consumable filament from container portion  14  and through guide tube  16 . As such, once each consumable assembly  12  is loaded, system  10  may begin to use the consumable filaments during one or more pre-printing operations (e.g., calibration routines) or during print operations without requiring the user to perform any additional loading tasks. 
     As shown in  FIG. 3 , coil  54  includes filament  56  retained in a figure-8 configuration, where filament is a consumable filament for use in system  10  (e.g., a part or support material filament). The figure-8 configuration of coil  54  is well known for materials such as wire, rope, communication cables, and the like, and is described in references such as U.S. Pat. Nos. 2,767,938 and 4,406,419, and the references cited therein. The figure-8 configuration of coil  54  has an inner layer  58  and an outer layer  60 , and provides a payout hole  62  that extends through coil  54  between inner layer  58  and outer layer  60 . 
     Payout tube  52  extends through payout hole  62 , and includes base end  64  having outlet opening  66  and collar  68 . Outlet opening  66  is an opening through which guide tube  16  extends to relay successive segments of filament  56  to print head  18 . Collar  68  extends around outlet opening  66  and provides a suitable mechanism to holding payout tube  52  against outer layer  60  of coil  54 , such as with liner  50  (shown in  FIG. 2 ). 
     This is further illustrated in  FIG. 4 , in which a segment of filament  56  extends into tip end  70  of payout tube  52 . Payout tube  52  has a body  72  between base end  64  and tip end  70  that extends through payout opening  62 , with tip end  70  extending inward toward the radial center of coil  54  from inner layer  60 . During assembly of consumable assembly  12 , filament  56  may be wound in the known figure-8 configuration, which creates payout hole  62 . Guide tube  16  may secured within payout tube  52 , and payout tube  52  may be inserted through payout hole  62  until collar  68  rests against outer layer  58  of coil  54 . 
     The leading end of filament  56  may inserted into an inlet opening of payout tube  52  at tip end  70  (not shown in  FIG. 4 ), and fed through guide tube  16  to print head  18 , as discussed above. Payout tube  52  and coil  54  may then be sealed in liner  50  and loaded into box  48  for transportation, storage, and use with system  10 . 
     As mentioned above, the figure-8 configuration of coil  54  is well known for use with strand materials such as wire, rope, communication cables, and the like. Such strand materials are also typically fed through payout tubes to prevent the strands from becoming entangled. Current commercially available payout tubes typically have inlet diameters that are large compared to the strands they receive. This allows the current payout tubes to accommodate the payout of such strands, for example, by allowing looped twists in the strands to pass through the payout tube. 
     It turns out, however, that the current payout tubes repeatedly cause consumable filaments, such as filament  56 , to become entangled at the inlet ends of the payout tubes. As mentioned above, this can disrupt printing operations in additive manufacturing systems (e.g., system  10 ). Instead, as discussed below, the payout tubes of the present disclosure (e.g., payout tube  52 ) have geometries that are different from those of the current payout tubes, and prevent payout entanglement for the consumable filaments. 
       FIGS. 5A-5D  further illustrate payout tube  52 . As shown in  FIG. 5A , body  72  of payout tube  52  extends from collar  68  along longitudinal axis  74 , between base end  64  and tip end  70 . At tip end  70 , payout tube  52  also includes inlet opening  76 , which has an inner diameter that substantially less than the average outer diameter of body  72 . As discussed below, this combination of a small diameter inner opening  76  and a substantially larger average outer diameter for body  72  prevents or reduces payout entanglement for consumable filaments such as filament  56 . 
     As shown in  FIGS. 5A and 5B , inlet opening  76  is also smaller than outlet opening  66 , where the larger inner diameter of outlet opening  66  allows guide tube  16  to freely move. In alternative embodiments, outlet opening  66  may be any suitable size that is at least as great as inlet opening  66 . As shown in  FIG. 5C , body  72  has an inner diameter that defines interior channel  78 , where, in the shown embodiment, interior channel  78  converges to narrowed gap  80  at tip end  70 . Narrowed gap  80  extends between interior channel  78  and inlet opening  76 , and provides a suitable location for receiving a tip or leading end of guide tube  16  (referred to as leading end  82 ). 
