Abstract:
Coded keys are produced by reference to a set of matrix keys, each matrix key of a set has uniform notch spacing and a uniform but different depth compared to the others. A holder carries a complete matrix key set. The holder, in turn, is securable to a carriage having a key blank-retaining vise. By manipulating the holder, any selected one of the matrix keys may be brought into fixed coplanar and linear registration with the key blank. As the holder and carriage are moved synchronously, a first matrix key is urged toward a stylus at a given code location defined by a notch of specific depth and a cutter removes material from the key blank to form a corresponding notch. The process is repetitively performed until a notch of the prescribed code depth is defined at each location along the key blank needed to form a replacement key.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates generally to key origination and duplication and, more particularly, to the field of forming a key from a key blank even when the original or pattern key to be duplicated is lost or otherwise unavailable. 
         [0003]    2. Discussion of the Background Art 
         [0004]    The need to fabricate duplicate keys undoubtedly dates back to the earliest implementation of the lock, the earliest methods of making duplicate keys being the exclusive province of skilled artisans who used files and other hand tools to slowly shape a small section of metal into the desired key form. The electric motor, of course, made it possible to mechanize the process of forming and shaping duplicate keys, and a key of moderate complexity can typically be duplicated-by a relatively unskilled worker in a matter of minutes. Since its introduction and subsequent widespread commercial acceptance, however, the mechanized key duplication process has changed very little over the years. 
         [0005]    Conventional key duplication systems operate on one of three general principles. Systems of the first type utilize a tracing principle wherein a specimen key with the essential pattern profile (i.e., a “pattern” key) is placed into a first vise clamp. A key blank to be contoured with the essential pattern is placed into a juxtaposed second vise clamp. The pattern key is brought into contact with a guiding stylus, while the key blank is brought into contact with a cutting wheel. A carriage associated with the vise clamps is then shifted laterally and angularly reoriented inwardly and outwardly, such that the engagement of the pattern key with the stylus imparts a corresponding pivotal movement of the carriage and the cutting wheel removes material from the working edge surface of the key blank to form a contoured profile matching that of the pattern key. When this process has concluded, the key blank is removed from the vise clamps, and any burrs or other imperfections formed during the cutting operation are removed with a file or a buffing wheel. Early machine configurations of the pattern key tracing type are exemplified by U.S. Pat. No. 1,752,668 entitled “Key Duplicator” issued to Johnson on Apr. 1, 1930. More recently, the inventors herein disclosed, in U.S. Pat. No. 7,530,884 entitled “System and Method for Duplicating Keys”, an improved key duplicating machine which utilizes a profiled cutter having an abrasive surface. This abrasive cutter is driven at a much higher rate of speed (e.g., 30,000 rpm) than the slower turning, toothed cutting wheels that had previously characterized the prior art. This configuration resolved a number of deficiencies in the prior art, including the tendency of the key blank to shift or jump out of the clamping vice under the action of the slow rotating cutting teeth. 
         [0006]    In conventional key duplication systems of the second type, height wise adjustment and spacing of the cuts along the working edge of the key blank are effected by indexing means which position the cutter and key blank in accordance with a code, so that if the code of the specimen key to be duplicated is known, the key may be duplicated without the actual presence of the pattern key. Apparatus configurations of the code key cutting type are exemplified by U.S. Pat. No. 1,750,218 entitled “Key Cutting Machine” and issued to Falk on Mar. 11, 1930, U.S. Pat. No. 1,811,922 by the same title and issued to Falk (on Jun. 30, 1911), and U.S. Pat. No. 3,469,498 entitled “Code Key Cutter Device” issued to Adler et al on Sep. 30, 1969. The Falk machines used sets of detachable and removable discs to regulate the spacing and depth of the notches to be cut along the working edge of the key blank. Each disc had a series of holes that were numbered to match the lock manufacturer&#39;s specifications. Space and depth keys were provided to set the spacing and depth of cut prior to originating keys. Over the years, more than 150 sets of discs were made for a now-discontinued machine known as the Universal Code Machine. More recently, computer controlled cutting machines that use complex electronic control systems, an onboard database of codes specifying notch spacing and depth have been introduced. Examples of this more recent type include the one disclosed in U.S. Pat. No. 5,711,643 issued on Jan. 27, 1998 to Parr et al. 
