Patent Document

FIELD OF THE INVENTION  
         [0001]    The present invention relates to a saw blade height/angle adjustment mechanism. More particularly, the present invention relates to a motor carrier for a table saw which provides a unique height/angle adjustment mechanism for a saw blade attached to the powered shaft of the motor.  
         BACKGROUND OF THE INVENTION  
         [0002]    A typical table saw includes a base which supports a generally flat table top having a longitudinally extending slot and a pair of side rails extending along opposite sides of the table top generally perpendicular to the slot. The side rails are utilized for mounting a rip fence assembly to assist in positioning an article to be cut in relation to a cutting tool. A motor is mounted beneath the table top and the cutting tool, which may be a circular saw blade, is mounted for rotation with the powered output shaft of the motor. When the cutting tool is mounted directly to the shaft of the motor, or if the cutting tool is mounted to a transmission powered by the motor, the mounting of the motor and/or transmission is provided with adjustments which selectively position the cutting tool to extend through the slot in the table top. One adjustment for the motor and/or transmission determines the amount of the cutting tool which extends through the slot to control the depth of cutting. Another adjustment for the motor and/or transmission determines the angle of the cutting tool with respect to the table top to control the bevel angle or the angle of cutting. The cutting tool is thus positioned to project upwardly through the slot and is rotated by the motor with both the height of the cutting tool with respect to the table top and the angle of the cutting tool with respect to the table top being determined by the mounting mechanism for the motor and/or transmission. Cutting of the workpiece is normally accomplished by moving the workpiece longitudinally through the rotating cutting tool.  
           [0003]    Machine tools are used for cross cutting (transverse cutting to the length of the workpiece), miter cutting (at an angle to the length of the workpiece) and rip cutting (longitudinal cutting along the length of the workpiece). For cross cutting and miter cutting, an angularly and laterally adjustable fixture or fence is used which positions the workpiece perpendicular to or at the desired angle relative to the cutting tool. For rip cutting, a separate rip fence assembly is mounted on the side rails and positioned at a pre-selected distance from the cutting tool in order to perform the longitudinal or rip cutting operation on the workpiece.  
           [0004]    When performing a cross cutting operation, a miter cutting operation or a rip cutting operation, it is advantageous to have the ability to control the depth of cut. This is accomplished by moving the saw blade generally perpendicular to the table top to change the amount of the cutting tool which extends through the table top. In addition, certain application will require the addition of a bevel angle during the particular cutting operation whether it be cross cutting, miter cutting or rip cutting. The introduction of a bevel angle is accomplished by angulating the cutting tool with respect to the table top or angulating the table top with respect to the cutting tool.  
           [0005]    Manufacturers of power tool equipment have developed a variety of mechanisms which provide for both the height adjustment and the angular adjustment of the cutting tool with respect to the table top when the power tool is a direct drive power tool. The continued development of the height and angle adjustment mechanisms is directed towards systems which rigidly hold the cutting tool at the pre-selected position while maintaining a simple and easily actuated system for moving the cutting tool to other desired positions. The system should be as rigid as possible to provide accuracy during the cutting operation but should maintain an easily actuated mechanism to facilitate the changes required by the user. The system should provide the above advantages while keeping both the weight of the system and the costs to manufacture the system at a minimum.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides the art with a height and angle adjustment mechanism for a cutting tool. The mechanism includes a motor and arbor support plate which is pivotably secured to the bottom of the work surface of the cutting tool by a pair of brackets to provide for the angular adjustment. A transmission or gear case is slidably connected to the support plate to provide for the height adjustment. The motor, arbor and cutting tool are attached to the gear case. The cutting tool height is adjusted by way of a crank and a threaded rod, upon which a rod follower is movably threaded. The rod follower is connected to a height adjusting lever for slidably moving the gear case and thus the motor, arbor and cutting tool upwardly and downwardly depending upon the direction in which the crank is rotated. The cutting tool angular position is adjusted by pivotably moving the support plate to change the angle of the blade. The angular position of the support plate is locked in position by a locking bar which extends through an arcuate slot in the front of the cutting tool base across the support plate and through a similar arcuate slot in a bracket attached to the rear of the cutting tool base. A cam lever mechanism is positioned outward of the front of the cutting tool base such that when the cam lever is pivoted to its locked position, the locking bar is pulled forwardly compressing and frictionally locking the support plate between the bracket and the front of the cutting tool base. The flexibility of the locking rod and the bracket provides the ability for the compressing of the support plate. The locking of the support plate to both the front and rear of the base provides increased rigidity to the system once it is locked.  
