Patent Abstract:
According to an aspect of the invention, a bench cutter like a miter saw including: a drive portion driving a cutting blade; a base portion supporting a workpiece; a cutting portion arranged on the base portion, pivotally supporting the cutting blade above the base portion, and configured to make the cutting blade come close to and separate from the base portion; and a supporting portion connected to the base portion and movably supporting the cutting portion, wherein the cutting portion including: a transmission portion for transmitting power of the drive portion to the cutting blade; and a gear case covering the transmission mechanism and having a lower face portion opposed to an upper face of the base portion, wherein the transmission portion including: a spindle concentrically supporting the cutting blade; and a cutting blade fixing portion having a flange for fixing the cutting blade to the spindle.

Full Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    The present invention relates to a bench cutter. 
         [0003]    2. Description of the Related Art 
         [0004]    In the conventional bench cutter shown in JP-A-2004-135501, when a thick material is cut, a cutting blade of a large diameter is used. In order to hold this cutting blade of the large diameter, a large bench cutter is conventionally used. As the conventional bench cutter, the bench circular sawing machine  501  shown in  FIG. 13  is provided. The bench circular sawing machine  501  has a cutting portion  504  for pivotally supporting the cutting blade  507  on the base portion  502 . As shown in  FIG. 14 , the cutting portion  504  includes: a first gear  541  to which a rotation of the motor  551  is transmitted through the belt  552 C; and a second gear  543  to which the cutting blade  507  is fixed and power is transmitted from the first gear  541 . The rotation of the motor  551  is reduced by two gears and the cutting blade  507  is rotated by a reduced speed. 
         [0005]    Since the rotation of the motor  551  is reduced by the second gear  543 , a diameter of the second gear  543  is extended. Therefore, a size of the gear case  504 B for accommodating the gears is increased in the radial direction of the gear. Accordingly, a cutting capacity (a cutting depth) of the cutting blade  507  is deteriorated. For the above reasons, in order to cut a thick material, it is necessary to ensure a cutting capacity by extending a size of the bench cutter. When the size of the bench cutter is extended, its weight is increased. Therefore, the transporting property of transporting the bench cutter is deteriorated. When the size of the bench cutter is extended, the accommodating property of accommodating the bench cutter is deteriorated. In the bench cutter, a gear case, in which a spindle attached with a cutting blade through a flange is accommodated and gears to drive the spindle are also accommodated, is larger than the flange for fixing the cutting blade to the spindle. Therefore, a region, in which the cutting blade can cut a material, is restricted with respect to the diameter of the cutting blade. As a result, at the time of cutting a thick material, it is necessary to use a cutting blade of a large diameter. In view of the above circumstances, an object of the present invention is to provide a small and light bench cutter capable of cutting a thick material by effectively using a cutting blade. 
       SUMMARY OF THE INVENTION 
       [0006]    In order to solve the above disadvantages, the present invention provides a bench cutter comprising: a drive portion for driving a cutting blade; a base portion for supporting a workpiece; a cutting portion, which is arranged on the base portion, pivotally supporting the cutting blade in an upper portion of the base portion and capable of making the cutting blade come close to and separate from the base portion; and a supporting portion, which is connected to the base, movably supporting the cutting portion, the cutting portion including: a transmission mechanism for transmitting power of the drive portion to the cutting blade; and a gear case, which covers the transmission mechanism, having a lower face portion opposed to an upper face of the base portion, the transmission mechanism including: a spindle for concentrically supporting the cutting blade; and a cutting blade fixing portion having a flange for fixing the cutting blade to the spindle, wherein while the cutting blade is being maintained in a state perpendicular to the upper face of the base portion, a distance between the lower face portion of the gear case and the upper face of the base portion is not less than a distance between the base portion side end face of the flange and the upper face of the base portion. 
         [0007]    Due to the above constitution, a range from the outer circumferential position of the cutting blade to the flange position can be made to be a cutting margin in the cutting blade. Therefore, it is possible to extend the range of the cutting blade capable of being used for cutting. It is also possible to increase a cutting depth of the cutting blade. Accordingly, even a thick material can be cut with a small cutting blade incorporated into a small bench cutter. 
