Patent Publication Number: US-2010116112-A1

Title: Cutting machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cutting machine such as an electric circular saw. 
     2. Description of the Related Art 
     Japanese laid-open patent publication No. 2001-62803 discloses an electric circular saw. The known electric circular saw has a cutting-line guide (cutting-line mark) on a front portion of a base in a blade cutting direction and an observation hole formed rearward of the cutting-line guide. An user of circular saw performs the operation of cutting a workpiece while aligning the marks on the cutting-line guide and the observation hole with a cutting line marked on the workpiece. 
     The above-mentioned cutting-line guide and observation hole serve to indicate the cutting direction of the blade and is therefore designed to be located on a cutting line of the blade. Due to manufacturing variations or assembling variations, however, the marks on the cutting-line guide and the observation hole may be deviated from the cutting line of the blade. In such a case, the precision of cutting of the electric circular saw is reduced. Therefore, in the known cutting machine, further improvement is required in this point. 
     SUMMARY OF THE INVENTION 
     It is, accordingly, an object of the invention to improve a precision of cutting work for a cutting machine. 
     The above-described object can be achieved by the claimed invention. Representative cutting machine according to the invention is provided to include a tool body having a blade which is rotationally driven to cut a workpiece, and a base having an opening through which part of the blade protrudes downward. The base is placed on an upper surface of the workpiece and moved together with the tool body in order to cut the workpiece by the blade. The “cutting machine” here typically represents a portable circular saw for wood cutting or a portable cutter for stone or metal cutting. 
     Further, according to the invention, the representative cutting machine further includes a blade cutting direction indicating member for indicating a cutting direction of the blade. The blade cutting direction indicating member is formed on a front end of the base in a direction of movement of the base and can be adjusted in mounting position with respect to the base by moving in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade. The “cutting direction of the blade” may refer to the direction in which the blade moves (the cutting machines moves) when the cutting machine cuts the workpiece. Further, the manner of “moving in a rotational manner” preferably includes both the manner in which the center of the rotational displacement of the blade cutting direction indicating member is fixed and the manner in which such center is variable. The blade cutting direction indicating member also serves as a blade positioning member for positioning the blade with respect to a cutting line marked on the workpiece. 
     The blade cutting direction indicating member for indicating the cutting direction of the blade is formed on a front end of the base in a direction of movement of the base and can be adjusted in mounting position with respect to the base by moving in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade. Therefore, if a deviation is caused between the indicating direction of the blade cutting direction indicating member and the cutting direction of the blade due to manufacturing variations or assembling variations, the indicating direction (orientation) of the blade cutting direction indicating member can be adjusted to be in agreement with the cutting direction of the blade. Further, the blade cutting direction indicating member also serves as a blade positioning member for positioning the blade with respect to a cutting line marked on the workpiece. Therefore, when a cutting operation is performed along a cutting line by utilizing the blade cutting direction indicating member, high precision of cutting can be realized by exactly adjusting the indicating direction of the blade cutting direction indicating member with respect to the cutting direction of the blade. 
     As another aspect of the invention, the blade cutting direction indicating member may have a first direction indicating part for indicating the cutting direction of the blade and a second direction indicating part for indicating the same line as the first direction indicating part, and the direction indicating parts are integrally formed with the blade cutting direction indicating member. Further, an observation hole for cutting-line alignment is formed in the base between the blade and the blade cutting direction indicating member. The first direction indicating part is located above the observation hole, and the second direction indicating part is located forward of the first direction indicating part. Therefore, the blade cutting direction can be indicated by utilizing the two direction indicating parts. Specifically, the cutting direction of the blade can be exactly indicated by adjusting the position (orientation) of the blade cutting direction indicating member such that the first and second direction indicating parts are parallel to the direction of the face of the blade. Further, the parallelism of the first and second direction indicating parts to the cutting line can be more exactly achieved. As a result, higher-precision cutting operation can be performed. Further, the blade cutting direction indicating member has the first and second direction indicating parts integrally formed therewith, and compared with the case in which these parts are separately formed, the blade cutting direction indicating member can be easily manufactured and assembling errors are not caused. 
