Patent Publication Number: US-2011073824-A1

Title: Railing system and coupling element and methods of assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 61/245,802, filed on Sep. 25, 2009, and U.S. Provisional Patent Application Ser. No. 61/369,440, filed on Jul. 30, 2010, the disclosures of which are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to railing systems and, more specifically, to extruded railing systems that utilize specialized connectors to reduce substantially the need for conventional fasteners. 
     BACKGROUND OF THE INVENTION 
     Railing systems are required by many building codes around decks and porches that are a certain height above the surrounding grade. For years, these railings were manufactured of wood or metal. With the advent of rigid plastics, however, these systems are now being manufactured of extruded hollow or solid polyvinyl chloride (PVC), composites of virgin polymer and recycled polymer waste, or other polymer compositions. Structurally, these systems usually include two vertical posts (usually wooden posts covered by plastic post sleeves) that provide anchoring structural support at either end of a length of railing. Secured near a bottom of the posts with a bracket, and spanning the distance between posts, is a lower rail that is substantially horizontal. Secured near the top of the posts with a bracket is a top rail that generally includes a retainer and a handrail secured thereto, which are usually parallel to the lower rail. A plurality of substantially parallel vertical balusters extend from the lower rail to the retainer. The balusters prevent children or large items from passing through the railing system and are often extruded or formed into straight, twisted, or other decorative shapes. The lower rail and top retainer connect to a top and bottom of each baluster with one or more screws that are screwed into the ends of each baluster. In constructions utilizing hollow balusters, a plug may be inserted into the hollow baluster to receive the screw and secure the baluster between the lower rail and the retainer. To hide the unsightly screw heads on the top retainer, a decorative handrail is slid onto the retainer to form the top rail. 
     Generally, the railing system is installed by first setting the wooden posts and sliding the post sleeves onto the posts. Next, the top and lower rails are cut to the appropriate length. Plugs are inserted into the top and bottom ends of the balusters and aligned with predrilled holes on each of the lower rail and the retainer. Screws inserted through the lower rail and retainer are used to secure the balusters in place. The handrail is then slid onto the top retainer, and a center support (if required due to railing length) is secured to the bottom side of the lower rail. The entire assembly is then placed between the posts, leveled, and the supporting brackets are then placed and marked. The entire assembly is then removed so the brackets may be secured to the post sleeves. Thereafter, the entire assembly is repositioned and the brackets are secured to the underside of the lower rail and the retainer. Additional screws are then used to secure the handrail to the retainer, from below. One exemplary embodiment of such a railing system is described in U.S. Pat. No. 6,702,259, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     As is readily apparent from this description of the installation, the number of screws or other fasteners required to install such a railing system is considerable. For example, each baluster requires two screws for installation, and a number of screws must be installed through the retainer into the handrail. This number of screws, while necessary to ensure joining of parts and structural integrity, entails additional material cost and increases assembly labor, making such systems relatively expensive to install. What is needed then, is an extruded plastic railing system that reduces or even eliminates the need for threaded fasteners, while maintaining the structural integrity of railing systems that utilize them. 
     SUMMARY OF THE INVENTION 
     In one aspect, the invention relates to a connector for attaching a hollow baluster to a hollow rail in an extruded railing system, the connector including a first section adapted to be received in an aperture formed in an end of the hollow baluster, and a second section adapted to be received in an aperture formed through a wall of the hollow rail, the second section having at least one resilient tab configured to engage an interior surface of the hollow rail when received therein. In an embodiment of the above aspect, the second section is sized and configured to preclude rotation of the connector relative to the rail when received therein. In another embodiment, the second section includes at least one projection, wherein the projection having a width and a thickness, wherein the width is greater than the thickness. In yet another embodiment, the resilient tab is a unitary part having two tines, each tine including a shoulder. In still another embodiment, the tines include a first, unstressed position and a second, deflected position. 
     In another embodiment of the above aspect, the shoulders contact an interior surface of the hollow rail when the tines are in the first, unstressed position. In another embodiment, the first section includes at least one raised ridge. In another embodiment, the connector includes at least one side surface and wherein the raised ridge projects from the side surface. In yet another embodiment, the raised ridge interacts with an interior surface of the hollow baluster, so as to form an interference fit between the baluster and the connector. 
