Abstract:
A miter saw includes a base, a table rotatably mounted on the base, and a extension arm rigidly connected to the periphery of the table and extending radially away from the axis of rotation of the table. The angular position of the table relative to the base may be fixed via a locking member mounted on the extension arm. The locking member can be linearly moved relative to the extension arm between a locked position where the angular position of the table is fixed relative to the base, and an unlocked position. The locking member is also pivotable between a locked position where the angular position of the table is fixed relative to the base, and an unlocked position.

Description:
[0001]     The present application derives priority from UK Patent Application No. GB 0404628.0, filed on Mar. 2, 2004.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a saw, and in particular, to a saw which is capable of making miter cuts and/or chop cuts and/or bevel cuts.  
       BACKGROUND OF THE INVENTION  
       [0003]     A sliding compound miter saw includes a base made from cast metal, a flat circular table rotatably mounted within the base about a vertical axis, an extension arm which is rigidly attached to the side of the circular table and extends radially outwardly from the axis of rotation of the table, a mount pivotably mounted onto the rear of the round table in such manner that it can pivot about a horizontal axis which axis intersects the vertical axis of rotation of the round table, a saw support structure pivotally connected to the mount and capable of being pivoted about a horizontal axis, perpendicular to the horizontal axis of pivot of the mount, through a limited range of angular movement in a vertical plane, and a saw unit slidably attached to the saw support structure which is capable of sliding towards or away from the saw support structure across the round table and extension arm. A groove is formed extends from the center of the round table radially outwardly across the table and then along the length of the arm into which the saw blade can be plunged. EP0242733 describes an existing design of such a saw in detail.  
       SUMMARY OF THE INVENTION  
       [0004]     An improved saw according to the invention may include a base, a round table rotatably mounted on the base, an extension arm rigidly connected to the periphery of the round table and which extends radially away from the axis of rotation of the round table, a saw unit mounted on the round table for cutting work pieces located on the round table or extension arm, a locking mechanism for angularly locking the position of the round table relative to the base to prevent rotation of the table relative to the base, wherein the locking mechanism has a locking member mounted on the extension arm that can be linearly slid in relation to the extension arm from a first position where a first engaging part of the locking mechanism is disengaged from the base to a second position where it engages a part of the base in order to prevent relative movement between the extension arm and the base, or vice versa; and be pivoted in relation to the extension arm from a first position where a second engaging part of the locking mechanism is disengaged from the base to a second position where it engages a part of the base to prevent relative movement between the extension arm and the base, or vice versa.  
         [0005]     According to a second aspect of the present invention, a saw may include a base, a table mounted on the base, a mount pivotally mounted onto the table, a saw unit connected to the mount for cutting work piece located on the table, and a locking mechanism for angularly locking the position of the mount relative to the table, where the locking mechanism may comprise an arcuate slot formed through the mount, a locking device attached to the table which extends through the arcuate slot which is capable of locking the angular position of the mount relative to the table when it is locked and is capable of sliding along the length of the arcuate slot when it is released allowing the mount to be pivoted relative to the table, and an angle limit mechanism moveable between a first position where the amount of angular movement of the mount relative to the table is a first predetermined amount, and a second position where the amount of angular movement of the mount relative to the table is a second predetermined amount, when the locking device is released.  
         [0006]     According to a third aspect of the present invention, an angle limit mechanism for a saw may include a base, a table mounted on the base, a mount pivotally mounted onto the table, a saw unit connected to the mount for cutting work piece located on the table, and a locking mechanism for angularly locking the position of the mount relative to the table, the locking mechanism preferably comprising an arcuate slot formed through the mount, a locking device attached to the table which extends through the arcuate slot which is capable of locking the angular position of the mount relative to the table when it is locked and is capable of sliding along the length of the arcuate slot when it is released allowing the mount to be pivoted relative to the table, the angle limit mechanism preferably comprising a tube having at one end, part of the wall of the tube removed and a bar extending perpendicular to the longitudinal axis of the tube attached to the other end wherein a peg is attached to the bar and projects in a direction which is parallel to the tube. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     An embodiment of each of inventions will now be described with reference to the accompanying drawings of which:— 
         [0008]      FIG. 1  shows a front view of a miter saw according to the present invention;  
         [0009]      FIG. 2  shows a side perspective view of the extension arm with the plastic insert removed;  
         [0010]      FIG. 3  shows a top view of the extension arm and round table;  
         [0011]      FIG. 4  shows a sketch of a side view of the locking mechanism of the round table;  
         [0012]      FIG. 5  shows a sketch of a vertical cross section of the rubber stop;  
         [0013]      FIG. 7  shows the component parts of the locking mechanism;  
         [0014]      FIG. 7  shows an under view of the extension arm;  
         [0015]      FIGS. 8 and 9  show an alternative embodiment of the locking mechanism;  
         [0016]      FIG. 10  shows a rear view of the mount locking mechanism;  
         [0017]      FIG. 11  shows a sketch at angle limit mechanism;  
         [0018]      FIG. 12  shows a sketch of the two positions of the angle limit mechanism. 
