Patent Abstract:
A reciprocating saw having a clamping arrangement with a clamp support base, first and second locking members and a release lever. The clamp support base defines first and second blade slots that are each configured to receive a saw blade therein. Each of the first and second locking members are movable between a disengaged position, which does not inhibit withdrawal of the saw blade from the a corresponding one of the first and second blade slots, and an engaged position that inhibits withdrawal of the saw blade from the corresponding one of the first and second blade slots. The release lever is pivotally coupled to the clamp support base and coordinates movement of the first and second locking members.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a division of U.S. application Ser. No. 12/731,934 filed Mar. 25, 2010, the disclosure of which is incorporated by reference as if fully set forth in detail herein. 
     
    
     FIELD 
       [0002]    The present disclosure relates in general to power tools. In particular, the present disclosure relates to a pivoting blade retainer for power tools having a saw blade mounted to a shaft for reciprocating cutting motion. 
       BACKGROUND 
       [0003]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0004]    Power reciprocating saws including jigsaws and other reciprocating saws are generally referred to in the trade as “recip” saws. These saws incorporate reciprocating drive shafts. The drive shafts can operate to drive generally linear saw blades along a predetermined path so as to provide one of a rectilinear or orbital cutting action. 
         [0005]    In a conventional manner, the saw blades used with such power tools can be attached to the reciprocating drive shafts through a blade holder having a slot for receiving the saw blade and a set screw which can be received in a hole in the blade. The blade can be clamped in place relative to the reciprocating drive shaft through tightening of the set screw. While this conventional manner of saw blade attachment has proven to be generally satisfactory and commercially successful, it is nonetheless desirable to provide an improved blade clamping mechanism. 
       SUMMARY 
       [0006]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0007]    A saw blade clamping arrangement for a power tool is disclosed. The saw blade clamping arrangement can be operatively configured for use with a power tool that includes a housing and a drive shaft mounted for reciprocating motion relative to the housing and having a longitudinal drive axis. A saw blade can be releasably interconnected with the drive shaft for reciprocating motion along a longitudinal axis. The saw blade clamping arrangement can include a clamp support base that is operatively coupled for movement with the drive shaft and has a first and a second, saw blade slots. First and second locking members can be operatively associated with the clamp support base and be movable between a locked position that selectively locks the blade in one of the corresponding first and second slots, and an unlocked position that releases the blade. 
         [0008]    A release lever can have a user engagement portion, a first cam surface and a second cam surface. The release lever can be mounted relative to the clamp support base for rotational movement about a pivot axis. The release member can be movable between a first position that corresponds to the locked position and a second position that corresponds to the unlocked position. Rotation of the release lever from the second position to the first position can cause the first cam surface to urge the first locking member at least partially into the first slot and the second cam surface to concurrently urge the second locking member at least partially into the second slot. 
         [0009]    According to additional features, the release lever can be unitary. A pivot pin can be coupled to the support base that defines a pivot axis that the release member rotates about. The pivot pin can be coupled to the support base at a location that can be equidistant and/or in line with the first and second slots. A biasing member can be operably associated with the clamp support base that urges the release lever into the first position. 
         [0010]    According to other features, the first and second cam members can directly contact the first and second locking members in the locked position. The first and second locking members can be spherically shaped. The release lever can include first and second concave surfaces that align with and nestingly receive the first and second locking members in the unlocked position. The clamp support base can define a first and a second cavity that accommodate the first and second locking members, respectively. The clamp support base can define a first and a second groove that oppose the respective first and second cam surfaces of the release lever. The release lever can be configured to rotate through substantially about forty-five degrees of motion around the pivot axis between the first position and the second position. 
         [0011]    According to additional features, the release lever can be configured to alternatively lock either the first or the second locking member in the locked position. 