         [0007]    A third type of key duplication system, a variation of the code key cutting type, utilizes a “key nipping tool” to remove material from along the working edge of the key blank. The user is guided by an index card that has predetermined code depth and spacing information. A system of this type is disclosed in U.S. Pat. No. 5,054,350 entitled “Key Punch Machine” and issued to Gartner et al. on Oct. 8, 1991. 
         [0008]    One of the benefits of the abrasive-cutter based system disclosed in U.S. Pat. No. 7,530,884 is that it is easy and economical to manufacture, maintain and operate. The &#39;884 system, sold by Roto-Smith Tools LLC of North Brunswick, N.J., is not limited to duplication of pattern keys. It has also been used for reproducing a key of which only the code number is known. In this case, individual depth-and-spacing or “matrix” keys have been used, one at a time, in place of the original key to be traced. Each matrix key comprises notches spaced apart from one another by a distance equal to the spacing between the notches of the key to be produced, all these notches having the same depth in a given matrix key and one matrix key existing for each figure of the code, i.e. for each possible depth for a notch. A first matrix key corresponding to the first figure of the code is fixed in front of the stylus and the stylus is engaged in the first notch of the matrix key so as to cut the first notch in the blank. The first matrix key is then replaced by a second matrix key corresponding to the second figure of the code and the stylus is engaged in the second notch of the second matrix key so as to cut a second notch in the blank. This operation is continued successively for all the figures of the code. 
         [0009]    The aforementioned process of using the &#39;884 system is far from optimal. After each notch has been cut, the next matrix key must be repositioned in the clamping vise to account for the next notch depth. This repositioning process is time consuming, complicated and a potential source of error. Furthermore, a determined notch of the matrix, and only this notch, must be scanned by the stylus. This operation is delicate; if the carriage slips relative to the stylus, the cutter forms a notch of incorrect shape and the blank being cut must be scrapped. This latter drawback may be overcome by providing one matrix per depth and per possible location of notch, but, in that case, the number of matrices is considerably increased. Great skill and precision on the part of the operator is demanded. 
         [0010]    A continuing need therefore exists for a code key machining system which is simple and economical to manufacture, easy to operate and maintain, and which does not introduce so much error into the process that the keys produced will not perform their intended function. 
         [0011]    A further need exists for a key machining system which can be optionally adapted to make use of an original key when the same is available. 
       SUMMARY OF THE INVENTION 
       [0012]    The aforementioned needs are addressed, and an advance is made in the art, by a system in which coded keys are produced by reference to a set of matrix keys. All of the matrix keys within a set have a uniform spacing between the notches formed thereon, in accordance with the pin and tumbler spacing specified by a lock manufacturer. However, each respective one of the matrix keys has notches of a uniform but different depth from all of the other matrix keys of that set. 
         [0013]    The system includes a base, a rotary cutter driven by the shaft of a high speed motor and supported by the base, and a stylus supported by the base in axial alignment with the cutter. The system further includes a carriage movable relative to the base and having a blank key retaining vise secured thereto, the carriage being manipulable so as to bring the key blank into engagement with the cutter. In one embodiment, the rotary cutter is a profiled abrasive cutter driven at a shaft rotation speed of 30,000. 
         [0014]    A first holder carries a complete set of matrix keys according to the notch spacing and depth specifications of a first lock manufacturer. The first holder, in turn, is secured to a carriage having a key blank-retaining vise. By appropriate manipulation of the first holder, any selected one of the matrix keys carried by it may be brought into fixed coplanar and linear registration with the key blank. The first holder and carriage are then moved synchronously, and as a first matrix key is urged toward the stylus within an indexing zone corresponding to a notch of a specific key code depth, a corresponding notch of that depth is formed by the cutter on the key blank. The process is repetitively performed until a notch of the prescribed code depth is defined at each indexing zone location along the key blank, thereby forming a replacement key conforming to the specified code. 
         [0015]    When it is desired to machine a code key conforming to the specifications of a second manufacturer whose notch spacing and depth convention does not match that of the first, the first holder is exchanged for a second holder carrying a second set of matrix keys. To this end, each holder has a modular design adapted for quick removal and re-attachment to the carriage. 