     Body  72  has a length  84  along longitudinal axis  74 , between base end  64  and tip end  70 . Suitable distances for length  84  range from about 130 millimeters (about 5 inches) to about 250 millimeters (about 10 inches). Length  84  is also desirably proportional to the thickness of coil  54  between outer layer  58  and inner layer  60 , such that base end  64  and tip end  70  are located outside the opposing ends of payout opening  62  in coil  54 . 
     Body  72  also has an average outer diameter  86  that is perpendicular to longitudinal axis  74 , and that is taken as an average of the outer diameters along longitudinal axis  74  between base end  64  (not including collar  68 ) and tip end  70 . In other words, average outer diameter  86  may be determined by (1) determining the diameters of the outer cross-sectional geometries of the payout tube body at multiple points along longitudinal axis  74  (not including collar  68 ), and (2) averaging the determined diameters. Examples of suitable dimensions for average outer diameter  84  range from about 38 millimeters (about 1.5 inches) to about 130 millimeters (about 5 inches). As can be appreciated, outer average diameter  84  is substantially greater than inlet opening  76 . 
     In the shown example, body  72  is conical with round outer cross-sectional geometries, and is wider at base end  64  than at tip end  70 . In an alternative embodiment, body  72  may be cylindrical (i.e., constant diameter). In these embodiments, the outer cross-sectional geometries of body  72  may be described in terms of diameters (e.g., average outer diameter  86 ). 
     In other embodiments, however, the payout tube body may not necessarily have a round cross-sectional geometry (see e.g., payout tube  452  in  FIGS. 9A-9F , and payout tube  552  in  FIGS. 10A-10H ). In these embodiments, “diameter” is not a suitable term to directly describe their outer cross-sectional dimensions. Instead, as discussed further below, the outer cross-sectional dimensions may be based on an average diameter of circumscribed circles of the outer geometry. 
     Accordingly, as used herein, the “average effective outer diameter” of a payout tube body is the average diameter of the circumscribed circles of the outer cross-sectional geometries of the payout tube body, taken along the longitudinal length of the payout tube body. In other words, the “average effective outer diameter” may be determined by (1) virtually creating circumscribed circles of the outer cross-sectional geometries of the payout tube body at multiple points along the longitudinal axis of the payout tube body (not including any collars, such as collar  68 ), (2) determining the diameters of the circumscribed circles, and (3) averaging the determined diameters. As can be appreciated, in embodiments in which the payout tube body is conical, cylindrical, or the like, the “average effective outer diameter” of the payout tube body is the same as its average outer diameter (e.g., average outer diameter  86 ). 
     Guide tube  16  may be secured to payout tube  52  by inserting leading end  82  through outlet opening  66 , interior channel  78 , narrowed gap  80 , inlet opening  76 . This positions leading end  82  outside of inlet opening  76 . E-clip  92  may then be inserted around leading end  82 , and leading end  82  may be withdrawn back into inlet opening  76 , where e-clip  92  is prevented from entering narrowed gap  80 . 
     As shown in  FIG. 5D , leading end  82  may then be secured within inlet opening  76 , such with an adhesive (e.g., adhesive  94 ). This prevents guide tube  16  from detaching from payout tube  52 , and allows filament  56  to directly enter guide tube  16  within payout tube  52 . Leading end  82  and adhesive  94  are desirably flush with the exterior surface of body  72  at inlet opening  76 . 
     As mentioned above, inlet opening  76  has an inner diameter (referred to as inner diameter  96 ) that is substantially less than average outer diameter  84  of body  72 , and this combination is believed to reduce or prevent payout entanglement of filament  56 . Additionally, in the shown embodiment, leading end  82  of guide tube  16  and adhesive  94  effectively reduce the dimensions of inner diameter  96  to the inner diameter of guide tube  16  at leading end  82  (referred to as inner diameter  98 ). 
     As discussed below, in alternative embodiments, guide tube  16  may be secured to payout tube  52  at different locations within interior region  78 , such as at base end  64 . In these embodiments, the effective inner diameter that filament  56  travels through would be inner diameter  96  of inlet opening  76 . 
