Abstract:
Embodiments of the present invention comprise a fence for a power saw having a table top with generally vertical front, rear and opposite side surfaces, at least one side surface having an elongated side element extending from a front portion toward said rear surface, said side element having a cross section defining a vertical groove with an inner vertical surface that merge into upper and lower opposed extensions that define upper and lower undercuts, said fence comprising an elongated fence member having a generally vertical front planar surface for engaging a work piece, a table extension having a top surface area coextensive with said saw table top and operatively connected to said fence member, said extension providing support for a work piece that extends beyond a side of the table top surface, said fence being configured so that the front planar surface can be positioned in front of the vertical front surface of the saw, i.e., off of the top surface.

Description:
BACKGROUND OF THE INVENTION 
     The present invention generally relates to power table saws and more particularly to fences for use with such saws. 
     Power saws of the type that have a saw blade that extends through an opening in the top surface of the saw are commonly known as table saws and typically have the ability to adjust the angle of the saw blade to provide bevel cuts on work pieces that are placed on the tabletop surface. Such saws also can adjust the height that the saw blade extends above the top surface. It is also a practical necessity for fences to be used with such saws and such fences are generally characterized as either miter fences or rip fences. The rip fences are generally removable and can also 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. 
     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 saw table top near the front of the saw to hold the work piece in place. When the knob is pulled toward the front, the saw blade is brought into cutting position to cut through the work piece. Because the saw blade and its undercarriage generally slide along guide rails or rods, the blade is very stable and makes very accurate cuts in a work piece. Such saws are favored by many European trim carpenters and artisans who require precise cuts in their work. 
     Many currently available universal fences limit the effective size of a push-pull table top in that there is insufficient table top surface area for larger work pieces and the fact that they can be locked in only one or a relatively few positions on the table top. Moreover, because they are often fixed in those few positions, they do not permit the convenient sliding function found on many miter saw designs that are currently available in the United States. 
     Embodiments of the present invention provide support for larger work pieces and also have the capability of moving the fence to move work pieces relative to the blade through the cutting region. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention comprise a fence for a power saw having a table top with generally vertical front, rear and opposite side surfaces, at least one side surface having an elongated side element extending from a front portion toward said rear surface, said side element having a cross section defining a vertical groove with an inner vertical surface that merge into upper and lower opposed extensions that define upper and lower undercuts, said fence comprising an elongated fence member having a generally vertical front planar surface for engaging a work piece, a table extension having a top surface area coextensive with said saw table top and operatively connected to said fence member, said extension providing support for a work piece that extends beyond a side of the table top surface, said fence being configured so that the front planar surface can be positioned in front of the vertical front surface of the saw, i.e., off of the top surface. 
     Other preferred embodiments are described in the specification. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a left front elevated perspective view of a table saw of the push-pull type which has a preferred embodiment of a universal fence attached to the left front thereof; 
         FIG. 2  is a left side elevated perspective view of the table saw shown in  FIG. 1  and illustrating the preferred embodiment of the universal fence shown at a rearward position on the table surface; 
         FIG. 3  is a top plan view of the embodiment of the universal fence shown in  FIG. 1 ; 
         FIG. 4  is an elevated perspective view of the universal fence shown in  FIG. 1 ; 
         FIG. 5  is a front plan view of a portion of the universal fence shown in  FIG. 1 , partially in section, and particularly illustrating a locking mechanism; 
         FIG. 6  is a bottom view of the universal fence shown in  FIG. 1 ; 
         FIG. 7  is a left plan view of the universal fence shown in  FIG. 1 , particularly illustrating a detent mechanism override; 
         FIG. 8  is a side view of the universal fence shown in  FIG. 1  and partially in cross section and particularly illustrating a detent mechanism; 
         FIG. 9  is a bottom view illustrating a second preferred embodiment of a universal fence; 
         FIG. 10  is a side view of the second preferred embodiment shown in  FIG. 9 ; and 
         FIG. 11  is a front view of the second preferred embodiment shown in  FIG. 9 , partially in section, but illustrating another locking mechanism. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments of the present invention illustrated and described herein are directed to a universal fence that is designed and configured to be used with not only a push-pull type of power table saw, but other types of power table saws, such as conventional table saws that are marketed in the United States. The fence is adjustable in many respects which contributes to its superior functionality and usefulness, both in being able to slide from front to rear and thereby push work pieces through the cutting area of a table saw, but can also to position and hold work pieces on the table top surface to enable the saw to make extremely accurate straight as well as angled cuts on work pieces that are placed on the table top surface. 