         [0016]    In one embodiment, each holder includes an annular turret defining peripheral slots for retaining the matrix keys in fixed relation relative to one another. Each groove is sufficiently deep and long as to receive and retain a corresponding matrix key, while exposing enough of the working edge as to allow the stylus to traverse the entire depth of a grove at each lock pin position. The manner in which each matrix key is retained in its respective groove is subject to variation. For example, an adhesive bond, mechanical friction-fit, weld, or any combination of these bonding techniques may be employed. As an alternative example, the matrix keys may be retained by a series of respective mechanical clamps disposed at equiangular locations along the periphery of the turret. It suffices to say that the matrix keys may be fixed to the holder, as exemplified by the aforementioned bonding techniques, or they may be removably mounted relative to the holder, as exemplified by the aforementioned mechanical clamping, A biasing spring and bolt arrangement urges the selected holder into registration with the carriage. To maintain a precise alignment between the selected matrix key and key blank, a detent mechanism comprising an axial projection on the carriage and a series of angularly spaced holes defined in the annular turret may be provided wherein alignment of the projection with each respective hole aligns precisely one of the matrix keys with a key blank held by the vise. Provisions can be made to incorporate a clamp along the periphery of the annular turret to accommodate an original key when one is available. Alternatively, the holder can be replaced with a detachable vise module dimensioned and arranged for registration with the above described detent mechanism and for holding an original key in the aforementioned coplanar and axial alignment relative to the key blank. 
         [0017]    Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The aspects of the present invention will become more apparent by describing in detail illustrative, non-limiting embodiments thereof with reference to the accompanying drawings, in which like reference numerals refer to like elements in the drawings. 
           [0019]      FIG. 1  is a front perspective view depicting a code key reproducing apparatus constructed in accordance with an illustrative embodiment of the present invention; 
           [0020]      FIG. 2  is perspective view of the illustrative apparatus of  FIG. 1 , broken apart to better illustrate the constituent components thereof and assist in understanding how the exemplary apparatus is assembled; 
           [0021]      FIG. 3A  is an elevation view of the carriage and holder assembly employed in the illustrative embodiment of  FIGS. 1 and 2 ; 
           [0022]      FIG. 3B  is a perspective view of the carriage and holder assembly of  FIG. 3A ; 
           [0023]      FIG. 3C  is a partial, lateral perspective view of the carriage and holder assembly of  FIG. 3B  depicting the manner in which the matrix keys are retained by the holder shown in  FIGS. 1-3B ; 
           [0024]      FIG. 3D  is a partial elevation view of the carriage and holder assembly shown in  FIGS. 1-3C , depicting an exemplary arrangement for retaining the holder and any selected matrix key in requisite alignment relative to a key blank clamped to the carriage; 
           [0025]      FIG. 3E  is a lateral elevation view of the carriage and holder assembly shown in  FIGS. 1-3D , depicting the angular movement of the holder assembly relative to the carriage and the peripheral arrangement of retained matrix keys thereon; 
           [0026]      FIG. 4A  is a partial perspective view of the blank key retaining portion of the carriage and holder assembly depicted in  FIGS. 1-3B ; 
           [0027]      FIG. 4B  is a partial perspective view of a specimen key retaining module for use with the blank key retaining module, which can be substituted for the holder structure shown in  FIGS. 3A-3E  when an original pattern key is available for duplication. 
