Patent Publication Number: US-2006011037-A1

Title: Miter saw having laser oscillator

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a miter saw, and more particularly, to such a miter saw having an angularly rotatable turntable, and a circular saw unit laterally tiltable relative to the turntable.  
      Japanese Patent Application Publication No.2000-254817 discloses a miter saw including a base section, a support section, and a circular saw unit. The base section includes a base and a turntable mounted on the base and rotatable about its axis. A workpiece is mounted on the turntable. The support section upwardly extends from the turntable and laterally tiltable. The circular saw unit is positioned above the base section and is pivotally movably supported to the support section. The circular saw unit includes a circular saw blade and a motor for rotating the blade.  
      For angled cutting, the turntable is angularly rotated about its axis to change the angle of the side surface of the circular saw blade relative to a fence. For slant cutting, the support section is laterally tilted to change the angle of the side surface of the circular saw blade relative to the upper surface of the turntable.  
      According to up to date electronic technology, it may be conceivable that a digital display portion is provided in the miter saw so as to display an angular rotation angle of the turntable and a tilting angle of the circular saw blade. To this effect, the miter saw must include detection units for detecting a rotation angle of the turntable and a tilting angle of the support section.  
      As a rotation amount detection unit, an optical sensor unit is conceivable. For example, the optical sensor unit includes a light emitting element, a disc like element, and an optical sensor. The disc like detected element is rotatable in synchronism with the rotation of the turntable and is formed with a plurality of slits arrayed in a circumferential direction of the disc and spaced away from each other by a constant distance in the circumferential direction. The disc like element generate optical pulse each time the light passes through each slit and non slit region shuts off the light. The optical pulse is detected by the optical sensor. If slit distance is configured to generate a single pulse as a result of rotation of the turntable by 0.05 degrees, 900 pulses are theoretically generated if the turntable is angularly rotated from 0 degree to 45 degrees. Such arrangement would be also available for a tilting amount detection unit.  
      Renewal of the display of the rotation angle of the turntable at the rate of 0.05 degrees in the digital display appears to be too minute. Therefore, renewal of the display at a unit rate of 0.2 degrees appears to be comprehensive or intuitive for the user. For example successive angle display in the order of 34.8 , 35.0 , 35.2 . . . are conceivable.  
      Similarly, renewal of the display of the tiliting angle of the circular saw blade at the rate of 0.05 degrees in the digital display appears to be too minute. Therefore, renewal of the display at a unit rate of 0.5 degrees appears to be comprehensive or intuitive for the user. For example successive angle display in the order of 34.0 , 34.5 , 35.0 . . . are conceivable.  
      In this way, intended angular rotational position of the turntable or a lateral tilting position of the circular saw blade can be easily set with reference to the angles displayed at the digital display. As a result, cutting operation can be started promptly.  
      However, there is a case where the rotation angle of the turntable or the tilting angle of the circular saw blade is unknown to the user. For example, a cut-marking line is provisionally drawn on the surface of the workpiece so as to force the user to cut the workpiece along the marking line. Alternatively, a new workpiece must be cut along a contour the same as a cut contour of the-previous workpiece, and the latter cut contour is unknown to the user for cutting the new workpiece. In such a case, the rotation angle of the turntable and the tilting angle of the circular saw blade are unclear, and it would be difficult to cut the workpiece along the cut-marking line with the correct orientation and posture of the circular saw blade.  
     SUMMARY OF THE INVENTION  
      It is therefore an object of the present invention to provide a miter saw facilitating cutting operation along a cut-marking line.  
      This and other object of the present invention will be attained by a miter saw including a base, a turntable, a circular saw unit, a support section, an adjustment mechanism, and a laser oscillator. The base supports a workpiece thereon. The turntable is supported on the base and rotatable about a rotation axis relative to the base. The circular saw unit rotatably supports a circular saw blade. The support section is provided to the turntable and pivotally movably supports the circular saw unit at a position above the turntable. The adjustment mechanism is disposed between the base and the turntable and is configured to perform fine adjustment as to a rotation angle of the turntable relative to the base. The laser oscillator is configured to generate a visible laser line indicative of a cutting position of the circular saw blade on a surface of the workpiece.  
      In another aspect of the invention, there is provided a miter saw including a base section, the circular saw unit, a support section, a clamp mechanism, a tilt amount fine control unit, and a laser oscillator. The base section supports a workpiece thereon, and has a tilt support. The support section pivotally movably supports the circular saw unit at a position above the base section. The support section has a tilting section laterally tiltingly movable together with the circular saw unit. The tilt support supports the tilting section in contact therewith. The tilting section is tiltingly movable along a tilting locus. The clamp mechanism presses the tilting section against the tilt support for fixing a lateral tilting posture of the support section. A tilt amount fine control unit is disposed between the tilting section and the tilt support and configured to perform fine adjustment as to a tilting angle of the tilting section. The laser oscillator is configured to generate a visible laser line indicative of a cutting position of the circular saw blade on a surface of the workpiece.  
      In still another aspect of the invention, there is provided a miter saw including the base, the turntable, the circular saw unit, the support section, an adjustment mechanism, a lock receiving portion, a locking portion, and a laser oscillator. The adjustment mechanism is disposed between the base and the turntable and is configured to perform fine adjustment as to a rotation angle of the turntable relative to the base. The lock receiving portion is provided at one of the base and the turntable and defines a predetermined rotation angle of the turntable. The locking portion is engageable with the lock receiving portion and is provided at remaining one of the base and the turntable to fix the turntable at the predetermined rotation angle. The adjustment mechanism performs fine adjustment as to a rotation angle of the turntable relative to the base adjustment when the locking portion is out of engagement from the lock receiving portion. The laser oscillator is configured to generate a visible laser line indicative of a cutting position of the circular saw blade on a surface of the workpiece.  
