Patent Publication Number: US-2012032382-A1

Title: Movable work piece clamping mechanism

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to power tools and more specifically, to a clamping mechanism for securing work pieces on such tools. 
     Many power tools and particularly table saws typically include a frame with a table top having an upper surface and a blade extending through an opening in the upper surface. The upper surface supports a work piece, such as a piece of wood, as it is pushed towards the blade for cutting. Relatively large stand-alone table saws are able to cut larger and heavier work pieces whereas the smaller portable table saws are used mostly for smaller work pieces. 
     A guide fence, such as a rip fence or a miter fence, is commonly attached to table saws for aligning and guiding a work piece during cutting. Rip fences are generally removable and can be adjustably positioned relative to the blade, and usually extend from the front to the rear of the table top and are oriented in a direction parallel to the plane of the saw blade. Miter fences generally have a lower extension that fits in a slot in the table top that is parallel to the plane of the blade and have a front fence surface that can be used to push the work piece through a cutting region adjacent to the cutting blade. A miter fence generally can either be fixed to the table top where a section of the table top is movable in a direction parallel to the blade so that the miter fence can support the work piece as the work piece and the sliding table top section are pushed through the blade, or the miter fence can be movable about a section of the table top that is fixed and the user manually pushes the miter fence and the work piece through the blade. 
     There are universal fences that are commercially marketed that perform the function of a miter fence as well as a rip fence and are particularly useful for table saws that are known as push-pull saws that are more prevalent in European markets than in the United States. This particular type of saw has a cutting blade that is mounted to a carriage assembly that rides along guide rails, elongated rods or the like underneath the saw table top, with the blade extending upwardly through an elongated slot. The blade can be vertically adjusted as well as angularly adjusted for bevel cuts and can be operated in the same manner as conventional table saws commercialized in the United States where a work piece is moved along the table top to engage the blade and make a cut. 
     The push-pull saw can also be operated in a manner wherein the user can manually pull a handle or knob to move the saw blade and carriage assembly from the rear part of the slot forwardly to make cuts on a work piece that is placed at a stationary position on the table top. Universal fences used with such push-pull saws are generally mounted on table top near the front or left of the saw blade to position and guide the work piece. When the saw is pulled toward the front, the saw blade is brought into cutting position to cut through the work piece. 
     During cutting, a user typically places one of their hands on the work piece to hold the work piece against the fence. By placing one or both hands on the work piece in close proximity to the cutting blade, the risk of a user&#39;s hands being injured by the blade is increased. The work piece can also move away from the fence during cutting causing inaccurate cuts. In some circumstances, a separate tool, such as a push stick, is used to engage and push the work piece into the cutting blade. The tool enables a user to position their hands away from the work piece thereby lessening the risk of injury. However, such tools are not secured to the work piece or the fence. As a result, the work piece can still move out of position relative to the fence, which leads to inaccurate cuts and wasted material. 
     Existing methods of guiding work pieces through a cutting blade on a table saw therefore pose significant safety issues and can increase costs due to cutting inaccuracies and waste. 
     SUMMARY OF THE INVENTION 
     Embodiments are disclosed for a clamping mechanism for securing a work piece on a power tool having a working surface and a guide fence. The clamping mechanism includes a support configured to be movable along the guide fence and a clamp interconnected to the support, the clamp being movable between a securing position and a release position, wherein in the securing position, the clamp engages a work piece, and in the release position, the clamp is disengaged from the work piece. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a power table saw including a clamping mechanism in accordance with an embodiment of the present invention. 
         FIG. 2  is a side perspective view of the clamping mechanism of the present invention. 
         FIG. 3  is an enlarged exploded view of the clamping mechanism of  FIG. 2 . 
         FIG. 4  is a cross-section view of the clamping mechanism and bracket attached to the fence shown in  FIG. 1 . 
         FIG. 5  is a perspective view of the bracket that secures the clamping mechanism to the fence. 
         FIG. 6  is a cross-section view of the clamping mechanism shown in  FIG. 4  taken substantially along line  6 - 6 . 
         FIG. 7  is a cross-section view of the securing member that secures the position of the bracket relative to the fence where the bottom end of the securing member is disengaged from the inner surface of the channel defined by the fence. 
         FIG. 8  is a cross-section view of the securing member of  FIG. 7  where the securing member is engaged with the inner surface of the channel. 
         FIG. 9A  is a schematic drawing of the clamping mechanism secured to the fence where the clamping mechanism is in the release position. 
         FIG. 9B  is a schematic drawing of the clamping mechanism of  FIG. 9A  where the clamping mechanism is in the securing position. 
