Abstract:
A portable, double bevel, combination table saw and slide miter saw comprising a horizontally disposed working platform with an elongated slot, is supported by a frame. A saw assembly is pivotably mounted beneath the working platform, with a saw blade that protrudes through the slot to cut a workpiece on the platform whereby stationary workpiece operations as well as moving workpiece operations may be executed. The stationary workpiece operations are executed from one side of the platform, and moving workpiece operations are executed from the opposite side of the platform, with separate appropriate controls on each side. The possibility of interference between saw assembly parts and the underside of the work platform inherent in double bevel configurations is avoided by the self-adjustment of the maximum depth for the workpiece bevel cuts.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a portable combination table saw. More specifically, it relates to a table saw wherein moving workpiece cutting, stationary workpiece cutting, and double beveling capabilities are provided in one device. 
   BACKGROUND OF THE INVENTION 
   For transportable personal or contractor use, there has been a steady progression of designs of bench saws. For moving work pieces, these range from simple single position saw blade table saws to beveling and depth cut adjustable table saws. The operational advantage of having stationary workpiece cross cutting was recognized early in design of bench saws, with the ensuing design of swinging saws and sliding saws having motors either above or below the work platform. Comprehensive designs such as radial arm saws and above the work platform slide miter saws have found recent popularity. 
   Another portable saw design is a saw that achieves long moving workpiece rip cutting, and also provides stationary workpiece cutting. Radial arm saws provide both functions, and have been commercially successful; however, their size and weight make them non transportable, and their rip cut widths are limited. To complete the package of functions, some recent saw designs have, for either above or below work platform saw motor applications, included double bevel cutting. Examples of these designs include U.S. Pat. No. 5,357,834 issued to Ito et al. entitled “Miter Saw”; U.S. Pat. No. 5,720,213 issued to Sberveglieri entitled “Bevel Table Saw Adjustment”; and U.S. Pat. No. 6,591,725 issued to Martin entitled “Circular Sawing Machine.” However, the prior art has not developed a table saw with slide miter cutting capabilities that is competitive with the prior art above platform slide miter saws Further, the manual control of prior art table saw slide cutting, is not compatible with operator accustomed procedures. 
   SUMMARY OF THE INVENTION 
   In order to overcome the deficiencies in the prior art, the present portable, double bevel, combination table and slide miter saw has been devised. It is the purpose of this invention to improve the cutting capabilities of known prior art double bevel table saws with the convenience of slide miter saws, and to be economically competitive. As will be more fully described herein, the present saw comprises a horizontally disposed working platform with an elongated blade slot supported by a frame, and a saw assembly pivotably mounted beneath the working platform with a saw blade that protrudes through the slot to cut a workpiece on the platform. Stationary workpiece operations as well as moving workpiece operations may be executed. The stationary workpiece operations are executed from one side of the platform, and moving workpiece operations are executed from the opposite side of the platform. Separate controls are provided on each side of the saw for the corresponding function. 
   More specifically, this design provides a generally horizontally disposed platform having a working surface, an underside, a saw blade slot, first and second opposing platform sides at opposite ends of the slot, and a blade slot axis. A frame supporting the platform has a first side and a second side corresponding to the first and second sides of the platform, and includes an arcuate gear rack mounted along the inside, near the bottom of each of the frame sides, the racks having a radially varying curvature. A cradle assembly is pivotally supported by the frame substantially about the slot axis, the cradle having first and second sides corresponding to the first and second sides of the frame. The cradle has two clamping mechanisms in selective engagement with the frame for releasably locking the cradle to the frame at selected pivotal positions of the cradle. A carriage is mounted on the cradle framework, and includes a mechanism for providing the slidable movement of the carriage in a horizontal direction parallel to the blade slot axis. A saw assembly is mounted on the carriage, and comprises a saw motor to which a circular saw blade is attached. 
   Two telescoping guide assemblies are mounted on the frame, in line with the blade slot, one each on the first and second sides, and engage the cradle for radial alignment thereof. 