     In the shown example, inlet opening  76  and leading end  82  of guide tube  16  each have round cross-sectional geometries. As such, their cross-sectional dimensions may be referred by their diameters (e.g., inner diameters  96  and  98 ). In other embodiments, however, inlet opening  76  and/or leading end  82  of guide tube  16  may not necessarily have round cross-sectional geometries (e.g., rectangular cross-sectional geometries). In these embodiments, “diameter” is not a suitable descriptive term to directly reference their inner cross-sectional dimensions. Instead, the inner cross-sectional dimensions may be based on an average diameter of circumscribed circles of the inner cross-sectional geometries. 
     Accordingly, as used herein, the “effective inner diameter” of an inlet opening (e.g., of inlet opening  76  and/or the inlet opening at leading end  82  of guide tube  16 ) is the diameter of the circumscribed circle of the inner cross-sectional geometry of the opening. In other words, the “effective inner diameter” may be determined by (1) virtually creating a circumscribed circle of the inner cross-sectional geometry of the inlet opening, and (2) determining the diameter of the circumscribed circle. As can be appreciated, in embodiments in which the inlet opening is circular, the “effective inner diameter” of the inlet opening is the same as its inner diameter (e.g., inner diameters  96  and  98 ). 
     Examples of suitable dimensions for the effective inner diameter of inlet opening  76  (e.g., inner diameter  98 ) include diameters less than about 7.6 millimeters (about 0.3 inches), more desirably less than about 6.4 millimeters (about 0.25 inches), and even more desirably less than about 5.1 millimeters (about 0.2 inches). Additionally, the effective inner diameter of inlet opening  76  is also proportional to the dimensions of filament  56 , which are discussed below. Suitable dimensions for the effective inner diameter of inlet opening  76  also range from about 110% to about 300% of the average outer diameter of filament  56 , with particularly suitable dimensions ranging about 150% to about 275% of the average outer diameter of filament  56 , and with even more particularly suitable dimensions ranging about 200% to about 250% of the average outer diameter of filament  56 . 
     As mentioned above, the effective inner diameter (e.g., inner diameter  98 ) of inlet opening  76  is also substantially less than average outer diameter  84  of body  72 . Average outer diameter  84  is desirably at least three times greater than the effective inner diameter of inlet opening  76 . In one embodiment, average outer diameter or width  84  is also at least four times greater than the effective inner diameter of inlet opening  76 , and more desirably at least five times greater. 
       FIGS. 6A-6C  illustrate an additional feature for payout tube  52 , namely capture tip  100  secured to tip end  70  at inlet opening  76 . As shown in  FIG. 6A , capture tip  100  includes conical portion  102 , which provides a conical surface at inlet opening  76  for receiving filament  56 . This eliminates surfaces that are perpendicular to the direction of movement of filament  56  as filament  56  enters payout tube  52  (i.e., surfaces that are perpendicular to longitudinal axis  74 ). 
     In some situations, even a small surface that is perpendicular to the direction of movement of filament  56  can create a shelf that catches filament  56  as it enters inlet opening  76 . Once caught on this shelf, filament  56  can pull itself to a decreasing radius until it kinks, where the kink can be large enough to prevent it from entering leading end  82  of guide tube  16 . This results in a jam of filament  56 , which can disrupt the printing operation in system  10 . Capture tip  100  provides a convenient mechanism for reducing or eliminating this shelving effect by providing a surface that is not perpendicular to the direction of movement of filament  56 . 
     As shown in  FIG. 6B , capture tip  100  also includes base portion  104 , which may be integrally formed with conical portion  102  from one or more polymeric and/or metallic materials. Capture tip  100  may be assembled to guide tube  16  and payout tube  52  using the same process discussed above. For example, leading end  82  of guide tube  16  may be inserted through payout tube  52 , thereby positioning leading end  82  outside of inlet opening  76 . E-clip  92  may then be inserted around leading end  82 , and leading end  82  may be inserted into base portion  104  of capture tip  100 . Guide tube  16  may then be withdrawn back into inlet opening  76 , where e-clip  92  and capture tip  100  are prevented from entering narrowed gap  80 . Base portion  102  may be secured within inlet opening  76  by frictional fit and/or snap-fit, and may optionally include an adhesive. 
     As shown in  FIG. 6C , when assembled, e-clip  92  and capture tip  100  retain leading end  82  of guide tube  16  within inlet opening  76 . In comparison to the surface formed by tip end  70  and adhesive  94  (best shown in  FIG. 5D ), which is substantially perpendicular to the direction of movement of filament  56 , conical portion  102  of capture tip  100  provides a sloped surface that is not perpendicular to the direction of movement of filament  56 , thereby reducing or eliminating the shelving effect. 