         FIG. 10  is a front perspective view of another embodiment of the clamping mechanism where the clamping mechanism is secured to a fence relative to a work piece. 
         FIG. 11  is a rear perspective view of the clamping mechanism shown in  FIG. 10 . 
         FIG. 12  is a side view of the clamping mechanism of  FIG. 10  showing the clamping mechanism in the securing position and the release position. 
         FIG. 13  is a side perspective view of another embodiment of the ratchet assembly associated with the clamping mechanism. 
         FIG. 14  is a cross-section view of the clamping mechanism and the ratchet assembly shown in  FIG. 13 . 
         FIG. 15A  is a schematic drawing of the clamping mechanism in the release position. 
         FIG. 15B  a schematic drawing of the clamping mechanism and the ratchet assembly where the ratchet assembly secures the clamping mechanism at a particular position relative to a work piece. 
         FIG. 16  is a side perspective view of a further embodiment of the clamping mechanism where the clamping mechanism is secured to a fence relative to a work piece. 
         FIG. 17  is an enlarged cross section view of the connecting portion of the clamping mechanism of  FIG. 16 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention are directed to a clamping mechanism for securing a work piece on a power tool such as a table saw having a working surface and a guide fence such as a rip fence, a miter fence, a universal fence or any other suitable fence used on a table saw, push-pull saw or miter saw. The clamping mechanism includes a support configured to be movable along the guide fence and a clamp interconnected to the support, the clamp being movable between a securing position and a release position, wherein in the securing position, the clamp engages a work piece, and in the release position, the clamp is disengaged from the work piece. 
     Certain embodiments of the present invention illustrated and described herein are particularly suited for use with a universal fence that is designed and configured to be used with push-pull type power table saws and conventional table saws. It should be appreciated that the present clamping mechanism can be used on other types of fences such as miter fences and rip fences. 
     Turning now to the drawings, and particularly  FIG. 1 , a push-pull type table saw is indicated generally at  10  and has a table surface  12  that is generally rectangular in shape, with a front vertical surface  14 , a rear vertical surface  16 , a left side vertical surface  18 , and a right side vertical surface  20 . The saw has a base frame, indicated generally at  22 , that includes a front  24 , and a table top insert  26  that fits within a recess  28 , with the insert  26  having a slot  30  through which a blade  32  extends. The blade has a blade guard  34  supported by a riving knife  36  that is mounted on a carriage mechanism (not shown) that supports a drive motor and gear arrangement and the blade, where the carriage mechanism is mounted for sliding movement on elongated rails, rods, extrusions or the like. The movement of the carriage mechanism is controlled by a mechanism that is connected to a front knob  40  that an operator can pull to move the blade forwardly from the position shown in  FIG. 1  preferably through the full length of the slot  30 . 
     The construction and operability of the push-pull saw is not in and of itself a part of the present invention except insofar as it has a fence in which the embodiments of the present clamping mechanism are particularly suited for use with. The saw  10  is also capable of making angled cuts on a work piece  39  and to this end, a rotatable knob  38  can be used to adjust the angle of the plane of the blade from the 90° or vertical position shown in  FIG. 1  to an angled orientation that is shown in a gauge  42  that indicates it can be adjusted to about a 45° angle. 
     A universal fence is indicated generally at  44 , and comprises a main body, indicated generally at  46 , which is preferably an aluminum casting which forms a table extension  48  that extends from a holding mechanism portion  50  that is located on the opposite or forward end of the mechanism. The holding mechanism portion  50  is designed and configured to hold an elongated fence assembly, indicated generally at  52 , which comprises an elongated rail member  54 , a miter base  56  and a miter frame  58  mounted on the miter base. An elongated fence member  60  is slidably attached to the miter frame  58 . 
     The universal fence  44  is adjustable so that different cuts can be made on a work piece. For example, in the position shown in  FIG. 1 , the universal fence  44  acts as a miter fence where a work piece is placed against the universal fence and the table saw  10  is pulled towards the work piece to cut it. The universal fence  44  can also be rotated plus or minus 90° to act as a rip fence where the work piece is aligned parallel to the fence and guided into the saw blade  32 . 
