Patent Publication Number: US-2004058634-A1

Title: Adjustable abrading tool, abrasive star and abrading kit

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to the field of rotating tools and, in particular, to a tool, abrasive star, and kit for abrading holes, bores, chamfers and the like.  
       BACKGROUND OF THE INVENTION  
       [0002] It is common practice in the machine tool industry to use abrading tools to finish the walls (e.g., removing about 0.001 to 0.005 inches of material) of a previously provided hole or similar interior surface of a workpiece. Abrading operations generally correct inaccuracies in straightness and roundness in bore holes, can provide a uniform hole surfaces, or can remove burrs or finish surfaces.  
       [0003] A number of abrading devices have been developed to abrade, finish, polish or grind workpiece holes. U.S. Pat. No. 6,152,814 issued Nov. 28, 2000 describes an expandable abrasive sleeve for use on an inflatable tool to abrade or condition a surface of a workpiece. The expandable abrasive sleeve comprises an elastomeric backing, for example, made of a rubber material, and a plurality of separate abrasive strips adhered to the elastomeric backing in an overlapping relationship such that the strips overlap when the sleeve is expanded. The expandable abrasive sleeve is disposed around an inflatable bladder and inserted with a bore to be abraded. The sleeve is then inflated, causing it to expands until it bears against the inner walls of the bore, and rotated to abrade the inner wall.  
       [0004] Although this inflatable sleeve successfully abrades the inner walls of the bore, this system has a number of serious drawbacks. First, the diameter of the bore to be abraded is both uncontrollable and non-uniform. Because of the sleeve is necessarily made of a relatively pliable elastomeric material, the sleeve it does not maintain a uniform diameter and tends both to flare out the exposed ends of the bore and under-abrade areas within the bore. Second, an inflated sleeve cannot be inserted into the bore and, therefore, the tool is not readily adapted for abrading chamfers or anything less than an entire bore. Finally, the sleeve and tool system are relatively expensive. The tool requires a source of compressed air proximate to the workpiece to be abraded, requiring a significant upfront investment. Further, the inflatable sleeve requires laborious fabrication due to the process of attaching the abrading material. Each piece of abrading material must be adhered onto the tool one at a time. This burdensome process guarantees a high price for a tool that must be discarded after use.  
       [0005] U.S. Pat. No. 5,672,096 issued Sep. 30, 1997 describes an inflatable tool for abrading or finishing a surface of a workpiece. The inflatable tool includes an inflatable bladder clamped at first and second ends of a core having an elastomeric outer core portion. The inflatable bladder is inflated by a pressurized medium and forms a pocket or chamber around the elastomeric outer core portion. An abrasive sleeve is disposed around and secured by the inflatable bladder when inflated.  
       [0006] While this invention allows a tool to be inflated to various sizes and to chamfer, its lack of uniformity creates a serious drawback. The diameter is uncontrollable. This lack of diameter variance only allows a craftsman to abrade holes at a preset diameter controlled by the manufacturer. Furthermore, this tool hardly stands alone; it requires an air mandrel to expand the sleeve in order to abrade. This could be a significant upfront investment.  
       [0007] U.S. Pat. No. 3,232,011 issued Feb. 1, 1966 describes a pneumatically actuated expanding tool for grinding, polishing, and lapping tubing inside diameters or cylindrical bores. The tool employs abrasive cloth or paper which may be inserted into a tube or the like, and expanded to provide a controlled radial force or pressure on the inner surface of the tube while the tool is linearly advanced and retracted and/or rotated or oscillated back and forth about its longitudinal axis. Means are also provided for blowing air through the tool to cool it and to exhaust particles of abrasive dust from a tube in which the tool is employed.  
       [0008] Although this tool expands to grind and polish a hole, any expansion is unmeasurable. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Aside from this, any expansion requires another instrument to pneumatically pressurize the tool.  
       [0009] U.S. Pat. No. 2,605,594 issued Aug. 5, 1952 describes a pneumatically inflatable abrasive cylinder disposed at an opposite end from a hand pump. Squeezing the pump forces air into the cylinder causing it to expand. Sandpaper is wrapped around the cylinder. To abrade, the machinist inserts the cylinder into a hole, inflates, and radially rotates the cylinder by hand.  
       [0010] Although this tool is certainly cost-effective, using sandpaper and no external tools, it potency is highly suspect. First, to be productively relevant, an abrading machine requires a means for fastening itself to drill or similar machine. Wrist power might be acceptable when dealing with wood, but time and work efficiency demands more power when dealing with metal. Second, as a cylinder this tool is incapable of chamfering. Third, any expansion is immeasurable.  