     Additionally, capture tip  100  precludes the need for an adhesive near inlet opening  76 . It turns out that if adhesive  94  (shown in  FIG. 5D ) is not sufficiently flush with the exterior surface of body  72  at inlet opening  76 , it may come in contact with filament  56  as filament  56  passes through inlet opening  76 . This contact can potentially increase the risk of the shelving effect. 
     Capture tip  100  has an inner diameter that is substantially the same as the inner diameter of guide tube  16 . As such, in this embodiment, the effective inner diameter of inlet opening  76  is the same as the dimensions of inner diameter  98 . However, in alternative embodiments, capture tip  100  may have an inner diameter that is different (e.g., smaller) than that of leading end  82  of guide tube  16 . In these embodiments, the effective inner diameter of inlet opening  76  is the same as the dimensions of the inner diameter of capture tip  100 . 
       FIGS. 7A-10H  illustrate alternative payout tubes of the present disclosure, referred to as payout tubes  252 ,  352 ,  452 , and  552 , where corresponding reference numbers in  FIGS. 7A-10H  are respectively increased by “200”, “300”, “400”, and “500” from those of payout tube  52  and guide tube  16 . Payout tubes  252 ,  352 ,  452 , and  552  each have an inlet opening with an effective inner diameter that is substantially less than the average effective outer diameter of the payout tube body, which reduces or prevents payout entanglement. 
     As shown in  FIGS. 7A-7E , payout tube  252  is similar to payout tube  52 , but does not include a curved geometry at tip end  270 . This embodiment is particularly suitable for use with a capture tip, such as capture tip  300  (shown in  FIG. 7E ), to provide a sloped surface that is not perpendicular to the direction of movement of filament  56 . 
     As shown in  FIGS. 8A-8E , payout tube  352  is also similar to payout tube  52 , where the geometry of body  372  converges with a sharper slope compared to payout tubes  52  and  252 . For example, the diameters of payout tubes  52  and  252  each reduce by about 20%. In comparison, the diameter of payout tube  352  reduces by about 70%. 
     Accordingly, in some embodiments, the average effective outer diameter reduces by less than 35%, and more desirably less than about 25%, as taken in a direction toward the tip end of the payout tube (e.g., tip end  70 ). Alternatively, in other embodiments, the average effective outer diameter reduces by amount ranging from about 60% to about 80%, as taken in a direction toward the tip end of the payout tube. 
     As shown in  FIGS. 9A-9F , payout tube  452  is also similar to payout tube  52 , but does not have a round outer cross-sectional geometry, as discussed above. Instead, body  472  of payout tube  452  includes central shaft  506  and four ribs  508  extending radially outward from central shaft  506  in an X-shaped pattern. As mentioned above, in this embodiment, “diameter” is not a suitable term to directly describe outer cross-sectional dimensions of body  472 . Instead, the outer cross-sectional dimensions may be based on the diameters of circumscribed circles of the outer geometry, such as circumscribed circles  488  shown in  FIG. 9D . 
     For example, the “average effective outer diameter” of body  472  (referred to as average effective outer diameter  486  may be determined by virtually creating circumscribed circles  488  along the length of body  572 , determining the diameters of each of circumscribed circles  488 , and averaging the determined diameters. Suitable dimensions for average effective outer diameter  486  includes those discussed above for average outer diameter  86  of body  72 . 
     The use of average effective outer diameter  486  is suitable for comparison to the effective inner diameter of inlet opening  476  because, for example, it is believed that ribs  508  allow body  472  to function like a conical or cylindrical tube body during the payout of filament  56 . As shown in  FIGS. 9E and 9F , inlet opening  476  has an effective inner diameter that is substantially less than average effective outer diameter  486  of body  472 . This reduces or prevents payout entanglement. Additionally, in this embodiment, outlet opening  466  is substantially the same size as inlet opening  476 . 
     As shown in  FIGS. 10A-10H , payout tube  552  is similar to payout tube  352 , and also does not have a round outer cross-sectional geometry. In this embodiment, payout tube  552  only includes one pair of ribs  608  that extend in opposing directions from central shaft  606 , rather than having four flanges in an X-shaped pattern. the outer cross-sectional dimensions may be based on the diameters of circumscribed circles of the outer geometry, such as circumscribed circles  588  shown in  FIG. 10F . 