     
    
     DETAILED DESCRIPTION  
       [0019]     A sliding compound miter saw may comprise a base  2  made from cast metal, a flat circular table  4  rotatably mounted within the base  2  about a vertical axis, an extension arm  6  which attaches to the side of the circular table  4  and extends radially outwardly from the axis of rotation of the table  4 , a mount  8  pivotably mounted onto the rear of the round table  4  in such manner that it can pivot about a horizontal axis which intersects the vertical axis of rotation of the round table  4 , a saw support structure (not shown) pivotally connected to the mount and capable of pivoting about a horizontal axis, perpendicular to the horizontal axis of pivot of the mount  8  through a limited range of angular movement in a vertical plane, and a saw unit (not shown) slidably attached to the saw support structure which is capable of sliding towards or away from the saw support structure across the round table. A groove  10  is preferably formed to extend from the center of the round table  4  radially outwardly across the table and then along the length of the arm  6  into which the saw blade can be plunged.  
         [0020]     A fence  12  may be disposed across the round table  4 . Fence  12  may have a series of notches  14  in to be used in assisting clamping a workpiece.  
         [0021]     Referring to  FIGS. 1, 2  and  3 , the groove  10  is preferably formed by a plastic insert  16  which may clip into the arm  6  and/or round table  4  of the saw. The round table  4  and extension arm  6  may be made as a single integral unit from cast metal. A trough  18  may be formed within the unit from the center of and extending radially outwardly across the round table  4  and along the arm  6 . Two bosses  20  may be formed in the center of the trough  18  on either side in symmetrical fashion. Bosses  20  may comprise threaded holes which are capable of receiving screws. Formed at either end of the trough  18  may be holes (not shown) which are capable receiving a clip  22  integrally moulded onto the ends of the plastic insert  16 .  
         [0022]     The plastic insert  16  preferably comprises an elongate sheet of plastic having straight sides and rounded ends having the same outline shape as the entrance to the trough  18  and may comprise an elongate slot  10  formed along the majority of the length of the insert  16 . Two holes  24  may be formed through the insert  16  centrally lengthwise which preferably align with the two holes formed in the two bosses  20  when the plastic insert  16  is inserted into the trough  18 . Plastic clips  22  may be integrally formed on the plastic insert  16  at both ends of it.  
         [0023]     In order to attach the plastic insert  16  into the trough  18 , the two clips  22  are preferably engaged with the holes formed at the ends of the trough  18 , where the two holes  24  in the plastic insert may align with the two holes of the two bosses  20 . Two screws may be then passed through the two holes and screwed into the bosses  20  to secure plastic insert  16  into the trough  18 . The elongate slot forms the groove  10 .  
         [0024]     The angular position of the round table  4  and extension arm  6  can be locked in relation to the base. The locking mechanism will now be described with reference to the  FIGS. 4, 5 ,  6 ,  7 ,  8  and  9 .  
         [0025]     The locking mechanism preferably comprises a knob  26  rigidly attached to one end of a metal rod  28 . A rubber stop  30  may be mounted on the other end of the metal rod  28 . The construction of rubber stop  30  will be described in more detail below. Preferably, a portion  32  of the length of the metal rod  30  is threaded. The threaded portion  32  of the rod  30  is preferably threaded through a metal block  34 . Rotation of the metal rod  30  about its longitudinal axis  36  results in the metal rod sliding left and right as indicated by Arrow A in  FIG. 4 .  
         [0026]     The metal block  34  preferably has two metal pins  38  of circular cross-section projecting from each side of the metal block  34  in opposite directions, perpendicularly to the longitudinal axis  36  of the metal rod  28 . The two pins  38  may form a pivot axle for the metal block  34 , the metal block  34  being capable of pivoting about a horizontal axis. The metal block  34  together with the pins  38  are preferably mounted on the underside of the extension arm  6 , the two metal pins  38  being located horizontally within slots (not shown) on the underside of the extension arm  6  and arranged in such manner that the metal block  34  can pivot about the axis of the pins  38 . The direction of movement caused by the pivoting of a block is indicated by Arrow B in  FIG. 4 . As the block  34  pivots, so the metal rod  28 , knob  26  and rubber stop  30  also pivot about the pins  38 .  
         [0027]     The knob  26  preferably extends from the end of the extension arm  6  away from the round table  4 .  