     In another aspect, the invention related to a method of assembling a railing system including a first post, a second post, a hollow lower rail, a hollow upper rail, and a hollow baluster, the method including the steps of providing a first connector having a first section and a second section including at least one resilient tab, inserting the first section of the connector into the hollow baluster, and inserting the second section of the connector into an aperture formed in a wall of the hollow lower rail, so as to engage the resilient tab with an interior surface of the hollow lower rail. In an embodiment of the above aspect, the method includes providing a second connector having a first section, and a second section having at least one resilient tab, inserting the first section of the second connector into the hollow baluster, and inserting the second section of the second connector into an aperture formed in a wall of the hollow upper rail, so as to engage the resilient tab of the second connector with an interior surface of the hollow upper rail. In another embodiment, the method includes securing a first end of the hollow upper rail to the first post with a first upper bracket. In another embodiment, the method includes securing a second end of the hollow upper rail to the second post with a second upper bracket. In yet another embodiment, the method includes securing a first end of the hollow lower rail to the first post with a first lower bracket. In still another embodiment, the method includes the step of securing a second end of the hollow lower rail to the second post with a second lower bracket. 
     In another aspect, the invention relates to a connector for attaching a hollow baluster to a hollow rail in an extruded stairway railing system. The connector may include a projection defining a first longitudinal axis and adapted to be received in an aperture defined by a wall of a hollow rail, and a plug portion fixed to the projection, the plug portion defining a second longitudinal axis and adapted to be received in an aperture formed in an end of a hollow baluster, wherein the first longitudinal axis is not collinear with the second longitudinal axis. In one embodiment, the first longitudinal axis and the second longitudinal axis form an included angle. In another embodiment, the included angle is from about 2° to about 45°. In yet another embodiment, the included angle is from about 29° to about 35°. In still another embodiment, the included angle is about 32°. 
     In one embodiment, the plug portion includes a front face and a back face, and the front face is oriented at a front angle including an angle between the front face and an axis parallel to the first longitudinal axis, and the back face is oriented at a back angle including an angle between the back face and an axis parallel to the first longitudinal axis. In another embodiment, the front angle and the back angle are from about 2° to about 35°. In yet another embodiment, the front angle is less than the back angle. In still another embodiment, each of the front angle and the back angle deviate from the included angle by about 3°. 
     In one embodiment, the plug portion includes a side wall surface projecting in a direction substantially parallel to the first longitudinal axis. In another embodiment, the side wall surface includes a crush rib. In yet another embodiment, the connector includes an enlarged shoulder element located between the projection and the plug portion. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention, as well as the invention itself, can be more fully understood from the following description of the various embodiments, when read together with the accompanying drawings, in which: 
         FIG. 1  is an exploded schematic perspective view of a railing system in accordance with one embodiment of the invention; 
         FIGS. 2A and 2B  are a schematic end view and a schematic perspective view of the lower rail of  FIG. 1 ; 
       FIGS.  2 C 1 - 2 C 4  depict several schematic views of the lower bracket of  FIG. 1 ; 
         FIG. 2D  is a schematic end view of the lower bracket and lower rail combination of  FIG. 1 ; 
         FIGS. 3A and 3B  are a schematic end view and a schematic perspective view of the top hand rail of  FIG. 1 ; 
       FIGS.  3 C 1 - 3 C 4  depict several schematic views of the upper bracket of  FIG. 1 ; 
         FIG. 3D  is a schematic end view of the upper bracket and top hand rail combination of  FIG. 1 ; 
         FIG. 4A  is a schematic perspective view of the baluster connector of  FIG. 1 ; 
         FIG. 4B  is a schematic sectional view of the baluster connector of  FIG. 1 ; 
         FIG. 5  is a schematic sectional view of a baluster, connector, and top hand rail combination in accordance with one embodiment of the present invention; 
         FIG. 6  is a flowchart depicting one method of assembling the railing system of  FIG. 1 ; 
         FIG. 7  is a schematic side view of an angled rail system, in accordance with one embodiment of the present invention; 
         FIG. 8  is a schematic side view of an angled baluster connector, baluster, and rail combination, in accordance with one embodiment of the present invention; 
         FIG. 9  is a schematic side view of the angled baluster connector of  FIG. 8 ; 
         FIGS. 10A-10D  depict several schematic views of the angled baluster connector of  FIG. 8 ; 
         FIG. 11  is a schematic perspective view of the angled baluster connector of  FIG. 8 ; and 
         FIGS. 12A and 12B  are schematic side views of an angled baluster connector installed in a baluster, in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts an exploded schematic view of a railing system  100  in accordance with one embodiment of the present invention. The system includes a 4″×4″ post  110  substantially vertically oriented. The base of the post  110  may be secured in or to a deck or porch structure with lag screws or bolts as know in the art. An extruded, hollow post sleeve  112  is inserted over the post, which may also be topped with a cap or other decorative feature. The system  100  also includes an upper rail  114  that may be extruded into virtually any decorative shape, and that is secured to the post  110  with an upper bracket  116  and one or more screws or bolts  118 . The upper rail  114  provides a gripper surface for a person&#39;s hand when moving along the railing system, especially while ascending or descending stairs. One flange or leg of the upper bracket  116  and underside of the upper rail  114  are sized and configured so as to provide a close fit or an interference fit between the two elements. If additional security is required, one or more screws may be inserted through the bracket  116  into the underside of the upper rail  114 , as depicted. The screw length is chosen to prevent the screw from penetrating through the top of the upper rail  114 . A lower rail  120  is secured to the post  110  with a lower bracket  122  and one or more bolts or screws  118 . Similar to the upper rail configuration, the underside of the lower rail  120  and a flange or leg of the lower bracket  122  are sized and configured to provide a close fit or an interference fit. Again, one or more screws  119  may be inserted through the lower bracket  122  and into the underside of the lower rail  120 . The screw length is chosen to prevent penetration of the screw through the top of the lower rail  120 . 
