Patent Publication Number: US-RE46103-E

Title: Quick change arbor, hole cutter, and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a reissue of U.S. Pat. No. 8,366,356, which is a continuation-in-part of U.S. patent application Ser. No. 12/043,740, filed Mar. 6, 2008, now U.S. Pat. No. 8,328,474, the contents of which are hereby incorporated by reference in their entirety as part of the present disclosure. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates arbors for hole cutters, hole cutters, and related methods, and more particularly, to arbors, hole cutters and related methods facilitating relatively quick attachment and release of a hole cutter and/or pilot bit to and from the arbor. 
     BACKGROUND 
     A typical arbor for a hole saw includes an arbor body with a threaded end portion that engages a corresponding threaded aperture in the end plate of the hole saw to secure the hole saw to the arbor. A pilot drill bit is receivable within the threaded end portion of the arbor body and extends through the center of the hole saw. The arbor further includes a drive pin plate that slidably mounts to the arbor body and has a pair of diametrically opposed drive pins that extend into corresponding drive pin holes formed in the end plate of the hole saw to rotatably drive the hole saw. A lock nut is threadedly mounted on the arbor body to prevent disengagement of the drive pins from the hole saw during use. 
     To mount the hole saw to the arbor, the end plate of the hole saw is threaded onto the threaded end portion such that the hole saw is secured to the arbor body and the drive pin holes are in alignment with the corresponding drive pins of the drive pin plate. Then the lock nut is tightened until the drive pins are fully received by the drive pin holes to secure the arbor to the hole saw. To mount the pilot bit, the bit is inserted into the center hole and secured by tightening a fastener. 
     One of the drawbacks associated with this type of arbor is that hole saws will lock up on the threads if the drive pin plate disengages from the hole saw during operation, presenting the end user with a difficult and time consuming task of removing the hole saw from the arbor. In many circumstances, the process of removing a locked up hole saw from the arbor permanently damages the arbor, the hole saw or both, necessitating the unwanted expense associated with replacing equipment prematurely. 
     Another drawback of this type of arbor is that it can be necessary to hold the hole saw in place to maintain alignment of the drive pin holes with the corresponding drive pins while simultaneously tightening the lock nut to avoid rotation of the hole saw that otherwise would prevent the drive pins from entering the drive pin holes. To address this problem, proprietary arbors have been devised that accept corresponding proprietary hole saws specifically designed to make hole saw mounting an easier task. However, the versatility of these arbors is greatly limited because they can only mount the particular manufacturer&#39;s proprietary hole saws and are not able to mount standard hole saws. Accordingly, it would be advantageous for such proprietary arbors to accept standard hole saws because they tend to be readily available in the event a proprietary hole saw needs replacing and is not available, or in the event a proprietary hole saw is not available in a desired size and/or cutting configuration. 
     Still another drawback of this type of arbor is that the process of inserting and removing pilot drill bits frequently requires the end user to manually engage a set screw. To address this issue, proprietary arbors have been devised that secure corresponding proprietary pilot drill bits having shanks configured for securement without the necessity of tools. However, the versatility of these arbors is greatly limited because they can only secure the particular manufacturer&#39;s proprietary pilot drill bits, and are not able to secure standard pilot drill bits which are readily available and easily obtainable in the event a proprietary pilot drill bit needs replacing and is not available, or in the event a proprietary pilot drill bit is not available in a desired size and/or drilling configuration. Further, such proprietary arbor and pilot drill bit systems can fail at fully securing the bits inside the arbor and/or can allow the bits to loosen during use causing off-axis wobble, especially at high rotational speeds. Off-axis wobble can cause undesirable vibration of the pilot drill bit that can reduce the drilling life of the bit and/or create an unacceptable degree of inaccuracy during use. 
     Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect, the present invention is directed to an arbor that is connectable to a quick change hole cutter, and in some embodiments of the present invention, also is connectable to a standard hole cutter. The hole cutter includes an end portion defining a first aperture, and at least one drive pin recess radially spaced relative to the first aperture. The arbor comprises an arbor body including a stop surface, and a hole cutter connecting portion extending axially from the stop surface and engageable within the first aperture of the hole cutter. A drive pin member defines a second aperture that receives therethrough the arbor body, and is configured to allow relative axial movement, but to prevent relative rotational movement, of the arbor body and drive pin member. The drive pin member further includes a first surface, and at least one drive pin radially spaced relative to the second aperture and extending axially from the first surface. The connecting portion is receivable within the first aperture of the hole cutter to define a first engagement position. The arbor body and/or the hole cutter is movable relative to the other between the first engagement position and a second engagement position to secure the hole cutter to the arbor body. In the second engagement position: (i) the at least one drive pin is substantially aligned with the at least one corresponding drive pin recess of the hole cutter; and (ii) the drive pin member is movable axially relative to the arbor body between a disengaged position axially spaced relative to the hole cutter, and an engaged position wherein the at least one drive pin is received within the corresponding drive pin recess of the hole cutter, and the first surface of the drive pin member contacts the end portion of the hole cutter. 
     Preferably, in the second engagement position, the end portion of the hole cutter is in contact with the stop surface of the arbor body. In some embodiments of the present invention, the arbor body and/or hole cutter is rotatable relative to the other between the first and second engagement positions. In some such embodiments, the connecting portion of the arbor body defines a first thread, and the first aperture of the hole cutter defines a second thread that is threadedly engageable with the first thread, to fixedly secure the hole cutter to the arbor body in the second engagement position. In some such embodiments, the threads on the connecting portion of the arbor body are configured to both (i) substantially align the at least one drive pin with the corresponding drive pin recess of the hole cutter in the second engagement position, and (ii) place the end portion of the hole cutter in contact with the stop surface of the arbor body in the second engagement position. In some such embodiments, the first and second threads define an axial clearance therebetween allowing the end portion of the hole cutter to substantially contact the stop surface of the arbor body in the both the first engagement position and the second engagement position. In some such embodiments, the arbor body and/or hole cutter is rotatable relative to the other between the first and second engagement positions, and the angular extent between the first and second engagement positions is within the range of about 10° and about 180°. 
     In some embodiments of the present invention, the first aperture of the quick change hole cutter defines a plurality of angularly extending protrusions, and a plurality of relatively recessed portions formed therebetween; and the connecting portion of the arbor body defines a plurality of angularly extending protrusions, and a plurality of relatively recessed portions formed therebetween. In the first engagement position, the protrusions of the connecting portion are received within the recesses of the first aperture, and the protrusions of the first aperture are received within the recessed portions of the connecting portion. In the second engagement position, the protrusions of the connecting portion are engaged with the protrusions of the first aperture. In some such embodiments, the protrusions of the connecting portion define a first thread, the protrusions of the first aperture define a second thread, and the first and second threads are threadedly engaged with each other in the second engagement position. In some embodiments, at least one of the angularly extending protrusions defines a greater or lesser angular extent than at least one other angular extending protrusion of the respective first aperture and connecting portion, to thereby permit receipt of the connecting portion within the first aperture in only the first engagement position. 
     Some embodiments of the present invention further comprise a collar coupled to the drive pin member, wherein movement of the collar between a first position and second position substantially simultaneously moves the drive pin member from the engaged to the disengaged position. Preferably, the collar defines an approximate diabolo shape. One advantage of this feature is that it facilitates handling during use by permitting the user to grasp the middle portion of the collar with, for example, an index finger and thumb of one hand, when moving the collar to attach or remove a hole cutter. 
     In some embodiments of the present invention, an axially elongated bearing surface is defined by the interface between the collar and the arbor body. One advantage if this feature is that it reduces or prevents unwanted play or movement between the collar and drive pin member, and the arbor body. 
     Some embodiments of the present invention further comprise a biasing member, such as a coil spring, that normally biases the drive pin member in the direction from the disengaged into the engaged position. Preferably, the biasing member automatically drives the drive pin member into the engaged position upon moving the hole cutter into the second engagement position. One advantage of this feature is that it facilitates one-handed attachment of the hole cutter to the arbor, or otherwise facilitates rapid attachment and detachment of the hole cutter to and from the arbor. 
     In accordance with another aspect of the present invention, the arbor body further defines a pilot bit aperture that is configured to alternatively receive both a quick change pilot bit and a standard pilot bit. In some such embodiments, the arbor further comprises (i) a pilot pin biased radially inwardly toward the pilot bit aperture and engageable with a quick change pilot bit received within the pilot bit aperture, and (ii) a fastener movable into the pilot bit aperture and engageable with a standard pilot bit received within the pilot bit aperture. 
     In some such embodiments, the arbor body further defines a pilot bit aperture for alternatively receiving both a quick change pilot bit and a standard pilot bit, and the arbor further comprises a pilot bit mechanism defining (i) a first state wherein the pilot bit mechanism engages the quick change pilot bit to prevent movement of the bit relative to the arbor body; (ii) a second state wherein the pilot bit mechanism engages the standard pilot bit to prevent movement of the bit relative to the arbor body; and (iii) a third state wherein the pilot bit mechanism disengages from the respective quick change pilot bit or standard pilot bit and allows movement of the respective bit relative to the arbor body. 
     In accordance with another aspect, the present invention is directed to an arbor that is connectable to a quick change hole cutter including an end portion defining a first aperture and at least one recess radially spaced relative to the first aperture. The arbor comprises first means for drivingly connecting a power tool to the hole cutter. The first means includes a stop surface, and second means of the arbor extends axially relative to the stop surface for releasably engaging the first aperture of the hole cutter and defining a first engagement position. Third means are provided for receiving therethrough the first means, and for allowing relative axial movement, but preventing relative rotational movement, of the first means and the third means. The third means includes a first surface, and at least one fourth means extending axially from the first surface for receipt within the at least one recess of the hole cutter for rotatably driving the hole cutter. Fifth means are provided for allowing rotational movement of at least one of the first means and the hole cutter relative to the other between the first engagement position and a second engagement position for securing the hole cutter to the first means, and for (i) substantially aligning the at least one fourth means with the at least one corresponding recess of the hole cutter in the second engagement position to, in turn, allow axial movement of the third means relative to the first means in the second engagement position between a disengaged position axially spaced relative to the hole cutter, and an engaged position with the at least one fourth means received within the corresponding recess of the hole cutter, and (ii) placing the first surface of the third means in substantial contact with the stop surface of the hole cutter in the second engagement position. 
     In accordance with another aspect, the present invention is directed to a quick change hole cutter that is attachable to an arbor. The arbor includes a threaded end portion defining at least one male threaded portion, a stop surface located adjacent to the threaded end portion, and a drive pin member including at least one drive pin thereon and movable axially relative to the arbor between an engaged position with the drive pin engaging the hole cutter, and a disengaged position with the drive pin disengaged from the hole cutter. The quick change hole cutter comprises a blade including a blade body and a cutting edge defined by a plurality of cutting teeth. An end portion of the hole cutter is fixedly secured to the blade body, and defines an approximately central aperture including on a peripheral portion thereof at least one female threaded portion, and at least one drive pin recess radially spaced relative to the central aperture. The female threaded portion cooperates with the male threaded portion of the arbor to define (i) a first engagement position wherein the lead male and female threads engage or substantially engage one another and define a first axial clearance relative to each other, and (ii) a second engagement position angularly spaced relative to the first engagement position. In the second engagement position, the male and female threads engage one another and define a second axial clearance less than the first axial clearance, the end portion is in engagement or substantial engagement with the stop surface of the arbor, and the drive pin recess is aligned with a respective drive pin of the arbor for receiving the drive pin with the drive pin member located in the engaged position. 
