Patent Document

BACKGROUND OF THE INVENTION 
     This invention relates generally to table saws and improvements thereto. More particularly, the invention relates to a table saw with a locking extendable table. 
     Table saws have been generally well known in the art for many decades. A recent trend with table saws has been to create portable table saws that enable a user to more easily transport the table saws from one work site to another. The advantages of portable table saws are readily apparent. Portable table saws may be quickly moved by hand, automobile, or other convenient transportation means without disassembling the table saw or transporting the saw in very large vehicles. Portable table saws are generally much smaller and easier to lift and carry than a conventional stationary table saw. Unfortunately, the compact nature of portable table saws often prevents the user from effectively using the portable table saw for cutting large and bulky items as the table surface is generally much smaller than a full size stationary table saw. This reduced cutting or ripping capacity of portable table saws has led to confining the table saw operator to decide between purchasing and using a portable table saw with its advantages and limitations, or purchasing a full size stationary saw with its different advantages and limitations. 
     Conventional portable table saws also often include rip fences that are less accurate than their stationary full sized counterparts. The operator may have to sacrifice cutting accuracy to afford himself the convenience of a portable table saw. 
     Additionally, conventional table saws often include many attachments such as a mitre gauge, rip fence, blade guard, and other attachments. Often with conventional portable table saws each of these attachments must be individually transported along with the table saw, increasing the inconvenience of using and transporting the portable saw. 
     Although there have been table saws manufactured with extendable tables, often the extensions are not lockable in any position and require the addition of other pieces not integral to the table itself. The extensions add the problem of rip fence scale adjustment. When an extension is added to a conventional table saw, the rip fence scale must somehow be adjusted to compensate for the change in table dimensions. 
     Still further, conventional table saws sometimes come equipped with a motor blade and cradle capable of adjustment. However, the accuracy of the adjustment often leaves much to be desired. With existing adjusting means, precise cutting angles often are not possible. 
     The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention, a table saw is provided. The table saw includes a first table mounted to a base and a second table substantially coplanar with the first table and attached to first and second rails. The second table is adapted to be slidably movable relative to the first table. 
     In accordance with another aspect of the present invention, a rip fence for a table saw is provided. The rip fence includes a longitudinal body with first and second ends, a head with at least one head glide, the head being attached to the first end and engagable with a first rail, and a spring finger incorporated onto the at least one head glide. 
     In accordance with another aspect of the present invention, a rip fence scale for use with a table saw is provided. The rip fence scale includes a flexible tape measure extending along a top side of the first rail and continuing around both first and second ends of the first rail to extend along at least a portion of the length of the underside of the first rail. 
     In accordance with another aspect of the present invention, a blade guard for use with a table saw is provided. The blade guard includes a mounting plate with at least two pins extending therefrom, and a guard connected to the support, wherein the at least two pins are engagable with the table saw to cause the guard to self align with a table saw blade. 
     In accordance with yet another aspect of the present invention, a cradle assembly for a table saw is provided. The cradle assembly may include a cradle, an elevation mechanism mounted to the cradle, a motor assembly mounted to the elevation mechanism, and a bevel mechanism. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features and aspects of the invention will become further apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a perspective view of the table saw in accordance with one embodiment of the present invention. 
         FIG. 2  is a perspective view of the table saw according to  FIG. 1  with the second table extended. 
         FIG. 3  is a partial bottom view of the table saw table according to FIG.  1 . 
         FIG. 3A  is a partial perspective view of the table saw according to  FIG. 1  illustrating the rip fence rail and slide. 
         FIG. 4  is a perspective view of the table saw according to  FIG. 1  with the second table unlocked. 
         FIG. 5  is a perspective view of a rip fence in accordance with one embodiment of the present invention. 
         FIG. 6  is a bottom view of the rip fence according to FIG.  5 . 
         FIG. 7  is an exploded view of the rip fence according to FIG.  5 . 
         FIG. 8  is a partial perspective view of the rip fence scale in accordance with one embodiment of the present invention. 