     For example, the “average effective outer diameter” of body  572  (referred to as average effective outer diameter  586  may be determined by virtually creating circumscribed circles  588  along the length of body  572 , determining the diameters of each of circumscribed circles  588 , and averaging the determined diameters. Suitable dimensions for average effective outer diameter  586  includes those discussed above for average outer diameter  86  of body  72 . 
     The use of average effective outer diameter  586  is suitable for comparison to the effective inner diameter of inlet opening  576  because, for example, it is believed that ribs  608  also allow body  572  to function like a conical or cylindrical tube body during the payout of filament  56 . As shown in  FIGS. 10D-10G , inlet opening  576  has an effective inner diameter that is substantially less than average effective outer diameter  586  of body  572 , which reduces or prevents payout entanglement. 
     Payout tubes  52 ,  252 ,  352 ,  452 , and  552  illustrate example embodiments for the payout tubes of the present disclosure, which have inlet openings with effective inner diameters that are substantially less than the average effective outer diameters of the payout tube bodies. Additionally, while payout tubes  52 ,  252 ,  352 ,  452 , and  552  described are illustrated with body outer cross-sections that converge from their base ends to their tip ends, in alternative embodiments, the payout tube bodies may have substantially constant outer cross-sections (i.e., cylindrical bodies), or any other suitable outer geometry. 
     As discussed above, the payout tubes of the present disclosure (e.g., payout tubes  52 ,  252 ,  352 ,  452 , and  552 ) enable payout of filament  56  from coil  54  to print head  18 , where print head  18  is a subcomponent of consumable assembly  12 . In one alternative embodiment, print head  18  may be a component of system  10 , rather than a subcomponent of consumable assembly  12 . In this embodiment, the guide tube (e.g., guide tube  16 ,  216 ,  316 ,  416 , and  516 ) may be loaded to print head  18  or another component of system  10 . 
     In another alternative embodiment, the guide tube may also be a component of system  10 , rather than a subcomponent of consumable assembly  12 . In this embodiment, for example, liner  50  may be penetrated, and guide tube  16  may be inserted through the resulting hole in liner  50  and secured to payout tube  52  for use. 
     In each of these embodiments, the filament drive mechanism that draws the successive segments of filament  56  is retained by print head  18  and/or system  10 . In a further alternative embodiment, the filament drive mechanism may be retained in the payout tube of consumable assembly  12 . For example, as shown in  FIG. 11A , payout tube  652  includes filament drive mechanism  710  retained within interior region  678 . Payout tube  652  may be any suitable payout tube of the present disclosure having sufficient volume within interior region  678  (e.g., payout tubes  52 ,  252 , and  352 ). 
     Filament drive mechanism  710  includes motor  712  and capstan assembly  714  retained by support walls  716 , where capstan assembly  174  engages and drives successive segments of filament  56  through payout tube  652  via rotational power from motor  712 . Examples of suitable designs for motor  712  and capstan assembly  714  include those disclosed in Swanson et al., U.S. patent application Ser. No. 12/976,111. Motor  712  may be powered and controlled by system  10  and/or a portable battery via one or more electrical and/or wireless connections (not shown). 
     Additionally, in this embodiment, leading end  82  of guide tube  16  is secured to body  672  at retention wall  718 , which is adjacent to base end  664  rather than at tip end  670 . As such, the effective inner diameter of inlet opening  676  is the same as the inner diameter of inlet opening  676  itself (rather than the inner diameter of guide tube  16 ). 
       FIG. 11B  illustrates another embodiment in which print head  18  is replaced with coupling adapter  820 , which is configured to engage a reciprocating mating panel of system  10  that is remote from head carriage  36 , as discussed in co-filed U.S. patent application Ser. No.  13 / 334 , 934 , entitled “COUPLING ADAPTER FOR CONSUMABLE ASSEMBLY USED WITH ADDITIVE MANUFACTURING SYSTEM”. In this embodiment, coupling adapter  820  includes a filament drive mechanism (not shown) that draws successive segments of filament  56  from coil  54  and through payout tube  52  (or any other suitable payout tube of the present disclosure, such as payout tubes  252 ,  352 ,  454 , and  552 ). As such, guide tube  16  may be secured to the tip end of the payout tube, as discussed above. 