   Two pinion gears are mounted on the cradle framework, one on each side. The pinion gears are in meshing relation with the arcuate gear racks on the frame for supporting the cradle assembly, for controlling the pivotal movement of the cradle assembly, and for automatically adjusting the saw blade exposure above the platform as the cradle assembly pivots. The pinion gears are arranged in a coaxially aligned opposing pair on opposite ends of a through shaft, rotatable in unison by hand cranks, one on each of the first and second sides of the frame. Hand-cranking the gear pair in unison by using either crank, the position of the cradle, and hence the bevel angle of the saw blade, can be manually adjusted. 
   The saw assembly is pivotally mounted to the carriage on side-suspended axles that permit movement of the motor assembly about an axis parallel to the axis of the saw blade; whereby, the saw blade is moved from a non-cutting position below the platform to cutting positions above the platform. A control arm is connected to the carriage for rotating and for moving horizontally the saw assembly. The control arm is connected to the saw assembly by a linkage such that the downward movement of the control arm causes the upward motion of the saw blade and the forward and backward movement causes the forward and backward motion of the saw blade. A control handle is attached to the end of the control arm whereby the full range of motion of the saw blade is controlled by the upward, downward, backward, and forward manual movement of the handle. A saw assembly positioning mechanism independent of the control arm, is mounted on the carriage; whereby, the vertical position of the saw blade with respect to the platform may be fixed at selected heights. Means at the second side of the frame are included for operating the saw assembly positioning mechanism. 
   Accordingly, it is the object of the present invention to provide a portable table saw that supports dual beveling, stationary workpiece cutting, and moving workpiece cutting. 
   It is further an object of this invention to provide better stationary cutting performance than known prior art slide miter saws. To this end, a cutting envelope is provided that maximizes performance for the applied hardware dimensions. 
   It is stiff further an object of this invention to provide a stationary workpiece cutting action that is directed away from the operator as is provided by the popular prior art over-platform slide miters. This cutting action is also to provide a cut initiation point that is located at the platform surface, conveniently visible to the operator, and that normally coincides with a standard workpiece marking edge. This provides the convenience of a laser line without the added cost. 
   It is yet further an object of this invention to provide stationary workpiece operation from the first side of the platform, and to provide moving workpiece operation from the second side of the platform, with full and separate controls for each operation on its associated side. 
   It is further an object of this invention to provide a bevel locking means that simultaneously locks two points, one at each first and second sides of the cradle, to the frame, to maintain a more rigid configuration. 
   From the following drawings and description of the preferred embodiment, it will be appreciated by those of skill in the art that the objects of the invention have been achieved. While the present invention will be described with the reference to a specific embodiment, the following description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications to the present invention can be made to the preferred embodiment by those skilled in the art without departing from the true spirit and scope of the invention. It will be noted here that for better understanding, like components are designated by the same reference numerals throughout the various figures of drawing which follow. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevation view partially cut away, with saw blade positions shown in phantom. 
       FIG. 2  is a top plan view partially cut away. 
       FIG. 3  is an isometric view with the platform and frame removed. 
       FIG. 4  is a miter mode side view with alternate saw blade bevel positions shown in phantom. 
       FIG. 5  is a table mode side elevation view partially cut away with the pivotal hardware and saw blade maximum positions shown in phantom. 
       FIG. 6  is a table mode side view with the maximum saw blade pivot bevel positions shown in phantom. 
       FIG. 7   a  is a top plan enlarged sectional view showing the bevel position locking mechanism in the unlocked state. 
       FIG. 7   b  is a top plan enlarged sectional view showing the bevel position locking mechanism in the locked state. 