         [0008]    It is preferable that the transmission mechanism includes: a first gear directly driven by the drive portion; a final gear integrally rotated together with the spindle; and an intermediate gear portion, which is respectively meshed with the first gear and the final gear, reducing a rotation of the first gear and transmitting the reduced rotation t o  the final gear. 
         [0009]    The transmission mechanism may includes: a first gear, which is arranged in the drive portion, driven through a belt or chain; a final gear rotated integrally with the spindle; and an intermediate gear portion, which is respectively meshed with the first and final gear, reducing a rotation of the first gear and transmitting the reduced rotation to the final gear. 
         [0010]    Due to the above constitution, power can be transmitted to the final gear while a rotation of the drive portion is being sufficiently reduced. Accordingly, it becomes unnecessary to use a large final gear. Therefore, a size of the gear case in the periphery of the spindle connected to the final gear can be reduced. 
         [0011]    It is preferable that the transmission mechanism includes a lock pin held by the gear case and engaged with the intermediate gear portion. 
         [0012]    Due to the above constitution, the intermediate gear portion is fixed to the gear case. Accordingly, the final gear meshed with the intermediate gear portion and the spindle can be fixed. Therefore, the flange fixed to the spindle can be easily detached. Since the lock pin is engaged with the intermediate gear portion, as compared with a case in which the lock pin is engaged with the final gear, a size of the gear case in the saw blade width direction can be prevented from increasing. 
         [0013]    It is preferable that the supporting portion including: an inclining mechanism for supporting the cutting portion with respect to the base portion so that the cutting portion can be inclined in a direction perpendicular to a side of the cutting blade, and the gear case includes: an inclined face opposed to the upper face of the base portion when the cutting blade is inclined, wherein an opening portion for operating the lock pin is formed on the inclined face. It is preferable that a lid capable of being freely opened and closed is arranged in the opening portion. 
         [0014]    It is preferable that the intermediate gear portion includes: a second gear meshed with the first gear; and a third gear concentrically fixed to the second gear and meshed with the final gear, wherein the lock pin is engaged with the second gear. 
         [0015]    Due to the above constitution, it is possible to have access to the lock pin easily. Since the lid is provided, it is possible to prevent an operator from touching the lock pin unexpectedly. 
         [0016]    It is preferable that while the cutting portion is being made to come the closest to the base portion being pivotally moved)and the cutting blade is maintained in a state perpendicular to the upper face of the base portion, the first gear is located at the uppermost position and separated most from the cutting blade and the final gear is located at the lowermost position and made to come the closest to the cutting blade, the intermediate gear portion is located at an intermediate portion between the first and the final gear, and the respective rotary shafts of the first gear, the intermediate gear and the final gear are positioned on the same axis perpendicular to the upper face of the base portion. 
         [0017]    Due to the above constitution, in the final gear, the intermediate gear and the first gear, when the first gear arranged at a position the most distant from the base portion is located in the perpendicular direction on the substantially same line, the first gear can be most separated from the base portion. In the above constitution of the final gear, the intermediate gear and the first gear, according to a distance from the cutting blade to the first gear and a distance from the base portion to the first gear, an inclination angle of the inclined face with respect to the cutting blade is prescribed. When the first gear is most separated from the base portion, an angle of the inclined face with respect to the cutting blade can be made to be an acute angle. When the angle of the inclined face is the acute angle, an inclination angle, at which the cutting portion is inclined, can be increased. 
         [0018]    It is preferable that the drive portion includes an output shaft portion for outputting torque, the first gear is a bevel gear and attached to the output shaft portion and the intermediate gear portion includes a bevel gear meshed with the first gear. 
         [0019]    It is preferable that the drive portion is arranged so that the output shaft portion can be positioned between the first gear and the cutting blade. 
         [0020]    Due to the above constitution, the output shaft portion of the drive portion can be arranged in parallel with the side of the cutting blade. Therefore, a distance from the side of the cutting blade to the drive portion can be decreased. Especially, when it is composed in such a manner that the output shaft portion is positioned between the first gear and the cutting blade, the distance from the side of the cutting blade to the drive portion can be decreased. Therefore, the drive portion can be prevented from coming into contact with the base portion at the time of inclining the cutting portion. Accordingly, the inclination angle can be more increased. 