      In still another aspect of the invention, there is provided a miter saw comprising a base section, a movable member, a circular saw unit, a moving angle detection unit, a digital display, and a laser oscillator. The base section is adapted for mounting a workpiece thereon. The movable member is supported to the base section and is movable relative to the base section. The circular saw unit is connected to the movable member for rotatably supporting a circular saw blade to cut the workpiece. The moving angle detection unit detects the moving angle of the movable member relative to the base section. The digital display displays the moving angle detected by the moving angle detection unit. The laser oscillator is configured to generate a visible laser line indicative of a cutting position of the circular saw blade on a surface of the workpiece. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings:  
       FIG. 1  is a perspective view of a miter saw as viewed from its front side according to a first embodiment of the present invention;  
       FIG. 2  is a perspective view of the miter saw as viewed from its rear side according to the first embodiment;  
       FIG. 3  is a front view of the miter saw according to the first embodiment;  
       FIG. 4  is a front view of the miter saw according to the first embodiment, and particularly showing a tilting state of a circular saw unit;  
       FIG. 5  is a bottom view of the miter saw according to the first embodiment;  
       FIG. 6  is a cross-sectional left side view of the miter saw according to the first embodiment;  
       FIG. 7  is an enlarged cross-sectional right side view showing an essential portion of the miter saw according to the first embodiment;  
       FIG. 8  is a bottom view of a turntable in the miter saw according to the first embodiment;  
       FIG. 9  is a cross-sectional right side view showing an adjustment mechanism for fine-adjusting the rotational position of the turntable in the miter saw according to the first embodiment;  
       FIG. 10  is a sight-through view as viewed from the bottom for showing the adjustment mechanism for fine-adjusting the rotational position of the turntable in the miter saw according to the first embodiment;  
       FIG. 11  is a view showing a lower face of the turntable in the miter saw according to the first embodiment;  
       FIG. 12  is a cross-sectional view showing a supporting arrangement for supporting rotation of the turntable at a base in the miter saw according to the first embodiment;  
       FIG. 13  is a plan view showing a rotation amount detection unit in the miter saw according to the first embodiment;  
       FIG. 14  is an enlarged cross-sectional view showing a pin and a screw for the rotation amount detection unit in the miter saw according to the first embodiment;  
       FIG. 15  is an exploded cross-sectional view showing the positional relationship between a tilt motion support and a tilt section in the miter saw according to the first embodiment;  
       FIG. 16  is a rear view showing the tilt section a rotation amount detection unit in the miter saw according to the first embodiment;  
       FIG. 17  is a view for description of the tilt section and an adjustment mechanism for finely adjusting the tilting angle of the tilt section in the miter saw according to the first embodiment;  
       FIG. 18  is a cross-sectional view taken along the line XVIII-XVIII of  FIG. 17 ;  
       FIG. 19  is a view showing a tilting amount detection unit in the miter saw according to the first embodiment;  
       FIG. 20  is a cross-sectional view taken along the line XX-XX of  FIG. 19 ;  
       FIG. 21  is a view showing the tilting amount detection unit in the miter saw according to the first embodiment;  
       FIG. 22  is a cross-sectional view taken along the line XXII-XXII of  FIG. 19 ;  
       FIG. 23  is a plan view of a digital display in the miter saw according to the first embodiment;  
       FIG. 24  is a control circuit in the miter saw according to the first embodiment;  
       FIG. 25  is a cross-sectional view taken along the line XXIV-XXIV of  FIG. 9 ;  
       FIG. 26  is a plan view showing the rotation amount adjusting mechanism for the turntable in the miter saw according to the first embodiment;  
       FIG. 27  is a plan view showing the rotation amount adjusting mechanism for the turntable, and particularly showing a temporary fixing position in the miter saw according to the first embodiment;  
       FIG. 28  is a plan view showing the rotation amount adjusting mechanism for the turntable, and particularly showing a fine-adjustment state in the miter saw according to the first embodiment;  
       FIG. 29  is a plan view showing the rotation amount adjusting mechanism for the turntable, and particularly showing a full fixing position in the miter saw according to the first embodiment;  
       FIG. 30  is a rear view showing the mechanism for finely adjusting tilting angle of the circular saw unit in the miter saw according to the first embodiment;  
       FIG. 31  is a flowchart showing a processing routine for displaying rotation angle of a turntable and a tilting angle of a circular saw blade in the miter saw according to the first embodiment;  
       FIG. 32  shows a first modification and is a plan view of a mechanism for fine-adjusting rotation angle of the turntable;  
       FIG. 33  shows a second modification and is a cross-sectional view of a mechanism for adjusting rotation angle of the turntable;  
       FIG. 34  is a bottom view of the second modification;  
       FIG. 35  is a frontal cross-sectional view of the second modification;  
       FIG. 36  shows a third modification and is a cross-sectional view of a mechanism for adjusting tilting angle of the circular saw unit;  
       FIG. 37  shows a fourth modification and is a rear view of a mechanism for adjusting tilting angle of the circular saw unit;  
       FIG. 38  is a rear view according to the fourth modification;  
       FIG. 39  shows a fifth modification and is a rear view of a mechanism for adjusting tilting angle of the circular saw unit;  
       FIG. 40  shows a six modification and is a rear view of a mechanism for adjusting tilting angle of the circular saw unit;  
       FIG. 41  shows a seventh modification and is a rear view of a tilting amount detection unit;  
       FIG. 42  is a cross-sectional view taken along the line XLI-XLI of  FIG. 41 ;  
       FIG. 43  shows an eighth modification and is a rear view of a tilting amount detection unit;  
       FIG. 44  shows a ninth modification and is a block diagram of a control circuit which is a modification to the control circuit of  FIG. 24 ;  
       FIG. 45  is a perspective view showing a slide type miter saw according to a second embodiment of the present invention;  
       FIG. 46  is a view showing a cut-marking like drawn at a surface of the workpiece, the surface being in confrontation with a fence in the second embodiment;  
       FIG. 47  is a block diagram showing two pulse trains generated in the rotation amount detection unit according to the first and second embodiments; and  
       FIG. 48  is a block diagram showing two pulse trains generated in the tilting amount detection unit according to the first and second embodiments. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      A miter saw according to a first embodiment of the present invention will be described with reference to  FIGS. 1 through 31 ,  47  and  48 . As shown in  FIG. 1 , the miter saw  1  includes a base section  2  installed on a stand or a floor for mounting thereon a workpiece such as a wood, a circular-saw unit  4  that cuts a workpiece, and a support section  3  supporting the circular saw unit  4  pivotally movably toward and away from the base section  2  and laterally tiltably relative to the base section.  
      As shown in  FIG. 1 , the base section  2  includes a base  11  serving as a ground section, a turntable  21  and a fence  12 . The turntable  21  is supported on the base  11  and is rotatable about its axis with respect to the base  11 . The turntable  21  cooperates with the base  11  to support a workpiece such as a wood block. The fence  12  laterally extends over the base  11  and is supported on the base  11 . The fence  12  has an abutment surface extending in the lateral direction and facing frontward in contact with a side surface of the workpiece for positioning the workpiece. In the following description, the facing side of the abutment surface is defined as the front side, the extending direction of the fence is defined as leftward/rightward or lateral direction, and a ground side of the base  11  is defined as a lower side.  