       FIG. 8  is a top plan partially sectioned view of the control wheel disengagement mechanism. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to the drawings, in which common components have been numbered the same,  FIG. 1  illustrates in one embodiment, a double bevel combination table saw and slide miter saw  10 , comprising a frame  37 , and having a working platform  35  in which is formed a saw slot  36 . The saw may be operated as a slide miter saw from a first side of the platform  35  (the left side of this figure), herein referred to as “the miter mode side”, or operated as a conventional table saw from the opposing side of the platform  35  (the right side of this figure), herein referred to as “the table mode side”. These opposing sides are at opposite ends of the slot  36 . Referring to  FIG. 5 , a pivot axis  15  for the bevel action of this invention, is established as a line substantially on the surface of platform  35  and coincident with the longitudinal center line of slot  36 . 
   Referring to  FIGS. 1 ,  2 , and  3 , a supporting cradle  38 , disposed beneath platform  35 , is the framework on which a saw assembly  11  is pivoted about axis  15 . The cradle  38  is supported by the frame  37  through a rack and pinion means as described below. Two radial alignment guide assemblies  60 , each comprising a half-round bracket  69  and a guide bar  65 , are disposed beneath the platform  35 . At each end of slot  36 , a bracket  69  is mounted on the top of frame  37 , and each bracket  69  has a half round track  64  with a center of curvature on axis  15 . Guide bars  65  slidably engage each track  64  for arcuate movement thereon. A guide sheath  66  is fixedly attached to each opposing end of cradle  38 , and further; the distal end or each bar  65  linearly slidably engages a respective sheath  66 . The guide assemblies  60  are in a telescoping relation with, and maintain the pivotal disposition of, cradle  38 . Cradle  38  is supported during pivotal adjustments by the frame  37 , by a rack and pinion means, and by bars  65 . Referring to  FIG. 2 , a bevel adjustment through shaft  34 , parallel to the pivot axis  15 , is rotatably connected to cradle  38  substantially near its base, and a bevel pinion  29  is fixedly attached near each end of shaft  34 , wherein pinions  29  reside between cradle  38  and frame  37 . On the lower portion of frame  37 , a support rack  28   a  is fixedly attached to the inside of the miter mode side, and a support rack  28   b  is fixedly attached to the inside of the table mode side. Racks  28   a  and  28   b  have substantially square cross sections, have geared upper sides, and have smooth under sides. The pinions  29  engage the upper sides of racks  28   a  and  28   b . Referring to  FIG. 1 , a containment roller  31  is disposed on the underside of each rack  28   a  and  28   b , directly opposing each pinion  29 , and each roller  31  is rotatably supported by a roller axle  32  fixedly attached to cradle  38 . Axles  32  are parallel to shaft  34 . Each roller  31  is disposed at a distance from its respective pinion  29 , that insures meshing contact is maintained for each gear  29  and its corresponding rack  28   a  or rack  28   b . Shaft  34  extends outside frame  37  through a control traveler slot  73  on the miter mode side, and through a control traveler slot  71  on the table mode side. A bevel adjustment crank wheel  33  is fixedly attached to each end of shaft  34 . Rotating either wheel  33  forces pinions  29  to progress on respective racks  28   a  and  28   b , and thus the pivotal position of cradle  38  is adjusted. Racks  28   a  and  28   b  are symmetrical and of a design established, irregular configuration, thus adjusting the radial dimension of the pivotal path of cradle  38 , relative to the axis  15 , automatically according to the bevel angle. 
