Abstract:
A modular guard system for a power saw of the type which has a table top having an opening through which a rotatable saw blade can extend includes a riving knife mounted to the saw rearwardly of the blade and having first and second notches with openings facing away from each other. A blade guard assembly is releasably mounted on the riving knife and configured to cover the blade. The blade guard assembly includes a mounting portion configured to receive a top portion of the riving knife having the first and second notches and a release mechanism provided in the mounting portion and having a spring member for engaging the first notch and a latch member connected to the spring member for engaging the second notch. The latch member exerts a force on the spring member to cooperatively hold the first and second notches between the spring member and the latch member to retain the riving knife in the mounting portion. The riving knife is released from the mounting portion when the force exerted on the spring member is removed by the latch member and the spring member is disengaged from the first notch.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention generally relates to power tools and, more particularly, to power table saws. 
         [0002]    Guard systems for power table saws typically include three components, namely, a splitter or riving knife, a kickback prevention device, and a blade guard that covers the blade. A kickback prevention device is a safety device that reduces the likelihood of a kick-back event where a work piece is somehow caught or bound up during a cutting operation and the inertia of the blade throws the work piece back toward the user. A riving knife is typically considered to function similarly to a spreader or splitter on a blade guard assembly, but does not extend above the top of the blade. 
         [0003]    Depending on the type of cut being made, there are times when it is desirable to separate and remove the blade guard from the riving knife. For example, when making a non-through cut, the user must remove the guard system if the guard system is of the type which is attached to the undercarriage or the rear of the table saw. These mounting configurations are typically utilized on most portable and bench top models that are presently commercialized. Because there is a need to remove the guard system during non-through and other special types of cuts and because special wrenches or the like are often necessary to do so on many commercial bench top models, many users simply leave the guard system off. While some table saws incorporate features in the blade guard for removing the blade guard without the use of tools, they utilize internal mounting with very limited spring action, which requires very high precision of all mating parts. 
       SUMMARY OF THE INVENTION 
       [0004]    A preferred embodiment of the present invention is directed to a modular guard system for a power saw of the type which has a table top, a rotatable circular saw blade, and an opening on the table top through which the saw blade extends. The system includes a riving knife mounted to the saw rearwardly of the blade. The riving knife has forward and rear notches that have openings facing away from each other. A blade guard assembly is releasably mounted on the riving knife and configured to cover the blade. 
         [0005]    The blade guard assembly includes a mounting portion configured to receive a top portion of the riving knife having the forward and rear notches. A release mechanism is provided in the mounting portion and has a spring member for engaging the forward notch and a latch member connected to the spring member for engaging the rear notch. The latch member exerts a force on the spring member to cooperatively hold the forward and rear notches between the spring member and the latch member to retain the riving knife in the mounting portion. The riving knife is released from the mounting portion when the force exerted on the spring member is removed by the latch member and the spring member is disengaged from the forward notch. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of the front right side of the preferred embodiment of a modular saw guard system of the present invention; 
           [0007]      FIG. 2  is a plan view of a riving knife of the saw guard system; 
           [0008]      FIG. 3  is an exploded perspective view of a portion of the saw guard system shown in  FIG. 1 , with parts omitted for clarity; 
           [0009]      FIG. 4  is a sectional view of the blade guard assembly shown in  FIG. 3  generally along line A-A, with a quick release mechanism in a locked position; 
           [0010]      FIG. 5  is a top view of the blade guard assembly shown with the quick release mechanism in a locked position; 
           [0011]      FIG. 6  is another top view of the mounting portion shown with the quick release mechanism in an unlocked position; 
           [0012]      FIG. 7  is a perspective view of a first alternate embodiment of the blade guard assembly, shown without side guard barriers; 
           [0013]      FIG. 8  is a sectional view of the blade guard assembly shown in  FIG. 7  generally along line B-B, with a quick release mechanism in a locked position; 
           [0014]      FIG. 9  is a top view of the blade guard assembly shown in  FIG. 7 , with the quick release mechanism in a locked position; 
           [0015]      FIG. 10  is a perspective view of a second alternate embodiment of the blade guard assembly, shown without side guard barriers; 
           [0016]      FIG. 11  is a sectional view of a mounting portion of the blade guard assembly shown in  FIG. 10  generally along line C-C, with a quick release mechanism in a locked position; and 
           [0017]      FIG. 12  is a top view of the mounting portion of  FIG. 11 , with the quick release mechanism in a locked position. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The preferred embodiment of the present invention comprises a modular saw guard system that has a blade guard assembly which can be quickly attached to and/or removed from a riving knife using a quick release mechanism. The release mechanism includes a spring clip and a latch that cooperatively hook on to a pair of notches on the riving knife to firmly mount the blade guard assembly to the riving knife. With the modular configuration of the embodiments of the present system, the end user is more likely to use the blade guard for a particular task being carried out on the table saw. Moreover, the spring action in the quick release mechanism of the present invention eliminates the need for high precision mating of operational parts, which typically has high fabrication cost associated with it. As a result, the manufacturing cost of the quick release mechanism and, accordingly, the blade guard assembly, is significantly reduced. 