     As further another aspect of the invention, the first direction indicating part may include a side surface of a projection which projects in a direction opposite to the cutting direction of the blade and faces the observation hole, and the second direction indicating part may include a side surface of a notch which is recessed in a direction opposite to the cutting direction of the blade. With this construction, the two direction indicating parts of the blade cutting direction indicating member can be rationally provided. 
     As further another aspect of the invention, two blade cutting direction indicating members having the same shape may be provided and arranged side by side in the cutting direction of the blade with respect to the base. With this construction, compared with the case in which only one blade cutting direction indicating member is provided, the cutting direction of the blade can be more exactly indicated. Further, the blade cutting direction indicating members can be designed as common parts, so that cost reduction can be achieved. 
     As further another aspect of the invention, a cutting edge plate is provided on an underside of the base. An end of the cutting edge plate which is visible via an opening of the base forms a direction indicating part for indicating the cutting direction of the blade, and the cutting edge plate can be adjusted in mounting position with respect to the underside of the base by moving in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade and thus also serves as the blade cutting direction indicating member. With this construction, an existing part or the cutting edge plate can be rationally utilized as a blade cutting direction indicating member. 
     Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view showing an entire circular saw  100  according to a first embodiment of the invention. 
         FIG. 2  is a plan view of the entire circular saw  100 . 
         FIG. 3  is a plan view showing a front portion of the circular saw  100  including a top guide  121  and an observation hole  117 , wherein a blade case  103  is not shown. 
         FIG. 4  is a plan view showing the front portion of the circular saw  100  including the top guide  121  and the observation hole  117 . 
         FIG. 5  is a sectional plan view showing the top guide  121 . 
         FIG. 6  is a sectional view taken along line A-A in  FIG. 2 . 
         FIG. 7  is a sectional view taken along line B-B in  FIG. 2 . 
         FIG. 8  is a view for illustrating a deviation α caused between the indicating direction of the top guide  121  and the cutting direction of the blade  113 , wherein  FIG. 8(A)  shows the deviation α caused therebetween and  FIG. 8(B)  shows a state in which the deviation α has been corrected. 
         FIG. 9  is a plan view for illustrating a structure of indicating the cutting direction of the blade  113  according to a second embodiment of the invention. 
         FIG. 10  is a plan view for illustrating a structure of indicating the cutting direction of the blade  113  according to a third embodiment of the invention. 
         FIG. 11  is a bottom view thereof. 
         FIG. 12  is a sectional view taken along line C-C in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Each of the additional features and method steps disclosed above and below may be utilized separately or in conjunction with other features and method steps to provide and manufacture improved cutting machine and method for using such cutting machine and devices utilized therein. Representative examples of the present invention, which examples utilized many of these additional features and method steps in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person skilled in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed within the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe some representative examples of the invention, which detailed description will now be given with reference to the accompanying drawings. 
     First Embodiment 
     A first embodiment of the invention is now explained with reference to the drawings.  FIG. 1  is a side view showing an entire circular saw  100  as a representative embodiment of the cutting machine according to the invention.  FIG. 2  is a plan view of the entire circular saw  100 . As shown in  FIGS. 1 and 2 , the circular saw  100  according to this embodiment mainly includes a base  111  which can be placed on a workpiece (not shown), and a circular saw body  101  disposed above the base  111  and connected to the base  111 . The circular saw body  101  is a feature that corresponds to the “tool body” according to this invention. 
     The contour of the circular saw body  101  is defined by a blade case  103  that houses a disc-like blade  113  which is driven to rotate in a vertical plane, a motor housing  107  that houses a driving motor (not shown), a gear housing  107  that houses a power transmitting mechanism part (not shown) for transmitting the rotating output of the driving motor to the blade  113 , and a generally D-shaped handgrip  109  which is integrally formed on the top of the motor housing  107 . The handgrip  109  has a trigger switch  109   a  that is depressed by the user to drive the driving motor. The blade  113  is a feature that corresponds to the “saw blade” according to this invention. 