         FIG. 9  is a partial perspective view of the rip fence scale according to  FIG. 8  with the second table extended. 
         FIG. 10  is a partial bottom view of the rip fence scale shown in FIG.  8 . 
         FIG. 11  is a perspective view of a blade guard in accordance with one embodiment of the present invention. 
         FIG. 12  is an opposite perspective view of the blade guard according to FIG.  11 . 
         FIG. 13  is a perspective view of the cradle assembly in accordance with one embodiment of the present invention. 
         FIG. 14  is another perspective view of the cradle assembly according to FIG.  13 . 
         FIG. 15  is a perspective view of the table saw in accordance with one embodiment of the present invention with the attachments in their respective storage positions. 
         FIG. 15A  is a close-up view of the blade storage illustrated in FIG.  15 . 
         FIG. 16  is another perspective view of the table saw according to FIG.  15 . 
         FIG. 17  is another perspective view of the table saw according to FIG.  15 . 
         FIG. 18  is another perspective view of the table saw according to FIG.  15 . 
         FIG. 19  is another perspective view of the table saw according to FIG.  15 . 
         FIG. 20  is a block diagram conceptually illustrating a rip fence scale in accordance the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, that will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
     Turning now to the figures, and in particular to  FIG. 1 , one embodiment of a table saw  2  in accordance with the present invention is illustrated. Table saw  2  includes a table that is generally constructed of two pieces that are independent of each other. Table saw  2  includes a stationary table, for example first table  6 , mounted to a base  4 . A table extension, for example second table  8 , is attached to at least one rip fence rail. In the embodiment shown in  FIG. 1 , second table  8  is rigidly mounted to first and second rails  10  and  12 , respectively. First rail  10  and second rail  12  are adapted to slide over slides  14  that are mounted on the first table, which allow second table  8  to be movable relative to first table  6 . Second table  8  can be moved toward or away from first table  6  as desired by the operator. Having the table extension as a movable member allows the tables to be slid together for storage or smaller projects and slid apart to allow for an increased work surface and increased work support for larger projects. Second table  8  also allows the rip capacity to be increased on the second table  8  side of blade  146  when second table  8  is in the extended position shown in FIG.  2 . Second table  8  affords portable table saw  2  the advantages of a smaller, easily portable saw while maintaining the ability to facilitate larger work products usually reserved for full size stationary saws. Second table  8  is a considerable advantage over other portable table saws which have only extending support bars that are not nearly as stable as second table  8 . 
     At least one miter gauge groove  36  is disposed in first table  6 , however, more than one groove may be part of first table  6 , such as the two grooves  36  and  38  shown in the figures. In addition, at least one handle  32  is formed into first table  6  to facilitate the portable transport of the table saw from place to place. In the illustrated embodiment, two handles  32  and  34  are formed in first table  6 . 
     Turning next to  FIGS. 3 and 3A , first table  6  includes a fence rail/table lock facilitated by lock  16 .  FIG. 3  shows a bottom view of first table  6  with lock  16  mounted to second surface  30 , and  FIG. 3A  illustrates a portion of first table  6 , with first rail  10  positioned to expose slide  14  attached to first table  6 . Lock  16  is used to lock second table  8  at any desired distance from first table  6  within preset limits of travel, for example, about 10.25 to 10.5 inches. Lock  16  is designed in such a manner so as to clamp first rail  10  and second rail  12  to front  17  and back  19  of first table  6  with approximately equal pressure. Lock  16  includes a cam mechanism  26  that is positioned in a bushing  28  that is free to float in a front to back direction. Mounted to cam mechanism  26  are first clamping rod  22  and second clamping rod  24 . First clamping rod  22  extends through a hole  11  in first table  6  and through a slot  13  in first rail  10  (slot  13  is shown, for example, in FIG.  17 ). A tee or other shaped member (not shown) larger than hole  11  is disposed at the distal end of first clamping rod  22 . In a manner similar to that disclosed in conjunction with first rail  10 , second clamping rod  24  extends through a hole (not shown) in first table  6  and a slot (not shown) in second rail  12  with a tee or other shape larger than the slot in the same manner as described for first clamping rod  22 . 
