Abstract:
A saw includes a base assembly, a circular table rotatably mounted on the base assembly, a bevel mount pivotally mounted on the rear of the circular table, and a saw assembly slideably and pivotally mounted on the bevel mount. The saw assembly includes a motor, a cutting blade driven by the motor, a fixed guard mounted on the saw assembly surrounding at least part of the top half of the periphery of the cutting blade, and a dust tube mounted on the fixed guard. A dust chute is mounted on the bevel mount for directing the flow of dust and debris generated by the cutting action of the blade into the fixed guard when the saw assembly is located in its closest position to the bevel mount.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to saws and in particular to sliding compound miter saws. 
       BACKGROUND 
       [0002]    Sliding compound miter saws comprise a motor unit pivotally mounted on a base. The motor unit is located above the base and can pivot between a high position where it is located furthermost away from the base to a low position where a circular saw blade, which is mounted on the motor unit and which is capable of being rotationally driven by a motor located within the motor unit, can engage with a work piece located on the base. A spring biases the motor unit to its uppermost position. 
         [0003]    Such saws have a sliding feature wherein the motor unit, in addition to be able to perform a pivotal or chopping movement, can slide linearly across the base to perform a slide cut. Furthermore, these types of saw include mechanisms by which they are able to perform miter and bevel cuts on work pieces located on the base. 
         [0004]    These types of saw comprise guards which surround the edge of the saw blade in order to prevent the operator from touching the cutting edge. Typically, such saws comprise a fixed guard which surrounds the cutting edge of the top half of the cutting blade and a pivotal guard which is capable of surrounding the cutting edge of the lower half of the cutting blade. The pivotal guard is capable of being pivoted from a first position where it surrounds the cutting edge of the lower half of the cutting blade to a retracted position where the cutting edge of the lower half of the cutting blade is exposed so that the cutting blade can be used to cut a work piece. The purpose of the pivotal guard is to enable the cutting edge of the lower half of the circular saw blade to be surrounded when the saw blade is not being used to provide protection to the operator while allowing the cutting edge of the lower half of the circular saw blade to be exposed when it is required to perform the cutting function. 
         [0005]    EP1772221 describes one example of a sliding compound miter saw. 
         [0006]    Referring to  FIG. 1 , the saw described in EP177221 comprises a base  2  in which is mounted a circular table  4 . The circular table  4  can rotate about a vertical axis. An arm  6  is attached to the front of the circular table  4  which extends through a recess  8  formed in the front of the base  2  and then forward of the base  2 . As the circular table rotates, the arm  6  swings within the recess  8 , the maximum amount of pivotal movement being limited by the sides  10  of the recess  8 . A latch  12  is attached to the underside of the end of the arm  6  which is capable of releasably locking the angular position of the arm  6  within the recess  8 . A fence  14  is rigidly attached to the base  2  and passes over the circular table  4 . 
         [0007]    Pivotally attached to the rear of the circular table  4  is a bevel support  16 . The bevel support  16  can pivot about a horizontal bevel axis  18 . The bevel support  16  can be locked in a range of angular positions relative to the circular table  4  using a locking handle  20 . 
         [0008]    Pivotally mounted onto the bevel support  16  is a slide support  22 . The slide support  22  can pivot about a chopping axis  24  which is parallel to the axis of rotation  26  of a cutting blade  28 . 
         [0009]    Rigidly mounted within the slide support  22  are the ends of two straight rods  30 ;  32 . The rods  30 ;  32  are prevented from sliding or rotating within the slide support  22 . The rods  30 ,  32  are located one above the other and are parallel to each other. Attached to the end  34  of the top rod  30  is a spring  36 . The other end of the spring  36  is attached to the bevel support  16 . The spring  36  is under tension, biasing the end  34  of the top rod  30  downwardly, biasing the ends of the two rods  30 ,  32  located remotely from the slide support  22  upwardly due to the pivotal connection of the slide support  22  to the bevel support  16 . 
         [0010]    Slideably mounted onto the two rods  30 ,  32  is a saw assembly  38 . The saw assembly  38  comprises a motor housing  40  in which is mounted an electric motor. The electric motor is powered via an electric cable  42 . 
