Abstract:
A broken conduit end portion is repaired by reducing its radial wall thickness and attaching thereto a repair coupling that is configured to provide an internal passage therethrough that is not smaller than the internal passages in the broken conduit end portion and in a second conduit that is attached to the repair coupling.

Description:
This invention relates to a method of repairing broken Electrical and plumbing conduit that extends outward from concrete foundations and a unique reaming tool bit and coupling used in the repair of the conduit. 
     BACKGROUND OF THE INVENTION  
     Electrical conduit is often embedded in concrete foundations and floors of commercial and residential buildings, so that electrical wiring can be run at a later time. Since concrete foundations and floor are poured before any internal walls and other structures are erected, short sections of conduits extend vertically above the foundation and floor at every location of an electrical source. In large construction projects, there may be hundreds of exposed conduit ends extending from the concrete foundation and floors. In the course of construction, these exposed ends of the electrical conduit are often broken off by workers and equipment in the course of moving materials, erecting interior walls and other construction activities. The broken conduit ends must be repaired so that additional sections of conduit can be connected to them to complete the installation of the electrical systems. 
     More often than not, the conduit breaks off near the foundation. Consequently, repairing the broken conduit requires breaking up the foundation around the broken conduit end to expose the end so that a coupling can be attached over it. Once the coupling is connected to the exposed broken end, the concrete foundation is patched around the repaired conduit. 
     Repairing the broken conduit embedded in a concrete foundation is an expensive and time consuming project. A large construction site may have hundreds of exposed conduit ends broken over the course of the construction project. Repairing broken conduit ends is a time consuming expense that is not factored into the cost of most construction projects. Consequently, a method for quickly and easily repairing broken conduit ends is needed. 
     SUMMARY OF THE INVENTION  
     The method and specialized repair component for repairing broken conduit ends of this invention eliminates the need to break up the concrete foundation around the broken conduit end. The specialized repair components include a reaming bit for milling out and turning down the inside wall of the broken conduit end and repair coupling for joining a new section of conduit to the broken conduit end. The reaming bit is designed to be used with any conventional handheld power drill. The reaming bit mills out the inside of the broken conduit end so that the repair coupling can be inserted into the broken conduit end. With the coupling fitted into the broken conduit end, a new section of conduit can be connected completing the repair. Because the coupling is inserted into the broken end of the conduit instead of over it, the concrete foundation around the conduit does not have to be disturbed. Consequently, this repair method provides a structurally more secure repair. 
     Accordingly, an advantage of this invention is that the method eliminates the need to breakup concrete foundations surrounding the broken conduit end, which greatly reduces the time and expense of the repair. 
     Another advantage of this invention is that the repair method provides a more structurally secure repair because the concrete foundation remains undisturbed. 
     Another advantage of this invention is that the repair method requires only two specialized repair components: a reaming bit and a repair coupling. 
     Another advantage of this invention is that the reaming bit is designed to be used in any conventional handheld power drill, which is common and readily available at any construction site. 
     Another advantage of this invention is that a single user in only a few minutes can prepare a large number of broken conduit ends for repair, turning down the inside walls of the conduit with the drill mounted reaming bit. 
     Other advantages will become apparent upon a reading of the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       A preferred embodiment of the invention has been depicted for illustrative purposes only wherein: 
         FIG. 1  is a perspective view of the reaming bit used in the repair method of this invention; 
         FIG. 2  is an elevated side view of the reaming bit of  FIG. 1 ; 
         FIG. 3  is an end view of the reaming tool bit of  FIG. 1 ; 
         FIG. 4  is an exploded view of the reaming tool of  FIG. 1 ; 
         FIG. 5  is a side view of the reaming tool bit mounted to the chuck of a conventional hand drill being inserted into a broken conduit end embedded in a concrete foundation (shown as a partial side sectional view); 
         FIG. 6  is a side view of the reaming tool bit mounted to the chuck of a conventional hand drill being withdrawn from the broken conduit end embedded in a concrete foundation showing the bored out inner wall of the broken conduit end (shown as a partial side sectional view); 
         FIG. 7  is a side sectional view of one embodiment of the repair coupling of this invention being inserted into the bored out broken conduit end; 
         FIG. 8  is a side sectional view of the repair coupling of  FIG. 7  connecting the repaired conduit end and a new section of conduit; 
         FIG. 9  is an exploded perspective view of a second embodiment of the repair coupling of this invention; 
         FIG. 10  is an exploded perspective view of a third embodiment of the repair couplng of this invention; 
         FIG. 11  is a side sectional view of the repair coupling of  FIG. 10  connecting the repaired conduit end and a new section of conduit; and 
         FIG. 12  is a side sectional view of the repair coupling of  FIG. 9  connecting the repaired conduit end and a new section of conduit. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     The preferred embodiment herein described is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is chosen and described to best explain the invention so that others skilled in the art might utilize its teachings. This invention entails a method of repairing broken electrical conduit embedded in a concrete foundation without breaking up the foundation and the specialized components used in the repair, namely, a reaming bit and various embodiments of a repair coupling. 