     A plurality of hollow balusters  126  join the upper rail  114  and the lower rail  120 . A connector  128  is located at each end of each baluster  126 . The connector  128  is sized and configured so as to provide a friction fit with the baluster  126 , but other means of securing the two elements (e.g., adhesives), may be utilized alone or in addition. Projecting from the end of the connector  128  is a locking extension or element  130 , described in more detail below. The locking extension  130  is sized and configured to mate with an upper opening in the bottom of the upper rail  114  (in the case of the upper connector) and a lower opening  132  in the top of the lower rail  120  (in the case of the lower connector). The upper opening and/or lower opening  132  may be formed during installation of the balusters  126  or machined or formed during manufacture of the upper and/or lower rails  114 ,  120 . 
       FIGS. 2A and 2B  depict a lower rail  120 , in accordance with one embodiment of the present invention. The lower rail  120  includes a lower rail profile  210  which may be virtually any desired shape. In the depicted embodiment, the lower rail profile  210  forms a lower rail void  212  with two lower rail extensions  214  projecting downward from the lower rail profile  210 . The two lower rail extensions  214  may be forced or elastically deflected outward, so as to snap lock over the lower bracket  122  (described below) so that the lower bracket  122  is received into a lower rail recess  216  located between the two lower rail extensions  214 . Alternatively, the lower bracket  122  can be slid into position from the end. A plurality of lower openings  132  are formed or machined in a top surface  218  of the lower rail profile  210 , and are sized to receive the locking extension  130  of the baluster connectors  128  described below. The upper openings and lower openings  132  may be formed so as to allow multiple orientations of the balusters  126 . For example, the lower openings  132  depicted in  FIG. 2  allow for baluster connection in two angular positions. The lower openings  132  include a first elongate portion substantially orthogonal to a longitudinal axis of the lower rail  120 , and a second elongate portion angled approximately 45 degrees from the axis of the lower rail  120 . 
     The upper rail  114 , lower rail  120 , balusters  126 , and connectors  128  may be made of any suitable solid material, such as polyvinyl chloride (PVC), blends of virgin polymer and recycled polymer waste, or other polymer compositions. Natural and/or man-made fibers or fillers may be included. Methods of forming the upper rail  114 , lower rail  120 , and balusters  126  include extrusion and injection molding. Connectors  128  may be formed typically by injection molding. 
     FIGS.  2 C 1 - 2 C 4  depict perspective, side, end, and top views of a lower bracket  122  in accordance with one embodiment of the present invention. The lower bracket  122  may be formed by known stamping methods and may be manufactured of a rigid metal such as aluminum, steel, stainless steel, etc., or made of a high strength polymer or reinforced fiber composite. The lower bracket  122  includes a lower post interface  232  and a lower rail interface  234 . The lower post interface  232  includes one or more lower post holes  236  sized to receive a bolt, screw, or other connection element to secure the bracket  122  to the post  110 . If screws are used to further secure the lower bracket  122  to the lower rail  120 , the lower rail interface  234  includes one or more lower rail holes  238  sized to receive a bolt, screw, or other connection element. Lower bracket edges  240  of the lower rail interface  234  are radiused to facilitate spreading of the lower rail extensions  214  during installation. The radiused lower bracket edges  240  also interface with the lower rail extensions  214  to prevent rotation of the lower rail  120  once installed on the lower bracket  122 . 
       FIG. 2D  depicts a cross-sectional view of the lower rail  120  secured to the lower bracket  122 . Notably, an inner portion of each lower rail extension  214  includes a lower protrusion  250  that is adapted to mate with the lower bracket edge  240  to prevent rotation once installed. Additionally, a lower channel  252  may be formed on the underside of the lower rail  120  that may mate with a raised protrusion on the lower rail interface  234  of the lower bracket  122 . This channel/protrusion interface can also help locate and limit rotation of the lower rail  120  on the lower bracket  122 , to prevent dislodgment of the lower rail  120 . 