         [0012]    In a further form, the present teachings provide a reciprocating saw that includes a housing, a drive shaft coupled to the housing for reciprocating motion along an axis and a clamping arrangement having a clamp support base, first and second locking members, a pivot pin, and a release lever. The clamp support base is coupled to the drive shaft for movement therewith and defines a first blade slot, a first cavity, a second blade slot and a second cavity. The first blade slot extends parallel to the axis and is configured to receive a saw blade therein. The first cavity is adjacent to the first blade slot. The second blade slot extends parallel to the axis and is configured to receive the saw blade therein. The second cavity is adjacent to the second blade slot. The first locking member is received in the first cavity and movable between a disengaged position, which does not inhibit withdrawal of the saw blade from the first blade slot, and an engaged position that inhibits withdrawal of the saw blade from the first blade slot. The second locking member is received in the second cavity and movable between a disengaged position, which does not inhibit withdrawal of the saw blade from the second blade slot, and an engaged position that inhibits withdrawal of the saw blade from the second blade slot. The pivot pin is coupled to the clamp support base. The release lever has a first unlocking surface, a second unlocking surface and a cam surface disposed between the first and second locking surfaces. The release lever is pivotally mounted on the pivot pin and movable between a first closed position and a second closed position. When the release lever is in the first closed position, the first unlocking surface is disposed in-line with the first cavity, permitting movement of the first locking member from its engaged position to its disengaged position, and the cam surface is in-line with the second cavity preventing movement of the second locking member from its engaged position to its disengaged position. When the release lever is in the second closed position, the cam surface is in-line with the first cavity preventing movement of the first locking member from its engaged position to its disengaged position, and the second unlocking surface is disposed in-line with the second cavity, permitting movement of the second locking member from its engaged position to its disengaged position. 
         [0013]    In another form, the present teachings provide a reciprocating saw that includes a housing, a drive shaft coupled to the housing for reciprocating motion along an axis and a clamping mechanism with a clamp support base, first and second locking members, a pivot pin, and a release lever. The clamp support base is coupled to the drive shaft for movement therewith and defines a first blade slot, a first cavity, a second blade slot and a second cavity. The first blade slot extends parallel to the axis and is configured to receive a saw blade therein. The first cavity is adjacent to the first blade slot. The second blade slot extends parallel to the axis and is configured to receive the saw blade therein. The second cavity is adjacent to the second blade slot. The first locking member is received in the first cavity and is movable between a disengaged position, which does not inhibit withdrawal of the saw blade from the first blade slot, and an engaged position that inhibits withdrawal of the saw blade from the first blade slot. The second locking member is received in the second cavity and is movable between a disengaged position, which does not inhibit withdrawal of the saw blade from the second blade slot, and an engaged position that inhibits withdrawal of the saw blade from the second blade slot. The pivot pin is coupled to the clamp support base. The release lever is pivotally mounted on the pivot pin and movable between a first position and a second position. Rotation of the release lever about the pivot pin between the first and second positions coordinates movement of the first and second locking elements between their disengaged and engaged positions. 
         [0014]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0015]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0016]      FIG. 1  is a front perspective view of an exemplary reciprocating saw that incorporates a clamping arrangement constructed in accordance to the present teachings, the saw blade clamping arrangement shown operatively associated with a saw blade in a first orientation; 
           [0017]      FIG. 2  is a perspective view illustrating a portion of the exemplary reciprocating saw of  FIG. 1 , the saw blade clamping arrangement shown operatively associated with the saw blade in a second orientation; 
           [0018]      FIG. 3  is a perspective view illustrating a portion of the reciprocating saw of  FIG. 1 , the saw blade clamping arrangement shown operatively associated with the saw blade in a third orientation; 
           [0019]      FIG. 4  is a perspective view illustrating a portion of the reciprocating saw of  FIG. 1 , the saw blade clamping arrangement shown operatively associated with the saw blade in a fourth orientation; 
           [0020]      FIG. 5  is an exploded perspective view of the saw blade clamping arrangement of  FIG. 1  and shown with an exemplary saw blade; 
           [0021]      FIG. 6  is a cross-sectional view of the saw blade clamping arrangement of  FIG. 5  and taken along lines  6 - 6 , the saw blade clamping arrangement shown with a release lever in the closed position; 
           [0022]      FIG. 7  is a cross-sectional view of the saw blade clamping arrangement of  FIG. 6  and shown with the release lever in the open position; 
           [0023]      FIG. 8  is a cross-sectional view of a saw blade clamping arrangement according to additional features and shown with a release lever in a first closed position; 
           [0024]      FIG. 9  is a cross-sectional view of the saw blade clamping arrangement of  FIG. 8  and shown with the release lever in a second closed position; and 
           [0025]      FIG. 10  is a front perspective view of the clamp support base. 