     The power transmitting mechanism part housed within the gear housing  107  decelerates the rotating output of the driving motor and transmits it to the blade  113 , so that the blade  113  is caused to rotate on a rotation spindle  113   a.  A lower edge portion of the blade  113  protrudes from the underside of the base  111  through an opening  111   a  (see  FIG. 3 ) of the base  111 . A safety cover  104  is rotatably attached to the rotation spindle  113   a  and covers the lower half of the blade  113 . 
     In cutting a workpiece, when the front end (right end as viewed in  FIGS. 1 and 2 ) of the base  111  is placed on the workpiece and moved forward (rightward as viewed in  FIGS. 1 and 2 ), the workpiece pushes the front end of the safety cover  104 , so that the safety cover  104  rotates on the rotation spindle  113   a  through the opening  111  and is housed within the blade case  103 . After completion of the cutting operation, when the circular saw  100  is lifted up from the workpiece, the safety cover  104  is returned by a spring (not shown) to its initial position to cover the lower edge portion of the blade  113 . 
     The blade case  103  is provided with a chips discharge tube  115  for discharging chips to the outside which are generated within the blade case  103  during an operation of cutting a workpiece by the blade  113 . A dust collecting bag or a dust collecting hose of a dust collecting machine can be connected to the chips discharge tube  115 . The chips generated during the cutting operation of the blade  113  fly out in a tangential direction of a front portion of a cutting region of the blade  113  on the front side in the cutting direction, or generally upward, and led into the dust collecting bag or the dust collecting machine through the chips discharge tube  115 . 
     As shown in  FIG. 2 , the base  111  is formed by a generally rectangular plate and has a top guide  121  on the front end of the base  111  on the front end side in the direction of movement for cutting the workpiece. The top guide  121  serves to indicate the cutting direction of the blade  113  and to align the blade  113  with a cutting line marked on the workpiece. Further, an observation hole  117  for cutting-line alignment is formed between the top guide  121  and the blade  113 . The top guide  121  is a feature that corresponds to the “blade cutting direction indicating member” and the “blade positioning member with respect to a cutting line” according to this invention. The observation hole  117  is a feature that corresponds to the “observation hole” according to this invention. 
       FIGS. 3 and 4  are enlarged plan views showing a front portion of the circular saw  100  including the top guide  121  and the observation hole  117 . In  FIG. 3 , however, the blade case  103  is not shown. Further,  FIG. 5  is a sectional plan view showing the top guide  121 .  FIG. 6  is a sectional view taken along line A-A in  FIG. 2  and  FIG. 7  is a sectional view taken along line B-B in  FIG. 2   
     The top guide  121  comprises a generally rectangular plate which is long in a direction transverse to the cutting direction (the direction of the face) of the blade  113 . The top guide  121  has a front direction indicating face  123   a  which is formed by a side surface of a notch  123  on the front side of the top guide  121  in the direction of movement, and a rear direction indicating face  125   a  which is formed by a side surface of a projection  125  on the rear side of the top guide  121  in the direction of movement. The rear direction indicating face  125   a  and the front direction indicating face  123   a  are features that correspond to the “first direction indicating part” and the “second direction indicating part”, respectively, according to this invention. 
     The notch  123  is generally U-shaped with a predetermined depth extending rearward from a front end surface of the top guide  121 , and a side surface of the notch which extends straight in the back-and-forth direction is defined as the front direction indicating face  123   a.  The projection  125  projects a predetermined length rearward from a rear end surface of the top guide  121 , and a side surface of the projection which extends straight in the back-and-forth direction is defined as the rear direction indicating face  125   a.  The front direction indicating face  123   a  of the notch  123  and the rear direction indicating face  125   a  of the projection  125  are arranged in line. 
     As shown in  FIGS. 5 to 7 , the top guide  121  having the above-described construction is overlaid on a top guide mounting part  131  which is formed on the upper surface of the front end portion of the base  111  in the direction of movement. Then the mounting position of the top guide  121  can be adjusted by moving the top guide in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade  113  (the direction of the rotation axis of the blade  113 ) with respect to the top guide mounting part  131 . Further, the top guide  121  can be fastened in the adjusted position by a fastening means in the form of a set screw  127 . 