           [0007]    Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    In the drawings which illustrate the best mode presently contemplated for carrying out the present invention:  
         [0009]    [0009]FIG. 1 is a perspective view of a table saw incorporating a unique height and angular adjustment mechanism in accordance with the present invention;  
         [0010]    [0010]FIG. 2 is a cut-away perspective view of the table saw shown in FIG. 1 with a portion of the upper surface of the work table removed and the base cut away to illustrate the adjustment mechanisms in accordance with the present invention;  
         [0011]    [0011]FIG. 3 is a cut-away perspective view similar to FIG. 2 with the motor, saw blade and gear case removed to illustrate the angular adjustment mechanism in accordance with the present invention;  
         [0012]    [0012]FIG. 4 is an exploded perspective view of the angular adjustment mechanism shown in FIG. 3;  
         [0013]    [0013]FIG. 5 is a side view of the support plate shown in FIGS.  1 - 3  with the motor, saw blade and mounting plate included to illustrate the height adjustment mechanism in accordance with the present invention;  
         [0014]    [0014]FIG. 6 is an end view of the height adjustment mechanism shown in FIG. 5;  
         [0015]    [0015]FIG. 7 is an exploded perspective view of the pivot quadrants incorporated into the angular adjustment mechanism of the present invention;  
         [0016]    [0016]FIG. 8 is a schematic cross-sectional view taken through the gear case illustrating the assembly of the gear case to the support plate;  
         [0017]    [0017]FIG. 9 is an exploded perspective view of the height adjustment mechanism shown in FIGS.  5 - 6 ;  
         [0018]    [0018]FIG. 10 is a side view illustrating the arbor locking mechanism in accordance with the present invention in the unlocked position;  
         [0019]    [0019]FIG. 11 is a side view similar to FIG. 10 but showing the locking mechanism in the locked position; and  
         [0020]    [0020]FIG. 12 is a side view schematically illustrating an adjustment mechanism for the bevel adjustment system of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a machine tool which is designated generally by the reference numeral  10  incorporating a height/angle adjustment mechanism for the cutting tool and motor carrier in accordance with the present invention. While the height/angle adjustment mechanism of the present invention is being illustrated for exemplary purposes as being used in conjunction with machine tool  10  in the form of a table saw, it is within the scope of the present invention to incorporate the height/angle adjustment mechanism of the present invention into any type of machine tool which utilizes a cutting tool.  
         [0022]    Referring to FIG. 1, machine tool  10  comprises a base  12  which supports a generally rectangular work table  14  defining a working surface  16 . Work table  14  includes a throat plate  18  which includes an elongated slot  20  through which a circular saw blade  22  protrudes. Saw blade  22  is capable to being adjusted for angularity with respect to working surface  16  by an angle or bevel adjustment mechanism  24  as well as being capable of being adjusted for depth of cut by a height adjustment mechanism  26 . Machine tool  10  is illustrated as a portable table saw which is easily movable from one job site to another. Table saw  10  can easily be picked up and carried utilizing work table  14  as the supporting locations when it becomes necessary to lift and carry table saw  10  from one job site to another.  
         [0023]    Referring now to FIG. 2, table saw  10  is illustrated with working surface  16  of work table  14  partially removed and a portion of base  12  cut away. Circular saw blade  22  is rotated by a motor  28  which powers saw blade  22  through a gear case  30 . Bevel adjustment mechanism  24  adjusts the angular position of saw blade  22  by pivoting saw blade  22 , motor  28  and gear case  30 . Height adjustment mechanism  26  adjusts the cutting depth of saw blade  22  by longitudinal movement of saw blade  22 , motor  28  and gear case  30 .  