     The present clamping mechanism  62  is attached to the fence member  60  of the universal fence. The clamping mechanism  62  includes a clamp support  64  and a pivot member  66  that is pivotably connected to the clamp support. The clamp support  64  includes a tubular portion  68  defining a through-hole  70  and two spaced apart support posts  72  having top ends  74  and bottom ends  76  where the posts are vertically oriented relative to the top surface of the fence member  60 . The bottom end  76  of each post  72  includes a threaded portion that is attached to a support bracket  78  by inserting the bottom ends  76  of the posts through corresponding through-holes  79  defined by the bracket as described below. Alternatively, the posts  72  can be secured in receptacles or holes defined by the fence member  60 . The top end  74  of each post  72  includes a boss  80  that is secured in a corresponding recess  82  on a bottom surface  84  of the clamp support  64  of the clamping mechanism  62  by welding or other suitable attachment method. Alternatively, the support posts  72  can be integrally formed with the clamp support  64 . To adjust the height of the clamping mechanism, a faceted nut  86  is threaded onto each of the support posts  72  on opposing sides of the bracket  78  to secure the support posts at a desired height above the bracket. It should be appreciated that the amount of thread on the support posts  72  is sufficient to allow the appropriate amount of vertical adjustment relative to the work piece. A C-clip  87  or other removable fastener is secured to the bottom ends  76  of the posts  72  below the bracket  78  after the bottom ends  76  are inserted through the through-holes  79  on the bracket to help prevent the support posts from moving out of the bracket when the posts are fully extended. 
     To adjust the vertical height of the clamping mechanism  62 , one of the nuts  86  on each of the posts  72  are rotated in a clockwise direction to move the posts through the nuts and downwardly through the through-holes  79 . The respective nuts  86  are rotated until the clamping mechanism  62  reaches a desired height or position relative to the fence member  60 . Alternatively, to raise the clamping mechanism  62 , the nuts  86  on each post  72  are rotated in a counterclockwise direction, which causes the posts  72  to move upwardly through the nuts  86  and the through-holes  79  on the bracket  78  until the desired height or position relative to the fence member  60  is reached. It should be appreciated that the support posts  72  may be adjusted to be any suitable height or distance above the fence member  60 . It is also contemplated that the clamping mechanism  62  can be supported by a single post or a support wall that extends at least partially along the length of the pivot member  72 . The adjustment of the position of the clamping mechanism  62  upwardly or downwardly relative to the fence member  60 , and more specifically, relative to a work piece, allows the clamping mechanism to be adjusted for work pieces having different thicknesses. It should be appreciated that the above embodiment describes one method of raising and lowering the clamping mechanism and that other suitable means or mechanisms of raising and lowering the clamping mechanism may be employed. 
     The pivot member  66  of the clamping mechanism  62  includes a first end  88  and a second end  90 . The first end  88  of the pivot member  66  includes spaced-apart tubular portions  92  that each define a through-hole  94  that corresponds to the through-hole  70  defined by the clamp support  64 . The tubular portion  68  of the clamp support  64  fits within or between the spaced-apart tubular portions  92  of the pivot member  66  so that the through-hole  70  of the clamp support  64  is aligned with the through-holes  94  defined by the tubular portions of the pivot member  66 . 
     Referring to  FIGS. 2-4  and  6 , a ratchet assembly  190  including a ratchet mount  192  is mounted to one of the posts  72  by welding or any other suitable connection method. The ratchet assembly  190  includes a gear  194  having an outer peripheral surface  196  with a plurality of teeth  198  that is attached to the pivot member  66  between the tubular portion  92  and the tubular portion  68  of the clamp support  64 . In an embodiment, the gear  194  is a separate part that is secured to the pivot member  66 . In another embodiment, the gear  194  is integrally molded with the pivot member. In the illustrated embodiment, the ratchet assembly  190  includes a ratchet arm  200  that is rotatably mounted to axle  202 . Axle  202  includes a first end or free end  204  and an opposing second end  206  that has a cylindrical cap  208 . The ratchet arm  200  is rotatably attached to the ratchet mount  192  by inserting the first end  204  of the axle  202  through a through-hole  210  defined by the ratchet mount  192  and a corresponding through-hole  212  defined by the ratchet arm  200  until the second end  206 , and more specifically, the cap  208  engages the ratchet mount. A nut  214  or other fastener is secured to the first end of the axle to prevent the ratchet arm from sliding off of the axle. 
     As shown in  FIG. 3 , the cap  208  includes a protruding grip  216  that allows a user to rotate the axle  202  and thereby the ratchet arm  200  upwardly or downwardly relative to the ratchet mount  192 . The ratchet arm includes a lip  218  at one end that is configured to matingly engage each of the recesses  220  formed between the teeth  198  on the gear  194 . A bias member, such as coil spring  222 , has an end that is attached to the ratchet arm  200  and an opposing end that is attached to the ratchet mount  192 . The coil spring  22  biases the ratchet arm  200  downwardly to maintain engagement between the lip  218  and the recesses  220  on the gear  194 . As the gear  194  rotates with the pivot member  66 , the lip  218  engages one of the recesses  220  to lock the pivot member  66  at a particular position relative to a work piece. To release the lip  218  on the ratchet arm  200  from the gear  194 , a user holds and rotates the grip  216  which causes the ratchet arm  200  to move upwardly away from the gear  194 . The pivot member  66  is biased upwardly due to the spring  98  until it reaches a desired position relative to the work piece. The user then releases the grip  216  to allow the arm  200  to pivot downwardly until the lip  218  re-engages one of the recesses  220  on the gear  194 . 