       FIGS. 3A and 3B  depict the upper rail  114 , in accordance with one embodiment of the present invention. The upper rail  114  includes an upper rail profile  310 , which may be virtually any desired shape. In the depicted embodiment, the upper rail profile  310  forms an upper rail void  312  with two upper rail extensions  314  projecting downward from the upper rail profile  310 . The two upper rail extensions  314  may be forced or elastically deflected outward, so as to snap lock over the upper bracket  116  (described below) so that the upper bracket  116  is received into an upper rail recess  316  located between the two upper rail extensions  314 . Alternatively, the upper bracket  116  can be slid into position from the end. A plurality of upper openings are formed or machined in a bottom surface  318  of the upper rail profile  310  in a similar manner to those in the lower rail profile  210 , and are sized to receive the locking extension  130  of the baluster connector  128  described below. 
     FIGS.  3 C 1 - 3 C 4  depict perspective, side, end, and top views of the upper bracket  116  in accordance with one embodiment of the present invention. The upper bracket  116  may be formed by known stamping methods and may be manufactured of a rigid metal such as aluminum, steel, stainless steel, etc., or other methods and materials similar to the lower bracket  122 . The upper bracket  116  includes an upper post interface  330  and an upper rail interface  332 . The upper post interface  330  includes one or more upper post holes  334  sized to receive a bolt, screw, or other connection element to secure the bracket  116  to the post  110 . If screws are used to further secure the upper bracket  116  to the upper rail  114 , the upper rail interface  332  includes one or more upper rail holes  336  sized to receive a bolt, screw, or other connection element. Upper bracket edges  338  of the upper rail interface  332  are radiused to facilitate spreading of the upper rail extensions  314  during installation. The radiused upper bracket edges  338  also interface with the upper rail extensions  314  to prevent rotation of the upper rail  114  once installed on the upper bracket  116 . 
       FIG. 3D  depicts a cross-sectional view of the upper rail  114  secured to the upper bracket  116 . Notably, an inner portion of each upper rail extension  314  includes an upper protrusion  350  that is adapted to mate with the upper bracket edges  338  to prevent rotation once installed. Additionally, an upper channel  352  may be formed on the underside of the upper rail  114  that may mate with a raised protrusion on the upper rail interface  332  of the upper bracket  116 . This channel/protrusion interface may also help locate and limit rotation of the upper rail  114  on the upper bracket  116 , to prevent dislodgment of the upper rail  114 . The interface also allows the upper bracket  116  to be installed directly to the upper channel  352  (i.e., without an intervening retainer, as typically required in prior art railing systems). 
       FIG. 4A  depicts the connector  128  in accordance with one embodiment of the present invention.  FIG. 4B  is a schematic sectional view of the connector  128  along a first axis A, depicted in  FIG. 4A . The connector  128  includes a first plug portion  410  that is sized and configured to fit within the end of a hollow baluster  126 . When inserted into the baluster  126 , it is desirable that a top edge  412  of the connector  128  does not extend substantially below the terminal end of the baluster  126 . This may be achieved in several ways. In one embodiment, the dimensions of the plug portion  410  may increase slightly as they approach the top edge  412 , such that an interference fit is obtained as the top edge  412  becomes approximately even with the terminal end. In another embodiment, the dimensions of the plug portion  410  may be substantially uniform, but the plug  410  may include one or more plug ridges  414  that project further from the side of the plug portion  410  as they approach the top edge  412 , as shown in  FIG. 4A . In yet another embodiment, the top edge  412  may be flared or include an enlarged edge to prevent insertion of the plug portion  410  past the top edge  412 . 
     Extending upward from a top surface  416  of the plug portion  410  is a second portion comprising one or more projections  418 , which are formed as a unitary part with the plug portion  410  of the connector  128 , in the depicted embodiment. The projections  418  are symmetrical along first axis A and a second orthogonal axis B of the connector  128 . The projections  418  have a projection height h 1  that is less than a depth of each of the lower rail void  212  and the upper rail void  312 . Similar to the tapered dimensions of the plug portion  410 , described above, the projections  418  may also taper (from wide to narrow as the height above the top surface  416  increases) so as to provide an interference fit of the projection  418  with the upper opening or the lower opening  132 , when fully inserted. This taper also facilitates manufacture of the connector  128  by injection molding. The connector  128  also includes one or more locking extensions or elements  130 , which, in this embodiment, are a pair of resilient tabs. Each tab includes a tine  422  and a hook or shoulder portion  424 . The distance from the top surface  416  of the plug portion  410  to the shoulder  424 , in certain embodiments, corresponds generally to a thickness of the extruded material of the upper and lower rails  114 ,  120 . Therefore, when the projection  418  and tabs are inserted into the upper opening or lower opening  132 , the tabs will deflect until they are passed completely through the material. At this point, the shoulder portion  424  will pass the material edge, the tine  422  will return to its unstressed position, and the connector  128  will be secured to the rail. 