         [0024]    Referring now to FIGS. 2 and 3, bevel adjustment mechanism  24  comprises a pair of pivot quadrants  32 , a support plate  34 , and a locking system  36 . Each pivot quadrant  32  is attached to a plurality of bosses  38  extending from the bottom of work table  14  using a plurality of bolts  40 . Each pivot quadrant  32  is designed to pivot around a center which is located on working surface  16  of work table  14  coincident with the plane of saw blade  22 . Thus, the axis for pivoting support plate  34  lies on working surface  16  and extends through the plane of saw blade  22  when saw blade  22  is generally perpendicular with working surface  16 . As shown in FIG. 7, pivot quadrant  32  is comprised of a support bracket  42 , a pivot bracket  44  and a retaining strap  46 . Support bracket  42  is an L-shaped bracket which defines a plurality of holes  48  to facilitate the attachment of pivot quadrant  32  to work table  14  on one leg of the L. The opposite leg of the L defines an arcuate slot  50  which controls the pivotal movement of pivot bracket  44  and locates the center of the pivoting at working surface  16  of work table  14 . Pivot bracket  44  extends between support bracket  42  and support plate  34  and defines a plurality of holes  52  at one end to facilitate the attachment of support plate  34 . The opposite end of pivot bracket  44  defines a stamped arcuate protrusion  54  which mates with slot  50  to control the pivoting of pivot bracket  44 . Protrusion  54  is formed out of the material of pivot bracket  44  and this forming operation defines an arcuate slot  56  once protrusion  54  has been formed. Retaining strap  46  extends across pivot bracket  44  and is attached to support bracket  42  to maintain the engagement of protrusion  54  with slot  50 . Retaining strap  46  defines a formed protrusion  58  which extends into slot  56  to both guide the pivotal movement of pivot bracket  44  and to act as a stop to limit the pivotal movement of pivot bracket  44 .  
         [0025]    Referring now to FIGS. 3 and 4, support plate  34  is a shallow drawn plate which is attached to pivot quadrants  32 . Support plate  34  is designed to support both height adjustment mechanism  26  and locking system  36 . Locking system  36  comprises a bearing block  60 , a locking rod  62 , a locking arm  64 , a bearing block cam  66 , a locking arm cam  68  and a return spring  70 . Bearing block  60  is a curved member which is attached to a bracket  72  which is in turn attached to support plate  34 . Bearing block  60  thus pivots with support plate  34  and bearing block  60  extends through an arcuate slot  74  in the front face of base  12 . While the pivotal movement of support plate  34  moves bearing block  60  within slot  74 , it should be understood that the movement of support plate  34  is controlled by pivot quadrants  32  and that a clearance will always exist between bearing block  60  and slot  74 .  
         [0026]    Locking rod  62  extends across support plate  34  and through bracket  72  and bearing block  60  in the front of support plate  34  and through a bracket  76  and a bracket  78  located at the rear of support plate  34 . Bracket  76  is attached to support plate  34  and defines an aperture for accepting and guiding locking rod  62 . Bracket  78  is attached to work table  14  and it defines an arcuate slot  80  which accepts locking rod  62  and allows for the pivotal movement of support plate  34 . While the pivotal movement of support plate  34  moves locking rod  62  within slot  80 , it should be understood that the movement of support plate  34  is controlled by pivot quadrants  32  and that a clearance will always exist between locking rod  62  and slot  80 . Once locking rod  62  has been inserted through brackets  76  and  78 , a washer  82  and a nut  84  are assembled to locking rod  62  to provide adjustment for locking system  34 . The front end of locking rod  62  extends through bearing block  60  and through a D-shaped embossment  86  which is an integral part of bearing block  60 . Locking arm  64  is assembled over the end of locking rod  62  and secured to locking rod  62  using a hardened washer  88 , a thrust bearing  90 , a hardened washer  92  and a nut  94  threadingly received on locking rod  62  as shown in FIG. 4.  
         [0027]    Bearing block cam  66  and locking arm cam  68  are disposed between locking arm  64  and bearing block  60 . D-shaped embossment  86  extends from bearing block  60  through slot  74  in the front face of base  12 . Bearing block cam  66  includes a D-shaped aperture which mates with embossment  86  and cam  66  is positioned such that the front face of base  12  is sandwiched between bearing block  60  and bearing block cam  66 . The engagement of the D-shaped aperture of cam  66  with D-shaped embossment  86  prohibits the rotational movement of cam  66  with respect to bearing block  60 . The face of cam  66  opposite to the front surface of base  12  defines a camming surface  96  which reacts with locking arm cam  68  to activate locking system  34 .  