           [0028]      FIG. 5  is a lateral elevation view of the exemplary carriage and holder assembly shown in  FIGS. 3A-3E ; and 
           [0029]      FIG. 6  is a front perspective view of a carriage assembly which may be substituted for the carriage and holder assembly shown in  FIGS. 1A-3E  when an original pattern key is available for duplication. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    With initial reference to  FIG. 1 , there is shown a code key reproducing system  10  constructed in accordance with an illustrative embodiment of the present invention. As seen in  FIG. 1 , system  10  includes a stationary base indicated generally at reference numeral  20 , a carriage assembly indicated generally at reference numeral  40 , and a matrix key holder indicated generally at reference numeral  60 . Together, base  20 , carriage assembly  40 , and holder  60  comprise a code key reproducing system attachment, as will be explained in greater detail shortly, for use in combination with an abrasive cutting element rotated at high speed. In exemplary embodiments of the invention, the cutting element is driven by a high speed motor of the type found in a conventional, high-speed rotary tool, the tool being attached in the same manner as that described in U.S. Pat. No. 7,530,844 which patent is expressly incorporated herein by reference in its entirety. It should, however, be emphasized that although a high speed abrasive cutting arrangement is preferred, a fixed mounted motor and cutter may also be utilized without departing from the spirit and scope of the present invention. The use of an abrasive cutter is preferred because only a small amount of material is removed with each rotation so that the jarring and vibrations associated with slower moving, “toothed” milling cutters is substantially avoided. Moreover, where the cutting teeth of the milling cutters would be quickly worn down by the harder alloys used in the manufacture of modern keys, an abrasive, profiled cutter is characterized by long hours of reliable and accurate operation. In any event, and with continued reference to  FIG. 1 , it will be appreciated and understood by those skilled in the art that commercially available rotary tools are generally equipped with both an on/off switch and a speed selector switch—the latter enabling the user to select a rotation speed of between, say, 8,000 and 36,000 rpm, and also a rotating, tool retaining chuck driven by the motor shaft. Insofar as the specific key cutting application contemplated herein does not require speed adjustment, substantial cost savings can be realized by foregoing the speed selector switch. In this regard, a fixed rotation speed of 30,000 rpm has been found to be more than adequate for the purposes of the various embodiments of the present invention. 
         [0031]    An illustrative rotary tool optimally adapted to use in accordance with the present invention is indicated generally at reference numeral  6  in  FIG. 1 , and includes an elongated dielectric housing  8  having a threaded tip  7  ( FIG. 2 ), an on/off switch  12  and, in place of a rotating chuck, an elongated central shaft  14 . In the embodiment depicted in  FIG. 1 , central shaft  14  is dimensioned and arranged so as to extend approximately 3 to 4 cm from tip  7 . To the distal end of central shaft  14 , a profiled, abrasive cutting element indicated generally at reference numeral  16  is affixed by a threaded fastener and washer indicated at reference numeral  17  and  19 , respectively. An annular collet  18 , having interior threads complementary to those of dielectric housing tip  7 , secures rotary tool  6  to base  20 . 
         [0032]    With reference now to both  FIGS. 1 and 2 , it will be seen that base  20  includes a transverse section  22  which extends between and interconnects a pair of aligned upright sections indicated generally at  24  and  26 . Each of sections  24  and  26  define an axial bore indicated at reference numerals  28  and  30 , respectively ( FIG. 2 ). Axial bores  28  and  30  are coaxial, with bore  28  being dimensioned and arranged to receive a region of dielectric housing  8  proximate threaded tip  7 . Upon insertion of the aforementioned portion of dielectric housing  8  into axial bore  26 , annular collet  18  is slid over shaft  12  and tightened onto the threads of tip  7  to thereby secure tool  6  to base  20  in the manner shown in  FIG. 1 . Thereafter, profiled cutting element  16  is mounted to the distal end of shaft  12  using screw  17  and washer  19 . 
         [0033]    A stylus assembly  32  includes an adjustment knob  33 , a profiled stylus element  34  defining a circumferential profile portion dimensioned and arranged to engaging the surface of a matrix key portion to be traced and to match a peripheral surface portion of cutting element  16 , a spacer  36 , a washer  37  and an axially adjustable hex nut indicated generally at  37 . The threaded distal portion of hex nut  37  is inserted through a correspondingly threaded aperture extending through the distal end of knob  33 . A desired axial spacing between cutting element  16  and stylus  34  is achieved by moving the axial hex head portion of hex nut  37  within aperture  30 . The stylus is then locked by tightening screw  88  within bore  31  ( FIG. 2 ) against hex nut  37 . 
         [0034]    The aforementioned axial adjustment of stylus  34 , relative to the abrasive cutting surface of cutting element  16 , achieves a precise spacing between target surfaces of a key blank  42  and a selected matrix key retained by holder  60 , as matrix key  62   a . In the latter regard, it will be seen in  FIG. 1  that matrix key  62   a  is shown in a position of axial and coplanar alignment with key blank  42 . In the illustrative examples of  FIGS. 1-2  and  3 A- 3 E, each matrix key is part of a set of matrix keys (of which only six—indicated generally at  62   a - 62   f —are shown carried by holder  60  in  FIG. 1 ). Throughout the various embodiments, each respective matrix key as matrix key  62   a  is adhesively bonded or otherwise affixed within a corresponding slot  63  defined in the peripheral surface of a cylindrical holder member  68 . 