     The fence has the capability of being attached to the table saw, which by virtue of its superior design and configuration, has a table top extension that is part of the fence. The extension increases the effective size of the table top and thereby enables larger work pieces to be supported during cutting. Moreover, the extension enables the fence member that contacts the work piece to be positioned in front of the front edge of the table top and thereby effectively increases the size of the table top for supporting larger work pieces. The use of clamping mechanisms with regard to many of the components of the fence facilitates extreme flexibility and adjustment which maximizes its utility and usefulness. 
     Turning now to the drawings, and particularly  FIGS. 1 and 2 , a push-pull type table saw is indicated generally at  10  which 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 has 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  that is supporting 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, and the carriage mechanism is mounted for sliding movement on elongated rails, rods or the like. The movement of the carriage mechanism is controlled by a mechanism that is connected to a front knob  38  that an operator can pull to move 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 fence 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 invention are particularly suited for use with. The saw  10  is also capable of making angled cuts on a work piece and to this end a rotatable knob  40  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 first preferred embodiment of the universal fence of the present invention is indicated generally at  50 . As best shown in  FIGS. 1 ,  2 ,  4  and  6 , the fence comprises a main body, indicated generally at  52 , which is preferably an aluminum casting which forms a table extension  54  that extends from a holding mechanism portion  56  that is located on the opposite or forward end of the mechanism. In this regard, the use of the term “forwardly” is intended to mean in the direction toward the front surface  14  of the saw. The holding mechanism portion  56  is designed and configured to hold an elongated fence assembly, indicated generally at  60 , which comprises an elongated rail member  62 , a miter base  64  and a miter frame mounted on the miter base  64 . An elongated fence member  68  is slidably attached to the miter frame  66 . 
     As is best shown in  FIG. 1 , the saw table top  12  has a grooved rail  70  located along the left side  18  as well as the right side  20 . The rail defines a captive groove  72  having a main opening, with the rail having upper and lower vertical extensions  74  and  76  which define upper and lower undercut portions of the groove in which the fence engages to be held to the table  10 . 
     In this regard, and referring to  FIG. 7 , the body  52  has a slide element  80  attached thereto which preferably extends along the entire length of the body from the front surface to the opposite end of the extension  54  as shown in  FIG. 6 . The configuration of the slide element  80  has a main portion  82 , an outer portion  84  and a narrower intermediate portion  86  which together define upper and lower flanges  90  and  92  which engage the upper and lower undercuts of the captive groove  72  defined in the rail  70 . The slide element  80  is preferably made of a strong plastic or plastic-like material that has a relatively low coefficient of friction, high strength and durability, such as Kevlar, for example. The slide element  80  is preferably attached to the body  52  with screws or similar fasteners, but may be adhesively attached. One consideration is that if it becomes worn and needs to be replaced, it should be capable of being disassembled and replaced without damaging the body  52 . It should also be understood that the rail  70  may be a metal extrusion, such as steel or aluminum that may be mounted to the side of the table, or it may be formed in the table top. 
     The fence member  68  is slidably retained by the elongated fence assembly  60  and to that end, as best shown in  FIGS. 4 and 11 , the fence member  68  is preferably an aluminum extrusion having a rear wall  84  in which a longitudinal slot  86  is formed. The miter frame  66  has a downwardly turned front face portion  88  that is preferably angled at 90° relative to the plane of the horizontal portion  66  and a clamping mechanism comprised of rotatable handle  90  pulls a clamp member  92  that is appropriately sized larger than the width of the slot  86  to pull the rear wall  84  into tight clamping contact with the front face portion  88  of the miter frame  66 . Thus, rotating the handle  90  to loosen the clamp member  92  enables the fence member  68  to be slidably adjusted relative to the elongated fence assembly  60 . 