         [0021]    It is preferable that the drive portion is arranged being horizontal, vertical or inclined with respect to the axial direction of the spindle. 
         [0022]    In order to solve the above disadvantages, the present invention provides a bench cutter comprising: a base portion capable of supporting a workpiece; and a cutting portion for supporting a cutting blade driven by a drive portion, capable of being pivotally moved between an upper position distant from the base portion and a lower portion close to the base portion and also capable of being inclined with respect to the base portion, the cutting portion including: a power transmission mechanism for transmitting a rotation of the drive portion, to which the cutting blade is fixed by a flange, to the cutting blade; and a gear case for accommodating the power transmission mechanism, the power transmission mechanism including: a first gear driven by a drive portion; a final gear fixed to a spindle to which the cutting blade is fixed; and an intermediate gear portion, which is respectively meshed with the first and final gear and transmitting a rotation of the first gear to the final gear, wherein while the cutting portion is being positioned at a lower position, a distance between the flange and the surface of the base portion in the radial direction of the spindle is made to be the same as or not more than a distance between the gear case and the surface of the base portion. 
         [0023]    In the above bench cutter, it is preferable that the drive portion is arranged in an upper portion of the cutting portion, the output shaft portion of the drive portion is arranged substantially in parallel with the spindle, and a rotation of the output shaft portion is transmitted to the first gear through a belt. 
         [0024]    Due to the above constitution, power can be transmitted to the final gear under the condition that a speed of the drive portion is sufficiently reduced. Therefore, it becomes unnecessary to use a large final gear and a size of the gear case in the periphery of the spindle connected to the final gear can be decreased. Since the size of the gear case is decreased, a range from the cutting blade outer circumferential position to the flange position can be made to be a cutting margin in the cutting blade. Therefore, a range capable of being used for cutting of the cutting blade can be extended with respect to the diameter of the cutting blade and further a cutting depth can be increased. Due to the foregoing, even a small cutting blade can cut a thick material. 
         [0025]    Accordingly, even a small bench cutter can cut the thick material. 
         [0026]    According to the bench cutter of the present invention, it is possible to reduce a size and weight. Further, it is possible to increase a cutting depth. 
         [0027]    According to an aspect of the present invention, there is provided a bench cutter including: a drive portion driving a cutting blade; a base portion supporting a workpiece; a cutting portion arranged on the base portion, pivotally supporting the cutting blade above the base portion, and configured to make the cutting blade come close to and separate from the base portion; and a supporting portion connected to the base portion and movably supporting the cutting portion, wherein the cutting portion including: a transmission mechanism for transmitting power of the drive portion to the cutting blade; and a gear case covering the transmission mechanism and having a lower face portion opposed to an upper face of the base portion, wherein the transmission mechanism including: a spindle concentrically supporting the cutting blade; and a cutting blade fixing portion having a flange for fixing the cutting blade to the spindle, wherein while the cutting blade is being maintained in a state perpendicular to the upper face of the base portion, a distance between the lower face portion of the gear case and the upper face of the base portion is not less than a distance between the base portion side end face of the flange and the upper face of the base portion. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0028]      FIG. 1  is a side view showing a bench cutter of an embodiment of the present invention. 
           [0029]      FIG. 2  is a front view showing a bench cutter of an embodiment of the present invention. 
           [0030]      FIG. 3  is a sectional view showing a cutting portion of a bench cutter of an embodiment of the present invention. 
           [0031]      FIG. 4  is a schematic drawing showing an arrangement of a transmission mechanism of a bench cutter of an embodiment of the present invention. 
           [0032]      FIG. 5  is a sectional view showing a cutting portion of a bench cutter of an embodiment of the present invention which is in a tilted state. 
           [0033]      FIG. 6  is a side view showing a cutting portion of a bench cutter of an embodiment of the present invention. 
           [0034]      FIG. 7  is a partial sectional view showing a cutting portion of a bench cutter of an embodiment of the present invention in which the second gear is locked. 