     An elongated rod  96  including a spring  98  is inserted through the aligned through-holes  70 ,  94  of the pivot member  66 , through-hole  224  defined by the gear  194  and the clamp support  64  as shown in  FIGS. 2 and 3  to allow the pivot member  66  to pivot relative to the clamp support  64 . Specifically, a first end  100  of the rod  96  is seated within one of the tubular portions  92  of the pivot member  66  and is secured to the clamp support  64  by inserting a removable pin  102  through holes  103  defined by the tubular portion  68  and  104  defined by the rod. An opposing, second end  106  of the rod  96  is seated within the other tubular portion  92  of the pivot member  66  and freely pivots or rotates within the through-hole  94  defined by the tubular portion as described below. The spring  98  surrounds a middle, narrowed portion  108  of the rod  96  so that the outer surface of the spring is substantially flush with the outer surface of the first and second  100 ,  106  ends of the rod. 
     The spring  98  includes a first end  110  and a second end  112  where the first end is secured to the first end of the rod ( FIG. 3 ) and the second end  112  is secured in an opening or slot defined by the pivot member  66  as shown in  FIGS. 2 and 3 . Thus, the first end  110  of the spring  98  remains stationary while the second end  112  rotates or twists with the movement of the pivot member  66 . Pressing down on the pivot member  66  causes the pivot member to move downwardly toward a work piece thereby causing the second end  112  of the spring  98  to pivot or rotate downwardly. The rotation or twisting of the second end  112  of the spring  98  creates torsional tension in the spring, which causes the spring to bias the pivot member  66  away from the work piece. 
     In operation, the pivot member  66  is movable between a release position, where the pivot member is disengaged from the work piece  39  ( FIG. 9A ), and a securing position, where the pivot member is engaged with the work piece ( FIG. 9B ). The pivot member  66  includes an upper surface  114  and a bottom surface  116 . As described above, the spring  98  shown in  FIGS. 3 and 4 , biases the pivot member  66  upwardly and away from the work piece  39 . It is contemplated that the spring  98  is a torsion spring or a coil spring but may be any suitable spring or combination of springs for biasing the pivot member  66 . 
     When the pivot member  98  is pushed downwardly from a release position (shown in  FIG. 9A ) towards the work piece  39  to be in the securing position ( FIG. 9B ), the spring  98  twists or stretches out and biases the pivot member  66  toward the release position. The ratchet assembly  190  secures the pivot member  66  in position relative to the work piece. Specifically, the lip  218  on the ratchet arm  200  engages successive recesses  220  between the teeth  198  on the gear  194  as the gear rotates with the pivot member  66 . It should be appreciated that the gear  194  can have smaller or greater number of teeth and the lip  218  on the ratchet arm  200  can be smaller or larger to change the adjustability of the ratchet assembly  190 . For example, finer adjustments can be made by increasing the number of teeth on the gear  194  thereby increasing the number of incremental rotational positions of the gear. 
     Each tooth  198  preceding the recesses  220  has a flat rear surface that prevents the lip  218  from moving out of the respective recess and locks the ratchet arm  200  in position on the gear  194 , which in turn, locks the pivot member  66  at a particular position. To release the pivot member  66 , a user presses downwardly on the pivot member causing the lip  218  to dis-engage from the respective recess  220  on the gear  194 . The user then grabs the grip  216  to rotate the ratchet arm  200  upwardly away from the gear  194 . Upon the release of the ratchet arm  200  from the gear  194 , the spring  98  contracts or returns to its unstretched position, and biases the pivot member  66  toward the release position. 
     The upper surface  114  of the pivot member  66  is contoured and slopes generally downwardly from the first end  88  towards an opposing second end  90  of the pivot member. Preferably, the upper surface  114  is shaped to correspond to the shape of a human hand as shown in the  FIGS. 6 and 9B  and includes a palm contacting portion  122  and a finger contacting portion  124 , where the palm contacting portion is at an angle “A” between 0° and 15° relative to a horizontal plane extending from the top of the clamp support  64  (see  FIG. 6 ) and the finger contacting portion  124  is at an angle “B” between 15° to 45° relative to that plane. It should be appreciated that the palm contacting portion  122  and the finger contacting portion  124  may be at any suitable angle or angles. The pivot member  66  also includes a finger pad  126  that extends at least partially over the upper surface  114  to provide a pushing surface for a user&#39;s fingers as well as to allow a user to better grip the pivot member where the finger pad helps to inhibit movement of the user&#39;s fingers beyond an outer edge of the upper surface. This provides a stable smooth surface for a user to control the pivot member  66  during a cutting operation. In an embodiment, the upper surface  114  of the pivot member  66  is made of a non-slip material, such as rubber, that helps to prevent a user&#39;s hand from slipping off of the upper surface during use. 