       [0011] U.S. Pat. No. 5,800,252 issued Sep. 1, 1998 describes an abrading device extending from a tool mandrel connected in a cantilevered arrangement to a machine for rotating machining operations. A rigid honing member is secured to the tool mandrel, and configured such that the effective diameter of the substantially rigid abrasive outer surface of the honing member can be uniformly and precisely varied in a radial direction relative to the longitudinal axis of the tool in response to pressure on the interior surface of the honing member. A fluid distribution system formed in the tool mandrel in a predetermined arrangement is in fluid communication with the source of pressurized fluid, and includes a pressure chamber that is configured to apply fluid pressure to the interior surface of the honing member. At least one passage extends through the honing member from the pressure chamber and has an opening on the exterior surface of the honing member for delivering fluid to dissipate heat energy and remove debris.  
       [0012] While this invention may effectively solve some problems associated with debris removal and precise pressurization, it still requires a tool mandrel to pressurize internal fluid in order to expand. Despite any increase in precision associated with this invention, there is no method on the tool itself to measure the bore diameter. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. As this invention expands after entry into a previously bore hole, it is incapable of chamfering.  
       [0013] U.S. Pat. No. 6,083,086 issued Jul. 4, 2000 describes an expanding device for grinding sleeves. The device has a cylindrical member with an outer surface, an interior chamber, an expanding chamber, and a locking mechanism. The outer surface receives the grinding sleeve, the interior chamber receives a rotatable shaft, and the expanding chamber comprises an expanding material, illustratively water, rubber, polyethylene and other known expandable polymers water-based solutions and oil-based solutions, that expands and contracts based upon pressure applied by use of a locking mechanism. The grinding sleeve can be sandpaper, diamond, emery cloth or any conventional material that grinds metal, wood, or plastic materials.  
       [0014] Although this grinding device allows cost-effective and simple replacements due to the use of conventional sand paper, the ability to control the diameter to an easily measurable degree is still absent. The invention works by using numerous expanding surfaces and diameters, in conjunction with liquid solutions. Using liquids in this manner of pressurizing is an improvement over previous air-pressure and liquid-pressure tools. This tool requires no external apparatus for pressurization. While this tool expands without use of a hand tool or mandrel, all the elaborate intricacies involved in the expansion ensure a hefty tool price. Also, this tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials.  
       [0015] U.S. Pat. No. 6,203,410 issued Mar. 10, 2001 describes a reamer with adjustable expansion/contraction and a bore finishing section comprising the reamer. The grinding section is cylindrically shaped, and has a plurality of axially-extending slits in its peripheral wall and a tapered inner surface. The rotation shaft is connected via threaded sections to a sliding shaft, which is in turn connected to a diameter expansion member consisting of a tapered cone fitted into the tapered inner surface of the grinding section. When the rotation shaft is operated to rotate, the rotational motion is converted into linear motion of the slide shaft due to a guide pin and a guide hole. The linear motion moves the diameter expansion member back and forth inside the grinding section, thereby contracting/expanding the outer diameter of the grinding section mechanically and precisely.  
       [0016] Although this tool&#39;s diameter expands or contracts by rotating a member located on its top, instead of using a pressurized medium, this expanded/contracted diameter is not measurable by the tool. The abrading material mentioned, diamond grindstone, is electrically deposited onto the tool. This expensive material combined with the fact that it is permanently attached to the tool, makes the tool&#39;s reusability impractical. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Furthermore, this cylindrical tool is incapable of chamfering.  
       [0017] Although this grinding device allows cost-effective and simple replacements due to the use of conventional sand paper, the ability to control the diameter to an easily measurable degree is still absent. The invention works by using numerous expanding surfaces and diameters, in conjunction with liquid solutions. While this tool expands without use of a hand tool, the elaborate expansion devices ensure a hefty tool price. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials.  
       [0018] U.S. Pat. No. 5,390,448 issued Feb. 21, 1995 describes a modular expandable honing tool or mandrel, which is adjustable within limits during a honing operation. The modular tubular honing assembly includes a drive member for attaching to a typical honing machine, a cage member adaptable for slidably receiving the abrasive sleeve member, and a retainer member for holding the abrasive sleeve member in operative position within the cage member. The abrasive sleeve member has inner and outer surfaces, the inner surface being conically tapered over its entire length while its outer surface includes a plurality of circumferentially spaced longitudinal projections positioned adjacent longitudinal channels, each projection including a honing surface having abrasive particles located thereon. The abrasive sleeve member also includes an elongated slot extending along its entire length on one side thereof which enables such member to uniformly radially expand and contract when the expander member is axially moved therethrough, the expander member having at least a portion of its outer surface which extends through the abrasive sleeve member likewise tapered at the same conical taper rate as the taper associated with the inner surface of the abrasive sleeve member for making surface-to-surface contact with the tapered inner surface of the abrasive sleeve member. Axial movement of the expander member within the abrasive sleeve member changes the diameter of the sleeve member uniformly along its entire length during a honing operation.  