     Preferably, in the second engagement position, the end portion of the hole cutter is in contact with the stop surface of the arbor body. In some embodiments of the present invention, the female threaded portion defines an axial clearance relative to the male threaded portion allowing the end portion of the hole cutter to substantially contact the stop surface of the arbor body in the both the first engagement position and the second engagement position. In some embodiments, the connecting portion of the arbor body defines a plurality of angularly extending protrusions and a plurality of relatively recessed portions formed therebetween; and the central aperture of the quick change hole cutter defines a plurality of angularly extending protrusions, and a plurality of relatively recessed portions formed therebetween. In the first engagement position, the protrusions of the arbor connecting portion are received within the recesses of the central aperture, and the protrusions of the central aperture are received within the recessed portions of the arbor connecting portion. In the second engagement position, the protrusions of the arbor connecting portion are engaged with the protrusions of the central aperture. 
     In accordance with another aspect, the present invention is directed to a quick change hole cutter that is attachable to an arbor. The arbor includes a threaded end portion defining at least one male threaded portion, a stop surface located adjacent to the threaded end portion, and a drive pin member including at least one drive pin thereon and movable axially relative to the arbor between an engaged position with the drive pin engaging the hole cutter, and a disengaged position with the drive pin disengaged from the hole cutter. The quick change hole cutter comprises first means for cutting a hole, and second means for releasably connecting the first means to the arbor. The second means includes third means for engaging the end portion of the arbor in a first engagement position defining a first axial clearance therebetween, allowing relative rotational movement of the hole cutter and/or arbor relative to the other between the first engagement position and a second engagement position angularly spaced relative to the first engagement position, and defining a second axial clearance therebetween less than the first axial clearance, and for placing the second means in engagement or substantial engagement with the stop surface of the arbor. Fourth means of the hole cutter are aligned with the drive pin of the arbor in the second engagement position for receiving the drive pin with the drive pin member located in the second engaged position. 
     In accordance with another aspect, the present invention is directed to a method comprising the following steps: 
     (i) providing an arbor including a connecting portion that is connectable to a quick change hole cutter, wherein the hole cutter includes an end portion defining a first aperture and at least one drive pin recess radially spaced relative to the first aperture, and the arbor includes an axially-elongated arbor body and a drive pin member movable axially, but not rotationally, relative to the arbor body, and including at least one drive pin extending therefrom; 
     (ii) inserting the connecting portion of the arbor body into the first aperture of the hole cutter to define a first engagement position; 
     (iii) moving the arbor body and/or hole cutter relative to the other between the first engagement position and a second engagement position and, in turn, securing the hole cutter to the arbor body; and 
     (iv) upon moving the arbor body and/or hole cutter relative to the other into the second engagement position, (i) substantially aligning the at least one drive pin with the at least one corresponding drive pin recess of the hole cutter in the second engagement position, and then either moving or allowing axial movement of the drive pin member relative to the arbor body between a disengaged position axially spaced relative to the hole cutter, and an engaged position with the at least one drive pin axially received within the corresponding drive pin recess of the hole cutter and, in turn, placing the drive pin member in substantial contact with the end portion of the hole cutter. 
     In some embodiments of the present invention, the method further comprises the steps of: 
     (i) providing a quick change hole cutter including a first aperture defining along a periphery thereof a plurality of angularly extending protrusions and a plurality of recesses formed therebetween; 
     (ii) providing an arbor having a connecting portion defining a plurality of angularly extending protrusions and a plurality of recesses formed therebetween; 
     (iii) inserting at least one of the protrusions of the connecting portion and the protrusions of the first aperture into the recesses of the other in the first engagement position; and 
     (iv) rotating at least one of the hole cutter and arbor body relative to the other from the first engagement position to the second engagement position and, in turn, engaging at least one of the protrusions of the connecting portion and of the first aperture with the other. 
     Some embodiments of the present invention further comprise the steps of normally biasing the drive pin member in the direction from the disengaged position toward the engaged position, and upon moving the hole cutter from the first engagement position into the second engagement position, automatically biasing the drive pin member into the engaged position to, in turn, drive the drive pin(s) into the corresponding drive pin recess(es) and attach the hole cutter to the arbor. 
     In accordance with another aspect, the present invention is direct to an arbor for a hole cutter including an outer surface defining a threaded aperture, and a drive member aperture spaced radially relative to the threaded aperture. The arbor comprises an axially-elongated arbor body including a drive shank on one end thereof, a threaded portion on an opposite end thereof relative to the drive shank that is engageable with the threaded aperture on the hole cutter, and an inner axially-extending bearing surface located between the drive shank and the threaded portion. The arbor body defines a first width, such as a diameter, along the inner axially-extending bearing surface. The arbor further comprises an axially-elongated collar including a proximal end and a distal end, a manually engageable surface extending axially between the proximal and distal ends and defining a reduced width in comparison to the proximal and distal ends, and a drive member, such as a plurality of angularly spaced drive pins, extending axially from the distal end of the collar. The collar is slidably mounted on the arbor body and movable between (i) an engaged position with the distal end of the collar adjacent to the threaded portion for engaging the drive member with the drive member aperture of a hole cutter threadedly attached to the threaded portion of the arbor body, and (ii) a disengaged position with the distal end of the collar axially spaced relative to the threaded portion of the arbor body. The collar includes an outer axially-extending bearing surface that slidably contacts the inner axially-extending bearing surface of the arbor when moving the collar between the engaged and disengaged positions, and the inner axially-extending bearing surface defines a length that is at least about 1¼ times the first width, such as the diameter, of the arbor body. The arbor further comprises a retaining member mounted on the collar and movable between (i) a first position holding the collar in the engaged position, and (ii) a second position allowing axial movement of the collar from the engaged position to the disengaged position. 
     In some embodiments of the present invention, the axially-extending bearing surface defines a length that is at least about 1½ times the first width, such as the diameter, of the arbor body. 
     In some embodiments of the present invention, the arbor body defines a pair of inner axially-extending bearing surfaces angularly spaced relative to each, and a pair of inner curvilinear axially-extending bearing surfaces angularly spaced relative to each other between inner axially-extending bearing surfaces. The collar defines a pair of outer axially-extending bearing surfaces angularly spaced relative to each other, and a pair of outer curvilinear axially-extending bearing surfaces angularly spaced relative to each other between outer axially-extending bearing surfaces. The pair of inner axially-extending bearing surfaces slidably engage the pair of outer axially-extending bearing surfaces, and the pair of inner curvilinear axially-extending bearing surfaces slidably engage the pair of outer curvilinear axially-extending bearing surfaces, when moving the collar between the engaged and disengaged positions. Preferably, the pair of inner axially-extending bearing surfaces are substantially flat, and the pair of outer axially-extending bearing surfaces are substantially flat. 
     In some such embodiments, each curvilinear axially-ex- tending bearing surface is defined by a diameter of the collar or arbor body, respectively. In some embodiments of the present invention, the outer axially-extending bearing surfaces are shorter than the inner axially-extending bearing surfaces. In some such embodiments, the collar defines a pair of axially-extending recessed surfaces located on substantially opposite sides of the collar relative to each other, and each recessed surface extends between a respective inner axially-extending bearing surface and the proximal end of the collar. In some such embodiments, the collar further defines a pair of first stop surfaces. Each first stop surface is formed between an axially-extending recessed surface and respective inner axially-extending bearing surface. The arbor body defines a pair of second stop surfaces, each second stop surface is formed at a proximal end of a respective inner axially-extending bearing surface, and first and second stop surfaces engage each other in the disengaged position to prevent further proximal axial movement of the collar. In some such embodiments, the second stop surfaces are defined by respective lips formed on the arbor body, and the lips and recessed surfaces form bearing surfaces that slidably contact each other when moving the collar between the engaged and disengaged positions. 
     One advantage of some currently preferred embodiments of the present invention is that the collar defines axially-elongated bearing surfaces that are at least about 1¼ times as long as the diameter of the arbor body to thereby provide extensive bearing surfaces and, in turn, substantially prevent any rocking or wobble of the hole cutter on the arbor body. Yet another advantage is that the collar defines an axially-extending manually engageable surface to facilitate manually engagement and movement of the collar between the disengaged and engaged positions in a single, one-handed motion. 
     Another advantage of some currently preferred embodiments of the present invention is that they enable a hole cutter to be relatively quickly engaged with, and disengaged from, the arbor. Yet another advantage of some currently preferred embodiments of the present invention is that they enable one arbor to accept both quick change and standard hole cutters. 
     Other objects, advantages and features of the present invention and/or of the currently preferred embodiments thereof will become more readily apparent in view of the following detailed description of the currently preferred embodiments and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an arbor for a hole saw according to an embodiment of the invention. 
         FIG. 2  is a top plan view of the arbor of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the arbor of  FIG. 1 . 
         FIG. 4  is a cross-sectional view of the arbor of  FIG. 1  further showing the pilot bit mechanism of the arbor in a first or quick change pilot bit state. 
         FIG. 5  is a perspective view of the arbor body of the arbor of  FIG. 1 . 
         FIG. 6  is a cross-sectional view of the arbor body of  FIG. 5 . 
         FIG. 7  is a front end view of the arbor body of  FIG. 5 . 
         FIG. 8  is a perspective view of the pilot pin of the arbor of  FIG. 1 . 
         FIG. 9  is a top plan view of the pilot pin of  FIG. 8 . 
         FIG. 10  is a perspective view of the end plate of a quick change hole saw of the present invention. 
         FIG. 11  is a perspective view of the arbor of  FIG. 1  showing the step of aligning the hole saw aperture with the end portion of the arbor body and with parts of the hole saw removed for clarity. 
         FIG. 12  is a perspective view of the arbor of  FIG. 11  showing the step of moving the aligned hole saw aperture into engagement with the end portion of the arbor body. 
         FIG. 13  is a perspective view of the arbor of  FIG. 12  showing the step of rotating the hole saw to fully engage the end portion of the arbor. 
         FIGS. 14A  and B are cross-sectional views of the arbor of  FIG. 13  showing movement of the drive pin plate between the first position ( FIG. 14A ) and the second position ( FIG. 14B ) so that the drive pins engage/disengage the corresponding drive pin apertures of the hole saw. 
         FIG. 15  is a perspective view of the arbor of  FIG. 13  showing the drive pin plate engaged with the hole saw cap. 
         FIG. 16  is a cross-sectional view of the arbor of  FIG. 1  showing the pilot bit mechanism in a second or standard pilot bit state. 
         FIG. 17  is a cross-sectional view of the arbor of  FIG. 1  showing the pilot bit mechanism in a third or neutral state disengaged from the pilot bit inserted therein. 
         FIG. 18  is a perspective view of a quick change pilot bit. 
         FIG. 19  is a perspective view of a standard pilot bit. 
         FIG. 20  is another embodiment of an arbor of the invention including a nut rotatably mounted on the arbor body for securing the axial position of the drive pin plate during use. 
         FIG. 21  is a perspective view of the arbor of  FIG. 20 . 
         FIG. 22  is a perspective view of an adapter for connecting relatively small hole cutters to the arbors of the invention 
         FIG. 23  is a cross-sectional view of the adapter of  FIG. 22 . 
         FIG. 24  is a side elevational view of another embodiment of an arbor of the invention wherein the drive pin plate is manually moved (rather than spring biased) between the engaged and disengaged positions, and including a ball detent mechanism for releasably securing the drive plate in the engaged position. 
         FIG. 25  is an exploded perspective view of the arbor of  FIG. 24 . 
         FIG. 26  is top plan view of the arbor of  FIG. 24 . 
         FIG. 27  is a cross-sectional view taken along line A-A of  FIG. 26 . 
         FIG. 28  is a somewhat schematic illustration of standard hole cutter thread form shown in solid lines, and a custom hole cutter thread form in accordance with the currently preferred embodiments of the present invention shown in broken lines. 
         FIG. 29  is a side elevational view of another embodiment of an arbor including an axially elongated collar defining axially elongated bearing surfaces that slidably engage corresponding axially-elongated bearing surfaces of the arbor body. 
         FIG. 30  is a top plan view of the arbor of  FIG. 29 . 
         FIG. 31  is a cross-sectional view taken along line A-A of  FIG. 30 . 
         FIG. 32  is a cross-sectional view taken along line B-B of  FIG. 30 . 
     