     As shown in  FIG. 5 , the top guide mounting part  131  comprises a rib-like protrusion which protrudes from the upper surface of the base and extends in the lateral direction of the base. Further, a circular fastening part having a screw hole  131   a  for the set screw  127  is formed in one extending end of this protrusion. A recess  129  is formed on the side (underside) of the top guide  121  facing the upper surface of the base  111  and has a shape that conforms to the outside shape of the top guide mounting part  131 . The top guide  121  is loosely fitted over the top guide mounting part  131  such that the top guide mounting part  131  is received in the recess  129 . In this state, the top guide  121  is fastened to the top guide mounting part  131  by the set screw  127 . 
     The recess  129  of the top guide  121  is larger than the outside shape of the top guide mounting part  131 . Thus, a predetermined clearance C is formed between the inner circumferential surface of the recess  129  and the outer circumferential surface of the top guide mounting part  131 , so that the top guide  121  is allowed to move with respect to the top guide mounting part  131  within the range of the clearance C. Specifically, with the set screw  127  loose, the top guide  121  which is loosely fitted over the top guide mounting part  131  is allowed to move in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade  113  with respect to the top guide mounting part  131  (the base  111 ). 
     The projection  125  extends from the top guide  121  toward the observation hole  117  along the upper surface of the base  111 . In other words, the projection  125  is located above the observation hole  117 . 
     Generally, the circular saw  100  is configured to perform a bevel cutting operation on a workpiece in the state in which the circular saw body  101  is tilted in the lateral direction (the direction transverse to the cutting direction of the blade  113 ) around a connection between the circular saw body and the base  111  so that the blade  113  is tilted with respect to a vertical plane. Such bevel cutting operation is generally performed at an angle of 45 degrees. Therefore, the top guide  121  is provided with a bevel cutting direction indicating face  133   a  in order to indicate the cutting direction of the blade  113  for 45° bevel cutting operation. The bevel cutting direction indicating face  133   a  is formed by a side surface of a notch  133  and arranged adjacent to the front direction indicating face  123   a.    
     Further, for alignment of the front direction indicating faces  123   a,    133   a  with a cutting line L on the workpiece, as shown in  FIG. 5 , a notch  111   b  for cutting-line alignment is formed in the front end portion of the base  111  and generally U-shaped in plan view. 
     Now, operation of the above-described circular saw  100  for cutting a workpiece is explained. First, a user holds the handgrip  109  of the circular saw  100 , places the base  111  of the upper surface of the workpiece, and positions the circular saw  100  such that the front and rear direction indicating faces  123   a,    125   a  are aligned with the cutting line L (see  FIGS. 3 and 4 ) marked on the workpiece. At this time, on the front direction indicating face  123   a  side, the cutting line L can be seen through the notch  123  and the notch  111   b  for cutting-line alignment, and on the rear direction indicating face  125   a  side, the cutting line L can be seen through the observation hole  114 , so that cutting-line alignment can be easily made. After positioning the circular saw  100  as described above, when the user depresses the trigger switch  109   a,  the driving motor  131  is driven to rotate the blade  113 . In this state, in order to perform the cutting operation on the workpiece, the user moves the circular saw  100  forward while aligning the front and rear direction indicating faces  123   a,    125   a  with the cutting line L. 
     The top guide  121  serves to indicate the cutting direction of the blade  113  and also to position the blade  113  (the circular saw  100  itself) with respect to the cutting line L marked on the workpiece. Therefore, in order to cut the workpiece along the cutting line L with high accuracy, it is important that the indicating direction of the front and rear direction indicating faces  123   a,    125   a  of the top guide  121  is in exact agreement with the cutting direction of the blade  113 . 
     In the circular saw  100 , the blade  113  is mounted on the circular saw body  101  side and the top guide  121  is mounted on the base  111  side, and then the base  111  and the circular saw body  101  are assembled together into the circular saw. In such construction, due to manufacturing variations or assembling variations, a deviation may be caused between the indicating direction of the top guide  121  and the cutting direction of the blade  113 . In the case of such an occurrence, when the circular saw  100  is moved along the indicating direction of the top guide  121 , an error is caused between the direction of the movement and the cutting direction of the blade  113 . 
