Abstract:
A powered saw including a saw blade configured to cut a workpiece and driven by a drive train having a narrow profile. The powered saw includes a miter saw having a chain drive disposed in a housing having a narrow profile. The powered saw includes a blade support assembly configured to reduce or eliminate interference between a workpiece and the powered saw. The miter saw enables a user to make right angle cuts, left angle cuts, and zero cuts of tall and atypically sized workpieces.

Description:
PRIORITY CLAIM 
       [0001]    This application is a non-provisional utility application of and claims priority to co-pending U.S. Provisional Application No. 61/914,654, filed on Dec. 11, 2013, the entire disclosure of which is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    This disclosure relates generally to the field of powered saws, and more particularly to a powered miter saw configured to cut a workpiece at left miter angles, at right miter angles, and at a zero miter angle. 
       BACKGROUND 
       [0003]    A miter saw uses a rotating saw blade to make crosscuts in a workpiece. The miter saw is adjustable, and when properly set up by a user, accurate crosscuts and accurate miter cuts are possible. 
         [0004]    Miter saws are used for cutting many different types of material, including lumber of different types as well as synthetic materials. The typical miter saw includes a base or a platform on which a turntable is positioned. The turntable includes a workpiece support surface to support a workpiece to be cut by the miter saw. A support assembly is coupled to the turntable and functions to support a cutting assembly that is operable to perform a cutting operation on the work piece. The support assembly includes adjustable components which enable the cutting assembly to move away from or toward the support surface in order to cut the workpiece. The support assembly also typically includes other adjustable components configured to pivot the cutting assembly about an angle inclined with respect to the support surface in order to produce beveled or angled cuts on the work piece. 
         [0005]    Tall workpieces, such as base boards and crown moldings, can be cut only at zero and left miter angles with a conventional miter saw. Right miter angle settings are not possible because a drive train prevents a saw blade from being adjusted through some or many angles which are necessary for certain applications. In addition, the drive train can be an obstruction when cutting different sizes and shapes of workpieces. In some situations, the workpiece cannot be placed at a desired location on the support surface to complete an intended cut. In addition, the drive train can present an unanticipated risk to the user, if the user does not understand or is unaware of the limitations of the miter saw when cutting tall or atypical workpieces. Therefore there is a need for a saw which is configured to provide left and right miter cuts and zero miter cuts without interference from the various components of the saw, including the drive train. 
       SUMMARY 
       [0006]    In accordance with one embodiment of the disclosure there is provided a miter saw having a motor and a drive to drive a saw blade for cutting a workpiece, in which the drive includes a chain drive operatively coupled between the motor and the saw blade. In another embodiment, a chain drive used in a miter saw is configured to provide a narrow profile such that a narrow drive train housing defining a narrow compartment for the chain drive does not interfere with or limit the user from making both left and right miter cuts. 
         [0007]    In still another embodiment, the drive does not include meshed gears configured to direct power from the motor to the saw blade. Instead, the drive incorporates pulleys in a configuration which allows for a compact drive train that does not interfere with a workpiece during a standard cutting operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic elevational side view of miter saw including a drive according to one disclosed embodiment. 
           [0009]      FIG. 2  is a schematic perspective view of the miter saw shown in  FIG. 1 . 
           [0010]      FIG. 3  is a schematic cross-sectional front view of a drive train and motor for the miter saw shown in  FIG. 1 . 
           [0011]      FIG. 4 a    is diagrams of a workpiece in a power tool of the prior art oriented for a right hand bevel cut. 
           [0012]      FIG. 4 b    is a diagram of a workpiece in a power tool according to the present disclosure oriented for a right hand bevel cut. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    For the purposes of promoting an understanding of the principles of the embodiments disclosed herein, reference is now made to the drawings and descriptions in the following written specification. No limitation to the scope of the subject matter is intended by the references. The disclosure also includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosed embodiments as would normally occur to one skilled in the art to which this disclosure pertains. 
         [0014]      FIG. 1  is a schematic elevational side view of saw device  100  including a turntable  102  supported by a base  104 . The saw device  100  can be any type of saw devices including a miter saw, a bevel saw, a compound saw, a table saw, a planar, a mini saw, a handheld saw, or devices with a saw blade or other type of blade that is capable of penetrating into a workpiece. The turntable  102  may be rotatably adjustable on the base  104  about a pivot axis extending generally perpendicular to a plane  106  defined by a support surface  108  of the turntable  102 . A support assembly  110  supports a cutting tool such as a saw blade  112  configured to cut a workpiece  114  supported on one side by the support surface  108  and on another side by a guide fence  116 . The guide fence  116  includes a workpiece guide surface  118  upon which the workpiece is positioned for a cutting operation. The guide fence  116 , as illustrated, may be adjustable to generally perpendicularly align with the turntable surface  108 . In other embodiments, the guide fence  116  may be adjustable such that the workpiece guide surface  118  is inclined with respect to the turntable surface  108 . 