    
    
     DETAILED DESCRIPTION OF THE CURRENTLY PREFERRED EMBODIMENTS 
     In  FIGS. 1-4 , an arbor embodying the present invention is indicated generally by the reference numeral  10 . The arbor  10  is usable with hole cutters, such as hole saws and sheet metal hole cutters. The term “hole cutter” is used herein to mean any of numerous different types of cutting tools for cutting holes in work pieces, such as hole saws, sheet metal hole cutters, etc. The term “arbor” is used herein to mean any of numerous different types of devices for supporting a rotating tool, such as a hole cutter, on a power tool such as a drill, and further includes, without limitation, mandrels. As shown, for example, in  FIGS. 4 and 10 , a typical quick change hole cutter  12  includes an end plate  14  defining a hole cutter aperture  16  extending through a central portion of the end plate, and at least one drive pin aperture  18  radially spaced relative to the aperture  16 . In the illustrated embodiment, there are two drive pin apertures  18  radially spaced relative to the aperture  16  and angularly spaced relative to each other by about 180°. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, any number of drive pin apertures may be provided in any of a variety of shapes and/or configurations. As shown typically in  FIG. 4 , a blade  13  extends axially from the end plate  14  and defines a plurality of cutting teeth  15  for cutting a hole in a work piece by rotatably driving the arbor  10  and hole cutter  12  and moving the rotatably-driven cutting teeth  15  into the work piece. As described further below, in the quick change hole cutter, the aperture  16  defines a plurality of raised threaded portions  17  that are angularly spaced relative to each other for threadedly engaging a connecting end portion  22  of the arbor  10 , and a plurality of recessed unthreaded portions  19  located between the threaded portions. 
     In a standard hole cutter or saw, on the other hand, the central aperture in the end plate or cap of the hole cutter defines a continuous or substantially continuous thread extending about the circumference of the aperture. Such standard hole cutters conform to the ASME B94.54-1999 standard, and in accordance with such ASME standard, define a standard thread form depending on the outside diameter of the hole saw as follows: For hole saws having outside diameters between 9/16 inch and 1 3/16 inches, the standard thread form is a ½-20 UNF-2B thread, and for hole saws having outside diameters between 1¼ inches and 6 inches, the standard thread form is a ⅝-18 UNF-2B thread. Accordingly, the term “standard” hole cutter is used herein to mean a hole cutter that has such a threaded aperture; whereas the term “quick change” hole cutter is used herein to mean a hole cutter that does not include a such a conventional threaded aperture, but rather includes a connecting aperture defining one or more features to facilitate a quick change attachment of the hole cutter to the arbor, such as the plural raised engagement portions and plural recessed portions located therebetween and described further below. 
     As shown best in  FIGS. 5-7 , the arbor  10  comprises an axially-elongated arbor body  20  defining an axially extending pilot bit aperture  29  for receiving a pilot bit, such as a quick change pilot bit  64  ( FIG. 18 ) or a standard pilot bit  66  ( FIG. 19 ). A standard pilot bit is a pilot bit that does not include a feature for allowing attachment of the bit to an arbor without tools. The arbor body  20  includes a body portion  26  defining a stop surface  28 , and an end portion  22  that extends axially from the stop surface  28  and defines an end surface  33 . As described further below, the end portion  22  is engageable within the hole cutter aperture  16  ( FIG. 4 ) to secure the arbor body to the hole cutter. In the illustrated embodiments, and as described further below, the end portion  22  threadedly engages the hole cutter aperture  16 ; however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, any of numerous other connection mechanisms or features that are currently known, or that later become known, equally may be employed. As can be seen in  FIGS. 5-7 , the body portion  26  of the arbor defines a “double D” cross-sectional configuration (i.e., a pair of opposing substantially flat side surfaces with a pair of opposing substantially curvilinear side surfaces extending therebetween); however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, this configuration is only exemplary, and numerous other shapes and/or configurations that are currently known, or that later become known equally may be used. A drive shank  24  is formed on the arbor body  20  opposite the end portion  22 . In the illustrated embodiment, the drive shank  24  is a quick-release power drive shank of a type known to those of ordinary skill in the pertinent art. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the shank  24  may take the form of any of numerous different types of shanks or other structures that are currently known, or that later become known for performing the function of the shank  24 . 
     As shown typically in  FIGS. 1-4 and 11-12 , the arbor  10  further includes a drive pin plate or member  30  defining an aperture  32  extending therethrough. The aperture  32  is configured for receiving the arbor body  20  and engaging the body portion  26  of the arbor body such that the drive pin plate  30  is prevented from rotating relative to the arbor body, but is allowed to move axially over the arbor body between a first position engaging the hole cutter  12  ( FIG. 14A ), and a second position disengaged from the hole cutter  12  ( FIG. 14B ). As best shown in  FIG. 2 , the aperture  32  defines a “double D” configuration to matingly engage the body portion  26  of the arbor body  20 ; however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, this configuration is only exemplary, and numerous other shapes and/or configurations that are currently known, or that later become known equally may be used. The drive pin plate  30  further includes a first or hole cutter bearing surface  34 , and a plurality of retaining members, which in the illustrated embodiment are drive pins  36 . The drive pins  36  extend axially from the first surface  34 , are angularly spaced relative to each other, and are radially spaced relative to the aperture  32 . Each drive pin  36  is received within a corresponding drive pin aperture  18  of the hole cutter  12  when the drive pin plate  30  is in a first (engaged) position engaging the hole cutter ( FIGS. 4 and 14A ), and is displaced from the respective drive pin aperture  18  when the drive pin plate is in a second (disengaged) position disengaged from the hole cutter ( FIG. 14B ). In the illustrated embodiment, the drive pin plate  30  includes two diametrically opposed drive pins  36 ; however, as may be recognized by those of ordinary skill in the pertinent art base on the teachings herein, the drive pin plate  30  can take any of numerous different configurations and can include any number of drive pins  36  that can take any of numerous different configurations that are engageable with corresponding drive pin apertures  18  or other recesses in the hole cutter. 
     As shown in  FIGS. 3 and 4 , a biasing member  38  biases the drive pin plate  30  in the direction from the second disengaged position toward the first engaged position. As described in further detail below, the biasing member  38  normally biases the drive pin plate  30  into the first engaged position when the drive pins  36  and corresponding drive pin apertures  18  are placed in alignment, such that the drive pin plate  30  abuts the end plate  14  of the hole cutter  12 , and supports the hole cutter in a manner that substantially prevents off-axis wobble and undesirable vibrations during use. One advantage of this feature is that it facilitates one-handed attachment of the hole cutter to the arbor, or otherwise facilitates rapid attachment and detachment of the hole cutter to and from the arbor. 
     Preferably, the arbor  10  is adapted to receive and mount both quick change hole cutters and standard hole cutters. However, the invention and aspects thereof may be embodied in arbors adapted to mount only quick change hole cutters. In a standard hole cutter (not shown), the threaded aperture in the end plate of the hole cutter (defining, for example, either a ½-20 UNF-2B thread or a ⅝-18 UNF-2B thread, depending on the outer diameter of the hole saw) threadedly engages the end portion  22  of the arbor body  20  to secure the arbor body thereto. In the quick change hole cutter  12 , on the other hand, and as shown typically in  FIG. 10 , the aperture  16  in the end plate  14  defines a plurality of curvilinear protrusions  17  angularly spaced relative to each other along the circumference of the aperture, and a plurality of curvilinear recesses  19  located therebetween. The curvilinear protrusions  17  define female threads that threadedly engage corresponding male threads formed on the end portion  22  of the arbor body  20 . More specifically, and as shown in  FIGS. 5 and 7 , the end portion  22  of the arbor body  20  defines a plurality of angularly extending, curvilinear arbor protrusions  23  that project radially outwardly, and are angularly spaced relative to each other about the circumference of the end portion  22 , and a plurality of angularly extending recesses or flats  25  located therebetween. In the illustrated embodiment, one or more of the protrusions  23  on the arbor body  20  and the corresponding protrusions  17  on the hole cutter  12  defines a greater or lesser angular extent than the other protrusions so that the quick change hole cutter can be fitted to the end portion  22  of the arbor body in only one first engagement position, and in that first engagement position, the lead male and female threads can properly engage when moving from the first engagement position to the second engagement position. More specifically, as shown typically in  FIG. 7 , a first protrusion  17  on the end portion  22  of the arbor body to the left in the drawing defines a greater angular extent than the opposite second protrusion  23  located to the right in the drawing. Similarly, the hole saw cap  14  of  FIG. 10  includes a first recess  19  defining a greater angular extent than the opposite second recess  19 . Accordingly, in the first engagement position, the first recess  19  receives the first protrusion  23 , the second recess  19  receives the second protrusion  23 , and this is the only position in which the end portion  23  of the arbor can be received within the central aperture of the hole cutter. In this first engagement position, the lead threads of the respective protrusions of the arbor and hole saw engage upon moving at least one of the hole cutter and arbor body relative to the other between the first and the second engagement positions. Because of the different angular extents of the opposing threaded protrusions of the quick change hole saw cap and arbor body,  17  and  23 , respectively, the end portion  22  of the arbor body can be received into the aperture  16  of the hole saw cap in only one position, and in that position, the lead male and female threads can engage upon moving the hole cutter and/or arbor body relative to the other between the first and second engagement positions. If desired, or alternatively, the hole cutter and/or arbor can include visual markings thereon that can be aligned or otherwise used to orient the position of the hole cutter aperture relative to the connecting portion of the arbor in order to ensure attachment of the hole to the arbor in the first engagement position. 