     Therefore, in this embodiment, the top guide  121  is loosely fitted over the top guide mounting part  131  via the recess  129 , so that the position of the top guide  121  with respect to the blade  113  can be adjusted, with the set screw  127  loose, by moving the top guide  121  in parallel or in a rotational manner within the range of the above-described clearance C with respect to the top guide mounting part  131  in a direction transverse to the cutting direction (the direction of the face) of the blade  113 . Therefore, if a deviation is caused between the indicating direction of the top guide  121  and the cutting direction of the blade  113 , an adjustment can be made to correct the deviation (in such a manner that the front and rear direction indicating faces  123   a,    125   a  are aligned with an extension line of the face of blade  113 ), for example, by using a ruler. In this manner, the circular saw  100  which is capable of high-precision cutting can be provided.  FIG. 8(A)  shows an example of a deviation α caused between the indicating direction of the top guide  121  and the cutting direction of the blade  113 , and  FIG. 8(B)  shows a state in which the deviation α has been corrected. 
     Further, in this embodiment, the top guide  121  is provided with the front and rear direction indicating faces  123   a,    125   a  which can indicate the same line. Therefore, by using the two direction indicating faces  123   a,    125   a,  indication of the cutting direction of the blade  113  and positioning of the blade  113  with respect to the cutting line L, or the parallelism to the face of the blade  113  and the parallelism to the cutting line L, can be more exactly achieved. As a result, higher-precision cutting operation can be performed. 
     Further, in this embodiment, the front and rear direction indicating faces  123   a,    125   a  are formed by forming the notch  123  and the projection  125  on the top guide  121 . Therefore, the front and rear direction indicating faces  123   a,    125   a  can be integrally formed with the top guide  121 , and compared with the case in which these faces are separately formed, the direction indicating faces can be easily manufactured and assembling errors are not caused. 
     Further, in the above-described first embodiment, the top guide  121  is described as being provided with the front and rear direction indicating faces  123   a,    125   a,  but it may be provided with one direction indicating face. In this case, it is preferable to provide the front direction indicating face  123   a  formed by the notch  123 . 
     Second Embodiment 
     A second embodiment of the invention is now explained with reference to  FIG. 9 . This embodiment is a modification of the cutting direction indicating technique for indicating the cutting direction of the blade  113 , and the circular saw  100  itself is similarly constructed as the above-described first embodiment. In the circular saw  100  according to this embodiment, as shown in  FIG. 9 , two top guides  141 ,  143  are disposed on the front end portion of the base  111  in the direction of movement and arranged in parallel in the longitudinal direction of the base. The front and rear top guides  141 ,  143  can be individually adjusted in position with respect to the base  111 . The top guides  141 ,  143  are features that correspond to the “cutting direction indicating member” according to this invention. 
     The front and rear top guides  141 ,  143  have the same shape without the rear direction indicating face  125   a  which is formed by the side surface of the projection  125  on the top guide  121  in the above first embodiment. Specifically, in this embodiment, the front and rear top guides  141 ,  143  each comprise a generally rectangular plate which is long in a direction transverse to the cutting direction of the blade  113 , and have respective front direction indicating faces  145   a,    147   a  which are formed on the front side by side surfaces of notches  145 ,  147  of the top guide  121 . The notches  145 ,  147  are each generally U-shaped with a predetermined depth extending rearward from front end surfaces of the top guides  145 ,  147 , and have respective side surfaces extending straight in the back-and-forth direction which are defined as the front direction indicating faces  145   a,    147   a.    
     In a top guide mounting region on the front end portion of the base  111 , as shown in  FIG. 9  by broken line, a generally U-shaped notch  111   c  is formed for cutting-line alignment for the front top guide  141 , and an observation hole  111   d  is formed rearward of the notch  111   c  for cutting-line alignment for the rear top guide  143 . Further, a top guide mounting part (not shown) which is similar to the top guide mounting part  131  described in the first embodiment is formed in the vicinity of the notch  111   c  and the observation hole  111   d.    