       [0019] While this invention allows for expansion of the tool&#39;s circumference, this expansion must occur during the abrading process. The honing surfaces require must be coated or plated with an abrasive material, instead of using a simple sleeve or sandpaper. There is no gauge to indicate precise measurement. As a primarily honing tool, this tool could not abrade delicate surfaces or non-uniform holes. Furthermore, due to its cylindrical shape, this tool is incapable of chamfering.  
       [0020] U.S. Pat. No. 5,155,944 issued Oct. 20, 1992 describes a device for honing a workpiece surface to be machined to provide a finished size and surface configuration comprising a honing tool with adjustable honing elements, the elements having a cutting zone and a calibrating zone, and also comprising a guide element with a surface sized to the finished size of the workpiece surface such that on the cutting stroke of the tool the cutting zone performs the cut and the tool is guided by the movement of the calibrated zone through the guide element and the abraded surface.  
       [0021] While this tool can manually adjust its diameter, this adjustment exists to compensate for abrasive deterioration. Any adjustments, which are minute, are neither readily measurable nor designed to allow an operator to work with holes of differing sizes.  
       [0022] U.S. Pat. No. 5,088,237 issued Feb. 18, 1992 describes a honing tool for machining a workpiece bore in one working stroke with honing coatings set in fixed manner to the desired size of the bore, has on a non-adjustable part of the tool body and preferably in the vicinity of a guide zone, air measuring nozzles. During the tool return stroke, these nozzles are subject to an action through the bore and measure the final size of the latter following the working zone. Optionally a readjustment can be automatically initiated as a function of the result via an adjustable body. The adjusting body is adjustable in its axial position by an adjusting device. It comprises a threaded bolt, which is rotatable by means of a hexagonal rod and moves the adjusting body in conjunction with a thread in the tool body. The tool body is circumferentially provided with five slots, which extend radially outwards from its bore and in which are guided honing strip or ledge carriers, which are covered on their outside by abrasive coatings. The honing strip carriers beveled on their inside corresponding to the conical bevel are pressed against the same by two tubular springs.  
       [0023] While this tool allows accurate measurement, it measures the hole after the abrasion is finished. This measurement purely exists to check accuracy, not to allow a machinist with the same tool to finish another differently sized hole. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. Furthermore, the abrasion is a part of the tool, requiring that the entire tool be discarded after significant abrasion-wear.  
       [0024] U.S. Pat. No. 3,861,091 issued Jan. 21, 1975 describes an internal honing tool that includes a tool body which has an outer periphery and a plurality of circumferentially spaced recesses therein. The recesses include first and second portions and extend through the outer periphery of the tool body. Abrasive members are mounted in the first portions of each of the recesses and extend outwardly beyond the outer periphery of the tool body for honing a work piece. Securing members removably secure guides and abrasive stones to the tool body. The structure avoids wear of the tool body while only the abrasive members and guide members require replacement.  
       [0025] Although this invention allows a machinist to replace the abrasives instead of the entire tool, the tool is overly complicated and replacing the abrasives is inconvenient. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. This attribute is designed to only prevent wear and in no way accurately expands or contracts the grinding diameter.  
       [0026] U.S. Pat. No. 4,065,881 issued Jan. 3, 1978 describes a generally cylindrical honing tool for internally honing a workpiece which may have an interrupted bore. It has plurality of radially disposed axially extending tool supported thermoplastic guide members for engaging the workpiece at a first relatively constant pressure to aid in aligning the tool with the workpiece and having a plurality of radially disposed axially extending tool supported abrasive elements for engaging the workpiece at a pressure which is variable and independent of the guide pressure for abrading material from the workpiece.  
       [0027] Although this invention allows the grinding section of the tool to expand, any expansion is immeasurable. This machine is designed to extend its abrasives after insertion into a hole. This tool could not effectively be used in conjunction with a portable drill. This prevents a machinist from abrading surfaces of deep holes, or abrading delicate or thin materials. It uses embedded grinding blocks instead of inexpensive sandpaper.  
       [0028] U.S. Pat. No. 3,166,876 issued Jan. 26, 1965 describes a coated abrasive construction adapted to be formed into a variety of abrading or polishing implements. It is capable of conforming to various contours and adjusting to various diameter openings. An abrasive band is mounted upon an expandable rubber mandrel which is adapted to be rotated by a suitable power source. Fixing the free end of the device at the desired degree of expansion can control the degree of expansion. This can be done permanently with the use of appropriate mandrels of temporarily by use of tape, threaded mandrels with an adjusting nut or by such other means as desired.  