     The clamping mechanism  62  also includes a foot or shoe  128  that extends downwardly from the bottom surface  116  of the pivot member  66 . Specifically, an upper end  130  of the shoe  128  is connected to the pivot member  66 . It is contemplated that the shoe  128  may be integrally formed with the pivot member  66  or separately attached to the pivot member by stretching the shoe over a portion of the pivot member or by using suitable fasteners. A lower end  132  of the shoe  128  includes an outer layer or gripping surface  134  that is configured to contact a work piece. The gripping surface  134  may be made of rubber, a rubber-like material or any other suitable non-slip material or materials. In another embodiment, the gripping surface  134  includes non-slip feature or non-slip member  135  such as one or more ribs, protrusions, knurling, abrasions and the like. The non-slip member  135  may be made of a non-slip material such as rubber, a metal such as steel or aluminum or any suitable material or combination of materials. In the illustrated embodiment, the gripping surface  134  of the shoe  128  grips and holds a work piece in position without damaging it so that the work piece does not slip out from under the clamping mechanism  62  during operation. 
     To adjust the lateral position of the clamping mechanism  62  relative to the universal fence  44 , the stepped bracket  78  is moved along the fence member  60 . The stepped bracket  78  has an upper end  136  and a lower end  138  that is attached to the fence member  60 . As shown in  FIG. 4 , the lower end  138  of the bracket  78  is generally planar and rests on a lower end of the fence member  60 . The lower end  138  includes a through-hole  140  that receives a securing member such as threaded bolt  142  having an upper end  144  and a bottom end  146 . The bottom end  146  includes a foot  148  ( FIGS. 7 and 8 ) that has a diameter that is greater than the diameter of the through-hole  140 . It should be appreciated that the foot  148  may be made of metal, a combination of metals or any suitable material or materials. It should also be appreciated that in another embodiment, the bottom end  146  does not include the foot  148 . The foot  148  fits closely to the top surface of the channel  150  such that when the handle  152  is rotated to clamp the bracket  78  in place, the foot  148  is in contact with fence member  60  and thereby keeps the foot from rotating relative to the fence member. This allows the bracket  78  to be clamped to the fence member  60 . 
     As shown in  FIGS. 5 ,  9 A &amp;  9 B, the fence member  60  defines an elongated channel  150  where the foot  148  is slidably secured in the channel. A knob  152  is connected to the upper end  144  of the bolt  142  and is rotated to adjust the height and tightness of the foot  148  relative to an inside surface of the channel  150 . Preferably the knob  152  is rotated so that the foot  148  and bolt  142  slide within the channel  150  defined by the universal fence  44 . This construction allows the clamping mechanism  62  to be movable or slidable laterally along the universal fence  44  to adjust the position of the clamping mechanism relative to the fence member  60 . This construction also allows a user to clamp and securely hold the work piece  39  close to the blade to prevent the work piece from moving due to the torque or moment that is generated when the work piece contacts the blade. 
     In another embodiment, the foot  148  is a square bolt head connected to the bolt  142  where the knob  152  defines a threaded through-hole, i.e., threaded all the way through the knob. The bolt  142  in this embodiment only has to be long enough to allow for clamping and unclamping of the bracket  78  to the fence member  60 . It is also contemplated that a stop such as a C-clip or other suitable clip or stop member can be secured above the knob  152  on the bolt  142  to prevent the knob from falling off of the bolt during use. 
     The upper end  136  of the bracket  78  extends laterally out beyond the edge of the fence member  60  and defines the through-holes  79  that are configured to receive the support posts  72 . As shown in  FIG. 4 , each of the through-holes  79  has a diameter that is greater than a diameter of the bottom ends  76  of the posts so that the posts can freely move through the through-holes. The posts  72  are secured to the bracket  78  by nuts  86  and C-clip  87 . As shown in  FIG. 4 , the nuts  86  are secured to each of the posts on the opposite side of bracket  78  thereby positioning a nut above and below the bracket  78  on the posts to allow the posts to be fully clamped and adjustable vertically relative to the bracket. In the illustrated embodiment, one of the nuts  86  on each of the posts  72  are rotated in clockwise or counterclockwise direction to respectively raise or lower the posts  72  relative to the bracket  78  to adjust the height of the clamping mechanism  62  relative to a work piece  39 . 