     As one of the clamping rods  22  or  24  makes contact with the rail  10  or  12  upon rotation of cam mechanism  26 , the entire cam mechanism is pulled toward the contacting clamp until the opposite clamp makes contact with its associated rail. The lock thus clamps with an approximately equal force on both rails  10 ,  12 . 
     A lock lever  18  is attached to cam mechanism  26  to aid in the locking rotation of the mechanism. Lock lever  18  is attached opposite second surface  30 . Lock lever  18  is located in a position such that it extends from a first surface  20  when in the unlocked position shown in FIG.  4 . The extended position is such that it obstructs the operator from using table saw  2  if the lock  16  is not engaged. This obstruction facilitates the safety of the operator as the table saw may not be conveniently used with the second table unlocked. When the locking mechanism  16  is rotated to the locked position as shown in  FIGS. 1 and 2 , lock lever  18  is flush or below the first, or top, surface  20 . 
     Table saw  2  further includes a rip fence  40 , an embodiment of which is illustrated in  FIGS. 5-7 . Rip fence  40  may attach to table saw  2  via first and second rails  10  and  12 . Rip fence  40  may include a longitudinal body  42  with a head  44  attached to a first end  43 . Head  44  has at least one bead glide  46 , preferably having two bead glides  46  and  47  shown in FIG.  6 . Head glides  46  and  47  are engagable with first rail  10 . Head  44  also includes at least one spring finger  136  incorporated onto the head glides such that head  44  is biased to squared engagement with first rail  10 , with bumpers  52  meeting a face  21  of first rail  10 . At a second end  45  of rip fence  40  is a second end glide  138  which is engagable with second rail  12 . A fence lock rod  9 , shown in  FIG. 7 , extends substantially the entire length of rip fence  40  and enables locking engagement of the rip fence with first and second rails  10  and  12 . At the head  44  end of fence lock rod  9 , the lock rod engages a fence cam lever  62 . Fence can lever  62  includes a pin cam  56  and annular contact ball bearings  58 . The opposing end of fence lock rod  9  is attached to a plate lock  60 . Rip fence  40  may be locked in essentially any position along rip fence rails  10  and  12  by placing the rip fence glides  46 ,  47 , and  138 , onto rip fence rails  10  and  12 , and then rotating fence cam lever  62  to the locked position. The rotation of fence cam lever  62  transmits a force along fence lock rod  9 , which in turn “squeezes” bumper  52  into frictional engagement with face  21  of first rail  10  while also forcing second end glide  138  into similar engagement with second rail  12 . Spring fingers  136  continue to ensure the engagement of head  40  with rail  10  remains square. 
     Turning next to  FIGS. 8-10 , a rip fence scale  64  attached to table saw  2  in accordance with one embodiment of the present invention is disclosed. Rip fence scale  64  is designed to allow a single scale to be used while second table  8  is in any of its infinite positions without having to readjust the scale every time the second table is moved. 
       FIG. 20  conceptually illustrates the operation of a rip fence scale such as rip fence scale  64  illustrated in  FIGS. 8-10 . Referring to  FIG. 20 , rip fence scale  264  includes flexible tape measure  266  having first end  278  and second end  280 . Flexible tape measure  266  extends around two guides  240  and  242  in a closed loop configuration. The loop is closed by a tensioned fastener  276  that connects first end  278  and second end  280 . One point  244  of flexible tape measure  266  is fixed to a stationary base portion  204  of table saw  202 . The fixed point  244  is substantially aligned with a blade  246  of table saw  202 . First guide  240  may be attached to a table extension, such as the table extension  218 , which may include the elements described above for second table  6 , or the extension may be any other conventional table saw extension known in the art. Flexible tape measure  266  travels around guides  240  and  242  in response to movement of table extension  218  toward or away from base  204 . The configuration conceptually illustrated in  FIG. 20  thus provides a scale  264  that extends along the entire extended working length regardless of the position of the table extension  218 , while ensuring that fixed point  244  remains aligned with blade  246 . 