     As shown in  FIGS. 11-13 , in order to attach the hole cutter  12  to the arbor body  20 , the protrusions  23  on the end portion  22  of the arbor body  20  are aligned with the correspondingly-sized recesses  19  of the hole cutter aperture  16 . Then, the hole cutter  12  is slipped over the end portion  22  of the arbor body  20  (or vice versa) until the end plate  14  of the hole cutter is adjacent to, substantially in contact with, or in contact with the shoulder  28  of the arbor body  20  to thereby place the hole cutter and arbor body in the first engagement position. As indicated above, in this position, the lead male threads of the arbor body and lead female threads of the hole cutter can engage upon rotating at least one relative to the other. Then, the hole cutter  12  is rotated relative to the arbor body  20  from the first engagement position to a second engagement position (or the arbor body is rotated relative to the hole cutter, or both the hole cutter and arbor body are rotated in opposite directions) to, in turn, threadedly engage the male threaded protrusions  23  of the end portion  22  of the arbor body with the corresponding female threaded protrusions  17  of the hole cutter, and thereby fixedly secure the hole cutter to the arbor body. 
     In the illustrated embodiment, the male threads of the arbor body protrusions  23  and the female threads of the hole cutter protrusions  17  are configured (or “clocked”) so that when the hole cutter and/or arbor body is rotated from the first engagement position to the second engagement position, the drive pins  36  of the arbor and drive pin apertures  18  of the hole cutter are substantially aligned in the second engagement position to, in turn, allow the drive pins to be axially received within the drive pin apertures and thereby further secure the hole cutter to the arbor. In addition, the male and female threads of the protrusions  23  and  17 , respectively, are preferably configured so that when the hole cutter  12  and/or the arbor body  20  are rotated into the second engagement position, the end plate  14  is in contact with, or substantially in contact with the shoulder  28  of the arbor body to, in turn, allow the shoulder to engage and further support the hole cutter during use. In the illustrated embodiments of the present invention, there is sufficient axial clearance between the male and female threads of the protrusions  23  and  17 , respectively, to allow the end plate  14  of the hole cutter to contact or substantially contact the shoulder  28  of the arbor body in the first engagement position, and to allow the end plate  14  of the hole cutter to remain in contact or substantial contact with the shoulder  28  during rotation between the first and second engagement positions, so that in the second engagement position, the end plate  14  is in contact with, or in substantial contact with the shoulder  28  of the arbor body. During rotation between the first and second engagement positions, the threads tend to drive the hole cutter  12  axially inwardly toward the shoulder  28  (or vice versa) and thus substantially eliminate or eliminate the axial clearance between threads in the second engagement position. 
     As indicated above, one advantage of the currently preferred embodiments of the present invention is that the threaded end portion  22  of the arbor is threadedly engageable with either quick change hole cutters or standard hole cutters. The combination of threaded protrusions  23  on the end portion  22  of the arbor body  20  forms an interrupted, but continuous thread pattern for engaging the female threads on a standard hole cutter as defined above (e.g., either a ½-20 UNF-2B thread or a ⅝-18 UNF-2B thread, depending on the outer diameter of the hole saw). Thus, in order to attach a standard hole cutter to the arbor body, the threaded aperture in the standard hole cutter cap is fitted over the threaded end portion  22  of the arbor body, and at least one of the hole cutter and arbor body is rotated relative to the other to engage the threads. Then, the hole cutter and/or arbor is rotated relative to the other to further engage the threads and, in turn, axially move the end cap of the hole cutter into engagement with the shoulder  28  of the arbor body ( FIG. 7 ). In this position, if the drive pins  36  are aligned with the drive pin apertures of the standard hole cutter, then the drive pin plate is moved downwardly, or allowed to move downwardly into engagement with the end plate on the hole cutter to, in turn, receive the drive pins within the drive pin apertures. If the drive pins and drive pin apertures are not aligned in this position, then the hole saw is rotated and backed away slightly from the shoulder  28  of the arbor until the drive pin apertures and drive pins are aligned. When so aligned, the drive pin plate is moved downwardly, or allowed to move downwardly into engagement with the drive pin apertures to complete the connection of the hole cutter to the arbor. 
     In the currently preferred embodiments of the present invention, the relative rotation of the hole cutter  12  and/or arbor  10  between the first and second engagement positions is within the range of about 10 degrees and about 180 degrees, is preferably within the range of about 30 degrees and about 120 degrees, and is most preferably within the range of about 40 degrees and about 100 degrees. In the illustrated embodiment, the relative rotation between the first and second engagement positions is about 45 degrees. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, these angular ranges and angles are only exemplary, and numerous other angles and/or angular ranges equally may be employed. 
     As shown typically in  FIG. 28 , the arbors and hole cutters of the currently preferred embodiments of the present invention define custom thread forms that allow the end portions of the arbors to be threadedly engaged to both quick change hole cutters and standard hole cutters; that allow the quick change hole cutters to engage or substantially engage the shoulder of the arbor in both the first and second engagement positions; and that are timed so that in the second engagement position the drive pins of the arbor are aligned or substantially aligned with the drive pin recesses of the hole cutter. As indicated above, standard hole cutters having hole saw diameters of 1 3/16 inches or less define a ½-20 UNF-2B thread (“small diameter” hole cutters), and standard hole cutters having hole saw diameters of 1¼ inches or greater define a ⅝-18 UNF-2B thread (“large diameter” hole cutters). Accordingly, the custom thread forms of the currently preferred embodiments of the present invention are based on these standard thread forms to allow attachment of the arbor to hole cutters with such standard threads; however, the custom thread forms also vary from the standard thread forms in order to allow attachment of quick change hole cutters as described. The currently preferred embodiments of the present invention define a “½-20 custom thread” for relatively small diameter hole cutters, and a “⅝-18 custom thread” for relatively large diameter hole cutters. Each custom thread defines the same thread height “H”, pitch “P”, and included angle “•”, as the respective standard thread form, but defines a different axial clearance “a”, root “R”, and crest “C”. In the illustrated embodiments, the customer thread forms differ from the standard thread forms as follows: 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Different Features 
                 Standard Thread Forms 
                 Custom Thread Forms 
               
               
                   
               
             
            
               
                 Root (“R”) 
                 0.25 P 
                 0.25 P + a 
               
               
                 Crest (“C”) 
                 0.125 P  
                 0.125 P − a  
               
               
                 Axial Clearance 
                 Not Specified, But 
                 a 
               
               
                   
                 Negligible or 
                   
               
               
                   
                 Approximately Zero 
               
               
                   
               
            
           
         
       
     
     The minimum clearance “a” for each custom thread form is preferably determined in accordance with the following formula: a=((1/pitch)/360))*D, where D equals the degree of rotation between the first and second engagement positions. For example, as indicated in the table below, if the hole cutter includes two threaded protrusions  17  (or “lobes”), it will rotate 90° between the first and second engagement positions; if the hole cutter includes 3 lobes, it will rotate 60° between the first and second engagement positions; if the hole cutter includes 4 lobes, it will rotate 45° between the first and second engagement positions, etc. The minimum axial clearance “a” is set to time the threads so that in the second engagement position the drive pins are aligned or substantially aligned with the respective drive pin recesses in the hole cutter to allow the drive pins to be moved into the engaged position. The following table lists exemplary minimum approximate clearances “a” for the ⅝-18 and ½-20 custom thread forms: 
     
       
         
           
               
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Minimum 
                 Minimum 
               
               
                   
                 Angular Rotation 
                 Approximate 
                 Approximate 
               
               
                 Number of Lobes 
                 Between First 
                 Clearance “a” for 
                 Clearance “a” for 
               
               
                 (or curvilinear 
                 And Second 
                 ⅝-18 Custom 
                 ½-20 Custom 
               
               
                 threaded 
                 Engagement 
                 Thread Form 
                 Thread Form 
               
               
                 protrusions) 
                 Positions 
                 (inches) 
                 (inches) 
               
               
                   
               
             
            
               
                 2 lobe 
                 90° 
                 0.014 
                 0.012 
               
               
                 (square/rectangle) 
                   
                   
                   
               
               
                 3 lobe (triangle) 
                 60° 
                 0.009 
                 0.008 
               