      As shown in  FIGS. 1 and 3 , the base  11  includes a right base  11 A and a left base  11 B interposing the turntable  21  therebetween. Each top surface of each base  11 A,  11 B serves as a workpiece mounting surface. As shown in  FIGS. 3 and 5 , the base  11  also includes an arcuate portion  16  disposed between the right base  11 A and the left base  11 B and protruding frontward. The arcuate portion  16  has a peripheral side whose center is coincident with a rotation axis of the turntable  21 . As shown in  FIG. 5 , the peripheral side has a lower end formed with a plurality of locking grooves  16   a  engageable with a protruding portion  26 B of a lock lever  26  described later.  
      The plurality of locking grooves  16   a  are positioned at a predetermined angles such as 15 degrees, 30 degrees and 45 degrees relative to a reference axis (0 degrees) extending frontward from the rotation axis of the turntable  21  in a direction perpendicular to the fence  12 . Further, as shown in  FIG. 5 , a linking portion  15  is provided for linking the right base  11 A to the left base  11 B at a position in direct confrontation with the installation spot such as a floor. The linking portion  15  has a center region provided with a rotation support  19  for rotatably supporting the turntable  21 . The rotation support  19  defines the rotation axis.  
      As shown in  FIGS. 1 and 3 , the fence  12  includes a right fence  12 A fixed to the right base  11 A and a left fence  12 B fixed to the left base  11 B. These fences  12 A,  12 B have abutment surfaces in abutment with the workpiece, and the abutment surfaces extend in a direction substantially perpendicular to the upper surfaces of the base  11  carrying the workpiece. As shown in  FIG. 3 , the left fence  12 B has a pivot shaft  12 D, and a separate pivotable fence  12 C is pivotally supported to the left fence  12 B through the pivot shaft  12 D. Thus, as shown in  FIG. 4 , a direct abutment of a circular saw blade  123  described later in the circular-saw unit  4  against the fence  12  can be avoided by pivotally moving the pivotable fence  12 C away from a locus of the blade  123 , even if the circular saw unit  4  is tilted laterally.  
      As shown in  FIGS. 5 and 6 , an arcuate outer gear teeth segment  20  is fixed with a screw  20 A to an upper surface of the linking portion  15  at a position rearward of the rotation support  19 . The arcuate outer gear teeth segment  20  is on an imaginary circle whose center is coincident with the central axis of the rotation support  19 . A rotation amount detection unit  51  ( FIG. 11  and described later) is displaceable relative to the arcuate outer gear teeth segment  20  for detecting an angular rotation amount of the turntable  21 .  
      As shown in  FIG. 1 , the turntable  21  includes a circular table section  22  interposed between the right and left bases  11 A and  11 B, and having an upper surface on which a workpiece is mounted. The circular table section  22  defines therein a rotation axis of the turntable  21 . The turntable  21  also includes a neck table section  23  extending frontward from the circular table section  22  and positioned above the arcuate portion  16 . The upper surfaces of the circular table section  22  and the neck table section  23  are flush with the upper surface of the base  11 . A semicircular recess  24  is formed at the turntable  21 . The semicircular recess  24  is open at the upper surfaces of the circular table section  22  and the neck table section  23  in a fusiform-shaped configuration, and has a semi-circular contour in the vertical direction in conformance with the contour of the circular saw blade  123 . The upper opening is covered with a fusiformed shaped slit plate  25  having a center portion formed with a slit  25   a  which allows the circular saw blade  123  to pass therethrough when the circular saw unit  4  is pivotally moved toward the turntable  21 .  
      A battery box  132  ( FIG. 6 ) is disposed in the semi-circular recess and at a left side of the slit  25   a.  the battery box  132  is adapted for supplying electric current to a microcomputer  142  described later.  
      As shown in  FIGS. 6 and 7 , a rotation shaft section  28  is disposed at a bottom of the semi-circular recess  24  and at a position in alignment with the center of the circular table section  22 . The rotation shaft section  28  is housed in a space defined by the rotation support  9  of the base  11 . The rotation shaft section  28  and the rotation support  9  are formed with through holes through which a bolt  32  extends so as to allow the turntable  21  to be rotatable relative to the base  11  without disassembly of the turntable  21  from the base  11 .  
      A protrusion  23 A ( FIG. 1 ) protrudes from a left side of the neck table section  23 . The protrusion  23 A is abuttable against the left base  11 B when the turntable  21  is angularly rotated. A corresponding protrusion also protrudes from a right side of the neck table section  23  so as to be abuttable against the right base  11 A. Thus, the turntable  21  is angularly rotatable relative to the base  11  within a range defined by the abutments.  
      An adjustment unit  41  ( FIG. 1 ) is provided at a front end of the neck table section  23  for adjusting angular rotational position of the turntable  21 . As shown in  FIGS. 7 and 8 , a pin fixing portion  30  and a screw fixing portion  31  protrude from a lower face of the turntable  21 . Further, the rotation amount detection unit  51  ( FIG. 8 ) in association with the outer gear teeth segment  20  of the base  11  is disposed below the pin fixing portion  30  and the screw fixing portion  31  for detecting the angular rotation amount of the turntable  21 .  
      As shown in  FIGS. 5 and 6 , a resilient lock lever  26  is fixed with screws  27  to the lower surface of the turntable  21  at a position below the arcuate portion  16  and in front of the rotation shaft section  28 . The lock lever  28  extends to a front end position of the adjustment unit  41  ( FIG. 8 ). The front end portion of the lock lever  26  is positioned below the adjustment unit  41 , and is folded upwardly along a front end surface of the adjustment unit  41 . A push-down portion  26 A is provided at the free front end of the lock lever  26 . The lock lever  26  is provided with an upward protrusion  26 B at a position in confrontation with a lower end face of the peripheral wall of the arcuate portion  16 . The upward protrusion is engageable with a selected one of the plurality of locking grooves  16   a  formed at the lower end face of the arcuate portion  16 . Accordingly, angular rotational position of the turntable  21  is fixed by the engagement of the upward protrusion  26 B with the selected one of the locking grooves  16   a,  since the lock lever  26  is angularly moved together with the angular movement of the turntable  21 .  
      The push-down portion  26 A is positioned at the front side of the miter saw  1 . Normally, the user is positioned in front of the miter saw  1 . Therefore, access to the push-down portion  26 A is easily made for the user.  