     In the embodiment shown in  FIG. 8 , rip fence scale  64  is incorporated into first rail  10 . Rip fence scale  64  includes a flexible tape measure  66  extending along a top side  68  of first rail  10  and continuing around both first  70  and second  72  ends of the first rail  10  to extend along at least a portion of the length of an underside  74  of the first rail  10 . A tension spring  76  is shown in  FIG. 10 , which connects first end  78  and second end  80  of flexible tape measure  66 . In the embodiment shown in  FIG. 10 , the connection of first  78  and second  80  ends is at underside  74  of rail  10 . Flexible tape measure  66  is fixedly mounted to first table  6  at least at one point  69 . In the illustrated embodiment, point  69  is fixed relative to the saw blade. 
     When second table  8  is moved away from first table  6 , flexible tape measure  66  is pulled under the first end  70  of fence rail  10 . At the same time, tape measure  66  is pulled up onto the top side  68  of rail  10  at second end  72 . Constant tension is maintained on the flexible tape measure with the use of tension spring  76  that connects first and second ends  78  and  80  of flexible tape measure  66 . It will be understood with the benefit of this disclosure that any other conventional tensioned fastener may take the place of spring  76 . 
     The exemplary rip fence  40  shown in  FIGS. 5-7  includes an indicator  81 . When rip fence  40  is attached to table saw  2  via first and second rails  10  and  12 , the indicator  81  is situated relative to rip fence scale  64  so as to indicate the distance from the saw blade to the edge of the rip fence  40 . 
       FIGS. 8 and 9  illustrate the movement of flexible tape measure  66  as second table  8  moves away from first table  6 .  FIG. 8  shows rip fence scale  64  with second table  8  in close proximity to first table  6 , while  FIG. 9  shows the change in rip fence orientation with second table  8  removed some distance from first table  6 . Fixed point  69  remains in place relative to the blade before and after movements of second table  8  to simplify the measurement capabilities of the user before and after moving the second table. The distance traveled by flexible tape measure  66  is substantially equal to the distance second table  6  moves relative to first table  8 . Substantial equality means that to one of ordinary skill in the art with the benefit of this disclosure, no readjustment of the flexible tape measure  66  would be necessary following the movement of second table  8  while maintaining accurate measurement abilities from readings on the scale. 
     Turning next to  FIGS. 11 and 12 , a blade guard  82  as first seen in  FIGS. 1 and 2  is shown in detail. Blade guard  82  includes mounting plate  84  with at least two pins  85  and  86  extending therefrom. In the embodiment shown in  FIGS. 11 and 12 , pins  85  and  86  are supplemented by an attachment device such as threaded knob  88 . It will be understood by one of skill in the art with the benefit of this disclosure that either or both of pins  85  or  86  may be replaced by threaded knob  88 , wherein only two protruding pins instead of the three shown in  FIGS. 11 and 12  would result. Threaded knob  88  is engagable with a hole  89  (shown in  FIG. 14 ) to securely fasten blade guard  82  to table saw  2 . Blade guard  82  is designed for easy removal to facilitate the portability and the making of non-through cuts with table saw  2 . Blade guard  82  is held in place by threaded knob  88  and is self aligned as pins  85  and  86  are inserted into mating holes  91  and  93  (shown in FIG.  14 ). One of skill in the art with the benefit of this disclosure will observe that according to the disclosed blade guard design, all adjustments to align the blade guard  82  with blade  146  are made independent of mounting plate  84 , and thus after a first alignment there is no need to realign the guard each time the guard is reinstalled. The pins ensure that the guard realigns in the position adjusted to by the first alignment. The first alignment may be accomplished by loosening one or both of bolts  95  and  97  of blade guard  82 , aligning the guard and blade, and subsequently tightening the bolts. After this initial alignment requiring the adjustment of bolts  95  and  97 , removal of the blade guard  82  and any subsequent re-attchments will result in a self aligned blade guard as pins  85  and  86  and threaded knob  88  engage their respective holes in table saw  2 . 