     In operation, a user adjusts the height of the clamping mechanism  62  relative to the work piece  39  by rotating or turning nuts  86  using their fingers or a wrench so that the clamping mechanism can securely hold the work piece  39  in position on the table top  12 . In particular, the pivot member  66  initially starts in the release position or the position in which the pivot member is disengaged from the work piece  39 . The user then places one of their hands on the upper surface  114  of the pivot member  66  and pushes downwardly on the pivot member until the shoe  128  engages the work piece  39 , i.e., the securing position. The shoe  128 , and more specifically, the gripping surface  134  of the shoe, grips the top surface of the work piece  39  under the pressure of the user&#39;s hand and remains clamped when the user removes their hand due to the engagement of the lip  218  of the ratchet arm  200  in one of the recesses  220  on the gear  194 . To release the pivot member  66 , the user pushes downwardly on the pivot member while rotating the ratchet arm  200  upwardly away from the gear  194  as described above. The user then releases pressure on the upper surface  114  of the pivot member  66 , which causes the spring  98 , to bias the pivot member upwardly away from the work piece  39  toward the release position. Another work piece can now be inserted under the clamping mechanism  62  and the operation repeated. Thus, the present clamping mechanism  62  quickly and safely holds a work piece in place during a cutting operation without exposing a user&#39;s hands or fingers to injury by the blade  32 . 
     In a further embodiment, and referring to  FIGS. 10-13 , a clamping mechanism  156  includes a generally L-shaped support  158  having a first generally vertical portion  160  and a second generally horizontal portion  162  integrally formed with the vertical portion. The first portion  160  defines a through-hole  164  including a threaded interior surface. The second portion  162  also defines a through-hole  166  that is spaced a designated distance from through-hole  164 . A securing member such as first threaded rod  168  extends through and is threadingly engaged with the through-hole  164  defined by the first portion  160 . The first rod  168  has a first end  170  and an opposing second end  172 . The first end  170  extends above the upper end of the first portion  160  and includes a first handle  174  that enables a user to grip and rotate the first rod  168 . The second end  172  extends below the first portion  160  and into the channel  150 ′ by the fence member  60 ′ as shown in  FIGS. 11 and 12 . A clamping ring  176  and a locking nut  178  are connected to the second end  172  within the channel  150 ′. The locking nut  178  is restrained from rotating by contact with walls  179  defining the channel  150 ′ of the fence member  60 . It should be appreciated that the locking nut  178  may also be restrained from rotating by other suitable restraining or locking devices or methods. 
     In the illustrated embodiment, the channel  150 ′ defines a slot having a width that is greater than a diameter of the first rod  168  to allow the second end  172  to extend through the slot and into the channel. The diameter of the clamping ring  176  is greater than the width of the slot in the channel  150 ′ so that when the first handle  174  is rotated in a clockwise direction, the first rod  168  moves downwardly in the slot in the first portion until the clamping ring  176  engages the fence member, i.e., the locked position. The locking nut  178  secures the clamping ring  176  in place so that the clamping ring securely engages the fence member  60 ′ to lock the clamping mechanism  156  in position. To loosen the clamping ring  176 , the first handle  174  is rotated in a counterclockwise direction, which causes the first rod  168  to move upwardly within the slot thereby disengaging the clamping ring  176  from the fence member  60 ′, i.e., the release position. This allows the second end  172  of the first rod  168  to slide in the channel  150 ′ relative to the fence member. 
     A second rod  180  extends through and threadingly engages the through-hole  166  defined by the second portion  162  of the L-shaped support  158 . A first end  182  of the second rod  180  includes a second handle  184  configured to allow a user to rotate the second rod in a clockwise or counterclockwise direction. A second opposing end  186  of the second rod  180  extends below the through-hole  166  and includes a clamp or foot  188  having a diameter that is greater than a diameter of the second rod  180 . The foot  188  has a generally circular shape but may be any suitable size or shape. Preferably, the foot  188  is made of rubber. It should be appreciated that the foot may be made of any suitable non-slip material or materials. When the clamping mechanism  156  is secured in place relative to the fence member  60 ′ as described above, the second handle  184  on the second rod  186  is rotated in a clockwise direction to cause the second rod to move downwardly through the through-hole  166  until the foot  188  contacts and securely engages a work piece  39 ′, i.e., the securing position. The rubber foot  188  helps to prevent the work piece  39 ′ from sliding relative to the foot and also helps to protect the work piece from being damaged by the end of the second rod  180  as it presses on the work piece. The second rod  180  is rotated in a counterclockwise direction to cause the foot  188  to disengage from the work piece  39 ′ as the rod moves upwardly through the through-hole  166 , i.e., move from the securing position to the release position. The second rod  180  has a designated length to adjust to work pieces having different thicknesses. It should be appreciated that the first and second handles  174 ,  184  can be knobs or any other suitable gripping member. It should also be appreciated that the clamping mechanism  156  rotates about the first rod  168  so that the clamping mechanism can be moved or rotated to different positions relative to a work piece to allow flexibility in securing the work piece. Thus, the clamping mechanism  156  can move linearly in the channel  150 ′ and also rotationally about the axis defined by the first rod  168 . 