               
                 4 lobe (cross) 
                 45° 
                 0.007 
                 0.006 
               
               
                 5 lobe (pent) 
                 36° 
                 0.006 
                 0.005 
               
               
                 6 lobe (hex) 
                 30° 
                 0.005 
                 0.004 
               
               
                   
               
            
           
         
       
     
     As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, these minimum clearances are only exemplary, and numerous other clearances equally may be employed. Preferably, the minimum clearance “a” is approximately as defined above; however, if desired, the clearance may be greater than the minimum as defined above. In some embodiments of the present invention, the clearance is within the range of about 1 to about 1½a. If, for example, the clearance is greater than the respective minimum clearance “a”, the drive pins will be allowed to move into the drive pins recesses when the hole cutter is located in the second engagement position. If, on the other hand, the clearance is too small such that the hole cutter cannot move into the second engagement position and thus cannot move the drive pin recesses into alignment with the drive pins, the hole cutter cannot be properly attached to the arbor. 
     As shown best in  FIGS. 4 and 16-17 , the arbor  10  further includes a pilot bit mechanism  40 , at least a portion of which is housed in the arbor body  20  and/or a housing in the drive pin plate  30 . The pilot bit mechanism  40  is designed to allow substantially automatic and/or manual engagement and disengagement of both quick change and standard pilot drill bits ( FIGS. 18-19 ). In the illustrated embodiment, the pilot bit mechanism  40  defines a quick change pilot bit state, shown in  FIG. 4 , a standard pilot bit state, shown in  FIG. 16 , and a neutral state shown in  FIG. 17 . In the quick change pilot bit state shown in  FIG. 4 , the pilot bit mechanism  40  engages a quick change pilot bit  64  to prevent movement of, and otherwise releasably secure the bit to the arbor body  20 ; in the standard pilot bit state shown in  FIG. 16 , the pilot bit mechanism  40  engages a standard pilot bit  66  to prevent movement of, and otherwise releasably secure the bit to the arbor body  20 ; and in the neutral state shown in  FIG. 17 , the pilot bit mechanism  40  is disengaged from the respective quick change pilot bit  64  or standard pilot bit  66  (whichever one is inserted in the pilot bit aperture  29 ) to release, remove and/or replace the bit. As described further below, the pilot bit mechanism  40  may include a visual indicator that alerts a user when a standard pilot bit  66  is inserted in the pilot bit aperture  29 . 
     As shown in  FIGS. 4 and 16-17 , the pilot bit mechanism  40  comprises a pilot pin  41  (shown separately in  FIGS. 8-9 ) movable between a first position and a second position. The first position corresponds with the quick change pilot bit state wherein the pilot pin engages the quick change bit  64  ( FIG. 4 ). The second position corresponds with either the standard pilot bit or neutral states wherein the pilot pin is either disengaged from the quick change bit, as shown in  FIG. 17 , or positioned to allow a standard bit  66  to be inserted into the arbor body  20 , as shown in  FIG. 16 . As shown in  FIG. 18 , the quick change pilot bit  64  includes a shank defining at least one pilot pin engaging feature  65  such as, for example, a groove, recess, aperture, notch, indentation, external boss or protrusion. In the illustrated embodiment, the quick change bit  64  has a rectangular notch for engaging the pilot pin  41 ; however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the quick change shank may take the form of any of numerous different types of shapes, and may include any of numerous different configurations or features that are currently known or that later become known for engaging the pilot pin. As shown best in  FIG. 8 , in order to universally engage the various types of quick change pilot bit shanks that are available, the pilot pin  41  has a substantially rounded tip  42 . As shown in  FIGS. 4 and 16-17 , the pilot bit mechanism  40  includes a biasing member  43 , such as a coil spring, that biases the pilot pin  42  into the first position in engagement with a pilot bit received within the pilot bit aperture  29 . 
     As also shown in  FIGS. 4 and 16-17 , the pilot bit mechanism  40  further comprises a fastener  48  movable between a first position ( FIG. 4 ) disengaged from a pilot bit received within the pilot bit aperture  29 , and a second position engaged with either a quick change  64  or standard pilot bit  66  received within the pilot bit aperture  29 . In the illustrated embodiment, the fastener  48  is a set screw; however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the fastener may take the form of any of numerous other types of fasteners that are currently known, or that later become known for releasable securing the inserted pilot bit. 
     The pilot bit mechanism  40  further comprises a shear pin or ball  46  that is disposed at least partially within a ball receiving aperture  39  defined in the drive pin plate  30 . The ball  46  is movable between a first position, wherein the ball  46  outwardly protrudes from the ball receiving aperture  39  when the pilot bit mechanism  40  is in the quick change pilot bit or standard pilot bit states, as shown in  FIGS. 4 and 16 , and a second position, wherein the ball  46  is substantially retained within the ball receiving aperture  39  when the pilot bit mechanism  40  is in the neutral state, as shown in  FIG. 17 . A biasing member  47  biases the ball  46  into the first position. In the illustrated embodiment, biasing members  38 ,  43  and  47  are coil springs; however, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the biasing members may take the form of any of numerous different types of biasing members that are currently known, or that later become known, such as any of numerous different types of springs or other components. 
     As also shown in  FIGS. 4 and 16-17 , the pilot bit mechanism  40  further comprises a shear plate  44  defining an aperture  45  for receiving therein the pilot pin  41  and/or ball  46  depending on the state of the pilot bit mechanism. The shear plate  44  is movable between a first position corresponding to the quick change pilot bit state shown in  FIG. 4 , and a second position corresponding to the standard pilot bit and neutral states of the pilot bit mechanism  40  shown in  FIGS. 16-17 . 
     The interaction between the shear pin  41 , shear plate  44 , ball  46 , drive pin plate  30  and pilot bit (quick change bit  64  or standard bit  66 ) define the three states of the pilot bit mechanism. Other components of the arbor  10  may also play a role in defining the states the pilot bit mechanism; however, attention will be focused on the above-mentioned components. Referring to  FIG. 17 , the neutral state of the pilot bit mechanism  40  is shown. From the neutral state, the pilot bit mechanism  40  can move into either the quick change pilot bit state ( FIG. 4 ) or the standard pilot bit state ( FIG. 16 ) depending on the type of pilot bit being used (i.e. quick change bit  64  or standard bit  66 ). As noted above, the pilot bit mechanism  40  is disengaged from the pilot bit while in the neutral state, which allows for the removal or insertion of any type of pilot bit. In the neutral state, the drive pin plate  30  is in its respective second or disengaged position ( FIGS. 14B and 17 ). In this position, the pilot pin aperture  31 , the shear plate aperture  45  and the ball receiving aperture  39  are substantially aligned, allowing the pilot pin  41  and ball  46  to move freely between their respective first and second positions depending on the type of pilot bit inserted into the pilot bit aperture  29 . 
     If a quick change pilot bit  64  is inserted into the pilot bit aperture  29 , and with the drive pin plate  30  in its second or disengaged position ( FIG. 17 ), the pilot bit mechanism  40  is positioned to transform from the neutral state to the quick change pilot bit state to engage the quick change pilot bit  64 . In the quick change pilot bit state, shown in  FIG. 4 , the pilot pin  41  is biased inwardly by its associated biasing member  43  into the recess  65  of the quick change pilot bit  64  to secure the bit  64 ; accordingly, the ball  46  is biased inwardly by its associated biasing member  47  into the shear plate aperture  45 , so that the ball  46  engages the shear plate  44 . With the ball  46  engaging the shear plate  44 , the position of the shear plate  44  is fixed relative to the drive pin plate  30  so that any movement of the drive pin plate  30  between its first and second positions causes the shear plate  44  to move between its first and second positions. To enter the quick change pilot bit state from the neutral state, the drive pin plate  30  must be moved from its second position ( FIGS. 14B and 17 ) to its first position ( FIGS. 4 and 14A ), which, in turn, causes the shear plate  44  to move from its second position ( FIG. 17 ) to its first position ( FIG. 4 ). Once in its first position, the shear plate  44  prevents outward movement of the pilot pin  41  to thereby releasably lock the pilot pin  41  in engagement with the quick change pilot bit  64  and secure the bit in the pilot bit aperture  29 . 
     If a standard pilot bit  66  is inserted into the pilot bit aperture  29 , and with the drive pin plate  30  in its second position ( FIG. 17 ), the pilot bit mechanism  40  is positioned to transform from the neutral state to the standard pilot bit state to engage the standard pilot bit  66 . In the standard pilot bit state, shown in  FIG. 16 , the standard pilot bit  66  having been inserted into pilot bit aperture  29  maintains the pilot pin  41  in its second position so that a portion of the pilot pin  41  is seated within the shear plate aperture  45 . In this position, the pilot pin  41  engages the shear plate  44  so that the axial position of the shear plate  44  is fixed relative to the arbor body  20 . To enter the standard pilot bit state from the neutral state, the drive pin plate  30  must be moved from its second position ( FIGS. 14B and 17 ) to its first position ( FIGS. 14A and 16 ). However, in contrast to the quick change pilot bit state, the shear plate  44  will not move from its second position to its first position when the drive pin plate  30  is moved; instead, the shear plate  44  will remain in its second position as a result of being engaged by the pilot pin  41 . In the standard pilot bit state, the ball  46  is biased into contact with the outer surface of the shear plate  44  further preventing the shear plate  44  from moving out of its second position. To fully secure the standard pilot bit  66 , the fastener  48  is moved into engagement with the pilot bit  66  to secure the bit within the bit aperture  29 , which in turn, maintains the pilot pin  41 , shear plate  44  and ball  46  in their respective positions associated with the standard pilot bit state ( FIG. 16 ) as described above. In one embodiment, in the standard pilot bit state, an end of the shear plate  44  protrudes visibly outwardly to provide a visual indication that a standard pilot bit is being used, and thus functions as visual alert to the user to manually engage the fastener  48  and, in turn, fixedly secure the standard pilot bit. 
     As shown in  FIGS. 1, 3 and 12 , the arbor  10  further comprises a collar  50 . The collar  50  defines a peripheral, axially-extending side wall  52 , a bore  53  formed on the inner side of the side wall  52 , and an expanded recess  55  formed on the inner end of the bore for receiving therein the drive pin plate  30  that is fixedly secured or coupled thereto. The collar  50  is movable between first and second positions corresponding to the engaged and disengaged positions of the drive pin plate  30 , respectively, so that movement of the collar from the first to the second position substantially simultaneously moves the drive pin plate  30  from the engaged to the disengaged position. The inner bore  53  of the collar  50  and the body portion  26  of the arbor body  20  define an annular, axially-extending compartment  56  for receiving and supporting therein the first biasing member  38  which, in the illustrated embodiment, is a coil spring, which biases the drive pin plate (and collar) towards the engaged position. 