         [0035]    Base  20  further includes a pair of mounting holes indicated generally at  38   a  and  38   b  for securing base  20  to a fixed support surface. Finally, a pair of coaxial bearing supports indicated generally at  39   a  and  39   b  ( FIG. 2 ) are defined in base  20 , the purpose of these being to support the indexing (axial and angular) shaft  44  to which carriage  40  is mounted. 
         [0036]    Matrix keys, also known as space-and-depth keys in the locksmithing trade, have heretofore been used mainly to cut keys for home and car entry locks using the bitting number without the use of a code machine. Even where the code is not known, a skilled locksmith can take a lock apart, so that just the plug with pins in it can be further examined. In many cases, the locksmith will remove and measure each pin separately to derive the code of the lock. In a basic six-pin lock set, the locksmith opens up the shafts in the cylinder and empties them out, obtaining six springs and 12 tiny pins. All of the upper pins are exactly the same size. The remaining six pins (the lower pins) will be of various lengths to match up with the notches on the key. The dimensions of the lower pins are such that when the properly coded key is inserted, the lower pins will push all the upper pins just above the shear line, allowing the cylinder to turn freely. (This process may vary depending on the particular design of the lock.) If a set of space and depth keys applicable to the make and model of a lock is available, however, the locksmith may employ a different approach. Here, the depth keys are inserted one at a time until the locksmith identifies which one renders the pin corresponding to the first notch position causes the upper pin to be flush with the shear line. The depth key which produces this alignment is recorded, and the process is repeated in order for the remaining pin positions. Many locks made by Schlage Lock Company of Colorado Springs, Colo., for example, have six tumbler pins. The number and spacing of notches on a key made to fit such a lock must match the number and location of the tumbler pins. In this example, there are ten possible depths at each of six discrete locations, and these are identified by corresponding code digits 0-9. 
         [0037]    A matrix key for depth 0 would thus have the code 000000, the matrix key for depth 1 would have the code 111111 and so on up to matrix key 999999. If one were to use the system disclosed by the inventors herein in U.S. Pat. No. 7,530,884, the disclosure of which is expressly incorporated herein in its entirety, a key having the code 103396 would be cut by first inserting matrix key 111111 into the specimen retaining vise, and the carriage assembly would indexed axially and angularly toward the key blank within a zone confined to the first notch location. After cutting this first notch, matrix key 111111 would be removed and matrix key 000000 would be inserted in its place and the next notch would be cut. The process would be repeated until all six (in this example) positions were cut at the proper depth. 
         [0038]    In the present invention, the tedious steps of removing and replacing matrix keys during a key reproducing process, is avoided. Specifically, and with continuing reference to  FIG. 1  and  FIGS. 3A-3E , it will be seen that holder  60  is coupled to carriage  40  and that both are moveable as a unitary assembly relative to base  20 . To this end, carriage  40  includes a carriage block indicated generally at reference numeral  45 , a stand  46  for supporting the carriage at fixed orientation while at rest, and a vise  48  for retaining key blank  42 . In the illustrative embodiment of  FIGS. 1 and 2 , vise  48  includes a clamping block  49 , a washer  50 , a threaded bolt  52  and a wing nut  51 . With particular reference to  FIG. 2-3B , it will be seen that carriage block  45  defines an axial bore  54  dimensioned and arranged to receive journal shaft  44 . A set screw  55  ( FIG. 5 ) fixes the location of carriage block  45  along journal shaft  44 , and also enables the separation of the latter (to accommodate, for example, the replacement of carriage  40  and holder  60 , with a two clamp vise exemplified by  FIG. 6 .  FIG. 3A  is a front elevation view depicting the position of carriage block  45  along shaft  44 , while  FIG. 3B  exemplifies the coplanar juxtaposition of a key blank held between carriage block  45  and clamping block  49  and a matrix key held by holder  60 .  FIG. 3B  also depicts a support element, indicated generally at reference numeral  46 . Support element keeps carriage block  35  at an elevated location relative to an underlying mounting surface (not shown) during, for example, those periods when the system  10  is not in use. 