         [0019]    While the illustrated embodiments of the present invention are shown in connection with a power table saw, it should be understood that the system mechanisms can be utilized in other tools and environments, and that such other applications should be considered to be within the spirit and scope of the present invention. For example, embodiments of the present invention may be used with saws that are known as combo saws and flip saws that are marketed in Europe and possibly elsewhere. 
         [0020]    Turning now to the drawings and particularly  FIG. 1 , there is shown a modular saw guard system, indicated generally at  20 , that includes a riving knife, indicated generally at  22  and a blade guard assembly, indicated generally at  24 . The blade guard assembly  24  is configured to be mounted to the riving knife  22  and can be separated from the riving knife quickly and easily by virtue of a quick release mechanism indicated generally at  26 . 
         [0021]    The riving knife  22  is adjustable so that its elevation relative to the blade can be adjusted. More particularly, it can be positioned to any one of three elevations, including a retracted position where the top of the riving knife  22  is completely below the surface of the tabletop, a fully extended position and an intermediate position. In the fully extended and the intermediate positions, the top of the riving knife  22  extends above the elevation of the top of the blade. The riving knife  22  is mounted to a motor and arbor gear box assembly (not shown but well known to those skilled in the art) that drives the blade and is vertically as well as angularly adjustable. 
         [0022]    The riving knife  22  is preferably a steel stamping and has an elongated generally curved thin body portion  28  as shown in  FIG. 2 , with a center slot  30  that extends from a bottom portion  32  to a top portion  34  of its height. A pair of apertures  36  are located on opposite sides of the slot  30  in the bottom portion  32 , and a pair of apertures  38  are located on the opposite sides of the slot  30  proximate the midway between the top and bottom portions  34 ,  32 . The apertures  36 ,  38  enable the riving knife  22  to be attached to the mounting post of the saw at its fully extended and intermediate positions. An aperture  40  along with an opening  42  positioned near the top portion  34  of the riving knife  22  enables the riving knife  22  to be attached to the mounting post at its lowest position. 
         [0023]    When the riving knife mechanism is in its fully extended or highest position, the blade guard assembly  24  can be easily mounted to the riving knife  22 . Alternatively, if better visualization is necessary, it is possible to remove the blade guard assembly  24 . 
         [0024]    The riving knife  22  further includes a pair of spaced forward and rear notches  44 ,  46 . The forward notch  44  opens forward at the top portion  34  of the riving knife  22 , and rear notch  46  rearward of the top portion, so that they open generally in the opposite directions. The forward and rear notches  44 ,  46  cooperate with a blade guard assembly quick release mechanism  26  (best shown in  FIG. 1 ) to mount the blade guard assembly  24  to the riving knife  22 . Also, the outside surface adjacent the rear notch  46  contains a flat surface  48  that cooperates with an aperture  50  for mounting a kickback prevention mechanism (not shown) to the riving knife  22 . 