       [0029] Although this tool uses inexpensive, although specialized, sandpaper as an abrasive means, the method of expansion is entirely impractical. No consideration is given for means to expand or contract the rubber implement, instead the machinist forces the rubber to contort and locks it into place. Next, the shape of the machine necessitates that sandpaper be cut into small, joined strips. During honing these small strips are not in sufficient contact with a support surface to effectively abrade. Using centrifugal force to expand an abrasive against an interior surface of a hole will frequently be inadequate. Also, these individual strands of sandpaper are more delicate than many jobs will require. Finally, any expansion is immeasurable.  
       [0030] Specialized sandpaper known as cloth stars exist to lightly grind the interior of tubing. This type of sandpaper consists of two sheets of sandpaper, each with multiple rectangular protruding blades, fastened to each other so that the rear sheet&#39;s blades fill any voids caused by the front sheet&#39;s blade gaps. Generally, a threaded metal plate fastens these two sheets.  
       [0031] While this type of sandpaper fits into a tube, it is wholly inadequate to expand or chamfer a hole. This paper is also restricted in the types of materials and shapes that it may sand, as the exposed edges on the front sheet of the star tend to catch on most non-uniform surfaces causing the edges to bend against the direction of radial motion exposing the non-abrading rear surface of the sandpaper to a workpiece. In addition, the use of multiple sheets of sandpaper makes these stars relatively stiff and unsuited to freely conform to the inside surfaces of bores. Finally, as a metal fastener must mechanically join the two pieces of specially cut sandpaper, the cost of these stars tends to be relatively high.  
       [0032] Therefore, there is a need for a tool that expands without the use of pressurizing material (liquids, air, etc.) and the machines inevitably required to administer and measure such material, that uses an inexpensive, easily replaceable material such as sandpaper, that can set its diameter before engaging a hole and hold the size to be abraded, that can chamfer a hole, that creates uniform diameters, that is versatile enough to engage hole of differing diameters, that abrades non-uniform holes, that can be extended to abrade surfaces of deep holes, that abrades delicate or thin materials, that can abrade hardened steel, that can be attached to a drill or similar apparatus, that can abrade soft or elastic materials, such as rubber. Finally, there is a need for an abrasive star that can abrade non-uniform surfaces in the interior of a tubular surface without catching.  
       SUMMARY OF THE INVENTION  
       [0033] The present invention is an abrading tool, abrasive material and abrading kit that overcome the drawbacks inherent in the prior art. In its most basic form, the abrading tool of the present invention includes a threaded drive rod, a means for retaining an abrasive material about the threaded drive rod, an expandable support disposed about the threaded drive rod and dimensioned to brace the abrasive material, and a means for expanding the expandable support.  
       [0034] In the preferred embodiment, the means for retaining the abrasive material includes a lock cap having an opening disposed about the threaded rod and an inside surface dimensioned to mate with the outside surface of the abrasive material, and a compressible locking member disposed about the threaded rod proximate to the inside surface of the abrasive material. The lock cap may be threaded to mate with the drive rod, but the preferred lock cap is not threaded but rather is engaged by a lock knob having a threaded opening to mate with the threaded rod and an engagement surface dimensioned to engage a mating surface of the lock cap. The preferred compressible locking member is an O-ring, though compressible protrusions extending from the means for expanding would also work.  
       [0035] The preferred embodiment uses an elastic drum for an expandable support. Rubber is an excellent material from which to construct the expandable support.  
       [0036] The preferred embodiment uses inner and an outer spacer, situated at both ends of the elastic drum as a means for expanding the elastic drum. The inner spacer and outer spacer are both dimensioned to contact the elastic drum. Axial movement of the outer spacer toward the inner spacer causes the elastic drum to expand. It is preferred that the inner spacer be threaded, but it is understood that this need not be so. The preferred embodiment also includes an adjusting knob that is threaded to mate with, and situated about, the drive rod and in communication with the outer spacer rod to adjust the outer spacer. Radial rotation of the adjusting knob axially moves the outer spacer. A second embodiment of the expandable support uses a substantially resilient cylinder having an open end, a closed end and a sidewall having a plurality of axial cuts. This sidewall may be forced outward to form a substantially conical surface. The preferred embodiment of this second type of expandable support is threaded to mate with the drive rod. The preferred means for expanding this second embodiment comprises an outer spacer dimensioned to engage the open end of the expandable support. Moving this outer spacer toward the closed end of the expandable support engages the resilient cylinder causing the diameter of the open end to increase. The preferred outer spacer for this second embodiment is substantially conically shaped so as to mate with this expandable support. As in the preferred embodiment this second embodiment uses an adjusting knob threaded to mate with the drive rod and in communication with the outer spacer. Radial rotation of the adjusting knob moves the outer spacer axially along the drive rod. Finally, the preferred embodiment of the tool also includes a means for setting a diameter of the expandable support and a means for quick-connection to a drill.  
