Abstract:
A tool for creating uniform thickness around the edge of a stone slab for seaming or profiling thereof. The tool is used with portable routers or other handheld machines. A spindle side spacer, bearing assembly and blade side spacer establish a fixed depth at which the cutting blade is set from the base of the machine. This fixed depth creates a uniform thickness when the tool is used on the edge of a stone slab.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a tool for use with granite or other hard stones. More specifically, it relates to a tool for preparing the edge of a stone surface for seaming, profiling or similar applications. The tool consists of a bit for use with a handheld machine having rotary action such as a router. The tool includes a cutting blade and spacer assemblies to assure uniform thickness of the edge of the stone surface. 
         [0002]    The National Building Granite Quarries Association (NBGQA) is the only association that provides thickness tolerances for granite. The NBGQA&#39;s current edition of the specifications for architectural granite lists the allowable variation in thickness for thicknesses between ⅜″ and 1⅝″ as plus or minus ⅛″. The Marble Institute of America Dimension Stone Design Manual adopts this same tolerance. This thickness variation affects the stone fabrication in many ways. Uneven edges, lips and steps are common defects when the thickness variation is outside the stated tolerance. 
         [0003]    According to the state of the art, there is a method for correcting the stone edge thickness which is only used on CNC (Computer Numeric Control) machines. In this method an abrasive tool known as a stone stubbing tool or a stone gauging tool is used prior to any profiling or seaming operation to gauge the stone to a predetermined thickness and in a continuous manner for the purpose of obtaining a uniform edge. 
         [0004]    In CNC operation, the stone is held in place by vacuum suction tools, polished side down. The machine uses the stone polished side as a datum where either the operator of the machine or a laser device adjusts the thickness width based upon this datum or reference point. When this adjustment is made, based upon a predetermined thickness, the machine engages the stone from a corner and travels along the bottom edge of the stone, i.e., on the rough side, and grinds the overall thickness down to the predetermined thickness. After this operation, the edge of the stone will have a uniform thickness along its length that will help the profiling tools create a consistent edge. The life of the stone surface is extended by avoiding contact with the tools necessary to engage an oversize slab which could potentially damage it. 
         [0005]    The tool according to the present invention is designed for a portable handheld machine and is intended to perform the same function as the stubbing tools or gauging tools described above. Since the majority of the stone fabrication shops already use handheld machines for other operations, the present invention will help these fabricators to produce work of the same or similar quality as CNC machines. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a tool for creating a uniform thickness on the edge of a stone slab. The tool comprises a spindle for attaching the tool to a handheld machine. The spacer assembly comprises a blade spacer, a bearing assembly and a spindle spacer. The spindle spacer is adjacent to the spindle. 
         [0007]    A blade is placed adjacent to the blade spacer. The blade is configured such that it engages a surface of the stone slab when the tool abuts the edge of the stone slab. The engagement of the blade with the surface is such that the blade removes material in excess of the uniform thickness. The blade is made by using a layer of an advanced metal bond (sintered) and diamond. 
         [0008]    The spacer assembly including the bearing assembly is preferably cylindrical. The cylindrical bearing assembly allows rotation of the tool with respect to the stone slab. The blade is also preferably cylindrical and of a diameter greater than that of the spacer assembly. The depth of the spacer assembly creates a uniform distance between the handheld machine and the blade corresponding to the uniform thickness of the stone slab. The spindle spacer and/or the blade spacer are replaceable to adjust the uniform distance between the handheld machine and the blade. 
         [0009]    The present invention is also directed to a process for cutting an edge of a stone slab to a uniform thickness. The process comprises the steps of determining a uniform thickness for the edge of the stone slab. Next, a user provides a handheld tool having a blade and a spacer assembly, wherein the spacer assembly has a depth equal to the uniform thickness. The base of the handheld tool is aligned with an upper surface of the stone slab such that the spacer assembly abuts the edge of the stone slab and the blade engages a lower surface of the stone slab. The handheld tool is then actuated to rotate the blade. Rotation of the blade removes excess material from the lower surface of the stone slab to create the uniform thickness on the edge of the stone slab. 
         [0010]    The process may also involve moving the handheld tool from one position on the edge of the stone slab to another position on the edge of the stone slab to create a consistent length of uniform thickness. The step of actuating the handheld tool is repeated until enough excess material is removed to achieve the uniform thickness desired around the edge of the stone slab. 
         [0011]    As described above, the spacer assembly is comprised of a spindle spacer, a bearing assembly and a blade spacer. The depth of the spacer assembly is determined by the combined thicknesses of the spindle spacer, bearing assembly and blade spacer. The process may further comprise the step of adjusting the depth of the spacer assembly by replacing the spindle spacer or blade spacer with another spindle spacer or blade spacer having a different thickness. 