     As shown best in  FIG. 12 , in the illustrated embodiment the collar is an elongated member defining a spool-like or diabolo shape. More specifically, the collar  50  defines an upper (distal) portion  57  defining a first laterally-extending diameter D 1  and an outer surface  67 , a middle portion  58  defining a second laterally-extending diameter D 2  and an outer surface  68 , and a lower (proximal) portion  59  defining a third laterally-extending diameter D 3  and an outer surface  69 . However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the collar  50  can take on of any of numerous different shapes and configurations that are currently known or that later become known, and thus, is not limited to the spool-like or diabolo shape shown. In the illustrated embodiment, the first laterally-extending diameter D 1  is approximately the same as the third laterally-extending diameter D 3 , and the second laterally-extending diameter D 2  is smaller than the first and second laterally extending diameters, thus forming the spool-like or diabolo shape. An advantage of this shape is that it provides an improved manually engageable surface that facilitates handling during use by permitting the user to grasp the middle portion  58  of the collar  50  with, for example, an index finger and thumb of one hand, when moving the collar  50  to attach or remove a hole cutter  12 . It should be noted that although the laterally-extending diameters of the upper and lower portions are approximately the same in the illustrated embodiment, in some embodiments the laterally extending diameters may differ; although such diameters preferably remain greater than the laterally-extending diameter of the middle portion. 
     In one embodiment of the invention, the axial length of the collar  50  is between about 1/22 inch to about 1⅜ inches, and in an exemplary embodiment, the axial length of the collar  50  is about 1⅕ inches. Additionally, in one embodiment of the invention, the axial length of the upper portion of the collar is between about ⅙ inch to about ½ inch, the axial length of the middle portion of the collar is between about ¼ inch to about ¾ inch, and the axial length of the lower portion of the collar is between about ⅙ inch to about ½ inch. In an exemplary embodiment, the axial length of the upper portion is about ⅓ inch, the axial length of the middle portion is about ⅖ inch, and the axial length of the lower portion is about ⅕ inch. 
     It should be noted that in the illustrated embodiment, the outer surfaces  67 ,  68 ,  69  of the respective upper, middle and lower portions  57 ,  58 ,  59  are substantially planar and substantially parallel to the central longitudinal axis of the arbor body  20 . Further, it should be noted that the upper and lower portions of the collar  50  do not directly abut the middle portion; rather, intermediate portions  71 ,  73  reside between the upper portion  57  and the middle portion  58  and the lower portion  59  and the middle portion  58  respectively. The intermediate portions  71 ,  73  define surfaces  75 ,  77  that slope towards the central longitudinal axis of the arbor body—i.e., the surfaces  75 ,  77  slope in a direction from the upper and lower portions of the collar  57 , 59  toward the middle portion  58  of the collar. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the upper, middle and lower portions  57 ,  58 ,  59  of the collar  50  can take on any of numerous different configurations that are currently known or that later become known; for example, the middle portion could include a plurality of axially spaced ribs, or any of the upper, middle and lower portions could take on an arcuate, curvilinear or sloped configuration. Additionally, the upper and lower portions could directly abut the middle portion without the inclusion of the intermediate portions, or the intermediate portions could take on any of numerous different configurations that are currently known or that later become known; for example, the intermediate portions could take on an arcuate or curvilinear configuration. Further, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the collar  50  and drive pin plate  30  can be integrated into a single component that can take on a diabolo configuration as defined above, or can take on any of numerous different configurations that are currently known or that later become known; for example, the single collar/drive pin plate component could take on a cylindrical shape having the same laterally extending diameter throughout. 
     As shown best in  FIGS. 3 and 12 , the arbor  10  includes a retaining clip or ring  60  connectable to a groove  62  formed in the body portion  26  of the arbor body  20 , a bushing  61  that engages on its end surface the clip  60 , and slidably engages on its outer surface the bore  53  of the collar  50  to guide the axial movement of the collar and drive pin plate between the first engaged ( FIGS. 4 and 14A ) and second disengaged ( FIG. 14B ) positions. As can be seen, the first biasing member  38  is axially fitted between the bushing  60  and the inner end of the drive pin plate  30  to normally bias the drive pin plate (and collar) outwardly into the first engaged position. As described further below, a user can manually engage the collar  50  to retract the collar against the bias of the first biasing member  38  into the disengaged position and can, in turn, release the collar to allow the first biasing member to drive the collar and drive pin plate from the disengaged to an engaged position. Alternatively, for one-handed attachment, a user can press the hole cutter cap  14  against the drive pin plate  30  to, in turn, correspondingly compress the coil spring  38  and place the hole cutter against the shoulder  28  of the arbor in the first engagement position. Then, upon rotating the hole cutter with the same hand from the first engagement position into the second engagement position, the coil spring automatically drives the drive pin plate  30  into the engaged position with the drive pins  36  received within the drive pin apertures of the hole cutter to complete attachment of the hole cutter to the arbor. 
     Having thus described the arbor  10  and its components, attention will now be drawn to a method of attaching and removing hole cutters and pilot drill bits to and from the arbor, respectively. With the drive shank  24  of the arbor  10  inserted and engaged by the chuck of a driving tool, such as a drill (not shown) or, prior to insertion and engagement with the tool, the end user aligns the hole cutter aperture  16  with the end portion  22  of the arbor. If a quick change hole cutter is used, the hole cutter recesses  19  are aligned with the arbor body protrusions  23  as shown, for example, in  FIG. 11 . Once in alignment, the hole cutter is fitted onto the end portion  22  of the arbor body  20  such that the arbor body protrusions  23  are received within the corresponding hole cutter recesses  19 , and the base of the hole cutter  14  rests on or about the stop surface  28 . During this step, the user substantially simultaneously moves the drive pin plate  30  from the first position to the second position and compresses the first biasing member  28  as shown, for example, in  FIG. 12 . Referring to  FIG. 13 , the hole cutter is then rotated from the first engagement position to the second engagement position such that the hole cutter protrusions  17  threadedly engage the respective arbor body protrusions  23  and, in turn, releasably secure the hole cutter to the arbor body. When the hole cutter and arbor body are in the second engagement position, the drive pin apertures  18  of the hole cutter are substantially aligned with the respective drive pins  36  of the drive pin plate  30 , thereby allowing the first biasing member  38  to automatically drive the drive pin plate from the second position ( FIG. 14B ) to the first position ( FIG. 14A ) and, in turn, drive the drive pins  36  into the corresponding drive pin apertures  18  as shown, for example, in  FIG. 15 . With the drive pins  36  fully received into the corresponding drive pin apertures  18 , the hole cutter  12  is fully engaged and attached to the arbor as shown, for example, in  FIG. 4 . 
     If a standard hole cutter (not shown) is used, the end user aligns the hole cutter aperture with the end portion  22  of the arbor body  20  fitting the hole cutter thereupon, such that the hole cutter aperture threadedly engages the threads on the arbor protrusions  23 . Like the quick change hole cutter, the standard hole cutter is then rotated to threadedly attach the hole cutter to the end portion of the arbor and receive the drive pins into the corresponding drive pin apertures of the hole cutter. Depending on the threads, the standard hole cutter may not engage or may not fully engage the shoulder or stop surface of the arbor when attached to the arbor; however, since the drive pins drive the hole cutter it is not always necessary that the hole cutter cap engage the stop surface of the arbor. 
     To attach a quick change pilot bit  64 , the drive pin plate  30  is moved from the first position engaging the hole cutter  12  to the second position disengaged from the hole cutter  12  by at least one of: (i) grasping and physically moving the drive pin plate  30 , and (ii) pressing downward on the drive pin plate  30  through engagement with the hole cutter  12  during the step of fitting the hole cutter onto the end portion of the arbor body ( FIG. 12 ). The quick change pilot bit  64  is then inserted into the pilot bit aperture  29 . As the pilot bit  64  is being inserted, the pilot pin  41  moves from the first position to the second position, wherein the pilot pin  41  slides into the pilot pin aperture  31  formed in the arbor body  20  and at least a portion of the pilot pin  41  enters the shear plate aperture  45  (see, for example,  FIG. 17 ). This allows the pilot pin  41  to exit the pilot bit aperture  29 , thereby enabling full insertion of the pilot bit  64 . Substantially simultaneously, the ball or pin  46  moves from the first position to the second position. In the second position, the ball  46  at least partially exits the shear plate aperture  45  and at least partially enters the ball receiving aperture  39  formed in the drive pin plate  30 . 
     Once the quick change pilot bit  64  is substantially fully inserted into the pilot bit aperture  29 , and the pilot pin  41  is in alignment with the quick change feature  65  of the pilot bit  64 , the biasing member  43  returns the pilot pin  41  to the first position such that the pilot pin  41  engages the respective quick change feature  65  of the bit  64  and prevents movement of the quick change pilot bit  64  relative to the arbor body. With the pilot pin  41  engaging the quick change pilot bit  64 , the biasing member  47  returns the ball  46  to the first position. In the first position, a portion of the ball  46  is received by the shear plate aperture  45  and engages the shear plate  44 , while a portion of the ball remains in the shear pin aperture  31  of the arbor body  20 . To fully secure the pilot bit  64 , the drive pin plate  30  is then moved from the second position to the first position engaging the hole cutter by at least one of: (i) releasing the drive pin plate  30 , and (ii) during the step of rotating the hole cutter, allowing the drive pin plate  30  to move when the drive pin apertures  18  align with the corresponding drive pins  36 . As the drive pin plate  30  moves, the shear plate  44  substantially simultaneously moves from the second position to the first position. In the first position, the shear plate  44  locks the pilot pin  41  into engagement with the quick change pilot bit  64 , and thereby prevents the pilot bit from moving out of the first position as shown, for example, in  FIG. 4 . 
     To attach a standard pilot bit  65 , as with a quick change pilot bit, the drive pin plate  30  is moved from the first position engaging the hole cutter to the second position disengaged from the hole cutter by at least one of: (i) grasping and physically moving the drive pin plate  30 , and (ii) pressing downward on the drive pin plate  30  through engagement with the hole cutter  12  during the step of fitting the hole cutter onto the end portion of the arbor body ( FIG. 12 ). The standard pilot bit  66  is then inserted into the pilot bit aperture  29 . As the pilot bit  66  is inserted, the pilot pin  41  moves from the first position to the second position. In the second position, the pilot pin  41  slides into the pilot pin aperture  31  in the arbor body  20  and at least a portion of the pilot pin  41  enters the shear plate aperture  45  and engages the shear plate  44  (see  FIG. 16 ), thereby allowing the pilot pin  41  to exit the pilot pin aperture  29  and enabling full insertion of the standard pilot bit  66 . Substantially simultaneously, the ball  46  moves from the first position to the second position. In the second position, the ball  46  exits the shear plate aperture  45  and enters the ball receiving aperture  39  in the drive pin plate  30 . 