       [0037] The abrasive star of the present invention is manufactured from a substantially flexible material having a plurality of abrasive particles disposed upon one surface thereof. The star includes a central hub from which a plurality of flaps extend. The flaps are defined by a plurality of gaps, and each flap includes a left side, a right side and an end. A slit is disposed through the left side of each flap proximate to the central hub and extends substantially tangentially to the hub toward the right side of each flap. The gaps and slit are dimensioned to allow the flaps to be folded upward such that right side of each flap to overlaps the left side of each adjacent flap, forming one of a substantially cylindrical outer surface and a substantially conical outer surface. In this manner, a single abrasive star may be fitted to the expandable support, providing a substantially flexible and unbroken abrasive surface that cannot be achieved using current abrasive stars.  
       [0038] The gaps of the preferred stars are substantially triangularly shaped and extend from the edge of the abrasive material to a first location on a circumference of a first circle located between the edge of the sheet and the opening. The right triangle gaps decrease in width from the end of each flap to the junction of each flap with the central hub.  
       [0039] The preferred abrading kit includes at least one abrading tool and at least one abrasive star in accordance with the present invention  
       [0040] Therefore, it is an aspect of the invention to provide an abrading tool that expands without the use of pressurizing material (liquids, air, etc.) and the machines inevitably required to administer and measure such material,  
       [0041] It is a further aspect of the invention to provide an abrading tool that uses an inexpensive, easily replaceable material such as sandpaper,  
       [0042] It is a further aspect of the invention to provide an abrading tool that can measure its diameter before engaging a hole.  
       [0043] It is a further aspect of the invention to provide an abrading tool that can chamfer a hole.  
       [0044] It is a further aspect of the invention to provide an abrading tool that creates uniform diameters.  
       [0045] It is a further aspect of the invention to provide an abrading tool that is versatile enough to engage hole of differing diameters.  
       [0046] It is a further aspect of the invention to provide an abrading tool that can be extended to abrade surfaces of deep holes.  
       [0047] It is a further aspect of the invention to provide an abrading tool that abrades non-uniform holes.  
       [0048] It is a further aspect of the invention to provide an abrading tool that abrades delicate or thin materials.  
       [0049] It is a further aspect of the invention to provide an abrading tool that can abrade hardened steel.  
       [0050] It is a further aspect of the invention to provide an abrading tool that can abrade soft or elastic materials, such as rubber.  
       [0051] It is a further aspect of the invention to provide an abrading tool and that can be attached to a drill or similar apparatus.  
       [0052] It is a further aspect of the invention to provide for an abrasive that can abrade non-uniform surfaces in the interior of a tubular surface without catching.  
       [0053] These aspects of the invention are not meant to be exclusive. Other features, aspects and advantages of the present invention will be readily apparent to those of ordinary skill in the art when read in conjunction with the following description, appended claims and accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0054]FIG. 1 is a cut away side view of one embodiment of the abrading tool of the present invention.  
     [0055]FIG. 2 is a cut away side view of the preferred embodiment of the abrading kit of the present invention.  
     [0056]FIG. 3 is a top view of the one embodiment of the abrasive star of the present invention.  
     [0057]FIG. 4 is a top view of the preferred embodiment of the abrasive star of the present invention.  
     [0058]FIG. 5 is a cut away side view of an alternative embodiment of the abrading kit of the present invention adapted to abrade a chamfer.  
     [0059]FIG. 6 is a side view of an alternative embodiment of the abrading kit of the present invention showing the preferred means for setting the diameter of the expandable support to a desired diameter.  
     [0060]FIG. 7 is a cut away side view of an alternative embodiment of the expandable support.  
     [0061]FIG. 8 is a side view of another alternative embodiment of the expandable support. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0062] Referring first to FIG. 1, one embodiment of the abrading tool  10  of the present invention is shown. In its most basic form, the abrading tool  10  includes a threaded drive rod  14 , a means  12  for retaining an abrasive material (not shown) about the threaded drive rod  14 , an expandable support  16  disposed about the threaded drive rod  14  and dimensioned to brace the abrasive material, and a means  18  for expanding the expandable support  16 .  