   Once the cradle  38  has been located at a desired bevel angle, two bevel position locking mechanisms  120 , shown in  FIG. 2 , one at each end of cradle  38 , are employed to lock cradle  38  in position. Mechanism  120 , as shown in greater detail in  FIGS. 7   a  and  7   b , comprises a clamp housing  121  fixedly connected to cradle  38 ; a bevel lock through shaft  127  rotatably and slidably connected to housing  121  by a shaft bearing  129 ; a pressure ring  126  fixedly attached to shaft  127  and adjacent to housing  121 , a cylindrical cam block  122  coaxial with, slidably attached to, and rotatably engaging shaft  127 ; a cylindrical clamping piston  123  coaxial with and slidably and rotatably attached to shaft  127 ; and a compression spring  124  coaxial with shaft  127  and positioned between block  122  and piston  123 . Shaft  127  extends outside the frame  37 , through slot  73  on the miter mode side, and through slot  71  on the table mode side. A clamp washer  125 , coaxial with shaft  127 , is placed on each side of frame  37  near each end of shaft  127 . A bevel lock handle  128  is fixedly attached to each end of shaft  127 . Handles  128  having a lock position and a release position. For at least the distance of slidable attachment of block  122  on shaft  127 , shaft  127  has a square cross section. Shaft  127  slidably engaging a square shaft along the axis of cylindrical block  122 , such that block  122  turns in unison with shaft  127 . The junctions of blocks  122  and housings  121  provide a common cam action, such that turning either handle  128  from its release position to its lock position, forces each block  122  toward frame  37 . The action of block  122  toward frame  37  is transferred through spring  124  forcing cylindrical piston  123  against a washer  125 . The spacing of handle  128 , washers  125 , and frame  37  are such that washers  125  compress against frame  37 , providing locking of cradle  38  to frame  37 , and thus locking the saw assembly  11  in a selected bevel position. Springs  124  provide stable locking states in a common manner. Rings  126  direct the counterforce of the locking pressure exerted by pistons  123  to shaft  127 . 
   Referring to  FIGS. 1 ,  2  and  3  of the accompanying drawings, the saw assembly  11 , comprising a circular saw blade  14  attached to a saw motor  12 , is rotatably mounted on a motor support carriage  40 , which in turn is slidably mounted on two slide bars  61  secured to cradle  38  by two bar supports  62 . The slidable mounting of carriage  40  is accomplished by a bearing assembly  63 , fixedly attached to carriage  40  and traveling on bars  61 . The saw motor  12  is rotatably mounted on carriage  40  by a two sectioned motor support axle  24  affixed to the sidewalls of the carriage  40 . Stops, not described herein, on a carriage brace  43  provide for limiting rotation of motor  12  in either direction. Referring to  FIG. 5 , the saw assembly  11  as shown in greater detail, comprises saw motor  12 , a saw blade axle  23  supporting the circular saw blade  14 , and a drive transmission mechanism  18  for transferring drive from motor  12  to saw blade  14 . Mechanism  18  comprises a beveled gear  25  driven by a motor drive shaft  13 , and a beveled gear  26  on a lay shaft  27 , driven by gear  25 ; further, a belt  22  mounted on shaft  27  drives axle  23  and subsequently blade  14 . This version of mechanism  18  is for demonstration purposes, and mechanism  18  could be configured, within the scope of this invention, in a variety of ways to maintain a minimal profile as required for double beveling. The rotation of motor  12  about axle  24 , permits blade  14  to travel between a recessed position, slightly beneath the surface of platform  35 , and a position for maximum cut depth above platform  35 . 
   As described earlier, the pivotal path of cradle  38  is automatically adjusted according to the bevel angle. This in turn determines the available exposure of saw blade  14  according to the bevel angle. With reference to  FIG. 5 , noting the phantom displacement lines, if the cradle  38  is swung in a circular path, 45 degrees to the right with saw blade  14  at its maximum exposure, there is sufficient space below the platform  35  for the saw assembly  11  and other parts of the pivoting apparatus to be accommodated without clashing with the platform  35 . However, swinging the cradle  38  in a circular path 45 degrees to the left with the saw blade  14  at its maximum exposure, would force portions of the saw assembly  11  to clash with the underside of the platform  35 . Hence the configuration of racks  28   a  and  28   b  is chosen such that the automatic adjustment of the cradle  38  radial disposition, avoids clashes between saw assembly  11  and platform  35  over the entire bevel range. 