       
    
    
       [0026]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0027]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0028]    The present disclosure provides an improved saw blade clamping arrangement for a power tool. While shown throughout the drawings in one embodiment for a saw blade clamping arrangement specifically adapted for a reciprocating saw, those skilled in the art will appreciate that the disclosure is not so limited in scope. In this regard, the various teachings of the present disclosure will be understood to be readily adaptable for use with any power tool incorporating one or more reciprocating cutting members (e.g., reciprocating saws, jigsaws, various surgical saws and culinary knives, etc.). 
         [0029]    With reference now generally to the drawings in which identical or equivalent elements have been denoted with like reference numerals, and specifically to  FIGS. 1-4  thereof, an exemplary power tool is shown and generally identified at reference numeral  10 . The exemplary power tool  10  embodies the teachings of the present disclosure and is illustrated in  FIG. 1  as a power reciprocating saw. In a conventional manner, the power reciprocating saw  10  can be powered by a motor (not shown) that can be actuated by a trigger switch  12 . The delivery of electrical energy to the motor through a power cord (partially shown at reference numeral  14 ) can be controlled by the trigger switch  12 . In other examples, the power tool  10  can be alternatively powered by a battery. 
         [0030]    In the exemplary embodiment illustrated, the power tool  10  can include a handle portion  16  that carries the trigger switch  12 . The power tool  10  can also include a housing  18  that has a centrally located motor housing portion  20  and a forwardly located gear case housing portion  22 . The power tool  10  can further include a drive shaft  26  that partially extends within a drive shaft channel (not specifically shown) and operatively connected with a drive mechanism (not specifically shown) housed within the gear case housing portion  22 . The inner connection between the drive mechanism and the drive shaft  26  can be in any manner well known in the art. The drive shaft  26  can be mounted for reciprocating motion generally along a longitudinal axis defined by the power tool  10 . A button or cover  28  can be arranged on the gear case housing portion  22  that communicates with a release lever as will become appreciated from the following discussion. 
         [0031]    The drive shaft  26  can be adapted to cooperate with a cutting member, such as a saw blade  30  (see also  FIG. 5 ) for driving the saw blade  30  back and forth in a cutting motion along a rectilinear path. In this regard, the reciprocating drive shaft  26  can be formed to include a transversely extending aperture for receiving a drive pin (not specifically shown). Additional description of the drive shaft  26  and its operation relative to other components of the power tool  10  may be found in commonly owned U.S. Pat. No. 7,325,315, which is expressly incorporated herein by reference. 
         [0032]    With brief reference now to  FIG. 5 , the exemplary saw blade  30  can conventionally include a forwardly located cutting portion  34  that has teeth  35  and is integrally formed with a rearwardly located mounting portion  36 . In a manner well known in the art, an aperture or blade hole  38  can be formed in the mounting portion  36  of the saw blade  30 . As will become appreciated from the following discussion, the aperture  38  is operable to selectively receive locking members to secure the position of the saw blade  30  relative to the power tool  10 . 
         [0033]    Returning now to  FIGS. 1-4 , the power tool  10  of the present disclosure further includes a clamping arrangement  50  for releasably maintaining the saw blade  30  in operative connection with the reciprocating drive shaft  26 . The saw blade clamping arrangement  50  according to the present disclosure can be operable to accommodate the saw blade  30  in various orientations. As will become appreciated below, this aspect of the present disclosure can provide a user of the power tool  10  with improved flexibility to avoid obstacles that may be encountered during cutting operations. 