      As shown in  FIGS. 9 and 10 , the adjustment unit  41  includes a front frame  42  with which a lock lever fixing pin  49  is laterally slidably supported for avoiding engagement of the upward protrusion  26 B with the one of the locking grooves  16   a.  As shown in  FIG. 5 , the lock lever fixing pin  49  has a tip end portion formed with an annular fixing groove  49   a.  Further, a spring  50  is disposed over the lock lever fixing pin  49  for urging the pin  49  rightward. A tongue  26 C extends upwardly from a left side of the lock lever  26 . The fee end of the tongue  26 C is positioned in superposed relation to the slide locus of the lock lever fixing pin  49 . Normally, the lock lever fixing pin  49  is biased rightward by the biasing force of the spring  50 . In this case, the tongue  26 C is out of engagement from the annular fixing groove  49   a,  so that the upward protrusion  26 B is engageable with one of the locking grooves  16   a.  On the other hand, if the push-down portion  26 A of the lock lever  26  is pushed down and the lock lever fixing pin  49  is pushed leftward in  FIG. 25 , the tongue  26  can be engaged with the annular fixing groove  49   a  when the push-down portion  26 A is released. As a result, the engagement of the upward protrusion  26 B with the one of the locking grooves  16   a  is prevented to allow the turntable  21  to be freely angularly rotated to a desired angle.  
      As shown in  FIGS. 8 through 10 , the adjustment unit  41  further includes a fixing handle  43 , an adjusting screw  44  and a table contact piece  45  in addition to the lock lever fixing pin  49 . The front frame  42  of the turntable  21  has a front wall  47  ( FIG. 9 ) and a rear wall  48  ( FIG. 9 ) and is formed with a front opening  42   a,  and lateral holes. The fixing handle  43  has a shaft portion  43 A extending through the front opening  42   a  in frontward/rearward direction, and has an inner distal end pressure contactable with the outer peripheral surface of the arcuate portion  16  of the base  11 . The adjusting screw  44  extends through the lateral holes in a direction perpendicular to the shaft portion  43 A. The adjusting screw  44  includes a shaft portion  44 A and a pair of knobs  44 B at both ends of the shaft portion  44 A. The shaft portion  43 A is formed with a male thread at a region crossing with the adjusting screw  44 . The adjusting screw  44  is also formed with a male thread at a region crossing with the shaft portion  43 A.  
      The table contact piece  45  is movable between the front wall  45  and the rear wall  48  and is selectively contactable with the front wall  45  in accordance with the frontward movement of the table contact piece  45  or with the rear wall  48  in accordance with a rearward movement thereof. The table contact piece  45  is formed with a first female thread  45   a  threadingly engageable with the male thread of the shaft portion  43 A, and a second female thread  45   b  threadingly engageable with the male thread of the adjusting screw  44 . The first and second female thread  45   a  and  45   b  extend perpendicular to each other, and are not intersected with each other but are offset from each other in the vertical direction. Thus, the fixing handle  43  and the adjusting screw  44  are directed perpendicular to each other by way of the table contact piece  45 . The fixing handle  43  and the table contact piece  45  constitute engagement components.  
      As shown in  FIGS. 9 and 10 , springs  46  are juxtaposed laterally and are interposed between the table contact piece  45  and the front wall  47  for permitting the piece  45  to abut on the rear wall  48 . By threadingly advancing the fixing handle  43 , the shaft portion  43 A is moved rearward relative to the piece  45 . However, after the distal inner end of the shaft portion  43 A abuts on the outer peripheral surface of the arcuate portion  16 , the fixing handle  43  cannot any more be moved rearward. Instead, the piece  45  is then moved frontward because of the threading engagement with the shaft portion  43 A.  
      Each end of the adjusting screw  44  is provided with the knob  44 B interposing the front frame  42  therebetween. Therefore, the adjusting screw  44  is not movable laterally, i.e., in its axial direction relative to the front frame  42 . By the rotation of the adjusting screw  44  about its axis, relative movement between the piece  45  and the shaft portion  44 A occurs. In this case, since the shaft portion  44 A is immovable in its axial direction, the piece  45  is moved laterally within the front frame  42 . The angular rotational position of the turntable  21  is fixed at a predetermined position by the engagement of the upward protrusion  26 B with one of the locking grooves  16   a.  However, the engagement between the upward protrusion  26 B and the locking groove  16   a  is prevented at positions nearby the particular locking grooves which define angular rotation angle such as 0 degree, and 15 degrees in order to perform fine angular position control of the turntable  21  nearby these angles.  
      When the tip end of the shaft portion  43 A is brought into tight contact with the outer peripheral surface of the arcuate portion  16   a  of the base  11 , the fixing handle  43  is considered to be integral with the base  11 . Therefore, the lateral movement of the table contact piece  45  relative to the front frame  42  implies the lateral movement of the front frame  42  relative to the base  11 , i.e., a minute lateral angular movement of the turntable  21  relative to the base  11 .  
      As shown in  FIGS. 12 and 13 , the rotation amount detection unit  51  includes a sealed housing  52  supported to the turntable  21 . In the housing  52 , an amplifier including a first gear set  56  and a second gear set  58 , a detected segment  60  and an optical sensor  62  are assembled. Shafts  57 ,  59  and  61  are disposed in and rotatably supported to the housing  52 . The first gear set  56  includes a first gear  56 A and a second gear  56 B. The first gear  56 A protrudes outwardly from the housing  52  and is meshedly engaged with the outer gear teeth segment  20 . The second gear  56 B is coaxially with and integral with the first gear  56 A and is meshedly engaged with the second gear set  58 . A diameter of the second gear  56 B is greater than that of the first gear  56 A. The first and second gears  56 A and  56 B are rotatable about the shaft  57 , and the second gear  56 B and a major part of the first gear  56 A are disposed in the housing  52 .  
      The second gear set  58  includes a third gear  58 A and a fourth gear  58 B. The third gear  58 A is meshedly engaged with the second gear  56 B. The fourth gear  58 B is coaxially with and integral with the third gear  58 A and is meshedly engaged with the detected segment  60 . A diameter of the fourth gear  58 B is greater than that of the third gear  58 A. The third and fourth gears  58 A and  58 B are rotatable about the shaft  59  and are disposed in the housing  52 .  