         [0025]    Referring back to  FIG. 1 , the blade guard assembly  24  includes an upper guard barrier, indicated generally at  52 , which includes a mounting portion  54  at one end that includes the quick release mechanism  26 , and a blade receiving portion  56  at the opposite end. The blade guard assembly  24  also includes a pair of side guard barriers  58 ,  60  which are attached to the mounting portion  54  by large headed screws  62 . The screws  62  are screwed into apertures  64  (best shown in  FIG. 3 ) located on each side of the mounting portion  54 . The side guard barriers  58 ,  60  thereby pivot around the attachment screws  62  which enables the side guard barriers to be lifted up when a work piece is pushed into position to be cut by a saw blade that is located between the side guard barriers  58 ,  60 . The front end portions  64 ,  66  are upwardly flared or angled so that when a work piece is advanced to be cut, the work piece will contact the underside of the front end portions and lift the side guard barriers  58 ,  60  when they engage a work piece. 
         [0026]    The side guard barriers  58 ,  60  each have an arcuate slot  68  that is provided to limit the rotational movement of the side guard barriers from the downward or lowermost position where a bottom position  70  of the side guard barriers engages the top surface of a table saw. A second screw  72  is provided for each side guard barrier  58 ,  60  with the screws engaging apertures  74  (best shown in  FIG. 3 ) on each side of the mounting portion  54 . The second screws  72  also have an enlarged head that contacts the outer surface of the side guard barriers  58 ,  60  adjacent the slot  68 , and a smooth cylindrical shank portion with a diameter slightly less than the width of the slot so as to permit pivoting of the barriers around the pivot screw  62  without interference. The side guard barriers  58 ,  60  are preferably made from a plastic or plastic-like material such as clear polycarbonate. 
         [0027]    Turning to  FIG. 3 , the blade guard assembly  24  includes the blade receiving portion  56  for accepting the saw blade in an elongated channel  76  formed by a pair of legs  78  extending from a body portion  80  of the upper guard barrier  52 . The legs  78  are angled away from the channel  76  to enable the operator to have a clear view of the blade. The upper guard barrier  52  is a rigid unitary piece preferably made of metal, but can also be made of other materials such as plastic. 
         [0028]    The mounting portion  54  includes a center channel  82  in which the quick release mechanism  26  is located. The quick release mechanism  26  includes a latch  84  having a handle  86 . It is pivotally connected to the mounting portion  54  at a pair of apertures  88  provided in spaced brackets  90  that form the center channel  82 . The latch  84  is connected to the brackets  90  by virtue of a pin  92  which extends through apertures  94  at the end of the latch  84  and into the apertures  88  of the brackets. 
         [0029]    The quick release mechanism  26  further includes a spring clip  96  which is pivotally connected to the latch  84  at a pair of apertures  98  provided generally about the middle portion of the latch, between the apertures  94  for receiving the pin  92  and the handle  86 . In one embodiment, the spring clip  96  is formed from a metal wire which is sufficiently rigid and has the tensile strength to maintain its shape when force is exerted on it by the latch  84 . The spring clip  96  may have two ends, each of which are inserted into the aperture  98  of the latch  84  and bent to prevent the ends from being pulled out. The two ends of the spring clip may also be welded, or otherwise connected together to prevent the ends from coming out of the aperture  98 . While the spring clip  96  opposite the two ends is shown to be generally curved, it can also be formed in a V-shaped tip for better centering the quick release mechanism  26  on the forward notch  44  of the riving knife  22 . 
         [0030]    Referring to  FIGS. 3-6  and in operation, the latch  84  locks and unlocks the blade guard assembly  24  onto and from the top portion  34  of the riving knife  22 . To effectuate the locking operation, the curved portion of the spring clip  96  is hooked onto the forward notch  44  and the pin  92  is inserted into the rear notch  46 . When the handle  86  of the latch  84  is depressed to be placed into a generally horizontal position, the pin  92  acts as an axel on which the latch  84  pivots and creates a tension on the spring clip  96 . In this manner, the forward and rear notches  44 ,  46  of the riving knife  22  are held tightly between the spring clip  96  and the axel pin  92  of the latch  84 . As a result, the quick release mechanism  26  is firmly locked onto the riving knife  22  and accordingly, the blade guard assembly  24  (best shown in  FIGS. 4 and 5 ). 
         [0031]    To assist in firmly locking the blade guard assembly  24  onto the riving knife  22 , the mounting portion  54  includes a pad  100  extending inwardly in the center channel  82  from each of the brackets  90  to snugly receive the riving knife  22  in a slot  102  formed within the center channel. The pads  100  can be made of steel or plastic, which may be welded, riveted or screwed to each of the brackets  90 . It is contemplated that the pads  100  be spring-loaded or have bosses to compensate for dimensional variety of parts in assembly and holding the riving knife  22  between them. 