       FIGS. 1-4  illustrate the specialized reaming bit of this invention (designated generally as reference numeral  10 ), which is used to bore out the inner wall of the broken conduit end. Reaming bit  10  has a conventional design and construction common for drill and milling tools and is intended for use with hand held power drills (reference numeral  8  in  FIGS. 5 and 6 ). As shown, reaming bit  10  includes an interchangeable cutting head  20  and pilot head  28  mounted on a mandrel  30 . It should be noted that the reaming bit could also be machined from a solid piece of metal stock (not illustrated in the figures) within the teaching of this invention. The multiple piece design allows interchangeable cutting heads of various sizes to be used with a standard mandrel assembly. 
     As shown in  FIGS. 1-4 , cutting head  20  has a cylindrical body  22  and six helical cutting blades  24 . Cutting head  20  also has an axial through bore  21 , through which the mandrel extends. Each cutting blade has a cutting edge and a cutting face that allows the material shaved from the conduit wall to be expelled upward. The outer diameter of cutting head  20  is sized to mill out and remove material from the inner wall of the broken conduit end to reduce the wall thickness to accommodate the repair coupling. Generally, cutting head  20  is sized to remove approximately one half the thickness of the conduit wall. Pilot head  28  has an axial through bore  29 , through which mandrel  30  extends. Mandrel  30  has an integral cylindrical shoulder stop  32  and axial shank  34  that extends axially from opposite ends of the shoulder stop. As shown, cutting head  20  and pilot head  28  are mounted to the proximal end of shank  34  by a bolt  36  that is turned into a threaded axial bore  35  in shank  34 . The distal end of shank  34  is used to secure the reaming bit to the chuck of a power drill. A pin  38  extends through lateral bores in cutting head  20  and shank  34  to secure and prevent the cutting head from turning on the mandrel. The outer diameter of the pilot head  28  and shoulder stop  32  are sized to accommodate the inner and outer diameters of the broken conduit end, such that the pilot head is insertable into the broken conduit end and the oversized shoulder stop will abut against the conduit end. 
       FIGS. 7-14  illustrate different embodiments of the repair couplings of this invention, which are used to join the broken conduit end to a new section of conduit. The repair couplings join the broken conduit ends to new sections of conduit. Because electrical conduit is available in various standardized diameter sizes and wall thicknesses, the repair couplings of this invention are intended to be dimensioned into standardize sizes that accommodate the various diameter sizes and conventions of both plastic and metal electrical conduit. For example, different sizes of repair couplings will be used with each standardized diameter of the electrical conduit, i.e. 1 inch, ¾ inch, etc... In addition, the teachings of this invention encompass variations in the repair coupling that will connect conduit of both identical (straight couplings) and differing diameter sizes (reducer couplings). 
       FIGS. 7 and 8  illustrate the repair coupling of this invention (designated a reference numeral  40 ). Repair coupling  40  has a single piece construction and is ideally formed from a plastic material, such as acrylonitrile-butadiene-styrene (ABS) or polyvinylchloride (PVC), but can also be cast from a metal such as brass, aluminum or steel. Repair coupling  40  has a tubular body with a larger diameter female end  42  and a smaller diameter male end  44 . Repair coupling  40  is dimensioned so that male end  44  can be inserted directly into the reamed conduit end with a snug fit and a new section of conduit can be inserted into the female end. As shown, the thickness of side walls of male end  44  are significantly thinner than the side walls of female end  42  and is approximately one half the thickness of the reamed conduit end in which it is inserted. For a ¾ inch sized repair coupling, the sidewall thickness at male end  44  is approximately 0.0640 inches (generally ranging between 0.0600-0.0700 inches) and the sidewall thickness at the female end is approximately 0.1260 inches (generally ranging between 0.1200-0.1300 inches). For a one inch sized repair coupling, the sidewall thickness at male end  44  is approximately 0.0675 inches (generally ranging from 0.0670-0.0680 inches) and the sidewall thickness at the female end is approximately 0.1425 (generally ranging from 0.1400-0.1500 inches). The tubular sidewalls of repair coupling  40  form a cylindrical passage there through. As shown in  FIG. 8 , the inner diameter of female end  42  is slightly greater than the inner diameter of male end  44 , which forms a shoulder  46 . Shoulder  46  acts as a stop of the new conduit section. 