         [0028]    Locking arm  64  defines a D-shaped embossment  98  which mates with a D-shaped aperture extending through locking arm cam  68  such that locking arm cam  68  pivots with locking arm  64  when locking arm  64  pivots on locking rod  62 . The face of cam  68  opposite to locking arm  64  defines a camming surface  100  which mates with camming surface  96  on cam  66  such that pivoting motion of locking arm  64  with respect to locking rod  62  will cause longitudinal movement of locking rod  62  to activate locking system  36 . Return spring  70  is disposed on locking rod  62  between an ear  102  formed on locking rod  62  and bearing block  60  in order to urge locking rod  62  towards the rear of base  12  or towards bracket  78 . Locking rod  62  is shown with an additional ear  102  on the opposite side of return spring  70  to capture spring  70  in the unassembled condition of locking rod  62 . The additional ear  102  requires that the aperture in bearing block  60  which accepts locking rod  62  be provided with a slot (not shown) to accept the additional ear  102 . In this arrangement, the engagement of the additional ear  102  with the slot in bearing block  60  will prohibit any rotational movement of locking rod  62 .  
         [0029]    When camming surface  96  is aligned with camming surface  100 , pivoting of support plate  34  and thus saw blade  22  and motor  28  is permitted. The biasing of locking rod  62  towards the rear of base  12  causes embossment  98  to bottom against embossment  86 . In this condition, there is a clearance created between camming surface  96  and camming surface  100  as well as a clearance created between bracket  76  and bracket  78 . These clearances allow for a smooth pivoting of support plate  34  and thus a smooth angular adjustment for saw blade  22 . The pivoting of support plate  34  is controlled by pivot quadrants  32  while bearing block  60  moves within slot  74  in the front face of base  12  and locking rod  62  moves within slot  80  in bracket  78 . When the desired angle of saw blade  22  is obtained, locking system  36  is activated by pivoting locking arm  64  on locking rod  62  which rotates cam  68  with respect to cam  66 . Camming surface  100  is cammed away from camming surface  96  causing longitudinal movement of locking rod  62 . The longitudinal movement of locking rod  62  compresses support plate  34  between bracket  78  and the front face of base  12  due to washer  82  and nut  84  engaging bracket  78  and bearing block cam  66  engaging the front surface of base  12 . The flexibility of locking rod  62  due to a center off-set area  104  and the flexibility of bracket  78  permit the compression of support plate  34 . The adjustment for locking system  36  is provided for by nut  84 .  
         [0030]    Referring now to FIGS. 2, 5,  6  and  9 , height adjustment mechanism  26  comprises a pivot link  110 , a biasing spring  112 , a follower nut  114 , a height adjustment screw  116  and a crank handle  118  which function to move saw blade  22 , motor  28  and gear case  30  longitudinally with respect to support plate  34 .  
         [0031]    Support plate  34  defines a generally rectangular opening  120  within which gear case  30  is located. Located adjacent to and extending generally the entire length of opening  120  are a pair of formed ribs  122  which provide stiffness to support plate  34 . Gear case  30  includes a housing  124  disposed on one side of support plate  34  and a cover  126  disposed on the opposite side of support plate  34 . Cover  126  is secured to housing  124  by a plurality of bolts  128  such that support plate  34  is sandwiched between cover  126  and housing  124 . Gear case  30  includes a pair of longitudinally extending surfaces  130  which engage the opposing sides of opening  120  to guide the movement of gear case  30  within opening  120 . Motor  28  is attached to housing  124  and includes an armature shaft  132  having a pinion  134  which meshes with an output gear  136  which is rotatably supported within gear case  30 . The output gear includes an arbor shaft  138  which provides for the attachment of saw blade  22 . Thus, when motor  28  Is powered, armature shaft  132  and pinion  134  rotate which rotates output gear  136  and arbor shaft  138  which in turn rotates saw blade  22 .  