     This configuration is depicted in  FIG. 5 , which is a schematic sectional view of the connector  128  along the first axis A, as installed in the upper rail  114  of the railing system  100 . To install the connector  128  in the railing system  100 , the first section, or plug portion  410 , is first inserted into a first end of the hollow baluster  126 . The plug portion  410  is dimensioned to fit within the baluster  126 , and plug ridges  414  located near the top of the plug portion  410  form an interference fit between the plug portion  410  and an interior surface  510  of the baluster  126 . This interference fit prevents inadvertent pull-out of the connector  128  once installed. In the depicted embodiment, the top surface  416  of the plug portion  410  is substantially flush with the terminal end of the baluster  126 . In other embodiments, the top surface  416  may be located above or below the terminal end of the baluster  126 . A flush configuration, however, may be more visually appealing and may prevent the ingress of dirt, water, snow, etc. 
     The second section of the connector  128  includes two projections  418 , which are inserted into an upper opening  512  in a lower wall  514  of the upper rail  114 . As the projections  418  are inserted, the tines  422  of the locking element  130  also penetrate the upper opening  512 . In the depicted embodiment, the locking element  130  is a unitary element having two flexible tines  422 . During insertion, the tines  422  deflect from their neutral, unstressed position to a deflected position. In the deflected position, the two tines  422  move closer to each other and, in certain embodiments, the facing surfaces of the tines  422  may contact. Once the shoulders  424  of the tines  422  pass an interior surface  516  of the lower wall  514  of the top railing  114 , the tines  422  return to their neutral, unstressed position. In certain embodiments, this return motion may be accompanied by an audible “click.” Once returned to their neutral position, the shoulders  424  of the tines  422  engage with the interior surface  516  of the wall  514 , thereby preventing inadvertent pull-out of the connector  128  from the upper opening  512 . An exposed height h e  of the projection  418  (i.e., the height of the projection  418  that extends above the interior surface  516  of the railing lower wall  514 ) is based at least in part on the total height within the upper rail void  312 . Generally, it is desired that the exposed height h e  be less than the height of the upper rail void  312 , although flexible projections  418  that bend when contacting the opposite surface of the upper rail  114  may be utilized. 
     As depicted, it is generally desirable that the distance from the top surface  416  of the plug portion  410  to the shoulder  424  be substantially similar to or slightly greater than a thickness T w  of the wall  514  of the upper rail  114 , although this is not required. Similarity between these two dimensions, however, may minimize play between the baluster  126  and the upper rail  114 , as well as prevent the ingress of contaminants. Additionally, while  FIG. 5  depicts the interface between the baluster  126  and the upper rail  114 , the interface between the baluster  126  and the lower rail  120  is similar. 
       FIG. 6  depicts a method  600  of assembling the railing system  100  in accordance with one embodiment of the present invention. In the depicted method  600 , the terms “upper” and “lower” are used to describe different rails, balusters, connectors, and portions thereof. For these purposes, these terms are generally interchangeable. That is, while the depicted order of this method first describes connecting a lower rail and a lower portion of a baluster with a lower connector, alternative methods may include first connecting an upper rail and an upper portion of a baluster with an upper connector. To assemble the railing system  100 , the upper and lower rails  114 ,  120  are first cut to fit between two posts  110 , which may also be predrilled and fitted with brackets to ensure proper rail length. The connector  128  as described herein is provided (step  610 ) to connect the balusters  126  to the upper and lower rails  114 ,  120 . The first or plug section  410  of the connector  128  is then inserted (step  612 ) into a lower opening of the hollow baluster  126 . A second section of the connector  128  (containing projections  418  and locking elements  130 ) is then inserted (step  614 ) into the lower opening  132  in the lower rail  120 , until the locking elements  130  engage with the interior surface  516  of the lower rail  120 . In the depicted embodiment, the above steps may be repeated until all balusters  126  for a given length of rail are secured to the lower rail  120 , via the connectors  128 . Once all of the balusters  126  are connected to the lower rail  120 , the opposite ends of the balusters  126  may be connected to the upper rail  114 . 
