Abstract:
A plug cutter for machining plug from a workpiece of wood, solid surface materials, and the like. The bit includes a straight shank portion adapted to be gripped in chucks or collets of a router or CNC machine, and a 1° tapered fluted cutting portion. Also, a process for using the plug cutter to machine plugs for inlaying into surfaces.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The invention relates to a device for cutting plugs from a workpiece, and a method for inlaying the plugs into a surface. 
         [0003]    2. Description of the Related Art 
         [0004]    The disclosed invention is directed generally to solid surface fabrication and woodworking and more specifically to plug repair and the tooling which is suitable to create plugs. 
         [0005]    In the fabrication of solid surfacing or wooden materials it is useful to inlay plugs of similar or dissimilar materials, for various reasons. For instance, a plug of similar solid surface material may be inlaid into a solid surface countertop to seamlessly and invisibly repair a flaw. Another example would be the inlaying of a hardwood plug into solid surfacing or softwood objects to provide a secure screw holding material when the material of construction of the object is not suitable for holding screws. A further example would be the inlay of dissimilar materials into an object for decorative effect. 
         [0006]    While different methods or techniques can be used for the machining of plugs, one popular approach is to use a plug cutter. Typically these cutters cut frustoconical plugs from a board. U.S. Pat. No. 5,681,134 to Ebert and U.S. Pat. No. 6,599,065 to Haughton et al. are representative of this class of cutter. In typical use the shank of a plug cutter is chucked into a drill press and rotated while the cutter is plunged into the board, cutting the frustoconical plug along the axis of the shank. A plug cutter machines a plug of a defined size. For each plug cutter a corresponding bevel bit is required. The bevel bit cuts a tapered hole in the surface to be repaired that matches the size of the corresponding plug. To accomplish plug repairs of various sizes, multiple matched sets of plug cutters and bevel bits are required. Matched plug repair sets suffer from limitations. Matched sets of plug cutters and bevel bits are expensive. Plug cutters and bevel bits are limited to their defined size. Matched sets are generally unavailable in sizes less than 10 mm. The plug cutters and bevel bits require periodic sharpening, and after sharpening the plug cutter and bevel bits are no longer a match. Furthermore, the plugs cut using frustoconical plug cutters suffer from limitations. Frustoconical plugs require pressure to be applied to the plug until after curing of the adhesive used to complete the repair. This entails labor intensive clamping of each plug. Also, the routing down and finishing of frustoconical plugs is labor intensive. 
         [0007]    There is a need for an economical tool for forming plugs of various sizes that does not require labor intensive techniques for inlaying the plugs. 
       SUMMARY OF THE INVENTION 
     Brief Description of the Drawings 
       [0008]      FIG. 1  is a perspective view of the plug cutter. 
         [0009]      FIG. 2A  is an isometric view of the plug cutter of  FIG. 1  cutting various sized plugs from a workpiece. 
         [0010]      FIG. 2B  is a side view of the board of  FIG. 2A  with plugs cut using the plug cutter of  FIG. 1 . 
         [0011]      FIG. 3  is an isometric view of various stages of the plug of  FIG. 2A  being inlaid into a surface. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0012]    The plug cutter  100  of the invention is a tapered router bit as shown in  FIG. 1 . The plug cutter is comprised of a straight shank  110  portion, and a tapered, fluted, cutting portion  120 . The straight shank  110  is sized and shaped to fit the collet of typical routers and CNC machinery. The tapered cutting portion  120  is tapered 1° in relation to the centerline  130  from the shank to the distal end of the bit. The tapered cutting portion  120  has fluted cutters of the type well known to the art. The bit may be made from steel, high speed steel, carbon alloy steel, carbide, or a combination thereof. Plug cutters of this design are inexpensive to manufacture. 
         [0013]    The plug cutter is used to machine plugs for inlaying into surfaces. The plug cutter may be used with a router or CNC machine to machine plugs. The preferred machine is a CNC machine. The process of machining a plug comprises orbiting the rotating plug cutter around a centerline of the plug while simultaneously plunging the plug cutter into a workpiece. The shank  110  of the plug cutter is chucked into a CNC machine and driven in a rotating manner by the chuck. In addition to rotating the bit, the CNC machine is programmed to orbit the bit around the centerline  230  of the plug. The bit is juxtaposed to a workpiece  200  from which plugs are to be machined. The plug cutter is rotated and orbited around centerline  230  while simultaneously plunging the plug cutter into the workpiece  200  to create a plug  210 , as shown in  FIG. 2A  and  FIG. 2B . The size of the plug  210  that is machined is related to the distance the plug cutter  100  is orbited about the centerline  230 . The CNC machine may be programmed to machine any combination of same or different sized plugs from the workpiece  200 . Plugs of large sizes may be conveniently made with the relatively small plug cutter  100 . Workpiece  200  may be of any material suitable for machining and inlaying. The preferred materials are wood and solid surface materials. 
         [0014]    The plugs  210  created by plug cutter  100  are used for inlaying into a surface  300 . The inlaying may be for decorative or functional purposes. The method comprises drilling a hole into the surface  300 , adhesively bonding a plug  210  into the hole in surface  300 , and finishing the surface to smooth the plug  210 . 
         [0015]    A hole  220  is bored into surface  300  using a typical drill bit, or router bit, with straight sides. Drill bits may be driven by hand drills, power drills, drill presses, or CNC machine. Router bits may be driven by routers, plunge routers, or CNC machines. The hole  220  is drilled at any location in surface  300  to achieve a decorative effect, or at a blemished or flawed location that requires a repair. In the case of a repair, the size of hole  220  should be larger than the blemish or flaw. 
         [0016]    A plug  210  with a 1° taper that was machined with plug cutter  100  is adhesively bonded into the hole drilled into surface  300 . The plug  210 , or the hole, or both are coated with an adhesive and the plug  210  is inserted into the hole. The plug  210  does not have to be pushed down firmly, just gently turned in. The preferred adhesive for solid surface materials is joint adhesive. The preferred adhesive for wood is wood glue. The 1° angle of plug  210  makes it slightly conical and it will tightly fit the straight hole without requiring means for continued pressure, such as a clamp. 
         [0017]    The surface  300  is finished after the adhesive has set. For inlays set into sold surface materials, it is found particularly useful to cut off any exposed portion of the inlaid plug by using an oscillating saw. The finishing is completed by sanding the area of the inlay. Finishing is very fast and easy, and creates almost no dust. The inlay created this way is very nicely finished, and shows no whitening. A strong and inconspicuous surface inlay is created.