     The front and rear top guides  141 ,  143  have respective recesses (not shown) similar to that of the first embodiment is formed on the lower surface (underside) of the top guide. The top guides  141 ,  143  are loosely fitted over the top guide mounting part of the base  111  via the recesses and, in this state, fastened to the top guide mounting part by respective set screws  149 . The mounting position of the top guides  141 ,  143  can be individually adjusted, with the respective set screws  149  loose, by moving the top guides in parallel or in a rotational manner with respect to the top guide mounting part in a direction transverse to the cutting direction of the blade  113 . 
     In this embodiment, as described above, the two identically shaped top guides  141 ,  143  are arranged side by side in the cutting direction of the blade  113  on the front end portion of the base  111 . Further, the position of the top guides  141 ,  143  with respect to the blade  113  can be adjusted, with the respective set screws  149  loose, by moving the top guides in parallel or in a rotational manner in a direction transverse to the cutting direction (the direction of the face) of the blade  113 . Therefore, if a deviation is caused between the indicating direction of the top guides  141 ,  143  (the direction indicating faces  145   a,    147   a ) and the cutting direction of the blade  113 , an adjustment can be made to correct the deviation (in such a manner that the front and rear direction indicating faces  145   a,    147   a  are aligned with an extension line of the face of the blade  113 ), for example, by using a ruler. In this manner, the cutting direction of the blade  113  can be exactly indicated. As a result, the circular saw  100  which is capable of high-precision cutting can be provided. 
     Further, by using the direction indicating faces  145   a,    147   a  of the front and rear top guides  141 ,  143 , indication of the cutting direction of the blade  113  and positioning of the blade  113  with respect to the cutting line L, or the parallelism to the face of the blade  113  and the parallelism to the cutting line L, can be more exactly achieved. Therefore, higher-precision cutting operation can be performed. Further, in this embodiment, the two top guides  141 ,  143  having the same shape can be designed as common parts, so that cost reduction can be achieved. 
     Further, in the above-described second embodiment, the front and rear top guides  141 ,  143  are described as being provided in order to indicate the cutting direction of the blade  113 , but only either one of the top guides  141 ,  143  may be provided. In this case, it is preferable to provide the front top guide  141 . 
     Third Embodiment 
     A third embodiment of the invention is now explained with reference to  FIGS. 10 to 12 . This embodiment is a modification of the cutting direction indicating technique for indicating the cutting direction of the blade  113 . In place of the rear top guide  143  according to the above-described second embodiment, a cutting edge plate  151  is utilized to form a cutting direction indicating member. 
     In this embodiment, the top guide  141  having the same construction as that of the second embodiment is provided on the front end portion of the base  111 , and a structure of mounting the top guide  141  on the base  111  also has the same construction. Therefore, the front top guide  141  is given the same numeral as that of the second embodiment and its description is omitted in this embodiment. 
     The cutting edge plate  151  which is utilized as a cutting direction indicating member is used as a member for preventing burrs and fuzz by pressing the upper surface of the workpiece during the operation of cutting the workpiece. Therefore, as shown, the cutting edge plate  151  is disposed in a recess  111   e  formed in the underside of the base  111  on the front side of the blade  113 . In this state, the cutting edge plate  151  can slide in a direction transverse to the cutting direction of the blade  113  (the direction of the rotation axis of the blade  113 ). Further, the underside of the cutting edge plate  151  disposed in the recess is flush with or slightly recessed with respect to the underside of the base  111 . 
     As shown in  FIGS. 10 and 11 , one end face of the cutting edge plate  151  in the direction of its movement faces an opening  111   a  which is formed in the base  111  in order to protrude the blade  113 . This end face forms a direction indicating face  151   a  for indicating the cutting direction of the blade  113 . The direction indicating face  151   a  is a feature that corresponds to the “direction indicating part” according to this invention. 