      The detected segment  60  includes a fifth gear  60 A meshedly engaged with the fourth gear  58 B, and a disc like detected element  60 B coaxially with and integral with the fifth gear  60 A. The detected segment  60  is rotatable about the shaft  61  and is disposed in the housing  52 . The disc like detected element  60 B is formed with a hundred of radial slits  60 C. The optical sensor  62  has a pair of arms for supporting the disc like detected element  60 B therebetween. Slits  60 C is detected at the arms for detecting rotation angle of the disc like detected element  60 B.  
      The optical sensor  62  includes two light emitting elements (not shown) and two light receiving elements (not shown) each positioned in confronting relation to each light emitting element. The disc like detected element  60 B is positioned between the light emitting elements and the light receiving elements. In accordance with the rotation of the disc like detected element  60 B, lights emitted from the two light emitting elements pass through the respective slits  60 C and reach the light receiving elements, and are shut off by a solid region of the disc like detected element  60 B alternately, the solid region being positioned between the neighboring slits  60 C and  60 C to generate optical pulses.  
      One of the pair of light emitting and receiving elements are angularly displaced from the remaining pair of light emitting and receiving elements in the circumferential direction of the disc like detected element  60 B. The microcomputer  142  receives two pulse trains A and B displaced from each other by 90 degrees as shown in  FIG. 47  corresponding to the angular displacement.  
      Since the two pulse trains A and B displaced from each other by 90 degrees are detected, rotating direction of the disc like detected element  60 B can be detected. In other words, the direction of the angular rotation of the turntable  21  can be detected, the direction being one of the clockwise direction and counterclockwise direction.  
      More specifically, regarding pulse trains A and B in  FIG. 47 , high level and low level are designated by “1” and “0”, respectively. Assuming that the present pulse in the pulse train A is “0”, and the present pulse in the pulse train B is ”0”. Then, if the pulse in the pulse train A is “1”, whereas the pulse in the pulse train B is “0”, the angular rotating direction of the turntable  21  is assumed to be clockwise direction, i.e., rightward in  FIG. 47 . On the other hand, assuming that the present pulse in the pulse train A is “0”, and the present pulse in the pulse train B is “0”, and if the pulse in the pulse train A is “0”, whereas the pulse in the pulse train B is “1”, the angular rotating direction of the turntable  21  is assumed to be counterclockwise direction, i.e., leftward in  FIG. 47 . Incidentally, the gear ratio of the rotation amount detection unit  51  is set so as to provide rotation of the detected segment  60  by 72 degrees per every rotation of the turntable  21  by 1 degree.  
      As shown in  FIG. 13 , in the rotation amount detection unit  51 , a pin extension hole  53  and a screw fixing region  54  are formed at the housing  52  in the vicinity of the first gear set  56 . A pin  63  extends through the pin extension hole  53 . The screw fixing region  54  has a C-shape configuration having an open end part. As shown in  FIG. 14 , when a screw  64  is attached to the screw fixing portion  31 , the screw fixing region  54  can be separated from the screw  64  as long as the screw  64  is unfastened. The Open end part of the screw fixing region  54  allows the rotation amount detection unit  51  to be pivotally moved while the unfastened screw  64  extends into the screw fixing portion  31 . Thus, the rotation amount detection unit  51  is pivotable with respect to the turntable  21  about a pin  63 . Further, the pivot position of the rotation amount detection unit  51  can be fixed relative to the turntable  21  at a desired angle by fastening the screw  64 . Incidentally, a spring  64 A is interposed between the screw  64  and the screw fixing portion  31  so that the spring  64 A functions as a spring washer. Thus, reaction force is always imparted on the screw  64  in its axial direction, which prevents the screw  64  from being freely rotated about is axis. Consequently, accidental release of the screw  64  from the screw fixing portion  31  due to vibration can be prevented even if the screw  64  is unfastened.  
      As shown in  FIG. 11 , the housing  52  has an abutment region  52 A, and the turntable  21  has an abutment plate  21 A protruding downward from the lower face of the turntable  21  and in confrontation with the abutment region  52 A. A spring  55  is interposed between the abutment plate  21 A and the abutment region  52 A when the rotation amount detection unit  51  is attached to the turntable  21 . By the biasing force of the spring  55 , the first gear  56 A of the first gear set  56  is pressed against the outer gear teeth segment  20 . Accordingly, rattling of the first gear  56 A relative to the outer gear teeth segment  20  can be restrained, and consequently, angular rotation of the turntable  21  relative to the base  11  can be accurately detected.  
      As shown in  FIGS. 6 and 7 , the turntable  21  has a rear end provided with a tilting motion support  71 . The support section  3  includes a tilt section  74  tiltable relative to the tilting motion support  71 .  
      As shown in  FIG. 6 , the tilting motion support  71  extends upward from the rearmost end of the turntable  21 . As shown in  FIG. 15 , The tilting motion support  71  is formed with a support bore  72  positioned flush with the upper surface of the turntable  21  and coaxially with the widthwise centerline of the slit  25   a  ( FIG. 1 ). The tilt section  74  has a pin bolt  76  inserted into the support bore  72 , so that the tilt section  74  is linked to the tilting motion support  71 . The tilting motion support  71  has a wall in contact with the tilt section  74 , and the wall is formed with a circular recess  71   a.  An arcuate inner gear teeth  77  is fixed to the circular recess  71   a  by a screw (not shown). The arcuate inner gear teeth  77  is on an imaginary circle whose center is coincident with a center axis of the support bore  72 .  
      As shown in  FIG. 18 , a slide wall  78  is provided at the tilt section  74  and at a position in sliding contact with the tilting motion support  71 . A pivot hole  75  is formed at an approximately center of the slide wall  78 , and the pin bolt  77  extends through the pivot hole  75 . Thus, the slide wall  78  is in sliding contact with a contour edge of the circular recess  71   a  at the rear side of the tilting motion support  71  when the tilt section  74  is pivotally moved relative to the tilting motion support  71 . A rear wall  74 A extends rearward from an edge of the slide wall  78 . That is, the rear wall  74 A extends substantially in parallel with the pin volt  76 , and in a direction from the tilting motion support  71  to the tilt section  74 .  
      As shown in  FIG. 16 , an arcuate elongated slot  79  whose contour is defined by an arcuate rib  80  is formed in the tilt section  74  and at a position rightward of the pivot hole  75  of the tilt section  74 . The elongated slot  79  is open at the surface of the slide wall  78 , and is located on an imaginary circle whose center is coincident with the center axis of the pivot hole  75 . The tilting motion support  71  is formed with a clamp hole  73  threadingly engageable with a clamp shaft  81  (described later). The clamp hole  73  is positioned in confronting relation to the elongated slot  79 .  