     The embodiments shown in  FIGS. 11A and 11B  may be used to as initial feed mechanisms to feed filament  56  from coil  54  to a remote filament drive mechanism retained by the print head of system  10 . Upon receipt of filament  56 , the filament drive mechanisms retained by consumable assembly  12  may then disengage from filament  56 , allowing remote filament drive mechanism of the print head to continue to draw filament  56 . Alternatively, filament drive mechanism  710  (shown in  FIG. 11A ) and coupling adapter  820  (shown in  FIG. 11B ) may function as the sole filament drive mechanisms for system  10 . This embodiment precludes a remote filament drive mechanism retained by the print head, thereby reducing the print head weight that head carriage  36  is required to support and move. 
     Suitable consumable filaments for filament  56  include those disclosed and listed in Crump et al., U.S. Pat. No. 5,503,785; Lombardi et al., U.S. Pat. Nos. 6,070,107 and 6,228,923; Priedeman et al., U.S. Pat. No. 6,790,403; Comb et al., U.S. Pat. No. 7,122,246; Batchelder, U.S. Patent Application Publication No. 2009/0263582; Hopkins et al., U.S. Patent Application Publication No. 2010/0096072; Batchelder et al., U.S. Patent Application Publication No. 2011/0076496; and Batchelder et al., U.S. Patent Application Publication No. 2011/0076495. Furthermore, the consumable filaments may each include encoded markings, as disclosed in Batchelder et al., U.S. Patent Application Publication Nos. 2011/0117268, 2011/0121476, and 2011/0233804, which may be used with sensor assemblies  44  of system  10 . 
     Filament  56  desirably exhibits physical properties that allow it to be used as a consumable material in system  10 . In particular, filament  56  is desirably flexible along its length to allow it to be retained in the figure-8 configuration and to be fed through guide tube  16  without plastically deforming or fracturing. For example, in one embodiment, filament  56  is capable of withstanding elastic strains greater than t/r, where “t” is an average cross-sectional thickness or average diameter of filament  56  in the plane of curvature, and “r” is a bend radius. 
     However, filament  56  also desirably has suitable thermal properties (e.g., a suitable glass transition temperature) for use in system  10 . Increasing flexibility of filament  56 , such as with the use of plasticizers, typically reduces the thermal properties of filament  56 . As such, to maintain suitable thermal properties, filament  56  is typically stiffer (i.e., less flexible) than many strand materials used with current payout tubes. 
     Additionally, filament  56  also desirably exhibits low compressibility such that its axial compression doesn&#39;t cause filament  56  to be seized within a liquefier of print head  18 . Examples of suitable Young&#39;s modulus values for the polymeric compositions of filament  56  include modulus values of about 0.2 gigapascals (GPa) (about 30,000 pounds-per-square inch (psi)) or greater, where the Young&#39;s modulus values are measured pursuant to ASTM D638-08. In some embodiments, suitable Young&#39;s modulus range from about 1.0 GPa (about 145,000 psi) to about 5.0 GPa (about 725,000 psi). In additional embodiments, suitable Young&#39;s modulus values range from about 1.5 GPa (about 200,000 psi) to about 3.0 GPa (about 440,000 psi). 
     In the shown embodiment, filament  56  has a substantially cylindrical geometry (i.e., a substantially circular cross section). In this embodiment, examples of suitable average outer diameters for filament  56  range from about 0.8 millimeters (about 0.03 inches) to about 3.8 millimeters (about 0.15 inches), with particularly suitable average outer diameters ranging from about 1.0 millimeter (about 0.04 inches) to about 2.0 millimeters (about 0.08 inches). In one embodiment, particularly suitable average outer diameters for filament  56  range from about 1.0 millimeter (about 0.04 inches) to about 1.5 millimeters (about 0.06 inches). In another embodiment, particularly suitable average outer diameters for filament  56  range from about 1.5 millimeters (about 0.06 inches) to about 2.0 millimeters (about 0.08 inches). The average outer diameters of filament  56  are based on measurements taken along at least 20 feet of filament  56 . 