     In operation, a work piece  39 ′ is placed on the table top  12  of the power saw  10  and the clamping mechanism  156  is moved laterally along the fence member  60 ′ and also rotationally about the first rod  168  to a desired position relative to the work piece. The user then rotates the first handle  174  on the clamping mechanism  156  while holding the clamping mechanism  156  from moving rotationally to cause the clamping ring  176  to engage an inside surface of the channel  150 ′. The locking nut  178  engages the clamping ring  176  to securely hold the clamping ring in position. After the clamping mechanism  156  is locked into position on the table saw  10 , the user rotates the second handle  184  in a clockwise direction until the foot  188  securely engages the work piece  39 ′. The user can now safely utilize the saw without having to hold the work piece in place with their hand, which is a safety concern. 
     After the work piece  39 ′ has been cut, the user rotates the second handle  184  in a counterclockwise direction, which disengages the foot  188  from the work piece. The work piece  39 ′ can now be removed from the table saw. The user can also loosen the clamping ring  176  from the channel  150 ′ by rotating the first handle  174  in a counterclockwise direction. This enables the user to move the clamping mechanism  156  laterally along the fence member  60 ′ and/or rotationally about the axis defined by the first rod  168  as needed. 
     Referring now to  FIGS. 13-15B , another embodiment of the ratchet assembly  190 ′ is illustrated where the clamping mechanism  156 ′ includes a mounting assembly  226  attached to the posts  72 ′ by screws or other suitable fasteners. It should be appreciated that the mounting assembly  226  may also be integrally formed with the posts  72 ′. In the illustrated embodiment, the mounting assembly  226  includes two spaced apart vertical supports  230  that each define generally horizontal through-holes  232  for receiving the rod  96 ′ as described above. In this embodiment, the rod  96 ′ includes an enlarged end or cap  234  that engages an outer surface of one of the vertical supports  230  when the rod is fully inserted through the through-holes  232  defined by the vertical supports  230  and the pivot member  66 ′. Alternatively, the cap  234  may be a separate part that is attached to the rod  96 ′ using a suitable attachment method. 
     The ratchet assembly  190 ′ is mounted on an extended portion  236  of the mounting assembly  226  as shown in  FIG. 13 . A gear  194 ′ is attached to pivot member  66 ′ and is configured to fit between the vertical supports  230 . The gear  194 ′ defines a through-hole  224 ′ configured to receive the rod  96 ′. Thus, the rod  96 ′ is inserted through the one of the vertical supports  230 , the gear  194 ′, the pivot member  66 ′ and the opposing vertical support  230 . The rod  96 ′ is secured in position as described above so that the rod does not slide out of the vertical supports  230  during operation. The gear  194 ′ is attached to the pivot member  66 ′ using any suitable fastener or fastening method so that the gear rotates or pivots in unison with the pivot member. Similar to the ratchet assembly described above, the illustrated ratchet assembly  190 ′ includes a ratchet arm  200 ′ having a lip  218 ′ at one end that engages one of the recesses  220 ′ defined between the teeth  198 ′ on the gear  194 ′. The ratchet arm  200 ′ is rotatably mounted to a ratchet mount  192 ′ integrally formed with the extending portion  236  of the mounting assembly  226  by inserting an axle  202 ′ through through-holes  210 ′ and  212 ′ defined by the ratchet mount and the ratchet arm as shown in  FIG. 13 . A cap  208 ′ having a grip  216 ′ is secured to one end of the axle  202 ′ rotates with the axle relative to the ratchet mount  192 ′. The grip  216 ′ is a rectangularly-shaped protrusion that can be grasped by a user to pivot the ratchet arm  200 ′ upwardly away from the gear  194 ′ as described above. A spring  222 ′ is connected between the ratchet arm  200 ′ and the extending portion  236  of the mounting assembly  226  to bias the ratchet arm downwardly into engagement with the gear. 