         [0034]    Prior to addressing the specific construction and operation of the clamping arrangement  50 , a brief description of the various saw blade orientations will be explained.  FIG. 1  illustrates a first cutting position in which the blade  30  can be disposed in a generally vertical plane and the teeth  35  of the blade  30  can be oriented downward. The blade orientation as illustrated in  FIG. 1  is typical of known reciprocating saws. As illustrated in  FIG. 2 , a second cutting position is shown in which the blade  30  can again be oriented in a generally vertical plane. In the second cutting position, the teeth  35  of the blade  30  can be oriented upward. Turning now to  FIG. 3 , a third cutting position in which the blade  30  can be oriented in a generally horizontal plane is shown. In the third position, the cutting position is perpendicular as compared to the first and second cutting positions. As illustrated in  FIG. 4 , a fourth cutting position is shown in which the blade  30  can again be oriented in a generally horizontal plane. In the fourth cutting position, the teeth  35  of the blade  30  can be oriented in a generally opposite direction to the third cutting position shown in  FIG. 3 . 
         [0035]    With additional reference now to  FIG. 5 , the clamping arrangement  50  can generally include a clamp support base  52 , a pivoting blade retainer or release lever  54 , a first locking member  56  and a second locking member  58 . According to the exemplary embodiment illustrated, the first and second locking members  56  and  58  can be in the form of spherical balls. Other configurations are contemplated such as, but not limited to cylindrical, oval, oblong and pin-shaped. The first and second locking members  56  and  58  can be formed of rigid material, including metal, such as stainless steel for example. The clamp support base  52  can define a first or vertical slot  60  for receiving the blade  30  in either the first cutting position (as shown in  FIG. 1 ) or the second cutting position (as shown in  FIG. 2 ). The clamp support base  52  can further include a second or horizontal slot  62 . The second slot  62  can receive the saw blade  30  in the third cutting position ( FIG. 3 ) or the fourth cutting position ( FIG. 4 ). Notably, the second slot  62  can be spaced relative to the first slot  60 . In this manner, the saw blade  30  can be off-center relative to the drive shaft  26  and positioned proximate to a sidewall of the tool housing  18 . Such positioning of the saw blade  30  closer to the sidewall of the tool housing  18  can facilitate a flush cutting of a workpiece with the saw blade  30 . Furthermore, the first slot  60  and the second slot  62  can be arranged in a non-intersecting manner on the clamp support base  52 . Other configurations such as intersecting are contemplated. 
         [0036]    Briefly, with continued reference to  FIG. 5  and additional reference to  FIGS. 6 and 7 , the release lever  54  of the saw blade clamping arrangement  50  can be operable to rotate between a first or closed position ( FIG. 6 ) where the first and second locking members  56  and  58  are urged into the first and second slots  60  and  62 , respectively, for engagement with a saw blade  30 . For illustrative purposes, the saw blade  30  is shown secured relative to the second cavity  62  however it is appreciated that the saw blade can similarly be positioned in the first cavity  60 . The release lever  54  can be selectively rotated to an unlocked or open position where the first and second locking members  56  and  58  are permitted to retract away from the first and second slots  60  and  62  in a direction toward the release lever  54 , such that the blade  30  can be selectively removed from the first or second slot  60  and  62 . 
         [0037]    The clamp support base  52  can include a mounting bore  70  that selectively receives a fastener or other mounting hardware for coupling a dust cover  71  ( FIG. 10 ). The clamp support base  52  can further include a first locking ball cavity  72  and a second locking ball cavity  74 . The first and second locking ball cavities  72  and  74  can be arranged for at least partially accommodating the first and second locking members  56  and  58 , respectively. A first groove  80  can be formed on the clamp support base  52  adjacent to the first slot  60 . The first groove  80  can oppose the first locking member  56  when release lever  54  is in the closed position ( FIG. 6 ). A second groove  82  can be formed in the clamp support base  52  that opposes the second locking member  58  when the release lever  54  is in the locked position ( FIG. 6 ). 