           [0035]      FIG. 8  is a side view showing a cutting portion of a bench cutter of an embodiment of the present invention in which a lid is closed. 
           [0036]      FIG. 9  is a side view showing a cutting portion of a bench cutter of a first variation of an embodiment of the present invention. 
           [0037]      FIG. 10  is a sectional view showing a cutting portion of a bench cutter of a first variation of an embodiment of the present invention. 
           [0038]      FIG. 11  is a sectional view showing a cutting portion of a bench cutter of a second variation of an embodiment of the present invention. 
           [0039]      FIG. 12  is a front view showing a bench cutter of a second variation of an embodiment of the present invention. 
           [0040]      FIG. 13  is a side view of a bench cutter of a conventional example. 
           [0041]      FIG. 14  is a sectional view showing a cutting portion of a bench cutter of a conventional example. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    Referring to  FIGS. 1 to 8 , an embodiment of the present invention will be explained below. The bench circular sawing machine shown in  FIG. 1 , which is a bench cutter as a miter saw  1 , includes a slide mechanism. The miter saw  1  also includes: a base portion  2 ; a supporting portion  3 ; a cutting portion  4 ; and a cutting blade  7 . A miter saw with a slide mechanism is described in following embodiments, but this invention may be adapted to a miter saw having no slide mechanism. 
         [0043]    The base portion  2  includes: a base  21  for holding a lumber W which is a member to be cut; a turn table  22  pivotally held on the base  21 ; and a fence  23  provided on the base  21 . As shown in  FIG. 2 , the base  21  is formed out of a pair of bases in which one is the left base  21 A and the other is the right base  21 B. A direction, in which the left base  21 A and the right base  21 B are arranged, is defined as a lateral direction. An upper portion of the face of the base  21 , on which the lumber W is put, is defined as “upper” and an opposite portion of the face of the base  21  is defined as “lower”. 
         [0044]    As shown in  FIG. 2 , the turn table  22  is arranged between the right base  21 B and the left base  21 A. As shown in  FIG. 1 , the turn table  22  includes: a turn table body portion  22 A, the shape of which is formed into a substantial circular truncated cone; a protruding portion  24  protruding to one side of the turn table body  22 A; and a cutting portion supporting portion  27  for supporting the supporting portion  3  described later arranged on the other side. A direction in which the protruding portion  24  protrudes from the turn table, that is, a direction perpendicular to the lateral direction is defined as “the front” and the opposite direction is defined as “the rear”. 
         [0045]    On the upper face  22 B of the turn table  22 , a series of groove  22   a  (shown in  FIG. 3 ) is formed in a range from the neighborhood of the cutting portion supporting portion  27  to the protruding portion  24 . This groove portion  22   a  is located at the same position as the cross line position at which the cutting blade  7  pivotally moves and crosses the turn table  22 . This groove portion  22   a  is a portion in which a tip of the cutting blade  7  is accommodated. 
         [0046]    As shown in  FIGS. 1 and 2 , the protruding portion  24  includes a regulation operating portion  28  which is an operating portion for regulating at the time of regulating a rotation of the turn table  22  with respect to the base  21 . As shown in  FIG. 1 , the cutting portion supporting portion  27  is arranged at a position on the opposite side to the protruding portion  24  with respect to the central axis of the turn table  22 . The cutting portion supporting portion  27  includes: a tilting shaft  27 A positioned on a prolonged line of the groove portion  22   a  (shown in  FIG. 3 ); and a tilting supporting portion  27 B by which the supporting portion  3  is fixed at an arbitrary inclination angle. 
         [0047]    As shown in  FIG. 1 , on the base  21  and at the upper position of the turn table  22 , the fence  23  is provided. As shown in  FIG. 2 , the fence  23  includes a left fence  23 A and a right fence  23 B corresponding to the left base  21 A and the right base  21 B. Front faces of the left fence  23 A and the right fence  23 B are arranged so that the front faces can be located on the same plane. Therefore, the front faces of the left fence  23 A and the right fence  23 B prescribe a position of the lumber W (shown in  FIG. 1 ). 