      A tilting amount detection unit  101  is disposed leftward of the pivot hole  75  and at a position surrounded by the slide wall  78  and the rear wall  74 A. The tilting amount detection unit  101  is adapted for detecting a tilting amount of the tilt section  74  relative to the tilting motion support  71  in association with the arcuate inner gear teeth  77  provided therein.  
      A pair of tilt support arms  84  extend upward from the tilt section  74  at a position above the pivot hole  75  for supporting the circular saw unit  4 . A tilt support pin  85  ( FIG. 15 ) extends between the pair of tilt support arms  84 , 84  for connecting the circular saw unit  4  to the support section  3 . A cover  87  ( FIG. 2 ) is provided at the end of the rear wall  74 A for protecting the elongated slot rib  80 , the tilting amount detection unit  101 , and the pin bolt  76 . Therefore, these components  80 ,  101  and  76  are not exposed to the atmosphere. An arm support  86  ( FIG. 1 ) is provided at the left tilt support arm  84  for supporting an arm  127  (described later,  FIG. 1 ).  
      As shown in  FIG. 18 , the clamp shaft  81  has a tip end formed with a male thread for threadingly engaging with the clamp hole  73 . Thus, a: tiltable range of the tilt section  74  relative to the tilting motion support  71  is defined by a movable range of the clamp shaft  81  within the elongated slot  79 . In the depicted embodiment, the tiltable range is 45 degrees.  
      As shown in  FIG. 18 , the arcuate rib  80  defining the elongated slot  79  extends rearward from the rear surface of the tilt section  74 . A clamp lever  82  is provided at a rear end of the clamp shaft  81 . A spacer  83  assembling therein a spring  83 A is interposed between the clamp lever  82  and the rear end face of the arcuate rib  80 . Since the clamp shaft  81  is threadingly engaged with the clamp hole  73  of the tilting motion support  71 , the clamp lever  82  and the spacer  83  are moved toward the tilting motion support  71  upon fastening the clamp shaft  81  in response to the pivotal motion of the clamp lever  82  about an axis of the clamp shaft  81 . Since the arcuate rib  80  which is a part of the tilt section  74  exists between the spacer  83  and the tilting motion support  71 , the arcuate rib  80  is nippingly interposed between the spacer  83  and the tilting motion support  71 . Accordingly, a frictional force is generated between the slide wall  78  and the tilting motion support  71  so that the tilt section  74  is fixed to the tilt motion support  71  at a desired tilting posture. Thus, a clamp unit is constituted by the clamp shaft  81 , the clamp lever  82 , the spacer  83  and the spring  83 A. Because of the provision of the spring  83 A within the spacer  83 , the clamp lever  82  is urged rearward relative to the tilting motion support  71  and the arcuate rib  80 . Consequently, accidental pivotal motion of the clamp lever  82  can be restrained to reduce rattling.  
      As shown in  FIGS. 17 and 18 , a tilt amount fine control unit  91  is disposed nearby the clamp shaft  81  for finely controlling tilting amount of the tilt section  74  relative to the tilt motion support  71 . The tilt amount fine control unit  91  includes an arcuate gear teeth  92  fixed to the tilt section  74 , a rotation shaft  93  meshedly engaged with the arcuate gear teeth  92 , and an adjustment knob  94  meshedly engaged with the rotation shaft  93 . The arcuate gear teeth  92  is located on an imaginary circle whose center is coincident with the center axis of the pivot hole  75 . Further, the arcuate gear teeth  92  is fixed at a position along a radially outer edge of the elongated slot  79  ( FIG. 17 ). The rotation shaft  93  is rotatably supported to the tilting motion support  71  and extends rearward in a direction approximately parallel with the clamp shaft  81 . The rotation shaft  93  includes a first gear  93 A meshedly engaged with the arcuate gear teeth  92 . The rotation shaft  93  also includes a second gear  93 B having a diameter greater than that of the first gear  93 A and provided at a rear end of the rotation shaft  93 . The adjustment knob  94  is coaxially with and rotatably disposed over the clamp shaft  81 . The coaxial arrangement of the adjustment knob  94  with the clamp shaft  81  can save a space, thereby improving implementation or packaging of the tilt amount fine control unit  91 .  
      Since the arcuate gear teeth  92  and the rotation shaft  93  are drivingly connected to each other, and since the rotation shaft  93  is connected to the adjustment knob  94 , the adjustment knob  94  is connected to the circular saw unit  4  through the rotation shaft  93 .  
      A third gear  94 A meshedly engaged with the second gear  93 B is provided integrally and coaxially with the adjustment knob  94  at a position in front of the adjustment knob  94 . Incidentally, since the arcuate gear teeth  92  is drivingly connected to the adjustment knob  94 , the adjustment knob  94  continues rotating as long as the tilt section  74  is tiltingly moved for tilting the circular saw unit  4 .  
      Further, since the gear ratio between the third gear  94 A and the second gear  93 B and between the first gear  93 A and the arcuate gear teeth  92  is desirably set, a small tilting angle of the circular saw unit  4  results even if the adjustment knob  94  is rotated at a large rotation angle. This facilitates the fine tilting angle control.  
      As shown in  FIGS. 19 and 20 , the tilting amount detection unit  101  includes a sealed housing  102 , an amplifier containing a first gear set  106  and a second gear set  108 , a detected segment  110  and an optical sensor  112 , those assembled in he housing  102 . Shafts  107 ,  109  and  111  are disposed in and rotatably supported to the housing  102 . The first gear set  106 , is supported to the shaft  107  and includes a first gear  106 A and a second gear  106 B. The first gear  106 A protrudes outwardly from the housing  102 , and the protruding part extends through a bore (not shown) formed in the tilt section  74 , and is meshedly engaged with the arcuate inner gear teeth  77 . The second gear  106 B is coaxially with and integral with the first gear  106 A and is meshedly engaged with the second gear set  108 . A diameter of the second gear  106 B is greater than that of the first gear  106 A. The first and second gears  106 A and  106 B are rotatable about an axis of the shaft  107 , and the second gear  106 B and a major part of the first gear  106 A are disposed in the housing  102 .  