         [0011]    Mounted on the front of the motor housing  40  is a handle  44 . A trigger switch  46  is mounted within the handle  44 , which when depressed, activates the motor. A drive spindle  48  projects from the housing  40 . A circular saw blade  28  is rigidly mounted onto the drive spindle  48 . When the motor, is activated, the drive spindle rotates, rotatingly driving the saw blade  28 . A fixed guard  52  is rigidly mounted onto the motor housing  40  and surrounds the top cutting edge of the saw blade  28 . A pivotal guard  54  is pivotally mounted on the motor housing  40  and can pivot about the axis of rotation  26  of the saw blade  28 . The pivotal guard  54  can pivot between an enclosed position where it surrounds the lower cutting edge of the saw blade  28  and a retracted position where it exposes the lower cutting edge of the saw blade  28 . When the pivotal guard is in the retracted position, it is telescopically pivoted into the fixed guard  52 . A pivotal guard spring biases the pivotal guard  54  to the enclosed position. 
         [0012]    The saw assembly  38  can slide along the two rods  30 ,  32  towards or away from the slide support  22 . 
         [0013]    In use, a work piece is placed on the base  2  and circular table  4  against the fence  14 . The pivotal movement of the circular table  4  about the vertical axis allows the saw to perform miter cuts on the work piece. The pivotal movement of the bevel support  16  in relation to the circular table  4  about the bevel axis  18  allows the saw to perform bevel cuts on the work piece. The pivotal movement of the slide support  22  on the bevel support  16  about the chopping axis  24  allows the saw to perform chop cuts on the work piece. The sliding movement of the saw assembly  38  along the two rods  30 ,  32  allows the saw to perform sliding cuts on the work piece. 
         [0014]    The saw comprises a pivotal guard actuating mechanism. The pivotal guard actuating mechanism causes the pivotal guard to pivot to its retracted position when the saw assembly is pivoted about the chopping axis  24  from its upper position to its lower position. The spring  36  biases the saw assembly  38  to pivot about the chopping axis  24  to its uppermost position. In this position, the pivotal guard  54  encloses the lower edge of the cutting blade  28 . As the saw assembly is pivoted downwardly towards the circular table  4 , the pivotal guard actuating mechanism causes the guard  54  to retract into the fixed guard  52 , exposing the lower cutting edge of the blade  28 . 
       SUMMARY 
       [0015]    Accordingly, there is provided a saw comprising a base assemblya circular table rotatably mounted on the base assembly, a bevel mount pivotally mounted on the rear of the circular table, a saw assembly slideably and pivotally mounted on the bevel mount and which is capable of pivoting towards or away from the base assembly and sliding away from or towards the bevel mount to a cut a work piece located on the base assembly and circular table, a motor mounted within the saw assembly, a drive spindle rotatably driven by the motor via a drive mechanism, a cutting blade mounted on the drive spindle, a fixed guard mounted on the saw assembly which surrounds at least part of the top half of the periphery of the cutting blade, and a dust tube mounted on the fixed guard which provides passageway through which dust and debris generated by the cutting action of the blade can pass from inside the fixed guard to outside of the fixed guard. A dust chute is mounted on the bevel mount which directs the flow of dust and debris generated by the cutting action of the blade into the fixed guard when the saw assembly is located in its closest position to the bevel mount. 
         [0016]    The embodiment of saw described below discloses a saw assembly slideably mounted on guide rods which in turn are pivotally mounted a bevel mount. However, it will be appreciated that that the invention is also applicable to saw which have the saw assembly pivotally mounted on the end of at least guide rod, the at least one guide rod being slideably mounted on the bevel mount. EP0752300 discloses such a saw. 
         [0017]    Preferably, there is a guard chute is added to rear of the fixed guard, which when the saw assembly is located in its closest position to the bevel mount  16  and its lowest position to circular table, aligns with the dust chute on the bevel mount to act as a single combined chute. 
         [0018]    It is appreciated that the guard chute guard is formed integrally with the fixed guard. However, ideally, the guard chute is manufactured from a flexible material and attached to the fixed guard. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    An embodiment of the present invention will now be described with reference to the accompanying drawings of which: 
           [0020]      FIG. 1  shows a perspective view of a prior art design of saw as disclosed in EP1772221; 
           [0021]      FIGS. 2A and 2B  show an exploded view of an embodiment of the saw according to the present invention; 
           [0022]      FIG. 3  show an exploded view of the pivotal and fixed guard mechanism of the embodiment; 
           [0023]      FIG. 4  shows a perspective view of the motor unit from a first side; 
           [0024]      FIG. 5  shows a perspective view of the motor unit from a second side; 
           [0025]      FIG. 6  shows an exploded view of the motor unit; 
           [0026]      FIG. 7  shows a perspective view of the dust extraction arrangement; 
           [0027]      FIG. 8  shows a schematic view of the base housing mounted on the two guide rods; 
           [0028]      FIG. 9  shows a perspective view of the arm support mechanism; 
           [0029]      FIG. 10  shows a schematic diagram of the air flow across the motor; and 
           [0030]      FIG. 11  shows a schematic diagram of the arm located in one of its extreme angular positions within the recess. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    An embodiment of the present invention will now be described with reference to  FIGS. 2 to 11 . The general construction of the saw in accordance with the present embodiment is similar to that disclosed in EP1772221. Where the same features are disclosed in  FIGS. 2 to 11  which have been previously disclosed in  FIG. 1 , the same reference numbers have been used. 