     Connection of upper portions of the balusters  126  to the upper rail  114  begins with providing (step  616 ) the connector  128  and inserting (step  618 ) the first or plug end  410  into an upper portion of the hollow baluster  126 . The second section of the connector  128  (containing the projections  418  and locking elements  130 ) is then inserted (step  620 ) into the upper opening  512  in the upper rail  114 , until the locking elements  130  engage with the interior surface  516  of the upper rail  114 . These steps are repeated until all of the balusters  126  for a given length of rail are secured to the upper rail  114 . Once the length of upper rail  114  is connected to the length of lower rail  120  via the balusters  126 , a first end of either the upper rail  114  or lower rail  120  is secured (step  622 ) to one of the posts  110 . This is followed by securing (step  624 ) a second end of the rail to a second post  110 . These steps are again repeated for the other rail. In addition to the assembly variations described above, other variations to the method  600  are also contemplated. 
     For example, the upper and lower rails  114 ,  120  may first be cut and the upper and lower brackets  116 ,  122  may be secured to the posts. Thereafter, one of the rails, e.g., the lower rail  120 , may be secured to the posts  110  with the brackets, then the lower connectors  128  may be used to secure the balusters  126  to the lower rail  120 . Thereafter, the upper connectors  128  may be inserted into the hollow balusters  126 , then secured to the upper rail  114 , which is then secured to the posts  110 . In another embodiment, the upper and lower connectors  128  may be inserted into both ends of all of the balusters  126 , then secured to the upper and lower rails  114 ,  120 . Other methods and acceptable orders in which to assemble the various railing system components are also contemplated. 
       FIG. 7  is a schematic side view of a stairway railing system  700  installed along a stairway or a ramp  710 , in accordance with one embodiment of the present invention. In a typical ramp or stairway installation, the ramp or stairway  710  is oriented at a ramp angle α 1  with respect to a horizontal direction  720 . The upper rail  114  and lower rail  120  are substantially parallel and define a rail longitudinal axis C. Rail longitudinal axis C is oriented at a rail angle α 2 , with respect to horizontal  720 , that is generally equal to the ramp angle α 1 . Balusters  126  between the upper and lower rails  114 ,  120  are substantially aligned with a vertical direction  722 . 
     The rail angle α 2  may be between about one degree and about 45 degrees, or more, depending on the application. For example, ramps  710  that are compliant with the Americans with Disabilities Act (ADA) have a rail angle α 2  of about five degrees. In typical stair installations, the rail angle α 2  is between about 29 degrees and about 35 degrees, or generally about 32 degrees. Other rail and ramp angles α 1 , α 2  may be utilized, depending on the desired or required application. 
     As depicted in  FIG. 8 , in one embodiment, the baluster to rail connector is an angled connector  828  connecting an upper rail  114  and a baluster  126 , along a ramp or stairway  710 . Installation of the angled connector  828  between a lower rail  120  and the baluster  126  is similar. Referring to  FIG. 8 , to connect vertically oriented balusters  126  to the sloped lower rail  120  and upper rail  114 , the projection  818  of the angled connector  828  extends into the upper rail  114  or the lower rail  126  in a direction perpendicular to the rail longitudinal axis C. The plug portion  810  of the angled connector  828  extends into the baluster  126  in the vertical direction  722 . As described above, the upper rail  114  and lower rail  120  include one or more upper openings  512  and lower openings  132 , respectively, to accommodate the projection  818 . Similarly, the baluster  126  may be hollow or include an aperture to receive the plug portion  810 . 
       FIG. 9  is a schematic side view of the angled connector  828 , in accordance with one embodiment of the present invention. In the angled connector  828 , depicted in  FIGS. 8 and 9 , the projection  818  extends along a first longitudinal axis D, the plug portion extends along a second longitudinal axis E, and the first longitudinal axis D is not collinear with the second longitudinal axis E. An included angle α 3  is the angle between the first longitudinal axis D and the second longitudinal axis E. The projection  818  and the plug portion  810  are connected at an interface  910 . In the depicted embodiment, the interface  910  includes an enlarged shoulder element  912  located between the projection  818  and the plug portion  810 . The shoulder element  912  may be a flat plate or sheet, or a portion thereof, having a top side  914  and a bottom side  916 , and the projection  818  may extend from the top side  914  and the plug portion  810  may extend from the bottom side  916 . The shoulder element  912  helps prevent torsional deflection or bending of the upper rail  114  or lower rail  120  at the connection point of the baluster  126 . Prevention of such deflection or bending may be particularly desirable for the upper rail  114 , which is subject to direct loading by hands of users of the stairs or ramp. 