      The second gear set  108  includes a third gear  108 A and a fourth gear  108 B. The third gear  108 A is meshedly engaged with the second gear  106 B. The fourth gear  108 B is coaxially with and integral with the third gear  108 A and is meshedly engaged with the detected segment  110 . A diameter of the fourth gear  108 B is greater than that of the third gear  108 A. The third and fourth gears  108 A and  108 B are rotatable about an axis of the shaft  109  and are disposed in the housing  102 .  
      The detected segment  110  includes a fifth gear  111 A meshedly engaged with the fourth gear  108 B, and a disc like detected element  110 B coaxially with and integral with the fifth gear  110 A. The detected segment  110  is rotatable about an axis of the shaft  111  and is disposed in the housing  102 . The disc like detected element  110 B is formed with a hundred of radial slits  110 C. The optical sensor  112  has a pair of arms for supporting the disc like detected element  110 B therebetween. Slits  110 C is detected at the arms for detecting rotation angle of the disc like detected element  110 B.  
      The optical sensor  112  includes two light emitting elements (not shown) and two light receiving elements (not shown) each positioned in confronting relation to each light emitting element. The disc like detected element  110 B is positioned between the light emitting elements and the light receiving elements. In accordance with the rotation of the disc like detected element  110 B, lights emitted from the two light emitting elements pass through the respective slits  110 C and reach the light receiving elements, and are shut off by a solid region of the disc like detected element  110 B alternately, the solid region being positioned between the neighboring slits  110 C and  110 C to generate optical pulses.  
      One of the pair of light emitting and receiving elements are angularly displaced from the remaining pair of light emitting and receiving elements in the circumferential direction of the disc like detected element  110 B. The microcomputer  142  receives two pulse trains A and B displaced from each other by 90 degrees as shown in  FIG. 48  corresponding to the angular displacement.  
      Since the two pulse trains A and B displaced from each other by 90 degrees are detected, rotating direction of the disc like detected element  110 B can be detected. In other words, the tilting direction of the circular saw unit  4  can be detected, the direction being one of the clockwise direction and counterclockwise direction.  
      More specifically, regarding pulse trains A and B in  FIG. 48 , high level and low level are designated by “1” and “0”, respectively. Assuming that the present pulse in the pulse train A is “0”, and the present pulse in the pulse train B is “0”. Then, if the pulse in the pulse train A is “1”, whereas the pulse in the pulse train B is “0”, the tilting direction of the tilt section  74  is assumed to be clockwise direction, i.e., leftward in  FIG. 48 . On the other hand, assuming that the present pulse in the pulse train A is “0”, and the present pulse in the pulse train B is “0”, and then if the pulse in the pulse train A is “0”, whereas the pulse in the pulse train B is “1”, the tilting direction of the circular saw unit  4  is assumed to be counterclockwise direction, i.e., rightward in  FIG. 48 . Incidentally, the gear ratio of the tilting amount detection unit  101  is set so as to provide rotation of the detected segment  110 B by 72 degrees per every tilting angle of the tilt section  74  by 1 degree.  
      As shown in  FIG. 19 , in the tilting amount detection unit  101 , a pin extension hole  103  and a screw fixing region  104  are formed at the housing  102  in the vicinity of the first gear set  106 . A pin  113  extends through the pin extension hole  103 . The screw fixing region  104  has a C-shape configuration having an open end part. As shown in  FIG. 22 , when a screw  114  is attached to the screw fixing portion  104 , the screw fixing region  104  can be separated from the screw  114  as long as the screw  114  is unfastened. The open end part of the screw fixing region  104  allows the tilting amount detection unit  101  to be pivotally moved while the unfastened screw  114  extends into the screw fixing portion  104 . Thus, the tilting amount detection unit  101  is pivotable with respect to the tilt section  74  about a pin  113  within a range defined by the size of the screw fixing region  104 . Further, the pivot position of the tilting amount detection unit  101  can be fixed relative to the tilt section  74  at a desired angle by fastening the screw  114 . Incidentally, a spring  114 A is interposed between the screw  114  and the tilt section  74  so that the spring  114 A functions as a spring washer. Thus, reaction force is always imparted on the screw  114  in its axial direction, which prevents the screw  114  from being freely rotated about is axis. Consequently, accidental release of the screw  114  from the tilt section  74  due to vibration can be prevented even if the screw  114  is unfastened.  
      As shown in  FIG. 19 , the housing  102  has an abutment region  102 A. A spring  105  is interposed between the abutment region  102 A and an annular rib defining the pivot hole  75  when the pivot amount detection unit  101  is attached to the tilt section  74 . By the biasing force of the spring  105 , the first gear  106 A of the first gear set  106  is pressed against the arcuate inner gear teeth  77 . Accordingly, rattling of the first gear  106 A relative to the arcuate inner gear teeth  77  can be restrained, and consequently, tilting amount (pivot amount) of the tilt section  74  relative to the tilting motion support  71  can be accurately detected.  
      Attachment of the tilting amount detection unit  101  to the tilt section  74  may be difficult to achieve if the first gear  106 A is biased to a position to be engageable with the arcuate inner gear teeth  77 . For facilitating the attachment work, the tilting amount detection unit  101  is provisionally fixed, with the screw  114 , to the tilt section  74  with a specific pivot posture where the spring  105  is compressed as shown in  FIG. 21 . This posture provides a sufficient space between the first gear  106 A and the arcuate inner gear teeth  77 . Then, the screw  114  is unfastened, so that the tilting amount detection unit  101  is pivotally moved toward the arcuate inner gear teeth  77  by the biasing force of the spring  105 . Thus, the first gear  106 A is brought into meshing engagement with the arcuate inner gear teeth  77 .  
      The circular-saw unit  4  includes a frame  121 , a motor housing  122 , a handle  128 , the circular saw blade  123 , a saw cover  125  and a safety cover  126 . The frame  121  is connected to the tilt support arm  84  through the tilt support pin  85 . A spring (not shown) is interposed between the frame  121  and the tilt support arm  84  for biasing the frame  121  upwardly. Thus, he circular saw unit  4  is at its upper-most position as a rest position in case of a non-cutting operation.  
      The motor housing  122  is disposed at the front side of the frame  121  for accommodating a motor (not shown). The handle  128  is disposed at an outer peripheral surface and front side of the motor housing  122 . A user grips the handle  128  to move the circular saw unit  4  downward for cutting operation. The motor housing  122  rotatably supports a rotation shaft  124  to which the circular saw blade  123  is concentrically fixed. The saw cover  125  is adapted to cover an upper half of the circular saw blade  123 . The safety cover  126  is pivotally movably supported to the saw cover  125  and is protrudable from and retractable into the saw cover  125  for selectively covering a lower half of the circular saw blade  123 . The arm  127  serves as a pivot moving mechanism for the safety cover  126 , and has one end attached to the safety cover  126 . The arm  127  has another end attached to the arm support  86 . A carry handle  129  ( FIG. 2 ) is provided at an approximately center portion of the frame  121  for hand-carrying the miter saw  1 .  