         [0015]    The cutting tool support assembly  110  includes a bevel arm  120  rotatably supported on the turntable  102  about an axis  122  generally parallel to the turntable surface and aligned with a cutting plane  124  of the blade  112 . (See  FIG. 3 ) The bevel arm  120  can be rotated left or right about the axis  122  to provide angled cuts into the workpiece. A pivotable handle  126  is provided to lock the bevel arm  120  at a selected location with a locking mechanism  128  as would be understood by one skilled in the art. 
         [0016]    The support assembly  110  further includes one or more support bars  130  supported for sliding movement in a collar  132  of the bevel arm  120 . One end of the bar(s)  130  extend(s) toward the saw blade  112  and terminates where a pivot mechanism  134  is rotatably coupled to a cutting arm  136 . The cutting arm  136  is rotatably positionable around a pivot  138 , the position of which is fixed and released by a handle (not shown) which is spring loaded with a spring  140 . Since the support bars  130  slide within the collar  132 , the saw blade  112  is positionable along the cutting plane  124  of the saw blade  122 . In addition, since the saw blade  112  is coupled to the cutting arm  136 , the position of the saw blade  122  is adjustable about an arc defined by the pivot  138 . The saw device  100  and support assembly  110  may be configured as is known in the art to allow multiple positions of the cutting blade and to allow the saw device to perform a wide range of cuts into the workpiece. 
         [0017]    As illustrated in  FIGS. 1 and 2 , the cutting arm  136  supports a blade drive including a motor  142  coupled to a drive assembly  144 . The drive assembly  144  includes a first driver or drive train section  146  and a second driver or drive train section  148 . The first drive train  146  extends from the motor  142  toward a location generally vertically disposed above a rotational axis  150  of the saw blade  112 . The second drive train  148  extends from first drive train  146  toward the turntable surface  108  and the rotational axis  150 , and may be oriented at a generally right angle with respect to the cutting arm  136 . A housing (not shown) is preferably provided that covers the drive assembly  144  and particularly both the first and second drive trains  146  and  148 . A blade guard  152  is also supported by the cutting arm  136  and may cover, in one embodiment, a top front quarter of the saw blade  112  as illustrated in  FIGS. 1 and 2 . Since the guard  152  covers the top front quarter of the saw blade  112 , a clearance space  154  is provided which greatly increases the operating clearance for the workpiece  114 . The clearance space  154  is delimited by a lower edge  156  of the cutting arm  136  and by either a back vertical edge  158  of the blade guard  152  or a portion of the drive train housing (not shown). It is contemplated that the drive train housing will generally follow the contour of the cutting arm and blade guard to maximize the clearance space  154 . 
         [0018]    The motor  142  includes a drive shaft  160  coupled to the first drive train  146  which includes a driving pulley  162  coupled to the drive shaft  160  for rotation with the drive shaft. In one embodiment, a driven pulley  164  is coupled to the driving pulley  162  by a belt  166 . The driven pulley  164  is rotatably supported by the cutting arm  136  by an idler shaft  168  so that the idler shaft rotates with the driven pulley. 
         [0019]    The second drive train  148  includes a driving sprocket  170  disposed on the idler shaft  168  to rotate with the idler shaft and driven pulley  164 , as best seen in  FIG. 3 . The driving sprocket  170  includes a plurality of teeth configured to engage a chain  172 . A driven sprocket  174  is connected to a drive input to the cutting element, which in the illustrated embodiment is an arbor  176  at the rotational axis  150  of the saw blade. The driven sprocket includes a plurality of teeth configured to engage the chain  172 . The driven sprocket is rotationally fixed to the arbor so that the arbor rotates with the driven sprocket. The arbor  176  is configured to rotationally engage the saw blade  112  in a known manner so that the saw blade rotates with the arbor, and thus with the driven sprocket  174 . The driven sprocket is a drive input for the saw blade. It is understood that for other types of workpiece cutting elements the arbor  176  may be coupled to the cutting element in an appropriate manner to drive the cutting element accordingly. For instance, the cutting element  112  may be a reciprocating blade and the arbor  176  engaged to a mechanism for converting rotation of the arbor to a reciprocating movement of the cutting element. 