     [0063] The threaded rod  14  is preferably manufactured of metal and has a fine pitch thread to allow fine adjustment of the diameter of the expandable support  16 . In the embodiment of FIG. 1, the threaded rod  14  has threads along its entire length and, therefore, is adapted to be secured into a female threaded coupling (not shown) that attaches to a source of rotation. However, in other embodiments, the threaded rod  14  is only be threaded at the end in which the means  12  for retaining an abrasive material and the expandable support  16  are disposed. In some of these embodiments, the other end of the rod is a drive end dimensioned to allow the rod to be gripped by a drill chuck, quick change system, or other art recognized means of securing a rotating tool to a source of rotation. In others, the non-threaded end of the threaded rod  14  is dimensioned to form a part of a calibration system (not shown), which allows a user to accurately set the diameter of the expandable support  16  such that the abrasive material will conform to an opening to be abraded.  
     [0064] The expandable support  16  and means  18  for expanding the expandable support  16  sit about the threaded rod  14  between the means  12  for retaining the abrasive material and the drive end of the threaded rod  14 . The expandable support  16  shown in FIG. 1 is manufactured of a compressible elastic material, such as natural or synthetic rubber, and is formed in the shape of a cylinder of suitable dimension to support the abrasive material as the tool is thrust into a workpiece. When compressed, the expandable support  16  of FIG. 1 bulges, causing its diameter to increase. Consequently, the diameter formed by the abrasive material supported thereby is likewise increased. In operation, one need only increase the diameter of the expandable support  16  to a diameter larger than that of the hole to be abraded to cause the abrasive material to abrade the inside of the hole.  
     [0065] When abrading holes greater than one and one half inches, the partially hollow expander  107  shown in FIG. 7 is the preferred expandable support. This expander  107  is preferably constructed of a more rigid rubber material, such as 65-Duralon® rubber, than the smaller expandable support in order to reduce vibration and or chatter caused by excessive deformation of the material. The higher rigidity of this material necessitates the inclusion of the hollow portion  104  to allow the support to expand. The preferred expander also includes a drum cap  105 , which that fits within the hollow portion  104  to seal the interior of the expander  107 .  
     [0066] As shown in FIG. 8, the expandable support may likewise take the form of an expanding drum  108  with axial slits  106 , which allows for a large contact surface with the abrasive star. Due to its elasticity and lack of brittleness, nylon is the preferred material from which to construct the expanding drum, although those of skill in the art would recognize that other materials may be readily substituted to achieve similar results.  
     [0067] Referring again to FIG. 1, the preferred means  18  for expanding the expandable support  16  includes an inner spacer  15  and outer spacer  17  disposed on opposite sides of the expandable support  16 . The spacers  15 ,  17  are each dimensioned to allow an axial force upon one of the spacers  15 ,  17  to compress the expandable support  16  against the other of the spacers  15 ,  17  such that the diameter of the support  16  is enlarged, and such that a removal of this axial force causes the diameter of the support  16  to be reduced. In some embodiments, the spacers  15 ,  17  are simple washers that are constructed of plastic and the means  18  for expanding the support also includes an adjusting knob (shown in FIG. 2) that drives the outer spacer  17  toward the inner spacer  15 , which is held in a stationary position by the means  12  for retaining the abrasive material. In other embodiments, one or both of the spacers  15 ,  17  are threaded may be actuated to provide the necessary compressive force. Aside from accepting force from the expandable support  16 , threading the inner spacer  15  allows a machinist to remove the means for retaining an abrasive material  12  without affecting the diameter of the expandable support  16 .  
     [0068] The means  12  for retaining the abrasive material is disposed proximate to the expandable support  16  and is sized to hold a portion of the abrasive material in position, while allowing the remainder of the material to conform to the expandable support  16 . In the embodiment of FIG. 1, the means  12  for retaining an abrasive material includes a lock cap  22  and a compressible locking member  26  that act to retain the abrasive material in position. The lock cap  22  has an opening  23  disposed about the threaded drive rod  14  and an inside surface  24  dimensioned to mate with the outside surface of an abrasive material. The lock cap  22  is preferably constructed of plastic and is a substantially hollow cylinder with one open face, allowing access to the inside surface  24 , and one closed face forming the end of the tool  10 . The lock cap  22  must remain stationary during operation of the tool and, therefore, the opening  23  therethrough is preferably threaded. However, in some embodiments the opening  23  is unthreaded and the lock cap  22  is retained by clips, pins, or other art recognized means for securing a cap to a rod.  