     An important consideration of the use of the slide element in the captive groove  72  defined by the rail  70  is the fact that the slide element is attached to the table extension  54  and provides support for the fence from the front surface of the body portion  52  to the rear edge of the table extension  54 . This is significant for the reason that as shown in  FIG. 1 , the fence  50  can be moved to the extreme front of the fence as shown in  FIG. 1  wherein the front face of the fence member  68  may be located beyond the front edge  14  of the table top and still be in position to engage a work piece that is placed on the fence. In other words, the front face of the fence member  68  may be located in space in front of the front edge  14  of the table top. This effectively increases the useful size of the tabletop  12  compared to many fence designs which must have a fence element resting on the table top surface. 
     It should also be appreciated that with the sliding engagement of the slide element  80  in the rail  70 , a work piece can be placed with the fence in the extreme forward position and can be pushed toward the rear to perform a cut by the saw blade  32 . Another capability of the fence  50  is the angular adjustment of the fence member  68  relative to the orientation of the rail  70 . While most of the drawings have the fence member  68  parallel to the elongated rail member  62 , as shown in  FIGS. 1-6 , the elongated fence assembly  60  permits the fence member  68  to be adjusted to be perpendicular to the elongated rail member  62  as shown in  FIG. 9 . 
     With regard to rotating the angle of the fence member  68 , and referring to  FIGS. 3 and 4 , the miter frame  66  and the miter base  64  are pivotable about a pivot connection  94  that comprises a bolt that extends through the miter base  64  and the miter frame  66  and screws into the elongated rail member  62 . As shown in  FIG. 4 , the miter base  64  has indicia  96  that indicates the angular orientation of the front face  82  of the fence member  68  and as shown in  FIG. 4 , the top of the elongated rail member  62  has a center line that is aligned with the zero mark on the miter base  64 . 
     The elongated fence assembly  60  also has another clamping handle  98  which is also screwed into a threaded aperture of the elongated rail member  62  and it also rides in an annular slot  100  located in both the miter base  64  and miter frame  66 , which when loosened enables the miter base  64 , miter frame  66  and the fence member  68  to be rotated in the clockwise direction as viewed from above in  FIG. 4  to a position that extends to 90° and then in the opposite direction back toward zero. It is contemplated that the fence  50  can also be mounted in the right side  20 , rail  70  of  FIG. 1 . 
     As is best shown in  FIGS. 4 ,  6  and  7 , the body  52  has three upwardly directed angular portions  100 ,  102  and  104  which are angled to be parallel to an angled base portion  106  of the elongated rail member. While not shown, the body  52  has a similar angled surfaces for engaging an angled base portion  108  located on the opposite side of the base portion  106 . A clamping handle  110  has a threaded post that is screwed into the body  52  and engages a clamping plate  111  (see  FIG. 6 ) so that tightening the handle  110  causes the plate  111  to be tightened into engagement with the elongated rail member  62  to hold it. When it is loosened, the rail member  68  can be slidably adjusted relative to the body  52 . 
     The miter angular adjustment capability of the miter base  64  and the miter frame  66  is also provided with a detent mechanism that enables a user to loosen the handle  98  and quickly rotate the miter base  64  and frame  66  to predetermined angular positions which are accurately and quickly set. Referring to  FIGS. 6 and 8 , the miter base  64  has a number of apertures  112  which are shown to be at 5° increments which correspond to the indicia on the miter base  64  shown in  FIG. 3 . The apertures are sized to receive a ball  114  (see  FIG. 8 ) which is contained within a vertical sleeve  116  and which includes a compression spring  118 . The ball has a diameter that is larger than the diameter of the apertures  112  so that the ball only penetrates a distance sufficient to retain the angular position that is defined by the location of the particular aperture  112  in which the ball  114  seats. Thus, a user can merely rotate the fence member  82  and feel it snap from angular position to angular position and by viewing the indicia on the miter base can quickly change the angle of the fence member to a desired one. 
     However, it should be understood that there may be special angles that require specific angular positioning and the detent mechanism can interfere with such positioning, particularly when the angle very close to one of the predetermined angles. For this reason, the preferred embodiment of the present invention includes a detent mechanism override for selectively disabling the detent mechanism. This override mechanism is best shown in  FIGS. 4 ,  7  and  11  and includes a detent override slide, indicated generally at  120  which comprises an elongated member having a top portion  122 , downwardly depending sides  124  and a gripping portion  126 . 