         [0038]    The release lever  54  can generally include a user interaction portion  84  and a locking portion  86 . The release lever  54  can be fixedly mounted around a pin  90  that is rotatably coupled to the clamp support base  52 . The release lever  54  can define a passage  91  that receives the pin  90 . In general, the release lever  54  can rotate with the pin  90  around an axis  92  defined by the pin  90  between the closed position ( FIG. 6 ) and the open position ( FIG. 7 ). In other examples, the release lever  54  can rotate around the pin  90  that is fixed relative to the clamp support base  52 . In the example shown, the release lever  54  can rotate about forty-five degrees around the pin  90  between the closed and open positions. Other configurations are contemplated. According to one example, the release lever  54  can be a unitary piece formed of rigid material, such as metal including stainless steel for example. A positive stop  93  can be provided on the release lever  54  that engages a surface of the clamp support base  52  ( FIG. 7 ) to preclude over-rotation in the counterclockwise direction as viewed in  FIG. 7 . A similar positive stop (not specifically shown) can be provided to preclude over-rotation in the clockwise direction. 
         [0039]    The locking portion  86  of the release lever  54  will now be described in greater detail. The locking portion  86  can have an engaging surface  96  that collectively includes a first concave surface  100 , a first cam surface  102 , a second concave surface  104  and a second cam surface  106 . In one example, the first and second concave surfaces  100  and  104  can substantially match the outer profile of the first and second locking members  56  and  58 , respectively. Notably, a smooth arcuate transition can be provided along the engaging surface  96  from the first and second concave surfaces  100  and  104  to the first and second cam surfaces  102  and  106 , respectively. The smooth arcuate transitions can facilitate a smooth and uniform engagement of the release lever  54  with the first and second locking members  56  and  58  during rotation of the release lever  54  between the closed and open positions. 
         [0040]    As illustrated in  FIG. 6 , with the release lever  54  in the closed position the first cam surface  102  of the locking portion  86  is substantially aligned for engagement with the first locking member  56  and the second cam surface  106  is substantially aligned for engagement with the second locking member  58 . In this regard, the respective first and second cam surfaces  102  and  106  can operatively urge the first and second locking members  56  and  58  at least partially into the respective first and second slots  60  and  62  in the closed position. With the first and second locking members  56  and  58  urged at least partially into the respective first and second slots  60  and  62 , the first and second locking members  56  and  58  can engage the blade  30 , such as at the blade hole  38 , to lock the blade  30  to the clamp support base  52  at the first or second slot  60 ,  62 . In one example, a biasing member  110  can be arranged for urging the release level  54  into the closed position illustrated in  FIG. 5 . A biasing member  110 ′ ( FIGS. 6 and 7 ) can additionally or alternatively be arranged around the pin  90  for urging the release lever  54  into the closed position. 
         [0041]    With specific reference now to  FIGS. 6 and 7 , rotation of the release lever  54  from the locked position ( FIG. 6 ) into the unlocked position ( FIG. 7 ) will be described. Rotation of the release lever  54  in the counterclockwise direction as viewed in  FIG. 7  can align the first and second concave surfaces  100  and  104  with the respective first and second locking members  56  and  58  and allow the respective first and second locking members  56  and  58  to at least partially withdraw from the first and second slots  60  and  62 . Concurrently, the first and second locking members  56  and  58  can be permitted to nestingly locate against the first and second concave surfaces  100  and  104  of the locking portion  86  of the release lever  54 . 
         [0042]    As can be appreciated, with the first and second locking members  56  and  58  retracted away from the first and second slots  60  and  62 , the saw blade  30  can be removed from the first or second slot  60 ,  62 . It will also be appreciated that manual withdrawal of the saw blade  30  can further encourage the first and second locking members  56  and  58  to move toward the first and second concave surfaces  100  and  104  by a ramping action of the first and second locking members over the saw blade  30  at the blade hole  38 . According to the exemplary embodiment, a distance D 1  measured between the pivot axis  92  and the first slot  60  can be equidistant and/or in line with a second distance D 2  measured between the pivot axis  92  and the second slot  62 . Such a relationship can facilitate uniform force transmission onto the first and second locking members  56  and  58  during rotation of the release lever  54  to the closed position. 