         [0039]    As will be readily apparent to those skilled in the art, the arrangement of  FIGS. 1 and 2  accommodates both linear and angular translation of carriage  40  relative to stationary base  20 . This indexing translation of carriage  40  brings key blank  42  into engagement with the profiled abrasive surface of rotary cutter  16 . By reference to  FIG. 3C , it will be seen that that holder  60  is removably secured to carriage block  45  of carriage  40 . Specifically, thumbscrew  66  is dimensioned and arranged for threaded engagement with a threaded bore  43  defined in carriage block  45 . A biasing spring indicated generally at reference numeral  64  is positioned within between cylindrical holder member  68  of holder  60  and thumbscrew  6 . Spring  64  serves to urge cylindrical holder member  68  against carriage block  45  in the manner shown in  FIGS. 1-3B , to thereby enable to aforementioned movement as a unitary assembly. 
         [0040]    After a first notch has been cut in a key blank as key blank  42  in  FIG. 1  by reference to a first matrix key as matrix key  62   a , a second notch having a different depth can be cut by reference to a different matrix key retained by holder  60 . By reference to  FIG. 3D , it will be seen that a proximal flat surface of cylindrical holder member  68  has defined therein a pattern of holes indicated generally at reference numeral  72  and radially arranged at equidistant locations from the axial bore through which bolt  66  extends. Each respective one of holes  72  is aligned with a corresponding one of the matrix key receiving slots. As such, when holder member  68  is pulled with sufficient force to overcome the urging of biasing spring  64 , the pin  74  which extends axially from the opposing surface of carriage block  45  is removed from within the hole corresponding to the matrix key previously in registration with key blank  42 . Holder member  68  can now be rotated in the direction of the arrows shown in  FIG. 3D  so as to bring a different hole  72  into registration with pin  74 . With reference to  FIGS. 1 and 3E , for example, rotation of cylindrical member  68  in a clockwise direction will bring the immediately adjacent hole  72  into alignment with pin  74 . This new alignment, in turn, will align matrix key  62   b  with matrix key  42 . Energization of the motor, rotation of the cutting element  16 , and movement of the matrix key against the stylus in the region of the next notch to be cut will produce of a notch of the correct depth. By appropriate manipulation of cylindrical holder member  68 , a series of notches can be cut by reference to those matrix keys needed to obtain the desired code.  FIG. 5  depicts the various components of the assembled carriage  40  and holder  60 , with the matrix keys omitted from cylindrical holder member  68  for clarity. 
         [0041]      FIG. 4A  is a perspective view of carriage block  45 , including the threaded bore  43  and pin  74 , but with the cylindrical member  68 , bolt  66 , and spring  64  removed. When an original key is available to be copied and resort to the use of matrix keys is not necessary, several options are available to the operator of system  10  in accordance with the teachings of the present invention. With reference to  FIG. 4B , for example, it will be appreciated by those skilled in the art that a specimen key retaining module  68 ′—comprising a clamping block (not shown), washer  50 ′, retaining nut  51 ′ and bolt  52 ′—can be used in place of cylindrical holder  68  of  FIG. 4A . By incorporating an alignment hole 72 dimensioned and arranged to register with projection  74  when a specimen key is retained by the clamping block of module  68 ′ (in the same manner as key blank  42  is retained by clamp block  49  of carriage  45 ), the specimen key and key blank can be held in the desired relationship. 
         [0042]    An alternate configuration for aligning a specimen key with a key blank utilizes the carriage assembly described in U.S. Pat. No. 7,530,844 and is shown in  FIG. 6 . Specifically, the carriage and holder assembly shown in  FIGS. 1-3E  and  5  can be removed in its entirety by loosening set screw  55  and sliding shaft  44  from within the bore defined within carriage block  45 . Once removal of carriage block  45  has been achieved, carriage assembly  45 ″ of  FIG. 6  is lined up with bores  39   a  and  39   b  ( FIG. 2 ), shaft  44  is reinserted, and operation proceeds as described in the aforementioned patent. 