     [0069] The compressible locking member  26  is disposed about the threaded rod  14  proximate to the inside surface of the abrasive material and is preferably dimensioned to create an interference fit with the inside surface  24  of the locking cap  22 . Because of this interference fit, positioning the abrasive material between the locking member  26  and the inside surface  24  of the locking cap  22  causes the compressible locking member  26  to exert a static frictional force to hold the hub of an abrasive flush against the lock cap  22 . However, it is recognized that the compressible locking member  26  may take various forms. For example, some embodiments, such as the embodiment of FIG. 4, utilize an elastic ring  17 , such as an O-ring  18 , to affect this compressive force. In others, the compressible locking member  26  is made up of a plurality of compressible protrusions  20  extending from the inner spacer  15 , or any directly adjacent structure.  
     [0070] Now referring to FIG. 2, the preferred embodiment of the abrading kit  50  is shown. The abrading kit  50  includes an abrading tool  10 , such as the tool  10  described with reference to FIG. 1, and an abrasive star  70  attached to the abrading tool.  
     [0071] In the embodiment of FIG. 2, the abrading tool  10  includes a means  18  for expanding the expandable support  16  that also includes an adjusting knob  30 , which acts to drive the outer spacer  17  toward the inner spacer  15 . The adjusting knob  30  is threaded and is preferably fabricated of plastic due to its low cost, although it is recognized an adjusting knob  30  manufactured of metal would offer advantages in many applications. In the preferred embodiment, the adjusting knob  30  contains gripping details, such as sloping walls, bumps, serrations, or the like, to allow a user to grip and radially turn the adjusting knob  30  by hand without the use of a separate tool. This radial turning motion translates into axial movement along the threaded drive rod  14 , causing the knob  30  to engage the outer spacer  17 , which is unthreaded in this embodiment, and moves the outer spacer  17  toward the expandable support  16 .  
     [0072] In the embodiment of FIG. 2, the inner spacer  15  is made of plastic and takes the shape of a squat cylinder. Unlike the preferred outer spacer  17  described above, the preferred inner spacer  15  is threaded. The threading anchors the inner spacer  15  to the threaded drive rod  14 , creating a stationary piece against which the expandable support  16  may bear. The expandable support  16  of this embodiment is similar in all respects to the support  16  described with reference to FIG. 1 except that it slopes at an angle towards the outer spacer  17  in order to aid in the compression thereof. However, it is recognized that other embodiments of the expandable support  16  do not include such an angle.  
     [0073] The preferred means  12  for retaining the abrasive star  70  includes a locking cap  22 , which engages the abrading portion of the abrasive and receives the static frictional force of the compressible locking member  26 , as described with reference to FIG. 1 above. However, the preferred lock cap  22  is not threaded and uses a lock knob  31  to provide the necessary compressive force to lock the abrasive star  70  in place between the lock cap  22  and locking member  26 . The preferred lock knob  31  is threaded, fabricated of plastic and contains sloping walls that allow the thumb and forefinger to rotate it. However, other embodiments may utilize a lock knob  31  that is dimensioned as a simple nut, having a polygonal outer surface adapted for gripping by a wrench or other tool commonly utilized for tightening a nut to a bolt. In still others, the lock knob  31  is a quick connect/disconnect type knob, allowing it to be attached and removed by a simple downward push and quarter turn motion.  
     [0074] The preferred abrading tool  10  also includes a drive member  33  attached to the drive end of the threaded rod  14 . The drive adapter  33  includes a threaded end  35 , that is dimensioned to accept the threaded rod, and a drive end  37  that is dimensioned to allow the adapter  33  to be gripped by a drill chuck, quick change system, or other art recognized means of securing a rotating tool to a source of rotation.  
     [0075] As shown in FIG. 2, the abrasive star  70  of the preferred kit is folded upward and over the expandable support to form in the shape of a cylinder having an open end and a closed end. However, it is recognized that as the expandable support  16  expands, this cylindrical shape to the outer surface will become a substantially conical shape, with the ends of the abrasive star  70  only conforming to the support  16  when opposed by the inside surface of a bore.  
     [0076] As shown in FIGS. 3 and 4, two embodiments of the abrasive star  70  of the present invention are shown. The star  70  includes a central hub  84  from which a plurality of flaps  71  extend. The flaps  71  are defined by a plurality of gaps  76 , and each flap  71  includes a left side  83 , a right side  85  and an end  72 . A slit  82  is disposed through one side of each flap  71  proximate to the central hub  84  and extends substantially tangentially to the hub  84  toward the opposite side of each flap  71 . The gaps  76  and slits  82  are dimensioned to allow the flaps  71  to be folded upward such that right side  85  of each flap  71  overlaps the left side  85  of each adjacent flap  71 . As described above with reference to FIG. 2, this forms a continuous substantially cylindrical outer surface or a substantially conical outer surface when the star  71  is attached to the abrasive tool.  