     As best shown in  FIG. 7 , the detent override slide  120  rides on the top of the elongated rail member  62  which has a pair of recesses  126  and  128  in the top thereof, and which have a depth that corresponds to the thickness of the top portions  122  and a length that enables the slide  120  to be moved into and out of disabling engagement of the detent mechanism. In this regard, the rightward end of the top portion  122  shown in  FIGS. 7 and 8  is positioned to be moved from the position shown in  FIGS. 7 and 8  to the right wherein the top rightward portion  122  will engage the ball  114  and push it downwardly thereby disabling the ball from engaging any of the apertures  112  in the miter base  64 . This enables the angular position to be set by a user at any desired position wherein tightening of the handle  98  will lock the angular position in place as is desired. As is evident from  FIGS. 1 and 2 , the detent mechanism override slide is eminently visible and its use is intuitively obvious. 
     To lock the fence  50  in the captive groove  72 , the fence has a clamping mechanism, indicated generally at  130 , in  FIGS. 5 and 6 . With this embodiment, a short section of the slide element  80  is removed so that a slidable plate  132  which has a front surface  134  is in position to engage the upper extension  74  of the rail  70 . A compression spring  136  is provided to bias the slidable plate  132  away from engagement with the rail  70 . The slidable plate  132  has a pair of slots  138  in which suitable bolts  140  having suitable spacers (not shown) are seated into the bottom of the extension  52  so that the plate  132  can move toward and away from the slide element  80 . The slidable plate  132  has an inclined end surface  142  against which the end of a threaded shaft  144  can bear, with the threaded shaft  144  engaging a threaded opening in a support block  146  that is attached to the surface extension  54  with bolts  148 . A knob  150  can be used by an operator to selectively lock and unlock the fence to position it in a desired location or to slide the fence  50  along the rail  70 . 
     The second preferred embodiment of the present invention utilizes a different mechanism that takes the place of a slide element  80  and a clamping mechanism that is different from the clamping mechanism  130 . In this regard, and referring to  FIGS. 9 ,  10  and  11 , the mechanism includes a number of rotatable slotted rollers, including lower rollers  152  which engage the lower extension  76  of the rail  70  and a pair of upper rollers  154  that are positioned to engage the upper extension  74  of the rail  70 . While the number of rollers and their configuration may be other than that shown, the disclosed configuration provides the necessary support and ease of sliding movement. 
     A clamping mechanism for this embodiment is indicated generally at  156  and is shown in  FIGS. 9-11  to have a clamping block  158  that has an outer surface  160  which cooperates with a short slide element segment  162  that has a cross section that is substantially similar to the cross section of the slide element  80  of the first preferred embodiment. A bolt  164  having a threaded end portion  166  is threadably engaged with a rotatable threaded sleeve  168  which is rotatable within a suitable aperture in the block  158  and which has a preferably hexagonal recess  170  in which a complimentary configured end  172  of a shaft  174  is rotatably mounted in a mounting bracket  176 . It should be understood that other complimentary configurations could be used. 
     The outer end of the shaft  174  is secured to a knob  178  so that selective rotation of the knob  178  causes the shaft to rotate the sleeve  168  and cause the bolt  164  to draw the slide element segment  162  into locking engagement or disengagement. Since the action of the clamping mechanism positively moves the slide element segment  162  in either direction, a spring is unnecessary with this configuration. 
     The fence member  68  may be provided with a pivotable stop element as shown in  FIG. 4  at the right end of the fence member  68 . The element is shown in its retracted position wherein a front face  182  does not extend beyond the front face  82  of the fence member  68 . However, it is preferably pivotable by a suitable pivoting attachment so that it can be rotated approximately 90° from that shown in  FIG. 4  in the counterclockwise direction so that the upper end portion  184  extends beyond the front face  82  of the fence member  68  and thereby defines a stop position which can be used to precisely locate an end of a work piece that may be placed on the table top. If the lateral position of the end is determined to make an appropriate cut, an operator may use such a stop element to rapidly and efficiently make successive cuts on multiple work pieces. It should be understood that such a stop element  180  may be provided at the opposite end of the fence member  68 . The exact manner in which the pivoting connection is made may include an appropriate insert that fits within an appropriate portion of the extruded fence member as is known to one of ordinary skill in the art. 
     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.