         [0012]    Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The accompanying drawings illustrate the invention. In such drawings: 
           [0014]      FIG. 1  is a front view of the tool of the present invention; 
           [0015]      FIG. 2  is an exploded perspective view of the tool of the present invention; 
           [0016]      FIG. 3  is a front view of the tool of the present invention engaging a stone slab; and 
           [0017]      FIG. 4  is a perspective view of the tool of the present invention engaging a stone slab. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    As shown in the drawings for purposes of illustration, the present invention relates to a tool for correcting the thickness of stone slabs, generally referred to in  FIGS. 1 through 4  by the reference numeral  10 . The tool  10  comprises a bit to be mounted on a portable handheld machine  34  with rotary action such as a router. The tool  10  includes a blade  12 . The blade  12  is designed to grind, cut or otherwise remove material from a stone slab which is engaged by the blade  12 . 
         [0019]    On one side of the blade  12  the tool  10  includes a spacer assembly  13 , which includes a blade side spacer  14  and a spindle side spacer  16 . Between the blade side spacer  14  and spindle side spacer  16  is a bearing assembly  18 . 
         [0020]    The blade side spacer  14  is designed to distance the blade  12  from the bearing assembly  18 . Likewise, the spindle side spacer  16  is designed to space the bearing assembly  18  from the base of the portable handheld machine  34 . The spacer assembly  13 , which comprises the combination of the blade side spacer  14 , spindle side spacer  16 , and bearing assembly  18 , sets the depth of the blade  12  from the base of the portable handheld machine  34 . This depth determines the thickness of the stone slab  32  after cutting or grinding and creates the uniform thickness required. 
         [0021]    The blade side spacer  14  includes a shoulder  20 . The shoulder  20  engages a circular opening  22  in the center of the washer-shaped blade  12 . The engagement of the shoulder  20  and opening  22  assure that the blade  12  remains in a fixed relationship with the blade side spacer  14 . 
         [0022]    An end cap  24  engages the blade  12  on the side opposite the blade side spacer  14 . A shoulder screw  26  passes through a central opening  28  in the end cap  24 . The shoulder screw  26  also passes through concentric central openings in the blade  12 , blade side spacer  14 , spindle side spacer  16  and bearing assembly  18 . A recess  30  in the spindle side spacer  16  permits a nut (not shown) to engage the end of the shoulder screw  26 . This engagement of the nut and shoulder screw  26  assures that the parts of the tool  10  are compressed together and remain as a single unit. The nut and shoulder screw  26  may be separated so that the spindle side spacer  16  and/or blade side spacer  14  may be replaced to adjust the fixed depth at which the blade  12  cuts the stone slab  30 . 
         [0023]    In operation, the tool  10  is connected to a portable handheld machine  34  in the manner in which a tool is usually connected to a router or other machine  34 . In one specific embodiment the tool  10  may be connected to a chuck  34   a.  A spindle  26   a  on the tool  10  connects to a threaded hole in the chuck  34   a.  This attachment occurs adjacent the spindle side spacer  16 . The tool  10  is then placed adjacent a stone slab  32  as shown in  FIG. 3 . One side of the spindle side spacer  16  is aligned with an upper or polished surface  32   a  of the stone slab  32 . This alignment is achieved through engagement of the spindle side spacer  16  and the upper surface  32   a  of the stone slab  32  with the underside  34   a  of the base of the portable handheld machine  34 . 
         [0024]    The combination of the blade side spacer  14 , spindle side spacer  16  and bearing assembly  18  set the blade  12  a fixed distance from the underside  34   a  of the machine  34 . This fixed distance is also maintained with respect to the upper surface  32   a  of the stone slab  32 . The blade  12  engages the bottom or rough side  32   b  of the stone slab  32  to cut or grind away that portion of the edge of the stone slab  32  in excess of the predetermined thickness. 
         [0025]    The machine  34  imparts a rotational movement to the blade  12 . The bearing assembly  18  facilitates the rotational movement of the blade  12  by permitting the blade side spacer  14  to rotate with respect to the spindle side spacer  16 . A person using the tool  10  moves the machine  34  along a side  32   c  of the stone slab  32 . The side of the blade side spacer  14 , spindle side spacer  16  and bearing assembly  18  is held flush against the side  32   c  of the stone slab  32 . After the tool is passed along the side  32   c,  that side  32   c  of the stone slab  32  is ground to the predetermined thickness set by the depth of the tool  10 . The user performs this operation on each side  32   c  of the stone slab  32  to be reduced to the pre-determined thickness. 
         [0026]    The blade  12  may be made by using a layer of an advanced metal bond (sintered) and diamond or other material commonly used to cut or grind stone. 
         [0027]    Although an embodiment has been described in detail for purposes of illustration, various modifications may be made without departing from the scope and spirit of the invention. Accordingly, the invention is not to be limited, except as by the appended claims.