         [0043]    Although not shown, yet another configuration for accommodating the duplication of original specimen keys when available would be to modify cylindrical holder member  68  so as to define an integral clamp configured to retain a specimen key in place of one of the matrix key slots depicted in the various views. Such a design could easily be achieved, for example, by defining a channel with a central bore, and a removable element affixed by a bolt and nut to hold a specimen key when required. 
         [0044]    Returning now to  FIG. 2 , it will be appreciated that the journals  39   a  and  39   b  within guide bearing supports  24  and  26  of housing  20  allow for the swinging upwardly and downwardly of carriage  40  and holder  60  relative to base assembly  20 . As such, profiled abrasive grinding element  16  and profiled stylus  34  may be brought into and out of engagement with corresponding surfaces of key blank  42  and any selected matrix key. Operation of the system  10  proceeds after the appropriate power rotary tool as tool  6  is attached to retaining arm  24 . In that regard, the rotary tool may be powered by 120 or 220 V A/C single phase household line current, by a battery source, or even by pneumatic means (e.g., compressed air). Securing nut  18  is turned clockwise to secure rotary tool  6  to carriage assembly  20 . Shaft  14  preferably extends at least 4 cm outside the exterior of dielectric housing  8 . Screw  17  maintains the cutter in fixed registration with shaft  14 . 
         [0045]    In a first mode of operation, an original or specimen key is positioned within a vise clamp  49   b  of clamp assembly  40 ″ ( FIG. 6 ) and key blank  42  is positioned within vise clamp  49   a  of clamp assembly  40 ″. The vise clamps are tightened by rotating respective wing nuts  51   a  and  451   b . To align a specimen key and key blank, stylus assembly  32  is moved so that the stylus  34  engages an extension on the key called the key shoulder and/or the tip end of the key—at the same location as where the cutting element touches the key blank. Set screw  88  is tightened to lock the stylus assembly  32  into position. 
         [0046]    In a second mode of operation, clamp assembly  40 ″ is removed and replaced with the clamp and holder assembly depicted in  FIGS. 1-3E  and  5 . A key blank  42  is positioned below clamp block  49  and nut  51  is tightened to hold key blank  42  in place. A first matrix key associated with the first notch of a first key to be duplicated is identified and cylindrical holder member  68  is pulled against the urging of spring  64  and rotated as necessary to establish coplanar and alignment of a first matrix key with the key blank. A first notch is cut in the key blank by operation of tool  6 , rotation of cutting element  16 , and urging a region of the first matrix key corresponding to the first code position against stylus  32 . Once the first code position is cut on key blank  42 , the holder element  68  is repositioned to align a second matrix key associated with a second notch of the first key to be duplicated, the second notch being in the second key code position along the working edge of the key blank. The tool  6  is again operated to cut this second notch in the key blank. This process is repeated until all key code positions have been cut. 
         [0047]    Since the spacing and depth of matrix key notches differ from one lock manufacturer to another, the present invention contemplates the replacement of one cylindrical holder for another to accommodate these differences. With particular reference to  FIGS. 2 and 4A , it will be appreciated that this can be easily achieved by removing thumbscrew  66  from threaded engagement with bore  43 . This results in spring  64  and cylindrical holder  68  being removed at the same time. A separate cylindrical holder  68  containing the matrix keys for the next lock configuration is then aligned with carriage  40  so that spring  64  and bolt  66  can be reinstalled, setting up system  10  for the next operation. 
         [0048]    With final reference to  FIG. 2  it will be seen that a transparent shield indicated generally at  80  may be optionally secured to base  20  in order to deflect any material removed from key blank  42  by rotary cutter  16 . To this end, holes  82  and  84  defined in shield  80  are dimensioned and arranged for alignment with corresponding holes  90  and  31  defined in base  20 . Thumbscrews  86  and  88  permit rapid installation and/or removal of shield  80 . Of course, it is expected that safety goggles or comparable eye protection will additionally be worn during operation of system  10 . 
         [0049]    It is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is therefore to be understood that all such variations, modifications and changes are believed to fall within the scope of the present invention. Although specific terms are employed herein, they are used in their ordinary and accustomed manner only, unless expressly defined differently herein, and not for purposes of limitation.