         [0048]    As shown in  FIG. 1 , the supporting portion  3  includes: a tilting portion  31 ; a slide supporting portion  33 ; a sliding portion  34 ; and an pivot shaft portion  35 . The tilting portion  31  is supported by the tilting shaft  27 A and capable of being fixed to the tilting supporting portion  278  by the clamp  31 A. When this clamp  31 A is loosened, the tilting portion  31  can be tilted. When this clamp  31 A is fastened, the tilting portion  31  is fixed to the tilting supporting portion  27 B. The slide supporting portion  33  is formed out of two cylindrical bodies and arranged in an upper portion of the tilting portion  31  integrally with the tilting portion  31 . The sliding portion  34  has two sliding pipes  34 A inserted into two cylinders of the slide supporting portion  33 . When the two sliding pipes  34 A slide with respect to the slide supporting portion  33 , the sliding portion  34  can be moved in the longitudinal direction. The pivot shaft portion  35  is provided in the sliding portion  34  and formed out of a pair of arms. Between the pair of arms, the pivot shaft portion  35 A is provided. The pivot shaft portion  35 A supports the cutting portion  4  so that the cutting blade  7  can be made to come close to and separate from an upper face of the turn table  22 . 
         [0049]    The cutting portion  4  is composed in such a manner that the housing  4 A (shown in  FIG. 3 ) supported by the pivot shaft portion  35 A is provided as an outer shell of the cutting portion  4 . As shown in  FIG. 3 , the motor  51  and the pulley portion  52  are arranged inside the housing  4 A. The housing  4 A includes: a gear case  4 B; a cutting blade cover  4 C; and a handle which becomes a holding portion at the time of cutting. 
         [0050]    The motor  51  is arranged so that the output shaft  51 A connected to the pulley portion  52  can be extended in parallel with the axial direction of the spindle  43 A described later. The cooling fan  51 B is mounted on the output shaft  51 A. The pulley portion  52  includes: a first pulley  52 A connected to the output shaft  51 A; a second pulley  52 C connected to the transmission mechanism  4 D described later; and a belt  52 B provided between the first pulley  52 A and the second pulley  52 C. 
         [0051]    As shown in  FIG. 3 , the gear case  4 B includes: a lower face portion  4 E opposed to the upper face portion  22 B under the condition that the cutting blade  7  comes close to the base  21  or the turn table  22  and is substantially perpendicular to the upper face  22 B of the turn table  22 ; and an inclined face  4 F which is arranged being inclined with respect to the lower face portion  4 E. Inside the gear case  4 B, the transmission mechanism  4 D is arranged. In this connection, the inclined face  4 F includes a portion of the housing  4 A. The lower face portion  4 E is composed so that a distance between the lower face portion  4 E and the upper face  22 B can be longer than a distance between the end face on the turn table  22  side of the flange  44  described later and the upper face  22 B under the condition that the cutting blade  7  is perpendicular to the upper face  22 B. 
         [0052]    The transmission mechanism  4 D includes: a first gear  41 ; an intermediate gear  42 ; and a final gear  43 . The first gear  41  is a helical gear and connected to the second pulley  52 B and pivotally supported by the gear case  4 B. The intermediate gear  42  includes: a second gear  42 A meshed with the first gear  41 ; and a third gear  42 B which is arranged on the same shaft as that of the second gear  42 A and meshed with the final gear  43 . The intermediate gear  42  is pivotally supported by the gear case  4 B through a pair of bearings. The second gear  42 A and the third gear  42 B are respectively composed of helical gears. Tooth traces of the second gear  42 A and the third gear  42 B are directed in the opposite directions. The number of teeth of the second gear  42 A is larger than the number of teeth of the third gear  42 B. Due to the above constitution, the rotating speed of the first gear  41  is reduced and transmitted to the final gear  43  and the thrust forces of the respective gears can be canceled to each other. The final gear  43  is a helical gear and meshed with the third gear  42 B and provided with a spindle  43 A on which the cutting blade  7  is mounted. The final gear  43  is pivotally supported by the gear case  4 B through a pair of bearings. 