         [0032]    Referring now to FIG. 8, the accurate positioning of saw blade  22  is required in order to provide accurate cuts. In order to accurately position saw blade  22 , the front face, or the face adjacent saw blade  22 , of support plate  34  is defined as a datum face. Cover  126  is provided with a plurality of accurately machines pads  140  which accurately position cover  126  and thus saw blade  22  with respect to support plate  34 . Machine pads  140  are biased against the datum face on support plate  34  by a plurality of elastomeric springs  142  each of which is disposed within an aperture  144  defined by housing  124 . A low friction wear pad  146  is disposed between each elastomeric spring  142  and support plate  34  to facilitate the movement of gear case  30  within opening  120 . Thus, gear case  30 , motor  28  and saw blade  22  move longitudinally within opening  120  guided by surfaces  130  with gear case  30  being biased against the datum face of support plate  34  by elastomeric springs  142 . As shown in FIGS. 2 and 5, cover  126  includes an extension  148  which can be utilized for supporting a splitter and/or guard mechanism for table saw  10  if desired The mounting of the splitter and/or guard mechanism on cover  126  allows the components to travel with saw blade  22  during cutting depth and/or angular adjustments.  
         [0033]    Referring back to FIGS.  2 , 5 , 6  and  9 , pivot link  110  is pivotably secured to support plate  34  by an appropriate fastener  150 . One arm of pivot link  110  defines a slot  152  which engages a pin  154  attached to gear case  30 . The second arm of pivot link  110  defines a slot  156  which engages follower nut  114 . Biasing spring  112  is a tension spring positioned around fastener  150  and is disposed between pivot link  110  and a retainer  158 . Retainer  158  is attached to follower nut  114  and biasing spring  112  is positioned such that its spring force biases gear case  30  towards a downward position. By biasing pivot link  110  in this direction, the play between the various components of height adjustment mechanism  26  can be eliminated. In addition, the biasing load provided by biasing spring  112  is resisted by follower nut  114  and not by adjustment screw  116  as in many prior art table saws.  
         [0034]    Height adjustment screw  116  is rotatably secured at one end by a bracket  160  which is a separate component or bracket  160  can be formed out of support plate  34 . A nylon bushing  162  is disposed between screw  116  and bracket  160  to facilitate the rotation of screw  116  and provide a smoothness of operation. The loading and thus the wear between screw  116 , bushing  162  and bracket  160  is significantly reduced due to the reaction of spring  112  occurring through follower nut  114  and not through screw  116 . The opposite end of adjustment screw  116  extends through and is rotatably supported by bearing block  60 . The portion of adjustment screw  116  which extends beyond bearing block  60  is adapted for securing crank handle  118  to adjustment screw  116  such that rotation of crank handle  118  causes rotation of adjustment screw  116 . Disposed between bearing block  60  and bracket  72  of support plate  34  is a hardened washer  164 , a powdered metal washer  166 , a spring thrust washer  168  and a hardened washer  170 . Powdered metal washer  166  is secured to adjustment screw  116  by press fitting or other means known in the art. The biasing of spring thrust washer  168  produces frictional resistance to the rotation of adjustment screw  116  allowing for the accurate positioning of saw blade  22  and the ability of height adjustment mechanism  26  to maintain the position of saw blade  22  during the cutting operation. The frictional resistance or drag produced by spring thrust washer  168  maintains the position of adjustment screw  116  and is not affected by the vibration produced by motor  28  and/or the cutting operation. In addition, the biasing porduced by spring thrust washer  168  removes any play which may exist between the various components of height adjustment  26 .  