         [0043]    Rotation of the release lever  54  from the open position ( FIG. 7 ) back to the closed position ( FIG. 6 ) will be briefly described. As the release lever  54  rotates in a clockwise direction as viewed from  FIG. 7 , the first locking member  56  transitions from engagement with the first concave surface  100  into engagement with the first cam surface  102 . As identified above, a transition from the first concave surface  100  to the first cam surface  102  along the engaging surface  96  can be a smooth arcuate surface that encourages a smooth ramping movement along the outer surface of the first locking member  56 . Similarly, the second locking member  58  transitions along the engaging surface  96  from engagement with the second concave surface  104  to the second cam surface  106 . Again, the transition from the second concave surface  104  to the second cam surface  106  on the locking portion  86  of the release lever  54  can include a generally smooth and arcuate surface that promotes a smooth ramping engagement with the second locking member  58 . Rotation back to the closed position is further encouraged by the biasing force of the biasing member  110  (and/or  110 ′). 
         [0044]    The blade clamping arrangement  50  according to the present teachings can be particularly robust over other blade clamps. More particularly, the blade clamp arrangement  50  can require only a rotational motion of a release lever that cams retaining balls into contact with a blade. Secondary components, such as sliders, etc. and/or additional motions, such as linear translations etc. are not necessary. In this regard, the blade clamping arrangement  50  can be less prone to binding up such as a result of debris build up, contamination or rust for example. 
         [0045]    Turning now to  FIGS. 8 and 9 , a clamping arrangement  150  constructed in accordance to additional features of the present teachings will be shown. Unless otherwise described herein, the clamping arrangement  150  can be constructed similar to the clamping arrangement  50  described above and shown in  FIGS. 6 and 7 . In this regard, like features have been identified with similar reference numerals increased by  100 . The clamping arrangement  150  can generally include a clamp support base  152 , a pivoting blade retainer or release lever  154 , a first locking member  156  and a second locking member  158 . According to the exemplary embodiment illustrated, the first and second locking members  156  and  158  can be in the form of spherical balls however other shapes such as described above with respect to the first and second locking members  56  and  58  are contemplated. 
         [0046]    The clamp support base  152  can define a first or vertical slot  160  receiving the blade  30  in either the first cutting position (as shown in  FIG. 1 ) or the second cutting position (as shown in  FIG. 2 ). The clamp support base  152  can further include a second or horizontal slot  162 . The second slot  162  can receive the saw blade  30  in the third cutting position ( FIG. 3 ) or the fourth cutting position ( FIG. 4 ). As will become appreciated from the following discussion, the release lever  154  is movable between a first closed position as shown in  FIG. 8  that clamps a saw blade  30  within the vertical cut slot  160  and a second closed position as illustrated in  FIG. 9  that clamps the saw blade  30  in the horizontal cut slot  162 . 
         [0047]    With specific reference now to  FIG. 8 , the release lever  154  of the saw blade clamping arrangement  150  can be operable to rotate between the first closed position where the first locking member  156  is urged into the first slot  160  for engagement with a saw blade  30 . While the release lever  154  is urging the first locking member  156  into locking engagement with the saw blade  30  in the first slot  160 , the second locking member  158  is in a retracted position relative to the horizontal slot  162 . With specific reference to  FIG. 9 , with the release lever  154  rotated into the second closed position, the first locking member  156  is retracted from the vertical slot  160  and the second locking member  158  is urged into the second slot  162  for engagement with a saw blade  30 . 
         [0048]    The clamp support base  152  can further include a first locking ball cavity  172  and a second locking ball cavity  174 . The first and second locking ball cavities  172  and  174  can be arranged for accommodating at least portions of the first and second locking members  156  and  158 , respectively. The release lever  154  can generally include a user interaction portion  184  and a locking portion  186 . The release lever  154  can be fixedly mounted around a pin  190  that is rotatably coupled to the clamp support base  152 . In general, the release lever  154  can rotate with the pin  190  between the first closed position ( FIG. 8 ) and the second closed position ( FIG. 9 ). In other configurations, the release lever  154  can rotate around the pin  190  that is fixed relative to the clamp support base  152 . In the example shown, the release lever  154  can rotate about ninety degrees with the pin  190  between the first and second closed positions. Other configurations are contemplated. 