     In the depicted embodiment, the plug portion  810  has a plug depth d 2  that is largest at a plug base  918  closest to the projection  818 , and smallest at a plug end  920 , at the opposite end of the plug  810 . In certain embodiments, the plug depth d 2  defines a distance between a front face  922  and a back face  924  of the plug portion  810 . A front angle α 4  is the angle formed between the front face  922  and an axis parallel to the first longitudinal axis D. Similarly, a back angle α 5  is the angle formed between the back face  924  and an axis parallel to the first longitudinal axis D. To achieve the depicted taper, the front angle α 4  is generally less than the included angle α 3 , which is in turn generally less than the back angle α 5 . 
       FIGS. 10A-10D  depict several views of the angled connector  828  of  FIG. 8 , in accordance with one embodiment of the present invention. The projection  818  is dimensioned to provide a secure connection with the upper and lower rails  114 ,  120 . For example, the projection height h 1  may be chosen to provide sufficient penetration of the projection  818  into the upper and lower rails  114 ,  120 . Similarly, a projection depth d 1  may be chosen to provide a tight interference fit with the upper and lower rails  114 ,  120 . The projection  818  may also be tapered (i.e., thicker at a projection base  1010  and narrower at a projection tip  1012 ) for ease of manufacture and/or insertion of the projection  818  into the upper and lower rails  114 ,  120 . 
     At any given distance along the first longitudinal axis D, the projection  818  may have any cross-sectional shape, including circular, square, rectangular, polygonal, oval, triangular, or any combination thereof. In one embodiment, the cross-section of the projection  818  is approximately rectangular. The projection  818  may also include one or more projection ridges  1016  along one or more of the sides of the projection  818  that provide an interference fit with the upper opening  512  or lower opening  132 . In addition, as described above with regard to  FIG. 5 , the projection  818  may include a locking element  130  that prevents inadvertent pull-out of the angled connector  828  from the upper rail  114  or the lower rail  120 . 
     The plug portion  810  is dimensioned to provide a secure connection within the baluster  126 . The plug portion  810  has a plug length h 2  that extends from the plug base  918  to the plug end  920 . In addition, at any given distance between the plug base  918  and the plug end  920 , along the second longitudinal axis E, the plug portion  810  may have any cross-sectional shape. For example, the cross-section of the plug portion  810  may be circular, square, rectangular, polygonal, oval, triangular, or any combination thereof. In the depicted embodiment, the cross-section of the plug portion  810  is approximately square and is tapered from the plug base  918  to the plug end  920 . Each side taper may be from about one degree to about ten degrees off of an axis parallel to the second longitudinal axis E. In the depicted embodiment, each taper angle is about three degrees. A plug width w 2  of the plug portion  810  is substantially constant from the plug base  918  to the plug end  920 . In other embodiments, the plug portion  810  is tapered so that the plug width w 2  decreases, along the second longitudinal axis E, from the plug base  918  to the plug end  920 . As described above, the taper may facilitate manufacture of the angled connector  828  and/or insertion of the plug portion  810  into the baluster  126 . In one embodiment, plug sides  1018  of the plug portion  810  include plug ridges  814  that extend along the plug length h 2 . The plug ridges  814  may help secure the plug portion  810  to the baluster  126  by providing an interference fit. The plug ridges  814  may also include one or more crush ribs  1022  that deform upon insertion into the baluster  126 . 
     In some embodiments, to achieve a tapered plug portion  810 , the difference between the front angle α 4  and the back angle α s  is between about one degree and about 30 degrees. In other embodiments, the difference between the front angle α 4  and the back angle α 5  is between about two degrees and about 10 degrees. In certain embodiments, the difference between the front angle α 4  and the back angle α 5  is about six degrees. For the angled connector  828  to be used in a typical stairway application, the included angle α 3  may be about 32 degrees, the front angle α 4  may be about 29 degrees, and the back angle α 5  may be about 35 degrees. Other included, front, and back angles are contemplated. For example, for an ADA compliant ramp, the included angle α 3  may be about five degrees, the front angle α 4  may be about three degrees, and the back angle α 5  may be about seven degrees. 
       FIG. 11  is a perspective view of the angled connector  828 , in accordance with one embodiment of the present invention. As depicted, the front face  922  and/or the back face  924  may include or be defined by one or more plug ridges  814 . In some embodiments, the plug ridges  814  extend from the plug base  918  to the plug end  920 . When the plug portion  810  is inserted into the baluster  126 , the front face  922 , back face  924 , or outer surfaces of the plug ridges  814  (if present) may contact interior wall surfaces of the baluster  126 . 