         [0032]    The saw comprises a base  2  in which is mounted a circular table  4 . The circular table  4  can rotate about a vertical axis. An arm  6  is attached to the front of the circular table  4  which may extend through a recess  8  formed in the front of the base  2  and then forward of the base  2 . As the circular table rotates, the arm  6  preferably swings within the recess  8 , the maximum amount of pivotal movement preferably being limited by the sides  10  of the recess  8 . A latch  12  may be attached to the underside of the end of the arm  6  which is capable of releasably locking the angular position of the arm  6  within the recess  8  in well known manner. 
         [0033]    A fixed fence  14  is rigidly attached to the base  2  and passes over the circular table  4 . A sliding fence  208  is preferably slideably mounted on top of the fixed fence  14  which is capable of sliding in the direction of arrow M. 
         [0034]    Pivotally attached to the rear of the circular table  4  is a bevel support  16 . The bevel support  16  can pivot about a horizontal bevel axis. The bevel support  16  can be locked in a range of angular positions relative to the circular table  4  using a locking handle  20 . 
         [0035]    Pivotally mounted onto the bevel support  16  is a slide support  22 . The slide support  22  can pivot about a chopping axis which is parallel to the axis of rotation of a cutting blade  28 . 
         [0036]    Rigidly mounted within the slide support  22  are preferably the ends of two straight rods  30 ,  32 . Slideably mounted onto the two rods  30 ,  32  is a saw assembly  38 . 
         [0037]    Referring to  FIGS. 2B ,  4 ,  5  and  6 , the saw assembly  38  comprises a motor unit  100  as shown in  FIGS. 4 to 6 . The motor unit  100  may comprise three housings, namely a base housing  102 , the motor housing  40  and an end cap  104 , which are connected together using bolts  106 . A motor is mounted within the motor housing  40  and comprises a stator  108  and an armature  110  rotatably mounted within the stator  108 . The armature comprises an output shaft  112  by which the rotary motion of the motor is provided to the saw. 
         [0038]    A radial fan  114  may be rigidly fixed to the output shaft  112  for drawing air over the motor. The fan  114  preferably locates inside a guide ring  116  which is rigidly mounted in the end of the motor housing  40 . The fan  114  may draw in air through holes  118  form through the end cap  104 , across the armature  110  and stator  108  and then expels it side ways through holes  120  formed through the side of the guide ring and motor housing  40  as indicated by arrows shown in  FIG. 10 . 
         [0039]    The output shaft  112  may project into the base housing  102  through an aperture  122  in the base housing  102 . The output shaft  112  is preferably supported by a bearing  124  located within the aperture  122 . A first drive wheel  126  may be rigidly mounted on the end of the output shaft  112  inside of the base housing  102 . 
         [0040]    An intermediate shaft  128  is preferably mounted within a second aperture  130  formed through the base housing  102 . The intermediate shaft  128  may be supported by a second bearing  132  located within the aperture  130  and is parallel to the output shaft  112 . Located on the end of the intermediate shaft  128  inside of the base housing  102  is a first driven wheel  134 . A rubber belt  138  is preferably wrapped tightly around the first drive wheel  126  and the first driven wheel  134  and frictionally engages with them so that rotation of the drive wheel  126  is transferred to the driven wheel  134  via the rotation of the belt  138 . As such rotation of the output shaft  112  is transferred to the intermediate shaft  128 . 
         [0041]    The diameter of the first drive wheel is preferably smaller that that the first driven wheel and therefore the rate of rotation the intermediate shaft  128  is reduced when compared to that of the output shaft  112 . 