         [0028]     A spring  40  may be mounted on the underside of the extension arm  6  and is preferably located between the underside  42  of the extension arm  6  and the metal rod  28 . The spring  40  may exert a downward biasing force in the direction of Arrow C in  FIG. 4  onto the metal rod  28  urging the end of the metal rod containing the knob  26  downwardly.  
         [0029]     An extension piece  44  may be integrally formed with the metal block  34 . A conical shaped pin  46  is preferably formed on the top of the extension piece  44 . Accordingly, the biasing force of the spring  40  may bias the conical pin  46  upwardly.  
         [0030]     A metal scale  48  may be attached rigidly to the base  2  of the saw as shown in  FIGS. 1, 2  and  3 . The scale  48  may be used by an operator to show the miter angle which would be cut when the extension arm  6  is located at that angular position. A series of oval holes  50  may be formed through the metal scale  48  at predetermined angles of cut. As the extension arm  6  and round table  4  are pivoted about their vertical axis, the extension piece  44  together with the conical pin  46  may move underneath the scale  48  as shown in  FIG. 4 . The series of holes  50  are preferably located along the path which is traveled by the conical pin  46  as it is moved under the scale  48 . When the conical pin  46  is aligned with a hole  50 , the biasing force of the spring  40  preferably urges the conical pin  46  into the hole  50  and locks the position of the extension arm  6  in relation to the scale  48 . Because the pin  46  is preferably conical, it provides an easy engagement with the hole  50  even when the pin  46  and hole  50  are not completely aligned.  
         [0031]     In order for a user to release the pin  46  from a hole  50 , the user preferably exerts an upward force onto the knob  26  causing the knob  26  to move upwardly relative to the extension arm  6 , pivoting the metal block  34  about the pins  38  and causing the conical pin  46  to be moved downwardly, withdrawing it from the hole  50 . The extension arm  6  and round table  4  can then the rotated about their vertical axis.  
         [0032]     The rubber stop  30  may face the base  2 . Rotation of the metal rod  28  about its longitudinal axis  36  using the knob  26  can cause the rubber stop  30  to move towards the base  2  or away from the base  2 . Rotation of the knob  26  sufficiently will cause the rubber stop  30  to frictionally engage with the outer surface of the base  2 . When the rubber stop  30  is engaged with the surface of the base  2 , the extension arm  6  and round table  4  are preferably prevented from rotation about their vertical axis. In order to allow the extension arm  6  and round table  4  to rotate, the knob  26  must be rotated to withdraw the rubber stop  30  away from the surface of the base  2 , thus releasing the arm  6  and allowed to rotate.  
         [0033]     The use of such a rubber stop  30  enables the extension arm and round table  4  to be locked at any angular position in relation to the base  2 . This is unlike the pin  46  which only allows the extension arm and round table to be fixed in relation to the base  2  at predetermined positions as determined by the positions of holes  50  within the scale  48  fixed to the base  2 .  
         [0034]     The construction of the rubber stop will now be described with reference to  FIG. 5 .  FIG. 5  shows a vertical cross section of the rubber stop  30  as mounted on the metal rod  28 . The end of the metal rod  28  may be inserted into an elongate passageway  52  formed within the rubber stop  30 . A metal ball bearing  54  may be located at the end of the metal rod  28 . The metal ball bearing  54  preferably allows the rod  28  to rotate whilst allowing the rubber stop  30  to remain stationary. The rubber stop  30  preferably has to remain stationary when it engages with the surface of the base  2  as the friction will prevent it from rotating. If no mechanism is provided to allow the rod  28  to rotate inside of the rubber stop  30 , the rod  28  could damage the inside of the rubber stop  30 . Furthermore, as pressure is exerted onto the rubber stop  30  by a rotation of the rod  28  about its longitudinal axis  36  which causes the rod  28  to move towards the base  2 , the spherical shape of a ball bearing  54  preferably applies a force in a more distributed fashion to the rubber stop  30  than the sharp edges of the end of the rod  28  would, and thus prevents damage.  
         [0035]     Though the holes  50  shown in the Figures are oval, it will be clear to a person that they could be any shape, e.g., square, round, slots, etc., including open ended slots or indents formed from the edge of the scale  48 .  
         [0036]     A metal stop  56  may be formed on the underside of the extension piece  44  is. A nut  58  is preferably threaded onto the threaded portion  32  of the metal rod  28  between the metal block  34  and the metal stop  56 . The nut  58  may restrict the amount of travel of the metal rod  28  through the metal block  34 , as the nut cannot pass the metal stop  56  in one direction or the metal block  34  in the other direction.  
         [0037]     A cover plate  60  may be used to enclose the locking mechanism which is attached to the underside of the extension arm  6 .  