   Referring now to  FIGS. 2 ,  4  and  5 , carriage  40  horizontal position locking is provided for transporting or storage, table mode operation, or miter mode operation when it is desirable to perform non sliding chop cuts. The locking is released for miter mode slide cutting operations. Operating the saw in the table mode where the work piece is moved through the blade, involves a horizontally fixed saw assembly  11 ; therefore, before entering this mode, saw assembly  11  is locked in a selected horizontal position by means of a latch control handle  97 . A transverse latch mechanism  94  provides the means to releasably lock the carriage  40  at a plurality of selected positions along the bars  61 . The mechanism  94  includes a traverse latch plate  95  having a plurality of receptor openings  98 , and is fixedly attached to carriage  40 . Mechanism  94 , of common latch bolt construction and fixedly connected to the cradle  38 , being controlled by a traverse latch shaft  96 . Referring to  FIG. 2 , shaft  96  is rotatably supported by cradle  38 , and extends outside the frame  37  through traveler slot  73 . Control handle  97 , having a latch position and a release position, is fixedly attached to the distal end of shaft  96  on the miter mode side of the frame  37 . Employing handle  97 , a latch bolt  99 , of the mechanism  94 , may be directed into a selected opening  98 . When bolt  99  engages an opening  98 , carriage  40  is locked relative to cradle  38 . 
   Referring to  FIGS. 1 through 4 , a miter mode control handle  41  provides a first means for cut depth adjustment used exclusively for the miter mode. A control axle  55  is rotatably connected to carriage  40 , and a handle arm  42  is fixedly connected to axle  55 . Arm  42  extends through an arm traveler slot  39  in cradle  38 , and outside frame  37  through a control traveler slot  72 . Handle  41  is fixedly connected to the distal end of arm  42 . Axle  55  is further fixedly connected to a miter mode control pulley  46 . Still further, pulley  46  is linked to a saw assembly pulley  17  by a miter mode control cable  45 , and pulley  17  is fixedly attached to axle  24 . The linkage is such, that the action of depressing handle  41  from its rest position through the full extent of its vertical freedom, moves saw blade  14  from its recessed position to its maximum cut depth position. A helical bias spring  56 , coaxial with axle  55 , affixed to axle  55  and carriage  40 , maintains a bias on motor  12 , through connecting linkages, that returns saw blade  14  to its recessed position when handle  41  is released. Handle  41  is further employed to move saw blade  14  the extent of its horizontal range. This horizontal movement being accomplished by urging handle  41  toward and away from frame  37 . A momentary power switch  76  is mounted in handle  41  for miter mode power control of motor  12 . 
   A maximum cutting envelope  20  for miter mode operations, indicated by dashed lines in  FIG. 1 , is generated by depressing handle  41  when in its extended position, its full range, then urging it through its full horizontal extent. 
   Referring now to  FIGS. 1 ,  2 ,  3  and  6 , a cut depth control crank wheel  113  provides a second means for cut depth adjustment and is used exclusively for the table mode. Wheel  113 , as described below, is rotatably linked to pulley  17  only when wheel  113  is urged toward frame  37 . Motor  12  rotation is controlled by rotating wheel  113 , moving saw blade  13  between its recessed position and its maximum cut depth position. Because the cut depth control is also affected by another linkage at the miter side of the frame, it is necessary that the wheel  113  linkage be operatively disconnectable. This disconnect being accomplished through the action of a control wheel disengagement mechanism  105 . Referring now to  FIG. 8 , means for providing the disengagement of this linkage are shown in detail. Wheel  113  is fixedly connected, outside frame  37 , to one end of an engagement shaft  107 . Shaft  107 , extending through slot  71 , is rotatably and slidably connected to mechanism  105 . Mechanism  105  is fixedly connected to cradle  38 , and comprises a disconnect housing  112 , an engagement gear  108 , and a geared block  115 . A cut depth control shaft  106 , coaxial with shaft  107 , and on the opposing side of housing  112 , is rotatably attached to housing  112 . Block  115  is rotatably connected to housing  112 , and is coaxial with shaft  106  and shaft  107 . Shaft  106  is fixedly attached to block  115 , and shaft  107  slidably and rotatably attaches to block  115  through a cylindrical guide  114 . A compression ring  111  is fixedly attached to shaft  107 , and a release bias spring  110  coaxial with shaft  107 , is disposed between ring  111  and cradle  38 , such that spring  110  maintains a bias, away from cradle  38 , on shaft  107 . Engagement gear  108  is fixedly attached to shaft  107 . Block  115  has a receptor gear  109 , such that when shaft  107  is urged toward cradle  38  using wheel  113 , gear  108  engages gear  109 , and wheel  113  is releasably linked to shaft  106 . The rotary motion of shaft  106  is transferred to a table mode control pulley  47  through a direction transmission  101 . Transmission  101  being of commonly known construction. Pulley  47  is linked to pulley  17  by a table mode control cable  44 . The connection of shaft  106 , shaft  106  having a square cross section, to transmission  101  is longitudinally slidable and rotationally engaging. When the pressure toward cradle  38  on wheel  113  is removed, the bias of spring  110  disengages gear  108  from gear  109 . 