         [0042]    Mounted rigidly on the other end of the intermediate shaft  128  outside of the base housing is a second drive wheel  136 . A drive spindle  48  is preferably mounted within a third aperture  140  formed through the base housing  102 . The drive spindle  48  may be supported by a third bearing  142  located within the aperture  130  and is parallel to the output shaft  112 . Located on the end of the drive spindle  48  outside of the base housing  102  is a second driven wheel  144 . A second rubber belt  146  is preferably wrapped tightly around the second drive wheel  136  and second driven wheel  144  and frictionally engages with them so that rotation of the second drive wheel  136  is transferred to the second driven wheel  144  via the rotation of the second belt  146 . As such rotation of the intermediate shaft  128  is transferred to the drive spindle  48 . 
         [0043]    The diameter of the second drive wheel  136  is preferably smaller that that the second driven wheel  144  and therefore the rate of rotation of the drive spindle  48  is reduced when compared to that of the intermediate shaft  128 . 
         [0044]    As such rotation of the output shaft  112  is transferred to the drive spindle via the two belts, the speed of the drive spindle  48  being considerably reduced compared to that of the output shaft  112 . 
         [0045]    Each of the belts  146 ,  138  can be slightly elastically deformed in a lengthwise direction allowing for impacts and sudden torque changes experienced by the blade during a cutting operation to be damped by the transmission system comprising the belts, thus protecting the motor. 
         [0046]    The open end of the base housing  102  may be sealed by a first side housing  150  which is rigidly attached to the base housing  102 . The first belt  138  is enclosed within the base housing by the first side housing  102 . By enclosing the belt  138 , no dust or debris generated during the operation of the saw can enter the base housing and interfere with the operation of the belt. The second belt  146  is preferably located outside of the base housing and is enclosed by a cover  158  which is attached to the base housing using a bolt  160 . A hole  152  is formed through the side housing through which the drive spindle  48  projects. A blade  28  can be rigidly mounted on the drive spindle  48  using two side plates  154  and a clamp nut  156 . 
         [0047]    An aperture  120  may be formed through the side of the cover  158  which aligns with the apertures  120  in the side of the guide ring and motor housing  40  when it is attached to the base housing  102  as best seen in  FIG. 10 . Air is blown by the fan  114  into the cover  158  and across the belt (as shown in  FIG. 10 ) before being expelled through vents  162  in the cover  158 . The flow of air across the belt  146  reduces the operating temperature of the belt  146  by about  15  to  20  degrees centigrade. 
         [0048]    The base housing  102  slideably mounts onto the two guide rods  30 ,  32  which are rigidly mounted to the slide support  22 . The rods  30 ;  32  are prevented from sliding or rotating within the slide support  22 . The rods  30 ,  32  are located in a vertical plane with one being above the other, and are parallel to each other. The top rod  30  passes through two tubular passageways  170 ,  172  formed within the base housing  102  as best seen in  FIG. 6 . The lower rod  32  locates in a third tubular passageway  174  within the base housing  102 . The base housing  102  can freely slide along the two rods  30 ,  32 . 
         [0049]    Referring to  FIG. 8  which shows a schematic view of the base housing  102  mounted on the two guide rods  30 ,  32 , the output shaft  112  preferably passes between the two guide rods  30 ,  32 , in a direction perpendicular to the plane within which the rods  30 ,  32  are located, the first belt  138  being located on the opposite side of the plane within which the rods  30 ,  32  are located to the motor. The intermediate shaft  128  is located above and passes over the two guide rods  30 ,  32  in a direction perpendicular to the plane within which the rods  30 ,  32  are located, the second belt  146  being located on the opposite side of the plane within which the rods  30 ,  32  are located to the first belt  138 . The drive spindle  48  passes between the two guide rods  30 ,  32  in close proximity to the lower rod  32  in a direction perpendicular to the plane within which the rods  30 ,  32  are located, the blade being located on the opposite side of the plane within which the rods  30 ,  32  are located to the motor. This provides a compact arrangement while maximising the depth of cut. 
         [0050]    The first side housing  150 , which is rigidly attached to the base housing  102 , may attach to a second side housing  180  using bolts  184  to form the fixed guard  52  and a dust chute  182 . During the cutting operation, dust and debris are preferably driven through the dust chute  182  by the rotary motion of the cutting blade  28 . An inner wall  186  is mounted within the first and second side housings to assist in guiding the dust and debris. A separate vacuum cleaner can be attached to the chute  182  to assist in the removal of the dust and debris. 