         [0038]     An alternative design to the rubber stop may be used which is shown in  FIGS. 8 and 9 . Where the same features are present, the same reference numbers have been used. Instead of the rubber stop, the end of the metal rod  28  may engage with a curved leaf spring  62  which is connected to the two ends  64  of cover plate  60  as shown in  FIGS. 8 and 9 . The curved leaf spring  62  preferably engages with the base  2  of the saw, the leaf spring  62  being sandwiched between the end of the elongate rod  28  and the base  2 .  
         [0039]     The mount  8  may be pivotably mounted onto the rear of the round table  4  in such manner that it can pivot about a horizontal axis which intersects the vertical axis of rotation of the round table  4 . The angular position of the mount  8  can be fixed in relation to the round table  4  by a mount locking mechanism which will now be described with reference to  FIGS. 10, 11  and  12 .  
         [0040]     The mount  8  preferably comprises a circular cast  70  which is located adjacent to and abuts against a similar circular cast  72  formed on the round table  4 . The two circular casts  70 , 72  may be connected together by a retaining bolt  74  and nut  76  which pass through the centers of the two circular casts  70 , 72 . The circular cast  70  of the mount  8  is able to pivot around the retaining bolt  74 , allowing the mount  8  to pivot in relation to the round table  4 .  
         [0041]     An arcuate slot  78  may be formed through the circular cast  70  on the mount  8 . A threaded rod (not shown) may be rigidly attached to the circular cast  72  of the round table  4  and may project through the arcuate slot  78 . The threaded rod is preferably parallel to the retaining bolt  74 .  
         [0042]     An angle limit mechanism  80  may be mounted on the threaded rod.  FIG. 11  shows a drawing of the angle limit mechanism.  
         [0043]     The angle limit mechanism  80  may comprise a metal tube  82  of circular cross section having at one end a teardrop shaped metal plate  84  attached as shown in  FIG. 1 . The passageway  86  through the metal tube  82  preferably extends through the tear drop shaped metal plate  84 . Preferably, part  88  of a side wall  90  around approximately half the circumference of the metal tube  82  has been removed at the other end. A metal peg  92  is preferably mounted on the teardrop shaped plate  84 , extending from the plate  84  in the same direction to the tube.  
         [0044]     The angle limit mechanism  80  may be mounted onto the threaded rod in such a manner that the metal tube  82  preferably extends into the arcuate slot  78  with the threaded rod located within the tube  82  while the teardrop shaped plate  84  preferably abuts against the entrance  94  of the arcuate slot  78 . The angle limit mechanism  80  can freely rotate about the threaded rod. The metal peg  92  then extends above the circular cast of the mount as shown in  FIG. 10 .  
         [0045]     A nut (not shown) is preferably screwed onto the threaded rod which can sandwich the tear drop plate  84  of the angle limit mechanism  80  between the nut and the entrance  94  of the arcuate slot  78 . A handle  96  surrounds the nut and is used by the operator to rotate the nut.  
         [0046]     In order to adjust the angle of mount  8 , an operator would unscrew the nut using the handle  96 , slackening the angle limit mechanism. The circular cast  70  and hence the mount  8  is able to be pivoted relative to the round table  4 . The user then tightens the nut sandwiching the rear drop shaped plate  84  of the angle limit mechanism  80  against the entrance  94  of the arcuate slot  78  in order to frictionally engage it to prevent the circular cast  70  from rotating. The circular cast  70  can be pivoted over a range of angles which is determined by the accurate slot and the position of the threaded rod within it.  
         [0047]     The angle limit mechanism  80  preferably enables the user to adjust the pivot angle to either 45 or 48 degrees. When the nut has been slackened, the angle limit mechanism  80  can freely rotate about the threaded rod. It can be pivoted such that the pin lies against the edge  98  of the top surface of the metal cast in the first direction (as shown in  FIG. 12  by reference number  100 ) or in the other direction (as shown in  FIG. 12  by reference number  102 ) so that it lies against the edge  98  of the metal cast.  
         [0048]     Metal pin  104  is preferably located within one end of the arcuate slot  78 . As the circular cast  70  rotates, so does the pin  104  within the arcuate slot  78 . When the angle limit mechanism  80  is located at that end of the arcuate slot  78  where the pin  104  is located, the pin  104  either engages with the side wall  90  of the end of the tube of the angle limit mechanism  80  when it is in the first position  100  or is able to travel further and engage directly the threaded rod when the angle engagement mechanism  80  is in the second position  102  due to the fact that the part  88  removed from the end of tube  82  faces the pin  104 . The rotation of the angle limit mechanism  80  between the two positions either causes the end  90  of the tube  82  to face the pin  104  or the part  88  of the tube  80  removed to face pin  104  allowing the additional distance of travel as it can continue to rotate until the pin  104  hits the threaded rod.  
         [0049]     Persons skilled in the art may recognize other additions or alternatives to the means disclosed herein. However, all these additions and/or alterations are considered to be equivalents of the present invention.