     As shown in  FIGS. 10 and 12 , the cutting edge plate  151  is connected to a mounting plate  153  disposed on the upper surface of the base  111 , via a connecting piece  155 . The connecting piece  155  and the mounting plate  153  are swaged together, and the connecting piece  155  and the cutting edge plate  151  are clamped together by a screw  156 , so that the cutting edge plate  151  is integrated with the mounting plate  153 . The connecting piece  155  is loosely fitted in a slot  111   f  formed through the base  111  in the vertical direction (the direction of the thickness) and can move in a direction transverse to the cutting direction of the blade  113  (the direction of the rotation axis of the blade  113 ). 
     The mounting plate  153  has a slot  153   a  extending in a direction transverse to the cutting direction of the blade  113  (the direction of the rotation axis of the blade  113 ). The mounting plate  153  is fastened to the base  111  by an adjusting screw  157  which is screwed into the base  111  through the slot  153   a.  Therefore, with the adjusting screw  157  loose, the position of the cutting edge plate  151  with respect to the blade  113  can be adjusted by moving the cutting edge plate  151  together with the mounting plate  153  in parallel or in a rotational manner in a direction transverse to the cutting direction (the direction of the face) of the blade  113  within a range allowed by the slot  111   f  of the base  111  and the slot  153   a  of the mounting plate  153 . 
     In this embodiment, as described above, the one top guide  141  and the cutting edge plate  151  located rearward of the top guide  141  are used to indicate the cutting direction of the blade  113 . Further, each of the top guide  141  and the cutting edge plate  151  can be individually adjusted in position with respect to the blade  113  by moving it with respect to the base  111  in parallel or in a rotational manner in a direction transverse to the cutting direction (the direction of the face) of the blade  113 . Therefore, if a deviation is caused between the indicating directions of the top guide  141  and the cutting edge plate  151  and the cutting direction of the blade  113 , in the same manner as in the above-described embodiments, an adjustment can be made to correct the deviation (in such a manner that the direction indicating faces  145   a,    151   a  are aligned with an extension line of the face of blade  113 ). In this manner, the cutting direction of the blade  113  can be exactly indicated. As a result, the circular saw  100  which is capable of high-precision cutting can be provided. 
     According to this embodiment, particularly, the cutting direction of the blade  113  can be indicated by utilizing an existing part or the cutting edge plate  151 , so that a rational mechanism of indicating the cutting direction of the blade  113  can be realized. 
     In view of the scope and spirit of this invention, the following features can be provided: 
     “The base has a protrusion which protrudes from the upper surface of the base and extends in a direction transverse to the cutting direction of the blade, and the blade cutting direction indicating member has a recess shaped to conform to the protrusion and is loosely fitted over the protrusion via the recess such that the blade cutting direction indicating member can move in parallel or in a rotational manner in a direction transverse to the cutting direction of the blade.” 
     “The blade cutting direction indicating member is fastened to the protrusion by a screw, and the protrusion has a circular fastening part having a screw hole.” 
     DESCRIPTION OF NUMERALS 
     
         
           100  circular saw (cutting machine) 
           101  circular saw body (tool body) 
           103  blade case 
           104  safety cover 
           105  motor housing 
           107  gear housing 
           109  handgrip 
           109   a  trigger switch 
           111  base 
           111   a  opening (cutting edge) 
           111   b  notch for cutting-line alignment 
           111   c  notch for cutting-line alignment 
           111   d  observation hole 
           111   e  recess 
           111   f  slot 
           113  blade (saw blade) 
           113   a  rotation spindle 
           115  chips discharge tube 
           117  observation hole 
           121  top guide (blade cutting direction indicating member) 
           123  notch for cutting-line alignment 
           123   a  front direction indicating face (second direction indicating part) 
           125  projection 
           125   a  rear direction indicating face (first direction indicating part) 
           127  set screw 
           129  recess 
           131  top guide mounting part 
           131   a  screw hole 
           133  notch for cutting-line alignment 
           133   a  direction indicating face for bevel cutting 
           141  front top guide 
           143  rear top guide 
           145  notch for cutting-line alignment 
           147  notch for cutting-line alignment 
           145   a  front direction indicating face 
           147   a  rear direction indicating face 
           149  set screw 
           151  cutting edge plate 
           151   a  direction indicating face 
           153  mounting plate 
           153   a  slot 
           155  connecting piece 
           156  screw 
           157  adjusting screw