         [0053]    Power is transmitted to the final gear  43  while the rotating speed is being reduced by the intermediate gear portion  42 . Therefore, it is unnecessary to use a gear, the diameter of which excessively large. Accordingly, the gear case  4 B provided in the periphery of the final gear  43  can be made small. The flange  44 , which is a cutting blade fixing portion for fixing the cutting blade  7 , and the bolts  44 C can be mounted on the spindle  43 A. 
         [0054]    Furthermore, as mentioned above, the pulley portion  52  includes the first pulley  52 A, the second pulley  52 C, and the belt  52 B. As shown in  FIG. 3 , the size (diameter) of the second pulley  52 C is configured to be larger than that of the second pulley  52 A. By having such a configuration, the rotation of the motor  51  is transmitted from the output shaft  51 A to the first gear  41  of the transmission mechanism  41  through the pulley portion  52  in a reduced manner. The sizes (diameters) of the intermediate gear  42  and the final gear  43  may be reduced in obtaining a desired speed reduction ratio, as compared with a case where the sizes (diameters) of the first pulley  52 A and the second pulley  52 B are the same. Accordingly, the intermediate gear  42  and the gear case  4 B in the periphery of the final gear  43  can be reduced in size. This is the case where the speed reduction is done in the three stages so that a capability of achieving a depth of cut can be improved. This configuration is to perform a speed reduction for one stage by setting the diameters of the pulleys different from each other. As compared with a case where the three-stage speed reduction is achieved by providing plural gears, it is possible to reduce the size of the gear case while having a simple configuration and improving the capability for achieving depth of cut at low cost. 
         [0055]    As shown in  FIG. 3 , the first gear  41 , the intermediate gear portion  42  and the final gear  43  are arranged so that these gears can be made to come most close to the upper face  228  of the turn table  22  of the base portion  2  (shown in  FIG. 1 ) when the cutting portion  4  is pivoted and so that the first gear  41  can be located at the uppermost position and separated from the cutting blade  7  most distantly and so that the final gear  43  can be located at the lowermost position and made to come most close to the cutting blade  7  and so that the intermediate gear portion  42  can be located at the intermediate position between the first gear  41  and the final gear  43  under the condition that the cutting blade  7  is perpendicular to the upper face  228 . Under the condition that the cutting portion  4  is pivoted and made to come most close to the upper face  228 , as shown in  FIG. 4 , the respective rotary shafts of the first gear  41 , the intermediate gear portion  42  and the final gear  43  are arranged in a line on the axis G which is perpendicular to the upper face  22 B. 
         [0056]    In the constitution of the final gear  43 , the intermediate gear portion  42  and the first gear  41  described above, an angle of the inclination of the inclined face  4 F with respect to the cutting blade  7  to accommodate these gears is prescribed according to the distance between the cutting blade  7  and the first gear  41  and also according to the distance between the upper face  22 B and the first gear  41 . When the respective shafts of the gears are arranged on the same axis G perpendicular to the upper face  22 B as described above, the first gear  41  can be most separated from the upper face  22 B under the condition that the cutting portion  4  is pivoted downward. When the first gear  41  is arranged at a position which is most separate from the upper face  22 B, an angle of the inclined face  4 F with respect to the cutting blade  7  can be made to be an acute angle. When the angle of the inclined face  4 F is the acute angle, as shown in  FIG. 5 , when the cutting portion  4  is tilted, the tilting angle θ of the cutting portion  4  can be increased. 
         [0057]    As shown in  FIG. 3 , the hole  42   a  is formed on the side of the inclined face  4 F of the second gear  42 A. As shown in  FIGS. 3 and 6 , the opening portion  4   a  is formed on the inclined face  4 F of the gear case  4 B. In the opening portion  4   a,  the lock pin  54  capable of moving toward the second gear  42 A side is arranged. It is composed in such a manner that an end portion on the second gear  42 A side of the lock pin  54  can be inserted into the hole  42   a  and the lock pin  54  is pushed by a spring onto the opposite side to the second gear  42 A side. Therefore, at the time of cutting, the lock pin  54  is located at a position distant from the second gear  42 A as shown in  FIG. 3 . Accordingly, there is no possibility that the second gear  42 A is locked by the lock pin  54 . 