         [0049]    The locking portion  186  of the release lever  154  will now be described in greater detail. The locking portion  186  can have an engaging surface  196  that collectively includes a first concave surface  200 , a cam surface  202 , and a second concave surface  204 . In one example, the first and second concave surfaces  200  and  204  can substantially match the outer profile of the first and second locking members  156  and  158 , respectively. A smooth, arcuate transition can be provided along the engaging surface  196  from the first and second concave surfaces  200  and  204  to the cam surface  202 . The smooth arcuate transition can facilitate a smooth and uniform engagement of the release lever  154  with the first and second locking members  156  and  158  during rotation of the release lever  154  between the first and second closed positions. 
         [0050]    With particular reference now to  FIG. 8 , with the release lever  154  in the first closed position, the cam surface  202  of the locking portion  186  is substantially aligned for engagement with the first locking member  156  and the second concave surface  204  is substantially aligned for engagement with the second locking member  158 . In this regard, the cam surface  202  can operatively urge the first locking member  156  at least partially into the first slot  160  in the first closed position. With the first locking member  156  urged at least partially into the first slot  160 , the first locking member  156  can engage the blade  30 , such as at the blade hole  38 , to lock the blade  30  to the clamp support base  152  at the first slot  160 . 
         [0051]    With reference now  FIG. 9 , with the release lever  154  in the second closed position, the cam surface  202  of the locking portion  186  is substantially aligned for engagement with the second locking member  158  and the first concave surface  200  is substantially aligned for engagement with the first locking member  156 . In this regard, the cam surface  202  can operatively urge the second locking member  158  at least partially into the second slot  162  in the second closed position. With the second locking member  158  urged at least partially into the second slot  162 , the second locking member  158  can engage the blade  30 , such as at the blade hole  38 , to lock the blade  32  to the clamp support base  152  at the second slot  162 . 
         [0052]    Turning now to  FIG. 10 , additional features of the clamp support base  52  will be described. While the foregoing additional features are described with respect to the clamp support base  52 , they may also be incorporated in the clamp support base  152 . For illustrative purposes, the release lever  54  and biasing member  110  have been removed. As shown, a pair of opposing rails  220  and  222  can extend from walls  224  and  226 , respectively on the clamp support base  52 . The walls  224  and  226  can have arcuate surfaces  227  and  228  that define apertures  230  and  232 , respectively that support the pin  90  ( FIGS. 6 and 7 ). A width of the release lever  54  can be configured to slidably engage respective surfaces of the opposing rails  220  and  222 . 
         [0053]    In one advantage, friction can be reduced on the release lever  54  as it may only slidably engage the reduced surface area of the rails  220  and  222  as opposed to the entire surface of the walls  224  and  226 . Furthermore, the rails  220  and  222  can encourage dust and debris to be scraped or otherwise removed from the outer surfaces of the release lever  54  during rotation of the release lever  54  with the pin  90 . In this regard, the rails  220  and  222  can minimize the surface area that can be contaminated by dust and debris. Moreover, the pin  90  can rotate around the arcuate surfaces  227  and  228  defining the apertures  230  and  232  (rather than the release lever  54  rotating around the pin  90 ). As the collective surface area of the surfaces  227  and  228  is relatively smaller than a surface area defined by the passage  91  ( FIG. 6 ) through the release lever  54 , a reduced friction can be realized during rotation of the release lever  54 . In addition, the friction areas (i.e., the surfaces of the opposing rails  220  and  222 ) that slidably engage the release lever  54  and the arcuate surfaces  227  and  228  that slidably engage the pin  90  are near the center of rotation of the release lever  54  (i.e., axis  92 ). In this regard, the moment arm created by the release lever  54  around the axis  92  can offer a user a mechanical advantage that can overcome the friction described above with minimal resistance during rotation of the release lever  54 . 
         [0054]    The dust cover  71  is shown covering the second slot  62 . The dust cover  71  can include a protruding tab  234  for user engagement during rotation. The dust cover  71  can be rotated about a pivot axis  236  to cover an entrance to the first slot  60 . 
         [0055]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Technology Classification (CPC): 1