         [0051]    A rubber chute  188  is preferably attached to lower rear end of the fixed guard  52  by the insertion of pegs  190  attached to the fixed guard  58  locating within holes  192  formed in the rubber chute and then being secured using clips  194  which attach to the ends of the pegs  190  as best seen in  FIG. 7 . The rubber chute assists in guiding dust and debris generated by the cutting action of the blade at the rear of the blade into the fixed guard  52  and towards the dust chute  182 . When the saw assembly  38  is located in its lowest position, the rubber chute  188  extends downwardly to a position where it is just able to pass of over the fixed and moveable fences  14 ,  208  as the saw assembly slides back and fourth on the rods  30 ,  32 . 
         [0052]    The bevel support  16  preferably attaches to the rear of the circular table  4  adjacent a circular support  200  integrally formed with the circular table  4 . Attached to the bevel support  16  using a screw  204  is a plastic guide chute  202  and which faces towards the rear of the blade. When the saw assembly  38  is located in its lowest rearward position, the rubber chute  188  is located behind the fence  14  in alignment with the plastic chute  200  so that the rubber chute  188  and plastic guide chute act as a single combined chute. When the saw assembly  38  is located in its lowest rearward position, the rear lower part of the saw blade  28  passes through the centre gap  206  of the fence  214  and rearwardly of the fence  14  in close proximity of the plastic guide chute  202 . The combined chute acts to guide dust and debris generated by the cutting action of the blade  28  at the rear of the blade into the fixed guard  52  and towards the dust chute  182 . 
         [0053]    The arm  6 , which extends forward of the base  2 , may have an L-shaped support  210  attached to its underside of the end of the arm remote from the circular table  6  using screws  218  as best seen in  FIG. 9 . The L-shaped support  210  comprises a vertical plate  214  and a perpendicular horizontal plate  216  connected to its lower end. When the saw is located on a flat work surface  212 , the horizontal plate  216  is located 4 mm above the work surface  21  indicated by arrow N. When the saw assembly is located in its forwardmost position, remote from the bevel support  16 , with the blade located at its further extent towards the end of the arm  6  remote from the circular table  4 , and a downward pressure is being exerted to cut a work piece, there is a force exerted onto the saw which can cause it to tip forward. In such circumstances the arm  6  will pivot forwards until the L-shaped support  210  engages with the work surface  212  preventing any further movement. 
         [0054]    Under normal circumstances it is desirable that the arm  6  and support  210  be located above the work surface to enable them to be freely rotated within the base  2  bout a vertical axis. The length of the arm  6  and the location of the L-shaped support  210  on the arm  6  are such that when the arm  6  is pivoted to its extreme angular positions within the recess  8 , the L-shaped support  210  is able to pass in front of and locate forward of the front side sections  220  of the base  2  as shown in  FIG. 11 . 
         [0055]    A light aperture  240  is preferably formed in the top of the fixed guard  52 . A light unit  242  comprising an LED may be mounted on the outside of the fixed guard  52  so that the light of the LED shines through the light aperture  240  inside of the fixed guard, the light passing on either side of the blade  28 . When the pivotal guard  54  is retracted inside of the fixed guard  54 , the light is able to pass the blade  28  and shine onto the circular table  4  and arm  6 , the blade  28  casting a shadow on the circular table  4  and arm  6 . When a work piece is located on the circular table  4  and arm  6 , the shadow is cast onto the work piece and provides an indication of where the blade  28  will contact the work piece when it is moved towards the work piece to cut it. 
         [0056]    A power supply  244  is to the top of the saw assembly and connects to the light unit via a cable  246 . A switch  248  on the power supply  244  is used to switch the LED on and off. The power supply  244  is powered by electricity provided through the cable  42 . 
         [0057]    The pivotal guard  54  is pivoted inside the fix guard  52  using a guard actuation mechanism comprising a lever  250  pivotally mounted on the handle  44  about an axis  254 , an elongate rod  252  pivotally attached at one end to the lever  250  via a bolt  256  which passes through a slot  260  formed in the rod  252  and screws into a threaded recess  258  and which is axially slideable within the saw assembly, and a cable  262  attached to the other end of the elongate rod  252  and to the pivotal guard. The cable  262  preferably wraps around a circular inner wall  264  formed on the pivotal guard  52  before attaching to it. Pivotal movement of the lever  250  results in a sliding movement of the elongate rod  252  which in turn pulls on the cable  262 . As the cable is wrapped around the inner wall, as it is pulled it causes the pivotal guard to rotate thus pivoting it inside of the fixed guard and exposing the blade  28 . A spring  268  biases the lever  2590  away from the handle  44 . A second spring  270  biases the pivotal guard shut. The slot  260  allows for movement of the guard  54  without movement of the lever  250 . 
         [0058]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the scope of the invention.