     Once the standard pilot bit  66  is substantially fully inserted into the pilot bit aperture  29 , the drive pin plate  30  is then moved from the second position to the first position engaging the hole cutter by at least one of: (i) releasing the drive pin plate  30 , and (ii) during the step of rotating the hole cutter, causing the drive pin plate  30  to move when the drive pin apertures  18  align with the corresponding drive pins  36 . As the drive pin plate  30  moves, the shear plate  44  remains in the second position due to engagement with the pilot pin  41 , which in turn, causes the ball  46  to partially extend outwardly from the ball receiving aperture  47  and into engagement with the shear plate  44  to further maintain the shear plate  44  in the second position. In one embodiment (not shown), the shear plate  44  visually protrudes from behind the drive pin plate  30  to alert the user to use the fastener  48  to engage the standard pilot pit  66 , which occurs when the drive pin plate  30  is in the first position and the shear plate  44  in the second position. To fully secure the standard pilot bit  66  in the arbor  10 , the user moves the fastener  48  from the first position to the second position, thereby engaging the pilot bit  66  and preventing movement thereof relative to the arbor body. 
     If desired, a user may employ the fastener  48  to secure a quick change pilot bit  64  in addition to the securement provided by the pilot bit mechanism  40 . As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the order in which the respective hole cutter and pilot bit are mounted is inconsequential; rather, the hole cutter may be mounted before the pilot bit, after the pilot bit, or at about the same time as the pilot bit. Additionally, if desired, the arbor can be used with the hole cutter only (no pilot bit) or with the pilot bit only (no hole cutter). 
     In  FIGS. 20 and 21  another arbor embodying the invention is indicated generally by the reference number  110 . The arbor  110  is substantially similar to the arbor  10  described above in connection with  FIGS. 1-19 , and therefore like reference numerals preceded by the numeral “1” are used to indicate like elements. The primary difference of the arbor  110  in comparison to the arbor  10  described above, is that the arbor  110  does not include a collar  50  and biasing member  38  (see, e.g.,  FIGS. 1 and 3  above), but rather includes a nut  150  that threadedly engages the body portion  126  of the arbor body  120 , and an o-ring  151  extending annularly about the body portion between the nut  150  and drive pin plate  130 . The nut  150  is movable axially over the body portion  126  by rotating the nut to, in turn, move the nut between a first position spaced away from a hole cutter (not shown) attached to the connecting portion  122 , as shown typically in  FIGS. 20 and 21 , and a second position engaging the drive pin plate  130  with the drive pins  136  received within the drive pin apertures of a hole saw to fixedly secure the drive pin plate to the hole saw (not shown). The o-ring  151  operates as a buffer between the nut  150  and drive pin plate  130  and otherwise allows a user to manually grip and turn the nut into engagement with the drive pin plate, and to manually grip and release the nut from the drive pin plate. In the illustrated embodiments, the nut  150  and the collar  50  prevent the drive pin plates  30 ,  130  from slipping off the rearward end of the arbor body  20 ,  120 , and the threaded protrusions  23 ,  123  prevent the drive pin plates from slipping off the front end of the arbor body when not in use. As may be recognized by those or ordinary skill in the pertinent art based on the teachings herein, the arbors may include any of numerous different components that are currently known or that later become known for axially engaging the opposite side of the drive pin plate relative to the hole cutter to secure the axial position of the drive pin plate during use and/or to prevent the drive pin plate from slipping off the arbor body. 
     In  FIGS. 22-23  an adapter for connecting relatively small hole cutters to the arbors of the invention is indicated generally by the reference numeral  70 . The adapter  70  defines an adapter aperture  72  extending through an approximately central region thereof, a plurality of angularly extending protrusions  74  that project radially into the aperture  72  and are angularly spaced relative to each other about the periphery of the aperture, and a plurality of angularly extending recesses  76  formed between the protrusions  74 . The protrusions  74  are threaded with a thread configuration that corresponds to and is engageable with the threaded portions  23 ,  123  of the end portions  22 ,  122  of the arbors  10 ,  110  for threadedly engaging the adapter to the arbors. The external periphery of the adapter  70  defines a plurality of curvilinear recesses  78  therein that are angularly spaced relative to each other about the external periphery, and are positioned relative to each other such that each recess  78  corresponds in position to, and receives therein a respective drive pin  36 ,  136  of the arbors when the adapter is attached to the arbor. The curvilinear shape of each recess  78  substantially conforms to the external shape of the respective drive pin to securely engage the respective drive pin and minimize any play therebetween. The underside of the adapter  70  includes a threaded boss  80  that is received within the threaded aperture on a hole cutter (not shown) to fixedly secure the hole cutter to the adapter. Accordingly, the adapter allows relatively small hole cutters that do not have drive pin apertures, or that do not have drive pin apertures that match the pattern of, or that otherwise are configured to receive the drive pins of the arbors. 
     In operation, the adapter  70  is attached to the hole saw by threadedly attaching the boss  80  to the hole saw. The assembled adapter and hole saw are attached to the arbor by inserting the threaded protrusions  23 ,  123  of the arbor end portion  22 ,  122  into the recesses  76  of the adapter to define the first engagement position. Then, at least one of the adapter/hole cutter assembly and arbor is rotated relative to the other to rotatably move from the first engagement position to the second engagement position. In the second engagement position, the protrusions  74  of the adapter threadedly engage the protrusions  23 ,  123  of the arbor to secure the adapter/hole cutter assembly to the arbor. When the adapter/hole cutter assembly and arbor are in the second engagement position, the drive pins are moved axially into the curvilinear recesses  78  to further prevent any relative rotational movement of the adapter and arbor during use and to rotatably drive the hole cutter. If desired, the axial depth of the adapter may be set so that the inner surface of the adapter engages the drive pin plate in the second engagement position. Also if desired, the threads on the threaded protrusions may define an axial clearance as described above in order to facilitate maintaining contact between the adapter and arbor shoulder  28 ,  128  in the first and second engagement positions. 
     In  FIGS. 24-27  another arbor embodying the present invention is indicated generally by the reference number  210 . The arbor  210  is substantially similar to the arbors  10 ,  110  described above, and therefore like reference numerals preceded by the numeral “2”, or preceded by the numeral “2” instead of the numeral “1”, are used to indicate like elements. The primary difference of the arbor  210  in comparison to the arbor  10  described above, is that the arbor  210  does not include a biasing member  38  (see, e.g.,  FIGS. 1 and 3  above) for biasing the drive pin plate  230  in the direction from the second disengaged position, where the drive pin plate  230  is disengaged from the hole cutter, to the first engaged position, where the drive pin plate engages the hole cutter. Rather, the drive pin plate  230  is manually moved between the engaged and disengaged positions without the aid of a biasing member, and is maintained in the first engaged position by a retaining member  280 . In the illustrated embodiment, the retaining member is a ball detent mechanism, which includes a ball  284  which is movable between a retracted position and an extended position, and a biasing member  286 , such as a coil spring. The biasing member  286  biases the detent member  284  in the extended position. The ball detent  280  is housed within an aperture  282  defined in the drive pin plate  230 . The aperture  282  extends radially between the drive pin plate aperture  232  and the outer surface of the drive pin plate  230 . A set-screw  288  is threaded into the aperture  282  to provide a backing surface against which the spring  286  can compress and serve as a mechanism for adjusting the tension in the spring  286 . As may be recognized by those or ordinary skill in the pertinent art based on the teachings herein, the components of the ball detent mechanism may be substituted by any of numerous different components that are currently known or that later become known so long as the detent mechanism is able to secure the axial position of the drive pin plate relative to the arbor body during use and/or to prevent the drive pin plate from slipping out of engagement with the hole cutter. As may be recognized by those or ordinary skill in the pertinent art based on the teachings herein, the retaining member  280  can be of any of numerous types of retaining members that are currently known or that later become known to secure the axial position of the drive pin plate relative to the arbor body during use and/or to prevent the drive pin plate from slipping out of engagement with the hole cutter. 
     Referring to  FIG. 25 , the arbor body  220  defines a groove  290  located about the perimeter of the arbor body  220  towards the end portion  222 . The groove  290  defines a first surface that is curved and/or angled towards the drive shank  224  and a second surface  294  that is substantially straight or substantially parallel to the end surface  233  of the connecting end portion  222 . The groove  290  is configured in this manner to allow rearward movement of the drive pin plate  230  from the first engaged position to the second disengaged position, and to prevent further forward movement of the drive pin plate  230  beyond the first engaged position. As noted above, the ball  284  is movable between a retracted position and an extended position. In the extended position shown in  FIG. 27 , a portion of the ball  284  is seated within the groove  290  and portion of the ball is seated within the aperture  282 , thereby securing the drive pin plate  230  axially in its first engaged position relative to the arbor body  220  to maintain engagement with the hole cutter. In the retracted position, the ball  284  is recessed within the aperture  282 , allowing the drive pin plate  230  to move axially over the arbor body  220  and disengage from the hole cutter. 
     Although not shown in the drawings, the drive pin plate  230  can define a spool-like or diabolo configuration as described above, with the same or approximately the same dimensions. Further, the drive pin plate can be elongated axially (with or without defining a spool-like diabolo shape) to define an axially elongated bearing surface between the drive pin plate  230  and the arbor body  220  to reduce or prevent unwanted movement or play between the drive pin plate and arbor body. 