     The dimensions of the consumable filaments (e.g., filament  56 ) may also be referred to based on their outer cross-sectional areas. Accordingly, suitable average outer cross-sectional areas of the consumable filaments range from about 0.5 square millimeters to about 11.3 square millimeters, with particularly suitable average outer cross-sectional areas ranging from about 0.8 square millimeters to about 3.1 square millimeters. In one embodiment, particularly suitable average outer cross-sectional areas of the consumable filaments range from about 0.8 square millimeters to about 1.8 square millimeters. In another embodiment, particularly suitable average outer cross-sectional areas of the consumable filaments range from about 1.8 square millimeters to about 3.1 square millimeters. The average outer cross-sectional areas of filament  56  are also based on measurements taken along at least 20 feet of filament  56 . 
     EXAMPLES 
     The present disclosure is more particularly described in the following examples that are intended as illustrations only, since numerous modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Example payout tubes of the present disclosure and comparative example payout tubes were tested for filament payout reliability with an additive manufacturing system. 
       FIG. 12  illustrates a test set up for each of the tested payout tubes. For each test, a coil of a consumable filament in a figure-8 configuration was laid flat on its side, as shown. The flat orientation of the coil was considered to be a worst case scenario for filament entanglement during payout. For each tested payout tube, the consumable filaments tested included a 1.78-millimeter (0.070-inch) diameter polycarbonate filament, and a 1.78-millimeter (0.070-inch) diameter break-away support structure filament, each commercially available from Stratasys, Inc., Eden Prairie, Minn. The payout tube was inserted into a payout hole of the coil and a leading end of a guide tube was secured to the payout tube. 
     The trailing end of the guide tube was connected to a coupling adapter as shown above in  FIG. 11B  and disclosed in co-filed U.S. patent application Ser. No. 13/334,934, entitled “COUPLING ADAPTER FOR CONSUMABLE ASSEMBLY USED WITH ADDITIVE MANUFACTURING SYSTEM”. The coupling adapter was engaged with a reciprocating mating panel of an additive manufacturing system commercially available from Stratasys, Inc., Eden Prairie, Minn. under the trademarks “FDM” and “FORTUS 400mc”. 
     I. Comparative Examples A and B 
     As shown in  FIG. 13A , the payout tube of Comparative Example A was commercially available from Reelex Packaging Solutions, Inc., Patterson, N.Y. under the trademark “EZ-TUBE” with a flared-end component available under the trademark “SHERGUIDE”. With flared-end component, the effective inner diameter of the payout tube of Comparative Example A was greater than its average outer diameter. 
     As shown in  FIG. 14A , the payout tube of Comparative Example B was commercially available from Reelex Packaging Solutions, Inc., Patterson, N.Y. under the trademark “EZ-TUBE”, but did not include a flared-end component. As shown in  FIG. 14B , the effective inner diameter of the payout tube of Comparative Example A was almost as wide as its average outer diameter. 
     The payout tubes of Comparative Examples A and B depicted situations in which the effective inner diameters of the inlet openings were comparable in size to the average outer diameter of the payout tube body, and were also substantially greater than the diameter of the consumable filaments. While these payout tubes are effective for enabling payout of a variety of material strands, such as wire, rope, and communication cables, each of them repeatedly resulted in tangles of the consumable filaments during the payout tests, as illustrated in  FIGS. 13B and 13C  (Comparative Example A) and in  FIG. 14B  (Comparative Example B). 
     II. Comparative Examples C-E 
     Comparative Examples C-E each incorporated a payout tube shown in  FIGS. 15A and 15B , which had symmetrical ends. However, in these comparative examples, a guide tube having an inner diameter of 0.381 millimeters (0.015 inches) (about 214% of the diameter of the consumable filaments) was extended through the payout tube by different lengths. As shown in  FIG. 16A , for Comparative Example C, a long segment of a guide tube was extended out of the inlet opening of the payout tube. As shown in  FIG. 17A , for Comparative Example D, a medium-length segment of the guide tube was extended out of the inlet opening of the payout tube. As shown in  FIG. 18A , for Comparative Example E, a short-length segment of the guide tube was extended out of the inlet opening of the payout tube. 