   Referring to  FIGS. 2 and 3 , when the motor  12  is adjusted by wheel  113  to provide the desired cutting depth, the motor  12  can be locked in place using a cut depth lock handle  92 . The locking means comprises a disk segment  16  fixedly attached to motor  12 , and a caliper locking mechanism  48 , of common construction, fixedly attached to carriage  40 , through which disc segment  16  passes. A cut depth lock shaft  90  with a square cross section, connects to handle  92  at one end outside frame  37 , extends through slot  71 , and is rotatably supported by cradle  38 . Further, shaft  90  longitudinally slidably attaches to and rotatably engages, the caliper locking mechanism  48 . Mechanism  48 , of well know cam design and under the control of shaft  90 , either clamps or releases disk segment  16 . This locks or permits respectively, the rotary motion of motor  12 . Thus in table mode, the cut depth position of saw blade  13  is either locked at a selected point, or the cut depth position is free to be adjusted. The saw blade  14  would normally be locked in the retracted position for transporting. 
   Referring to  FIGS. 1 and 6 , power to motor  12  for the miter mode is turner on and off by a momentary switch  76  on handle  41 , and for the table mode, is turned on and off by a toggle power switch  75  on the table mode side of frame  37 . The lock shaft  90  extends towards the miter mode side at least through a power selection switch  77 . Shaft  90  engages switch  77  rotatably, and is longitudinally slidably attached thereto. Switch  77  is of a configuration, not shown herein, such that when cut depth lock handle  92  is in the lock position and the saw blade  13  is locked in position for table mode cutting, switch  75  is enabled and switch  76  is disabled. Further, when cut depth lock handle  92  is in the release position and the saw blade  14  may be freely located for miter mode cutting, switch  76  is enabled and switch  75  is disabled. 
   Referring to  FIGS. 1 and 3 , to compliment circular protractor paths, two bevel indicators  67 , one at each operating side, are attached to guide bars  65 , and each protrudes through an indicator traveler slot  68  in its respective sheath  66 . Further, miter mode indicator  67  extends through slot  72 , and table mode indicator  67  extends through a protractor traveler slot  70 . 
   Referring to  FIG. 1 , a miter mode dust guard assembly  80  is supported by a guard support sheath  86  fixedly attached to cradle  38 . The assembly  80  comprises a miter dust guard  87  and a guard support shaft  85 . Guard  87  is rotatably attached to shaft  85 . Shaft  85  fits through slot  36 , and slips into sheath  86 . A guard lock mechanism  82  fixedly attached to sheath  86 , locks shaft  85  in sheath  86 , and is of common construction. A guard lock shaft  84  is rotatably attached to mechanism  82 , rotatably supported by cradle  38 , and extends outside frame  37  through slot  72 . A guard lock handle  83  is fixedly attached to the distal end of shaft  84 . Handle  83  has a lock position and a release position to respectively lock and release shaft  85  in sheath  86 . 
   A common table saw dust guard assembly for table mode operation, not included in the description, would be attached in the same manner as the miter mode dust guard assembly  80 . 
   It should be understood that there may be modifications and changes to the present invention that will be obvious from the foregoing description to those skilled in the art; however, the present invention should be limited only by the following claims and their legal equivalents.