     [0077] As shown in FIG. 3, the slits  82  are merely extensions of the left side  83  of each flap and extend substantially into the right side  85  of each adjacent flap. However, as shown in FIG. 4, the slits  82  may be disposed on the left side  83  to achieve similar results. It is preferred the that gaps  76  between flaps  71  be substantially triangularly shaped and extend from the end  72  of adjoining flaps  71  toward the central hub  84 . As is evident by a comparison of FIGS. 3 and 4, the extension of each gap  76  toward the hub  84  will vary depending upon the size and disposition of each slit  82 . Accordingly, the gaps  76  and slits  82  work in combination to produce the desired continuous surface.  
     [0078] Regardless of the form taken by the abrasive star  70 , it is preferably that it be manufactured from a substantially flexible material having a plurality of abrasive particles disposed upon one surface thereof. Generally any type of sandpaper fashioned to fit about the expandable support is suitable. A “J” weight flex-back sandpaper is preferred in smaller diameter applications because it conforms to a rubber expandable support as the tool turns. Supports having expanded diameters in excess of one and one half inches are preferably manufactured of heavier “X” weight sandpaper. However, it is recognized that other types of abrasives having flexible backing, such as common cloth or rubber-backed abrasives, could be substituted to achieve similar results.  
     [0079]FIG. 5 shows another embodiment of the abrading tool  10  that is adapted for abrading a chamfer on an opening. This embodiment of the tool is substantially the same as those described with reference to FIGS. 1 and 2 except for the use of a different expandable support  16  and different means  18  for expanding the expandable support  16 .  
     [0080] In the embodiment of FIG. 5, the expandable support  16  is a substantially resilient cylinder  90  having an open end, a closed end and a side wall  92  having a plurality of axial cuts  94  disposed therethrough, which allow the side wall  92  may be forced outward to form a substantially conical surface. The preferred resilient cylinder  22  is manufactured of a nylon, which is threaded to receive the drive rod  14 . However, other embodiments may include a separate threaded member mounted opposite the closed end for holding the cylinder in place. In the embodiment of FIG. 5, the means  18  for expanding the expandable support  16  is a plunger  96  having a substantially conical shape that allows it to gradually force the side wall  92  of the cylinder  90  outward as it is moved toward the cylinder. It is preferred that the plunger  96  be unthreaded and fabricated of plastic, as the lack of threading allows it to remain substantial radial stability during axial movement to provide a smoother mating between it and the adjacent resilient cylinder  90 . In this preferred embodiment, the plunger  96  is moved axially by an adjusting knob  30 , such as those described with reference to FIG. 2. However, in other embodiments, the plunger  96  is threaded and is provided with details to allow it to be rotated on the threaded rod  14  and the adjusting knob  30  is eliminated. Likewise, in some embodiments, the plunger  96  includes a plurality of notches (not shown) therein that are dimensioned to mate with the side wall  92  of the cylinder  90  and act to prevent the side wall  92  from catching against the material to be abraded. In still other such embodiments, an elastic band (not shown) such as those used to disable the claws of live lobsters is wrapped around the cylinder  90  and acts both as a spring, depressing the cylinder  90  against the plunger  96 , and as a frictional member that provides a better grip on the abrasive star than the preferred nylon cylinder  90 .  
     [0081] Referring now to FIG. 6, another embodiment of the abrading tool  10  is shown. In this embodiment, a means for setting the diameter of the expandable support  16  to a desired diameter is provided. As shown in FIG. 6, this means includes a sleeve  130  that fits within a bore  134  in the adjusting knob  132  and includes a plurality of marks  138  disposed incrementally along its outer surface  36  in positions corresponding to a plurality of diameters of said expandable support. The location of each mark  138  is easily determined empirically. In operation, the user will tighten or loosen the adjusting knob  132  until the end  140  of the adjusting knob  132  is aligned with a mark  138  corresponding to the desired diameter. However, it is understood that those of ordinary skill in the art would readily recognize other means for setting the diameter of the expandable support. Further, it is understood that the marks  138  may be disposed to set the angle of chamfer in relation to a side of a hole in substantially the same manner.  
     [0082] In addition to serving as part of the means for setting the diameter of the support, the sleeve  130  of FIG. 6 also serves as part of a quick disconnect system. Here, the sleeve  130  threads to the threaded rod  14  at one end and includes an bore  136  dimensioned to accept a drill driver  142  or other art recognized connector to allow the tool to be readily connected and disconnected from its source of rotation.  
     [0083] Although the present invention has been described in considerable detail with references to certain preferred versions thereof, other versions would be readily apparent those of ordinary skill in the art. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contains herein.