         [0032]    To disengage or detach the blade guard assembly  24  from the riving knife  22 , the latch  84  is pushed upwardly in a direction away from the riving knife  22 , so as to release the tension on the spring clip  96 . This allows the spring clip  96  to be disengaged from the forward notch  44 , as shown in  FIG. 6 , and enable the riving knife  22  to be slipped off the axel pin  92  and completely out of the slot  102  and the center channel  82 . 
         [0033]    Turning now to  FIG. 7 , an alternate embodiment of the quick release mechanism  26  is shown, which illustrates components as having the same reference numbers and a prime designation. Thus, the above description with regard to the quick release mechanism  26  has applicability in the alternate embodiment. The alternate quick release mechanism  26 ′ includes a flat spring  104  which is pivotally connected to a pin  106  at its rear end and has a hook portion  108  configured to releasably hook onto the forward notch  44  of the riving knife  22 . The pin  106  is configured to be received in the apertures  98  provided between the handle  86  and the axel pin  92  in the apertures  94  at the opposite end of the latch  84 ′. To accommodate the flat spring  104 , the latch  84 ′ includes an opening  110  which allows the flat spring  104  to be connected to the pin  106 , which acts as a hinge for the flat spring  110 . 
         [0034]    In operation, the latch  84 ′ is placed in an up position where the handle  86  is lifted away from the mounting portion  54 , and the hook  108  on the flat spring  104  is allowed to engage the forward notch  44 . The handle  86  of the latch  84 ′ is pushed down so that it is generally at a horizontal position with respect to the upper guard assembly  52  to lock the blade guard assembly  24  onto the riving knife  22 . The quick release mechanism  26 ′ in a locked position is shown in  FIGS. 8 and 9 . As in the embodiment described above, the latch  84 ′ pivots about the axel pin  92 . 
         [0035]    To release the blade guard assembly  24  from the riving knife  22 , the handle  86  is pushed in an upwardly direction, away from the riving knife  22  to release tension on the flat spring  104 . The hook  108  is then disengaged from the forward notch  44  and the pin  106  from the rear notch  46 . 
         [0036]    Referring now to  FIGS. 10-12 , another embodiment of a quick release assembly is shown. In the quick release assembly  112 , a single integrated flat spring acts both as a latch and a spring clip. A latch  114  of the quick release assembly  112  includes a handle portion  116  at one end and a connection portion  118 , which is pivotally connected to an axel pin  120  provided between the brackets  90  generally towards the end closer to the body portion  80  of the upper guard barrier  52 . The connection portion  118  is connected to the pin  120  only at the opposite end of the pin, leaving an opening  122  therebetween to expose the pin, so that the pin is received in the forward notch  44  of the riving knife  22 . The handle portion  116  of the latch  114  is connected to a curved tip  124  which is configured to be removably latched to the rear notch  46  of the riving knife  22 . 
         [0037]    Preferably, the latch  114  is an integrated single piece of metal which is formed or crimped into the shape described above and as shown in  FIGS. 10 and 11 . Accordingly, the metal material should have sufficient rigidity to hold its shape and also to firmly mount the blade guard assembly  24  onto the riving knife  22 . 
         [0038]    In operation, to mount the blade guard assembly  24  on the riving knife  22 , the axel pin  120  is inserted into the forward notch  44  and the curved tip  124  is pressed onto the rear notch  46  until it is snapped on. In this position, the latch  114  is generally in a horizontal position with respect to the upper guard barrier  52  (best shown in  FIGS. 10 and 11 ), and the forward end rear notches  44 ,  46  of the riving knife  22  are held firmly between the connection portion  118  and the tip  124  by the tension on the flat spring. 
         [0039]    To remove the blade guard assembly  24  from the riving knife  22 , the handle portion  116  is pressed upwardly to release the curved tip portion  124  from the rear notch  46 . In this position, the riving knife  22  can be disengaged from the pin  120  and allowed to be removed from the mounting portion  54 . 
         [0040]    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. 
         [0041]    Various features of the invention are set forth in the appended claims.