     In operation, the pivot member starts in the release position shown in  FIG. 15A  where the lip  218 ′ at the end of the ratchet arm  200 ′ engages each successive recess  220 ′ between the teeth  198 ′ on the gear  194 ′ as the pivot member  66 ′ and the gear  194 ′ rotate downwardly toward a work piece. The ratchet arm  200 ′ locks the pivot member  66 ′ in a particular position relative to the work piece as shown in  FIG. 15B . To release the pivot member  66 ′ so that it can pivot or rotate upwardly away from the work piece, a user pushes down on the pivot member to cause the ratchet arm  200 ′ to dis-engage from the respective recess  220 ′ on the gear  194 ′. At the same time, the user grasps the grip  216 ′ and rotates or pivots the ratchet arm  200 ′ upwardly away from the gear  194 ′ which allows the pivot member to pivot or rotate upwardly due to the coil spring  98 ′ to the release position shown in  FIG. 15A . The work piece can now be removed and a new work piece can be inserted under the clamping mechanism where the process is repeated to secure the new work piece in position. 
     Referring now to  FIGS. 16 and 17 , another embodiment of the clamping mechanism  156 ′ includes a generally L-shaped support  158 ′ having a first generally vertical portion  160 ′ and a second generally horizontal portion  162 ′ integrally formed with the vertical portion. The vertical portion  160 ′ is secured to the fence member  60 ′ by a connecting portion  238  including a connecting bracket  240  defining a pair of holes  242  on opposing sides of the vertical portion  160 ′ configured to receive fasteners  244 . It should be appreciated that the fasteners  244  may be bolts, screws or any suitable fasteners. Each of the fasteners  244  include head portions  245  and are positioned in channel  246  such that the head portions engage an inner surface of the channel and threaded ends  247  of the fasteners extend through the holes  242 . A wing nut  248  is threadingly secured to the ends  247  of each of the fasteners  244  to secure the bracket  240  and the clamping mechanism  156 ′ in position relative to the fence member  60 ′. 
     To move the clamping mechanism  156 ′ relative to the fence member  60 ′, a user loosens the wing nuts  248  by rotating them in a counterclockwise direction. The clamping mechanism  156 ′ then slides relative to the fence member  60 ′ in either direction. The fastener heads  245  have a diameter that is greater than a diameter of the holes  242  so that the fasteners  244  remain in engagement with the fence member  60 ′ while the clamping mechanism  156 ′ is being moved relative to the fence member. Once the clamping mechanism  156 ′ is at a desired position on the fence member  60 ′, the wing nuts  248  are rotated in a clockwise direction to tighten and secure the bracket  240  against the fence member. 
     In the illustrated embodiment, the clamping mechanism  156 ′ includes a position control  250  that adjusts the vertical position of the clamping mechanism relative to a work piece. The position control  250  includes a handle or knob  252  and a threaded end  254  connected to the knob. The horizontal support  162 ′ includes a boss  256  defining a threaded hole configured to receive the threaded end  254  of the position control. The knob  252  is rotated in a clockwise direction to tighten and secure the clamping mechanism  156 ′ at a particular vertical position. To adjust the vertical position of the clamping mechanism  156 ′, a user rotates the knob  252  in a counterclockwise direction, moves the clamping mechanism upwardly or downwardly relative to a work piece  39 ′, and then rotates the knob in a clockwise direction to secure the clamping mechanism at a desired vertical position relative to the work piece. 
     A second rod  180 ′ extends through and threadingly engages the L-shaped support  158 ′. A first end  182 ′ of the second rod  180 ′ includes a handle or round knob  256  configured to allow a user to rotate the second rod in a clockwise or counterclockwise direction. A second opposing end  186 ′ of the second rod  180 ′ includes a clamp or foot  188 ′ having a diameter that is greater than a diameter of the second rod  180 ′. The foot  188 ′ has a generally circular shape but may be any suitable size or shape. Preferably, the foot  188 ′ is made of rubber. It should be appreciated that the foot may be made of any suitable non-slip material or materials. When the clamping mechanism  156 ′ is secured in place relative to the fence member  60 ′ as described above, the round knob  256  on the second rod  186 ′ is rotated in a clockwise direction to cause the second rod to move downwardly until the foot  188 ′ contacts and securely engages a work piece  39 ′, i.e., the securing position. The rubber foot  188 ′ helps to prevent the work piece  39 ′ from sliding relative to the foot and also helps to protect the work piece from being damaged by the end of the second rod  180 ′ as it presses on the work piece. The second rod  180 ′ is rotated in a counterclockwise direction to cause the foot  188 ′ to disengage from the work piece  39 ′ as the rod moves upwardly, i.e., moves from the securing position to the release position. As stated above, the clamping mechanism  156 ′ can move linearly in the channel  246  and also rotationally about the axis defined by the vertical support  160 ′. 
     While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
     Various features of the invention are set forth in the following claims.