       FIGS. 9-12  illustrate another embodiment of the repair coupling of this invention (designated as reference numeral  50 ). Repair coupling  50  has a two piece component design that includes an inner sleeve  52  and an outer collar (designated as  60  in  FIGS. 9 and 12  and  70  in  FIGS. 10 and 11 ). Both the inner sleeve  52  and outer collar  60  and  70  may be formed from a plastic material, such as acrylonitrile-butadiene-styrene (ABS) or polyvinylchloride (PVC), or cast from a metal such as brass, aluminum or steel. Again, repair coupling  50  is intended to be sized and dimensioned into standardize sizes that accommodate the various diameter sizes and conventions of both plastic and metal electrical conduit. Generally, inner sleeve  52  is constructed of plastic and outer collars  60  and  70  are constructed of metal and is a conventional conduit connector of standard size. Inner sleeve  52  has a generally tubular body with a smooth axial bore  53 . As shown in  FIGS. 11 and 12 , one end  54  of sleeve  52  is dimensioned for insertion into the reamed conduit end while the other end  56  is dimensioned for insertion into one end of outer collar  60  or  70 . As shown, outer collars  60  and  70  differ only in that collar  60  has a threaded mouth  62  for receiving threaded electrical conduit  6   a  ( FIG. 12 ), while collar  70  has a smooth mouth  72  for receiving non-threaded conduit  6  ( FIG. 11 ), such as EMT (electrical metallic tubing). A small screw  74  is turned into a threaded side bore  73  in collar  70  to secure the new section of conduit into the collar. 
       FIGS. 5-12  illustrate the various steps in the method of this invention for repairing the broken conduit end (designated generally as reference numeral  2 ) embedded in a concrete foundation  3 . Often the broken conduit end extending from the concrete foundation is jagged and uneven and may extend some distance above the foundation. Initially, broken conduit end  3  is often cut at the surface of foundation  3  to provide a clean and straight end for repair, as shown in  FIG. 5 . As illustrated in  FIGS. 5 and 6 , reaming bit  10  is used to mill out the inside of the broken conduit end  2 . Pilot head  28  guides and centers cutting head  20  as a user inserts reaming bit  10  into broken conduit end  2 . The user inserts reaming bit  10  into the broken conduit end until shoulder stop  32  abuts the end of the conduit, whereby the rotating cutting head  20  reams out the inside of sidewall  4  to reducing the thickness of the conduit sidewall to a set depth substantially equal to the length of the cutting head. When reaming bit  10  is withdrawn from broken conduit end  2 , the inside of conduit sidewalls  4  has been reamed out (turned down) to receive the repair coupling. Next, the repair coupling is fitted to the reamed conduit end  2  ( FIGS. 6 and 7 ). Typically, the male end of the repair coupling is hand pressed into the reamed conduit end and a joint compound is used to permanently join the repair coupling to the conduit. The last step, illustrated in  FIGS. 8 ,  10  and  12  is to connect a new section of conduit (designated as reference numeral  6 ) to the repair coupling. Again a joint compound is typically used to join the new conduit section  6 . Once the new conduit section is joined, wiring can be run within the repaired conduit system. 
     ADVANTAGES 
     One skilled in the art will note several advantages of this repair method and specialized repair components of this invention. The method eliminates the need to breakup concrete foundations surrounding the broken conduit end, which greatly reduces the time and expense of the repair. The repair method requires only the specialized reaming bit and a repair coupling. The reaming bit is designed to be used in any conventional handheld power drill, which is common and readily available at any construction site. In a matter of minutes, a single user can prepare a large number of broken conduit ends for repair, turning down the inside walls of the conduit with the drill mounted reaming bit. The reaming bit is a relatively small component that can be carried by workers with little inconvenience. The repair method also does not require the repairer to carry any other additional tools. 
     The repair couplings are small, inexpensive piece parts, whose cost is significantly less than the cost of repairing concrete foundation. The repair couplings are generally constructed from plastics and can be produced in various sizes in large quantities with great cost effectiveness. The single piece design of the first embodiment of the repair coupling is well suited for low cost plastic construction. The two piece design of the repair coupling of the second embodiment allows the combination of both plastic and metal conduit. Building codes often require metal conduit be run from the foundation up. Consequently, plastic conduit must often be mated with metal conduit at the foundation. The two piece design of the second embodiment allows plastic inner sleeves to be mated with plastic or metal collars. The repair coupling provides a convenient interconnection between the plastic conduit inside the foundation and metal conduit run above the foundation if required. In addition, the inner sleeves are designed to fit into conventional collars that are common and readily available in the industry further reducing costs. 
     It should be noted that the repair method of this invention also provides a more structurally secure repair. Patched concrete foundation never has the integrity of the original foundation and is subject to cracks, as well as an unsightly appearance. Consequently, eliminating the need to break up and patch the concrete foundations is a significant advantage of this repair method. While the inside of the sidewalls of the conduit are turned down, the concrete foundation, which is left undisturbed around the conduit end, provides sufficient structural support to the repair coupling and new conduit sections. Because the concrete foundation surrounds the broken conduit end, the turned down sidewall of the conduit is reinforced from outside forces that may fracture or crack the conduit. 
     It is understood that the above description does not limit the invention to the details given, but may be modified within the scope of the following claims.