     Turning next to  FIGS. 13 and 14 , a cradle assembly  90  for holding a motor assembly  120  and blade  146  for use with table saw  2  in accordance with one embodiment of the present invention is disclosed. Cradle assembly  90  preferably includes both an elevation mechanism  98  and a beveling mechanism  128 , but it may include only one of the two mechanisms. As shown in  FIGS. 13 and 14 , cradle assembly  90  may include a cradle  96  having a pivotal mount comprising first mount  92  and second mount  94 . Elevation mechanism  98  is mounted to cradle  96 . Elevation mechanism  98  is used to raise and lower motor assembly  120  and blade  146  so as to allow the operator to adjust the depth of the table saw cuts. Elevation mechanism  98  includes a first bar  100  with a first end  102  and a second bar  104 . First bar  100  has a threaded portion  106  and has a first bevel gear  108  attached to first end  102 . A second bevel gear  110  engages first bevel gear  108 , the second bevel gear being attached to a first end  114  of a crankshaft  112 . A crank handle  118  is attached to a second end  116  of crankshaft  112 . 
     Motor assembly  120  is attached to elevation mechanism  98  at three mounting points. This constitutes an advantage over conventional elevation mechanisms that typically include more than three mounting points and more than two bars. First mounting point  122  may be seen in  FIG. 14  between motor assembly  120  and second bar  104 . Preferably, the mounted connection between second bar  104  and first mounting point  122  is slidable. Second bar  104  is a guide bar and restricts motor assembly  120  from pivoting left and right (as viewed in FIG.  13 ). A second mounting point  124  shown in  FIG. 13  connects motor assembly  120  to first bar  100 . In the embodiment shown in  FIG. 13 , second mounting point  124  attaches to an unthreaded portion of first bar  100 , however, threaded portion  106  may extend all the way to second mounting point  124  in an alternative embodiment. A third mounting point  126  connects motor assembly  120  to the threaded portion  106  of first bar  100 . The combination of first bar  100  and second and third mounting points  124  and  125  prevent motor assembly  120  from rotating from front to back (as viewed in FIG.  13 ). 
     The threaded portion  106  of first bar  124  engages third mounting point  126  such that with the rotation of first bar  100 , motor assembly  120  moves up or down along the longitudinal axis of first and second bars  100  and  104 , depending on the direction of rotation. Rotation is normally facilitated by crank handle  118 , which may be rotated by an operator, which in turn rotates first bar  100  via bevel gears  108  and  110 . 
     Cradle assembly  90  may also include the beveling mechanism  128  as shown in  FIGS. 13 and 14 . Beveling mechanism  128  includes a gear rack  130  along an edge of first cradle mount  92 . Engagable with gear rack  130  is a gear  132 . Gear  132  and gear rack  130  enable an operator to rotate cradle  96  to any desirable angle, most typically in the range of between 0 and 45 degrees. Gear  132  is part of a sliding sleeve  166  with a hand wheel  167  opposite the gear. Sliding sleeve  166  is mounted around the outer diameter of second end  116  of crankshaft  112 . Sliding sleeve  166  rotates independently of crankshaft  112  to allow independent adjustment of elevation and bevel angle. Sliding sleeve  166  may also be slid along the longitudinal axis of crankshaft  112  to disengage gear  132  from gear rack  130  to facilitate quick rotation of large bevel angles that may take more time by rotation of the gear while engaged with the gear rack. A spring  151  biases gear  132  into engagement with gear rack  130 , but a small force on sliding sleeve  166  transmitted by an operator may easily disengage the gear from the rack. 