     The payout tubes of Comparative Examples D-E depicted situations in which the effective inner diameters of the inlet openings were comparable in size to the average outer diameter of the payout tube body, in this case, the outer diameter of the guide tube. However, the outer diameter of the guide tube was not substantially greater than its effective inner diameter. Each of these payout tube assemblies repeatedly resulted in tangles of the consumable filaments during the payout tests, as illustrated in  FIG. 16B  (Comparative Example C), in  FIG. 17B  (Comparative Example D), and in  FIG. 18B  (Comparative Example E). 
     III. Comparative Example F 
     Comparative Example F incorporated a payout tube shown in  FIG. 19A-19C , which included a large outer diameter and an inlet opening with an effective inner diameter that was comparable in size to the outer diameter. This payout tube also depicted a situation in which the effective inner diameter of the inlet opening was comparable in size to the average outer diameter of the payout tube body, and was also substantially greater than the diameter of the consumable filaments. This payout tube repeatedly resulted in tangles of the consumable filaments during the payout tests, as illustrated in  FIG. 19D . 
     IV. Examples 1-6 
     As shown in  FIG. 20A , the payout tube of Example 1 corresponded to payout tube  52  (best shown in  FIGS. 5A-5D ) with the guide tube secured to the inlet opening with an e-clip and adhesive. This payout tube was successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIG. 20B . 
     During successive tests on the payout tube of Example 1, it was found that excess adhesive located at the tip end of the payout tube enhanced the shelf effect at the inlet opening, which occasionally caused the consumable filament to be caught. As discussed above, a capture tip with the sloped surface eliminated surfaces at the inlet opening that were perpendicular to the direction of movement of the consumable filament. 
     As shown in  FIG. 21A , the payout tube of Example 2 corresponded to payout tube  52  with capture tip  100  (shown in  FIGS. 6A-6C ) with the guide tube secured to the inlet opening with an e-clip and the capture tip. This payout tube was also successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIGS. 21A and 21B . It is further believed that the capture tip is beneficial for use with any of the payout tubes of the present disclosure. 
     As shown in  FIG. 22A , the payout tube of Example 3 corresponded to payout tube  252  (best shown in  FIGS. 7A-7D ) with the guide tube secured to the inlet opening with an e-clip and adhesive. This payout tube was also successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIG. 22B . 
     As shown in  FIG. 23A , the payout tube of Example 4 corresponded to payout tube  352  (best shown in  FIGS. 8A-8D ) having the sharp-sloped outer geometry, with the guide tube secured to the inlet opening with an e-clip and adhesive. This payout tube was also successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIG. 23B . 
     As shown in  FIG. 24A , the payout tube of Example 5 corresponded to payout tube  352  (best shown in  FIGS. 9A-9E ) having the X-shaped-ribbed outer geometry, with the guide tube secured to the inlet opening with an e-clip and adhesive. This payout tube was also successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIG. 24B . 
     As shown in  FIG. 25A , the payout tube of Example 6 corresponded to payout tube  352  (best shown in  FIGS. 10A-10G ) having the opposing-ribbed outer geometry, with the guide tube secured to the inlet opening with an e-clip and adhesive. This payout tube was also successful in repeatedly paying out the consumable filaments during the payout tests, as illustrated in  FIG. 25B . 
     The payout tubes of Examples 1-6 each depicted an embodiment in which the effective inner diameter of the inlet opening was same as the inner diameter of the guide tube, which was 0.381 millimeters (0.015 inches) (about 214% of the diameter of the consumable filaments). Additionally, for each payout tube of Examples 1-6, the effective inner diameter of the inlet opening was substantially smaller than the average effective outer diameter of the payout tube body. This combination of a small effective inner diameter and substantially larger average effective outer diameter enabled payout of the consumable filaments without payout entanglement. This allowed successive segments of the consumable filaments to be fed from the consumable assembly to the additive manufacturing system without interruption. 
     Effective payout coils of the consumable filament (in a figure-8 configuration) opens the door to consumable assemblies having larger volumes of the consumable filaments. This is because, unlike spools of filaments in which the weight of the filaments increase the rotational friction of the spools (which could break the filaments), the payout of the consumable filament from the coil is not affected by the size of the coil. This allows the consumable assembly to be any desired size, such as from small coils (e.g., hand-sized coils) to large coils (e.g., palette-sized coils), allowing the printing runs of different durations to be uninterrupted. 
     The terms “about” and “substantially” are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variabilities in measurements). Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.