         [0058]    At the time of detaching the bolt  44   c  fixing the cutting blade  7 , as shown in  FIG. 7 , the final gear  43  and the spindle  43 A are locked when the second gear  42 A is locked. At this time, when the lock pin  54  is pushed onto the second gear  42 A side and engaged with the hole  42   a,  the second gear  42 A can be suitably locked. In the opening portion  4   a  which has access to the lock pin  54 , the lid  4 G is provided as shown in  FIG. 8 . Therefore, unless the lid  4 G is opened and the lock pin  54  is pushed, the lock pin  54  is not moved on the second gear  42 A side. Accordingly, it is possible to prevent the malfunction of the lock pin  54 . 
         [0059]    As shown in  FIG. 1 , the cutting blade cover  4 C covers an upper portion of the cutting blade  7 . As shown in  FIG. 3 , the cutting blade cover  4 C is composed so that it can not protrude onto the lower side of the flange  44  when the cutting portion  4  is pivoted downward. 
         [0060]    In the case of cutting the lumber W with the miter saw composed as described above, as shown in  FIG. 3 , the cutting portion  4  is pivoted downward and cuts the lumber W with the cutting blade  7 . At this time, the thickness of the lumber W capable of being cut with the miter saw  1  is set according to a distance from the lowermost position of the cutting blade  7  to the position at which the cutting portion  4  comes into contact with an upper face of the lumber W. In the miter saw  1  described here, the position at which the cutting portion  4  comes into contact with the upper face of the lumber W is the lowermost position of the flange  44 . Due to the foregoing, a value obtained when a radius of the flange  44  is subtracted from a radius of the cutting blade  7  can be made to be a cutting depth, that is, a diameter of the portion from which the cutting blade  7  is exposed can be made to be a cutting depth. 
         [0061]    In the conventional miter saw, before the flange comes into contact with the lumber, the gear case, the housing or the cutting blade cover comes into contact with the lumber. 
         [0062]    Therefore, a diameter of the portion in which the cutting blade  7  is exposed can not be made to be a cutting depth. On the other hand, in the miter saw  1  of the present case, for example, a lumber, which can not be cut without using a conventional cutting blade of 8 inches, can be cut by using a cutting blade  7  of 7 inches. When the miter saw, the upper limit of the usable cutting blade diameter of which is 8 inches, is compared with the miter saw, the upper limit of the usable cutting blade diameter of which is 7 inches, the miter saw, the upper limit of the usable cutting blade diameter of which is 8 inches, is larger and heavier than the miter saw, the upper limit of the usable cutting blade diameter of which is 7 inches. Therefore, when the constitution of the present case is employed, the thick material can be cut even by using the small, light miter saw. 
         [0063]    It should be noted that the miter saw of the present invention not limited to the above specific embodiment. Variations and improvements can be made without departing from the scope of claims of the present invention. 
         [0064]    For example, as shown in  FIGS. 9 and 10 , it is possible to employ a constitution in which the first gear  141  is directly mounted on the output shaft  151 A of the motor  151 . In this case, the cutting portion  104  can be inclined onto one side with respect to the base portion  121 . In another embodiment in which the first gear is directly fixed to the drive portion as shown in  FIG. 11 , the first gear  241  and the second gear  242 A may be respectively formed out of helical gears and the motor  251  may be arranged so that the output shaft  151 A can be perpendicular to the axial direction of the spindle  243 A. Due to the above constitution, as shown in  FIG. 12 , a protruding portion to the right of the cutting portion  204  is suppressed and an inclination angle to the right of the cutting portion  204  can be increased. 
         [0065]    As shown in  FIG. 11 , when the motor  251  is arranged so that the output shaft  251 A can be located between the first gear  241  and the cutting blade  207 , a protruding portion to the right of the cutting portion  204  shown in  FIG. 12  is further suppressed. The third gear  242 B and the final gear  243  may be formed out of helical gears. In this case, a direction of the helical teeth of the third gear  242 B may be determined to be a direction in which a thrust force direction is directed to the left, that is, a direction in which the second gear  242 A is pushed to the first gear  241 .

Technology Classification (CPC): 1