     Bevel mechanism  128  may also include a locking mechanism  134  for securing the cradle assembly  90  in any desired bevel angle. The locking mechanism includes a locking bar  156  with first end  158  and second end  160 , which extends through first slot  150  and second slot  152 , respectively, of mounts  92  and  94 . Typically first and second slots  150  and  152  will span approximately 45 degrees in an arcuate manner. In the embodiment of  FIGS. 13-14 , locking bar  156  is U-shaped, but one of skill in the art with the benefit of this disclosure will recognize that other shapes for locking bar  156  may be used. The exemplary U-shaped locking bar  156  illustrated allows clearance for the other parts in the assembly. First end  158  of locking bar  156  is connected to a cam  164  and lever  162 . Cam  164  and lever  162  are rotatable to a locked and an unlocked position. When cam  164  and lever  162  are rotated to the locked position shown in  FIG. 13 , a clamping force from the cam is transmitted to first and second mounts  92  and  94  via locking bar  156 . The U-shape of locking bar  156  causes it to act as a spring. When lock  134  is locked, it attempts to straighten locking bar  156 . The resistance of U-shaped locking bar  156  causes mounts  92  and  94  to clamp down on the cradle. This clamping action keeps the cradle assembly  90  in the desired angled position. 
     Operation of the beveling mechanism may be as follows. When a user is required to set motor assembly  120  and blade  146  at a precise cutting angle, the user may rotate gear  132  via hand wheel  167 , thereby precisely rotating cradle  96  to the desired angle. The user may then rotate lever  162  to lock cradle  96  in position. Since, for precise adjustments, gear  132  is engaged with gear rack  130 , the motor assembly  120  remains at the desired cutting angle even after the user releases the hand wheel  167 . This facilitates “one-handed” adjustments, wherein the user may set the cutting angle via hand wheel  167 , then release hand wheel  167  and actuate lever  162  with the same hand to lock cradle  96  at the set angle. 
     If, on the other hand, the operator wants to quickly adjust the bevel angle from 0 to 45 degrees, for example, the operator may press on hand wheel  167  to disengage gear  132  from rack  130  and quickly rotate the cradle to the desired angle before again locking the cradle in position. Thus, this disengagable gear  132  and rack  130  offer considerable advantages over the prior art in ease of use and precision of bevel angle. 
     As discussed above, cradle  96  includes a plurality of holes  89 ,  91 , and  93  for receiving aligning pins  85 ,  86 , and threaded knob  88 . Holes  89 ,  91  and  93  are accessible via an opening  87  in second mount  94 . Including holes  89 ,  91 , and  93  on second mount  94  facilitates alignment between blade guard  82  and blade  146 . 
     Turning next to  FIGS. 15-19 , the portable table saw  2  has the capacity to store a number of accessories to facilitate easy transport. Moreover, base  4  is a two-part assembly—lower part  180  adds stiffness and acts a skid to allow table saw  2  to slide easily on rough or uneven surfaces. Storage for rip fence  40 , miter gauge  192 , blade guard  82 , blade wrenches  182 , blades  184 , and power cord  194  are all provided on the saw. The storage is designed such that the saw  2  can be turned and tilted in virtually any direction without the components detaching while in the stored positions. Referring to  FIG. 15A , spacers  185  are provided that may be placed between spare blades  184  that are being stored on the saw  2 . When the spacers are placed between the blades, the tips  187  of the blades  194  are protected from contacting one another which protects tips  187  from being chipped or broken. 
     Base  4  has multiple sized grooves  186  sized for standard 2-by stock on edge or for 2×4 laying flat as shown in FIG.  19 . Holes  189  are also provided above each groove  186  to allow table saw  2  to be screwed down to a sawhorse  191 . Holes  188  are provided for both screws and bolts on all four corners of base  4  as well as a flat area  190  that may be used for clamping the saw down. 
     While the present invention has been particularly shown and described with reference to a particular illustrative embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention. The above-described embodiment is intended to be merely illustrative, and should not be considered as limiting the scope of the present invention.

Technology Category: 4