     In operation, with the drive pin plate  230  in the first engaged position (see  FIGS. 24 and 27 ) and engaging a hole cutter (not shown), a user grasps and manually moves the drive pin plate  30  rearward towards the drive shank  24  As the drive pin plate  230  begins to move, the ball  284  is forced against the curved and/or angled surface  292  of the groove  290  and, as the drive pin plate continues its rearward movement, the ball is forced out of the groove and into its retracted position within the aperture. With the ball in its retracted position, the pilot pin plate  230  is moved to its second position disengaging the hole cutter and allowing removal of the hole cutter. If a user decides to re-attach the hole cutter, or attach a replacement hole cutter, the cutter is threaded onto the end portion  222  of the arbor body  220  as described above. The user then grasps and manually moves the drive pin plate  230  in the forward direction away from the drive shank  224  until the aperture  282  is substantially aligned with the groove  290 . As this occurs, the spring  286  biases the ball  284  into its extended position, thereby securing the axial position of the drive pin plate  230  relative to the arbor body  220  and into engagement with the hole cutter. 
     Referring now to  FIGS. 29-32 , another arbor embodying the present invention is indicated generally by the reference number  310 . The arbor  310  is substantially similar to the arbor  210  described above, and therefore like reference numerals preceded by the numeral “3” instead of the numerals “2” are used to indicate like elements. A primary difference of the arbor  310  in comparison to the arbor  210  is that in the arbor  310  the drive pin plate is replaced by an axially-elongated collar  350 . The arbor  310  comprises an axially-elongated arbor body  320  including a drive shank  324  on one end thereof, a threaded portion  322  on an opposite end thereof relative to the drive shank  324  that is engageable with the threaded aperture on the hole cutter (not shown), and an inner axially-extending bearing surface  327  located between the drive shank  324  and the threaded portion  322 . The arbor body  320  further defines a first width W, which in the illustrated embodiment is a diameter, along the inner axially-extending bearing surface  327 . 
     As shown in  FIGS. 29, 31 and 32 , the arbor  320  further comprises the aforementioned axially-elongated collar  350 , which includes an upper or distal end  397 , a lower or proximal end  399 , and a middle portion  358  defining a manually engageable surface  368  extending axially between the proximal and distal ends. The middle portion  358  defines a reduced width or diameter D 2  in comparison to the respective width or diameters D 1 , D 3  of the proximal and distal ends. The collar  350  further includes a drive member, which in the illustrated embodiment is a pair of angularly spaced drive pins  336 , extending axially from the distal end  397  of the collar  350 . The collar  350  is slidably mounted on the arbor body  320  and movable between: (i) an engaged position with the distal end  397  of the collar  350  adjacent to the threaded portion  322  for engaging the drive member  336  with the drive member aperture of a hole cutter threadedly attached to the threaded portion  322  of the arbor body  320 , and (ii) a disengaged position with the distal end  397  of the collar  350  axially spaced relative to the threaded portion  322  of the arbor body  320 . The collar  350  further defines an outer axially-extending bearing surface  363  that slidably contacts the inner axially-extending bearing surface  327  of the arbor body  320  when moving the collar between the engaged and disengaged positions. In the illustrated embodiment, the inner axially-extending bearing surface  327  defines a length L that is at least about 1¼ times the first width W of the arbor body; and preferably the axially-extending bearing surface defines a length L that is at least about 1½ times the first width W of the arbor body. 
     In the illustrated embodiment, best shown in  FIGS. 31-32 , the arbor body  320  defines a pair of inner axially-extending bearing surfaces  327 ,  327 ′ angularly spaced relative to each other, and a pair of inner curvilinear axially-extending bearing surfaces  385 ,  385 ′ angularly spaced relative to each other between the inner axially-extending bearing surfaces  327 ,  327 ′. Additionally, the collar  350  defines a pair of outer axially-extending bearing surfaces  363 ,  363 ′ angularly spaced relative to each other, and a pair of outer curvilinear axially-extending bearing surfaces  389 ,  389 ′ angularly spaced relative to each other between the outer axially-extending bearing surfaces  363 ,  363 ′. The pair of inner axially-extending bearing surfaces  327 ,  327 ′ slidably engage the pair of outer axially-extending bearing surfaces  363 ,  363 ′, and the pair of inner curvilinear axially-extending bearing surfaces  385 ,  385 ′ slidably engage the pair of outer curvilinear axially-extending bearing surfaces  389 ,  389 ′, when moving the collar  350  between the engaged and disengaged positions. In the illustrated embodiment, the pair of inner axially-extending bearing surfaces  377 ,  327 ′ are substantially flat and are located on substantially opposite sides of the arbor body  320  relative to each other, and the pair of outer axially-extending bearing surfaces  363 ,  363 ′ are substantially flat and are located on substantially opposite sides of the collar  350  relative to each other. However, as may be recognized by one skilled in the art based on the teachings herein, surfaces  327 ,  327 ′,  363 ,  363 ′ can take on any of numerous different configurations that are currently known or that later become known; for example, the surfaces could include a plurality of mating protrusions and recesses, and the surfaces need not be located on substantially opposite sides of the arbor body and collar respectively. 
     In the illustrated embodiment, each curvilinear axially-extending bearing surface  385 ,  385 ′,  389 ,  389 ′ is defined by a diameter of the collar  350  or arbor body  320 , respectively. Also in the illustrated embodiment, the outer axially-extending bearing surfaces  363 ,  363 ′ are shorter than the inner axially-extending bearing surfaces  327 ,  327 ′. The collar  350  defines a pair of axially-extending recessed surfaces  391 ,  391 ′ located on substantially opposite sides of the collar relative to each other, and each recessed surface  391 ,  391 ′ extends between a respective axially-extending bearing surface  363 ,  363 ′ and the proximal end  399  of the collar. The collar  350  further defines a pair of first stop surfaces  393 ,  393 ′. Each first stop surface  393 ,  393 ′ is formed between an axially-extending recessed surface  391 ,  391 ′ and a respective outer axially-extending bearing surface  363 ,  363 ′. Additionally, the arbor body  320  defines a pair of second stop surfaces  395 ,  395 ′. Each second stop surface  395 ,  395 ′ is formed at a proximal end of a respective inner axially-extending bearing surface  327 ,  327 ′. The first and second stop surfaces are configured to engage each other when the collar  350  is in the disengaged position to prevent further proximal axial movement of the collar  350 . The second stop surfaces  395 ,  395 ′ are defined by respective lips  396 ,  396 ′ formed on the arbor body  320 , and the lips  396 ,  396 ′ and recessed surfaces  391 ,  391 ′ form bearing surfaces that slidably contact each other when moving the collar  350  between the engaged and disengaged positions. 
     As shown in  FIG. 29 , the collar  350  further defines a distal rim  357  at the distal end  397  of the collar, a proximal rim  359  at the proximal end  399  of the collar, and an annular manually engageable surface  368  extending between the proximal and distal rims. In the illustrated embodiment, the distal and proximal rims  357 ,  359  are defined by a first diameter (D 1  or D 3 ), and the manually engageable surface  368  is defined by a second diameter D 2  that is less than the first diameter (D 1  or D 3 ). Preferably, the second diameter D 2  is within the range of about 70% to about 95% of the first diameter (D 1  or D 3 ); and most preferably, the second diameter D 2  is within the range of about 80% to about 90% of the first diameter (D 1  or D 3 ). Also in the illustrated embodiment, the proximal and distal rims are substantially defined by the first diameter (i.e. D 1  equals D 3 ). As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, these dimensions, and the specific shapes and configurations illustrated are only exemplary, and may be changes as desired or otherwise required. 
     As shown in  FIG. 29 , the manually engageable surface  368  defines an axial length L 2 , and the proximal and distal rims each define an axial length (L 1  and L 3 , respectively), and the axial length of the manually engageable surface L 2  is greater than the axial length of each of the proximal and distal rims L 1 , L 3 . Preferably, the axial length L 2  of the manually engageable surface is about 30% to about 60% greater than the axial length of each of the proximal and distal rims L 1 , L 3 . 
     Drawing attention to  FIGS. 30 and 31 , the arbor  310  further comprises a retaining member  380  mounted on the collar  350  and movable between (i) a first position holding the collar  350  in the engaged position, and (ii) a second position allowing axial movement of the collar  350  from the engaged position to the disengaged position. In the illustrated embodiment, the retaining member  380  is a ball detent mechanism similar to the mechanism  280  described above. However, as may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, the retaining member  380  can be of any of numerous different types of retaining members that are currently known or that later become known to retain the axial position of the collar  350  relative to the arbor body  320  and/or to prevent the collar  350  from slipping out of engagement with the hole cutter (not shown) during use. 
     As may be recognized by those of ordinary skill in the pertinent art based on the teachings herein, numerous changes and modifications may be made to the above-described and other embodiments of the present invention without departing from the scope of the invention as defined in the appended claims. For example, the components of the arbor may take on any of numerous different configurations, or may be formed of any of numerous different materials, that are currently known, or that later become known; any of a variety of the disclosed components may be eliminated, or additional components or features may be added; and the arbors may be used with any of numerous different types of tools that are currently known, or that later become known. For example, the retaining members may can be of any of numerous different types that are currently known or that later become known, such as, for example, cylindrical or tapered drive pins, that engage corresponding apertures on a hole cutter, or drive dogs defining flats that engage corresponding apertures or recesses on the hole cutter. Similarly, the drive pin apertures or recesses can take any of numerous different configurations for receiving or otherwise engaging any of numerous different types of drive members. The drive pin member or plate can likewise can take any of numerous different configurations, including, for example, a plate form or a circular or other shaped collar or housing that is movable relative to the arbor body and includes one or more drive pins. The threads on the arbor connecting portion and/or on the central aperture of the hole cutter can take the form of the standard or timed threads (or combinations thereof) as described above, or can take the form of any of numerous different thread configurations that are currently known, or that later become known. Alternatively, the connecting portion and/or central aperture of the hole cutter may define a structure other than threads for engaging the hole cutter to the arbor upon moving the arbor and/or hole cutter relative to the other between the first and second engagement positions. Furthermore, as may be recognized by those or ordinary skill in the pertinent art based on the teachings herein, the retaining member can be of any of numerous types of retaining members that are currently known or that later become known to secure or otherwise return the axial position of the drive pin plate and/or collar relative to the arbor body during use and/or to prevent the drive pin plate and/or collar from slipping out of engagement with the hole cutter; additionally, more than one retaining member could be employed. Accordingly, this detailed description of the currently-preferred embodiments is to be taken in an illustrative, as opposed to a limiting sense.