         [0020]    The chain  172  extends from the driving sprocket  170  to the driven sprocket  174  and may be maintained at a suitable tension by a tensioning mechanism  178  disposed adjacent to the chain  172 . The tensioning mechanism  178  may include an adjuster  180  and a sprocket  182  configured to engage the chain  172 . The adjuster  180  is configured to position the sprocket  182  closer to or further away from the chain to maintain the chain at a desired tension. The adjuster  180 , in different embodiments, may be controlled either manually, electronically, automatically through the force of a spring (not shown), or a combination thereof, as is known in the art. 
         [0021]    The second drive train  148  includes the chain  172  as a part of the drive assembly  144  of the miter saw  100  to transmit the torque and speed of the motor  142  to the saw blade  112 . In the illustrated embodiments of  FIGS. 1 and 2 , the drive assembly  144  combines a belt drive, in the form of the first drive train  144  and belt  166 , with a chain drive, in the form of the second drive train  146  and chain  172 , which cooperate to drive the blade  112 . The belt drive transmits the torque and speed provided from the motor  142  to the idler shaft  168 . In response thereto, the chain drive transmits the torque and speed of the idler shaft  168  to the blade  112 . Speed reduction of the motor, in one embodiment, may be accomplished as illustrated by the belt drive portion of the drive assembly in which the circumference of the driven pulley  164  is larger than the circumference of the driving pulley  162 . Alternatively speed reduction can be accomplished by adjusting the circumferences the driving sprocket  170  and the driven sprocket  174  of the chain drive portion of the drive assembly, either alone or in combination with the relative circumferences of the belt drive component. 
         [0022]      FIG. 3  is a schematic cross-sectional front view of the drive train  144  and the motor  142 . In particular, a back portion of the chain  172  is illustrated as extending generally vertically from the driving sprocket  170  to the driven sprocket  174 . The vertical orientation of the chain  172  allows the drive assembly  144  to be clear of the clearance space  154  ( FIG. 1 ) which thus increases the cutting capacity of the miter saw. This increased clearance reduces or eliminates the chance of interference with tall, larger, or atypical work pieces  114  altogether, as illustrated in  FIG. 1 . Moreover, the drive assembly  144  also provides clearance for right angle or miter cuts in which the cutting blade  114  is pivoted about the bevel axis  122  at the side of the drive assembly (i.e., right side). It can be appreciated that the clearance space  154  at the side of the drive assembly  144  would ordinarily be reduced by the drive assemblies found in prior tools, but with the drive assembly  144  disclosed herein the drive trains  146 ,  148  are clear of the space  154 . Thus, as illustrated in  FIG. 4 a   , the drive assembly D of a prior tool would interfere with the workpiece W at the illustrated bevel angle. On the other hand, as shown in  FIG. 4 b   , the drive train  146  of the drive assembly  144  disclosed herein is clear of the workpiece W at the same bevel angle. It is noted that the drive train  148  is forward of the workpiece in the view of  FIG. 4 b    so it cannot interfere with the workpiece. 
         [0023]    While the chain  172  is illustrated as driving the driven sprocket  174  on the arbor  176 , in another embodiment a belt is used instead of the chain  172 . Likewise, in another embodiment, a chain is used in place of the belt  166 . Consequently, in different embodiments, both drive trains may include belts only, chains only, or a combination of a chain and a belt. In still other configurations, additional chains and/or belts may be included. 
         [0024]    As seen in  FIG. 3 , the drive assembly  144  includes a generally narrow profile or width when measured in a direction  190  substantially perpendicular to the cutting plane  124 . The profile or width extends from a first side  192  of the drive assembly to a second side  194  of the drive assembly  144 . In particular, the width of the drive, including the housing  192 , is approximately less than a third of the length of the motor  142  when measured along a direction substantially perpendicular to the cutting plane  124 . While the width of the drive assembly  144  is greater than a width of the blade guard  152  in the illustrated embodiments, other embodiments include a drive of different widths. In each embodiment, however, the width of the drive is generally sufficiently narrow to enable zero angle cuts and left and right angle cuts up to and including an angle of forty-five (45) degrees with respect to the plane of the cutting surface  106 . 
         [0025]    It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements may be subsequently made by those skilled in the art that are also intended to be encompassed by the following embodiments. The following embodiments are provided as examples and are not intended to be limiting.