         [0035]    Follower nut  114  is threadingly received on a threaded portion  172  of screw  116  which is located between bracket  160  and bearing block  60 . Follower nut  114  includes a cylindrical finger  174  which extends into retainer  158 , into slot  156  of pivot link  110  and into a slot  176  located in support plate  34  to cause the pivoting of pivot link  110  by follower nut  114 . Slot  176  in support plate  34  prohibits rotation of follower nut  114  and tends to guide follower nut  114  as it moves along screw  116 . In addition, the contact between finger  174  and the edge of slot  176  provides the reaction point for spring  112 . Thus, when crank handle  118  is rotated, adjustment screw  116  is rotated which causes follower nut  114  to move longitudinally along threaded portion  172  of adjustment screw  116 . The direction of movement of follower nut  114  will be determined by the design of threaded portion  172  and the direction of rotation of crank handle  118 . The longitudinal movement of follower nut  114  causes pivotal movement of pivot link  110  due to the engagement of finger  174  which engages slot  156 . The pivotal movement of pivot link  110  causes the longitudinal movement of gear case  30 , motor  28  and saw blade  22  due to the engagement of slot  152  with pin  154 . The longitudinal movement of gear case  30 , motor  28  and saw blade  22  sets the height of saw blade  22  extending through work table  14  and thus the depth of cut.  
         [0036]    Referring to FIGS. 8, 10 and  11 , cover  126  of gear case  30  supports another unique feature for machine tool  10 . One of the problems associated with machine tools is the changing of the cutting tool. Saw blade  22  is assembled to arbor shaft  138  and is frictionally held in position by a pair of washers  180 ,  182  and an arbor nut  184 . Arbor shaft  138  includes a pair of flats  186  which accept a wrench (not shown) in order to stop arbor shaft  138  from rotating when arbor nut  184  is to be loosened or tightened during the changing of saw blade  22 . The wrench for engaging flats  186  is normally a separate piece which is easily misplaced which then leads to the wedging of a block of wood or other material against saw blade  22  to hold arbor shaft  138 . The wedging of the block against saw blade  22  is both dangerous and leads to unnecessary loading of the bearings supporting arbor shaft  138 . The present invention includes a lever  188  which is pivotably secured to cover  126 . A wrench  190  is pivotably secured to lever  188  and moves within a pocket  192  formed by a ridge  194  which is an integral part of cover  126  between an unlocked position shown in FIG. 10 and a locked position shown in FIG. 11. A spring  196  biases wrench  190  into its unlocked position.  
         [0037]    The unlocked position of wrench  190  is shown in FIG. 10 where wrench  190  is disconnected from flats  186  and arbor shaft  138  is free to rotate. The locked position is shown in FIG. 11 where wrench  190  engages flats  186  to prohibit rotation of arbor shaft  138 . The end of wrench  190  engages ridge  194  at both the front of wrench  190  adjacent arbor shaft  138  to provide support for wrench  190  in the locked position and at the rear of wrench  190  adjacent to lever  188  to provide support to counteract the torque being allied to arbor nut  184 . Lever  188  is accessible to the operator of table saw  10  through the opening in work table  14  which accepts throat plate  18 . Lever  188  is designed to extend into the throat plate opening of work table  14  when wrench  190  is in the locked position and saw blade  22  is in its full upward position as shown in FIG. 11 to prohibit the assembly of throat plate  18  with work table  14  while wrench  190  is in the locked position. Once wrench  190  is moved to its unlocked position, lever  188  will be removed from the throat plate opening in work table  14  and throat plate  18  can be assembled to work table  14 .  
         [0038]    [0038]FIG. 12 illustrates a bevel angle stop system for bevel adjustment mechanism  24 . An adjustment cam  200  is attached to the front panel of work table  14  at opposite ends of slot  74 . A protrusion  202  is formed at both ends of bearing block  60 . When saw blade  22  is positioned at a point perpendicular to working surface  16 , adjustment cam  200  at the zero degree position is rotated until it contacts the zero degree protrusion  202  on bearing block  60 . Adjustment cam  200  is tightened in position using a bolt  204  to set the zero degree position of saw blade  22 . The tightening of bolt  204  has a tendency to rotate cam  200  in a clockwise direction. The rotation of cam  200  in a clockwise direction urges cam  200  into contact with protrusion  202  due to the external spiral shape of cam  200  to provide an accurate positioning of the bevel angle for saw blade  22 . The perpendicularity of saw blade  22  can be set by a square or other means known well in the art. In a similar manner, the 45° position of saw blade  22  with respect to working surface  16  can be set by a similar adjustment and locking of adjustment cam  200  located on the opposite side of slot  74 .  
         [0039]    While the above detailed description describes the preferred embodiment of the present invention, it should be understood that the present invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.

Technology Category: 4