     In many applications, due to imperfections in stairway or ramp components and/or installation, design tolerances, or other design constraints, the installed rail angle α 2  may deviate from the anticipated or nominal ramp angle α 1 . For example, while most stairways have a nominal ramp angle α 1  of 32 degrees, the actual ramp angle α 1  for any given stairway may deviate from that nominal angle, and this may cause a corresponding deviation in rail angle α 2 . As a result, once upper and lower rails  114 ,  120  are installed, the actual rail angles α 2  may range from, for example, about 29 degrees to about 35 degrees. Despite such deviations in the rail angle α 2 , it is desirable to use a connector that allows the balusters  126  to be installed in a vertically aligned orientation. Accordingly, the angled connector  828  of the present invention incorporates novel dimensional relationships to allow for vertical baluster alignment, regardless of rail angle α 2 , within the design range of the connector  828 . 
       FIGS. 12A and 12B  are side views of the angled connector  828  installed in a baluster  126 , in accordance with one embodiment of the present invention. As depicted, by providing tapered plug portion  810 , balusters  126  may be vertically installed despite deviations in the rail angle α 2 . For example, the angled connector  828  to be used for an installation may have an included angle α 3  equal to the nominal rail angle α 2 , a front angle α 4  that is three degrees less than the included angle α 3 , and a back angle α 5  that is three degrees greater than the included angle α 3 , resulting in a three degree taper angle on the front and back of the plug portion  810 . Referring to  FIG. 12A , when the installed rail angle α 2  is equal to the front angle α 4 , the front face  922  of the plug portion  810  is in contact with or substantially parallel to a front wall of the baluster  126 . In such an installation, the baluster  126  is still oriented vertically, even though the rail angle α 2  deviated from the nominal angle by three degrees. Additionally, due to the taper in the plug portion  810 , this deviation may be addressed without modifying the angled connector  828 , or using an angled connector  828  with a different included angle α 3 . Similarly, referring to  FIG. 12B , when the installed rail angle α 2  is equal to the back angle α 5 , the back face  924  of the plug portion  810  is in contact with or substantially parallel to a back wall of the baluster  126 . Any rail angle α 2  between the front angle α 4  and the back angle α 5  could also be accommodated using the same angled connector  828 , although in those instances the front face  922  and/or back face  924  would likely not be parallel with the front wall or back wall of the baluster  126 . In this particular embodiment, the installed rail angle α 2  may deviate by about three degrees on either side of the nominal rail angle α 2 , but the tapered plug portion  810  still allows for vertical installation of the balusters  126  with use of the same angled connector  828 . 
     For a typical stairway railing system  700  installation, the angled connector  828  may be designed so that the included angle α 3  is approximately equal to the nominal ramp angle α 1  of the ramp or stairway. For example, if the ramp angle α 1  is anticipated to be 32 degrees, as used in many stairway applications, then angled connectors  828  having an included angle α 3  of about 32 degrees may be utilized. As another example, if the ramp angle α 1  is anticipated to be about five degrees, as is typical for many wheelchair ramp applications, then angled connectors  828  having an included angle α 3  of about five degrees may be used. Front and back angles α 4 , α 5  may also deviate from the include angle α 3  by about one degree to about 10 degrees, about two degrees to about eight degrees, and about three degrees to about six degrees. Other deviations are also contemplated. As is apparent from the above disclosure, the greater the deviation of the front or back angles α 4 , α 5  from the included angle α 3 , the greater the range of rail angle α 2  deviation that may be accommodated. The baluster ends may be trimmed, if desired, to mate closely with the shoulder element  912 . 
     While the stairway railing system  700  may be installed using the assembly method  600  described above and depicted in  FIG. 6 , additional assembly methods are contemplated. For example, in one embodiment, assembly begins by securing the bottom rail  120  to posts  110  located near the top and bottom of a flight of stairs. The projections  818  of the angled connectors  828  are then inserted into the lower rail  120  and the lower ends of the balusters  126  are inserted over the plug portions  810  of the angled connectors  828 . Next, the projections  818  of additional angled connectors  828  are inserted into the upper rail  114 . The upper rail  114  is then positioned above top ends of the installed balusters  126  and the plug portions  810  of the upper angled connectors  828  are inserted into the tops of the balusters  126 . As a final step, the upper rail  114  is secured to the posts  110 . 
     The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. In addition, having described certain embodiments of the invention, it will be apparent to those of ordinary skill in the art that other embodiments incorporating the concepts disclosed herein may be used without departing from the spirit and scope of the invention. The features and functions of the various embodiments may be arranged in various combinations and permutations, and all are considered to be within the scope of the disclosed invention. Accordingly, the described embodiments are to be considered in all respects as only illustrative and not restrictive. Furthermore, the configurations described herein are intended as illustrative and in no way limiting. Similarly, although physical explanations have been provided for explanatory purposes, there is no intent to be bound by any particular theory or mechanism, or to limit the claims in accordance therewith.