      As shown in  FIG. 1 , a digital display such as a liquid crystal display  131  is provided immediately above the adjustment unit  41 . As shown in  FIG. 23 , the digital display  131  displays the angular rotation angle of the turntable  21  at a rate of 0.2 degrees, and displays the tilting angle of the circular saw unit  4  at a rate of 0.5 degrees. Therefore, even minute angular rotation angle and the tilting angle can be accurately and easily recognized by the user. Further, the digital display  131  is provided at the front side of the miter saw  1 . Generally, the user is positioned in front of the miter saw for cutting operation. Therefore, the user can easily recognize the displayed angle.  
      The digital display  131  displays the angles based on output signals transmitted from the microcomputer  142 . The microcomputer  142  includes a computing means that performs computation based on the detection made by the units  51  and  101 .  FIG. 24  shows a control circuit  140 . To the microcomputer  142 , are connected a EEPROM  143 , a Miter encoder  144 , a bevel encoder  145 , AC/DC converter  146 , a regulator  147 , a battery box  132  and the digital display  131 .  
      The EEPROM  143  is adapted for electrically rewriting a content. The Miter encoder  144  is adapted for converting a signal from the optical sensor  62  of the rotation amount detecting unit  51  into a signal available for the microcomputer  142 . The Bevel encoder  145  is adapted for converting a signal from the optical sensor  112  of the tilting amount detecting unit  101  into a signal available for the microcomputer  142 . The AC/DC converter  146  is adapted for converting alternate current from a main power source into direct current. The regulator  147  is adapted for regulating or stabilizing an electric power. The battery box  132  and the AC/DC converter  146  are also connected to the Miter encoder  144 , the Bevel encoder  145 , and the digital display  131  for supplying electric power thereto. An electric power supply is controlled such that if a main power source through the AC/DC converter  146  is rendered OFF, an electric power from the battery box  132  is supplied to these components  144 , 145  and  131 . On the other hand, if the main power source is rendered ON, an electric power from the main power source is supplied to these components  144 , 145 ,  131 . Incidentally, the electric power from the battery box  132  is not supplied to the motive component such as the motor (not shown), but is only supplied to the microcomputer  142 , the Miter encoder  144 , the Bevel encoder  145  for the purpose of a control and measurement.  
      A Miter reset switch  148  for resetting the angular rotation of the turntable  21 , a Bevel reset switch  149  for resetting the tilting angle of the tilt section  74 , and a backlight switch  150  for lighting a backlight of the digital display  131  are also connected to the microcomputer  142 . The digital display  131  is adapted for displaying a result of computation executed in the microcomputer  142  based on the outputs from the optical sensors  62 ,  112 .  
      Cutting operation with the miter saw  1  will next be described. First, the workpiece is mounted on the upper surface of the base  11  while the workpiece is pushed onto the abutment surface of the fence  12 . Then, the circular saw unit  4  is moved downward by pulling the handle  128  for cutting. For the cutting, the angled cutting is intended in which a cutting face is angled with respect to the abutment surface of the fence  12 , or a slant cutting is intended in which a cutting face is slanted with respect to the upper surface of the base  11 . For these cuttings, the following procedures are taken.  
      If the workpiece is to be cut with a cutting face angled with respect to the abutment surface of the fence  12 , the turntable  21  is angularly rotated. Since the circular saw unit  4  is positioned above the turntable  21 , the circular saw unit  4  is moved together with the turntable  21 . Since the fence  12  is fixed to the base  11 , the side surface of the circular saw blade  123  is angled relative to the workpiece as viewed from the above point of the workpiece. This cutting mode will be referred to as “angled cutting mode”.  
      In the angled cutting mode, a cutting angle can be determined by the engagement of the upward protrusion  26 B with one of the locking grooves  16   a.  For the engagement, the turntable  21  is angularly rotated while the lock lever  26  is not pressed down. Then, the upward protrusion  26 B is brought into engagement with the desired one of the locking grooves  16   a  at the desired angle. With this state, the fixing handle  43  is fastened until the fixing handle  43  cannot be rotated any more, whereupon the tip end of the fixing handle  43  is pressed against the arcuate portion  16  of the base  11 . Thus, the turntable  21  is fixed to the base  11 . In this state, the angular rotation angle of the turntable  21  relative to the base  11  is precisely determined by the engagement between the locking groove  16   a  and the upward protrusion  26 B. Therefore, fine adjustment to the angular rotation of the turntable  21  is not required.  
      For setting the cutting angle at a desired angle offset from the predetermined angles defined by the locking grooves  16   a,  the push-down portion  26 A of the lock lever  26  is pushed down. Further, as shown in  FIG. 25 , the lock lever fixing pin  49  is pushed into a space within the frame  42 , so that the tongue  26 C is engaged with the annular fixing groove  49   a.  With this engagement, the engagement of the upward protrusion  26 B with one of the locking grooves  16   a  is prevented even if the upward protrusion  26 B is vertically in alignment with the locking groove  16   a.  Thus, the angular rotation angle of the turntable  21  can be set at a desired angle. After the tongue  26 C is engaged with the annular fixing groove  49   a,  the turntable  21  is angularly rotated to a position near the desired angle. In the miter saw  1  according to the first embodiment, the angular rotation angle can be displayed at every 0.2 degrees. Therefore, a desired angular rotating position of the turntable  21  cannot be easily provided by gripping the fixing handle  43  and moving the fixing handle  43 . Therefore in the present embodiment, after the turntable  21  is angularly rotated to a position near the desired angle, then, a fine adjustment is performed to accurately provide the desired angle.  
      More specifically, as shown in  FIG. 26 , the adjustment unit  41  provided at the turntable  21  is positioned near the desired angle relative to the arcuate portion  16  provided at the base  11 . In this state, the tip end of the fixing handle  43  is separated from the outer peripheral surface of the arcuate portion  16 , and further, the table contact piece  45  is in abutment with the rear wall  48  by the biasing force of the spring  46 . This position of the table contact piece  45  is referred to as a release position.  
      Then in  FIG. 27 , the fixing handle  43  is rotated about its axis so as to press the tip end of the fixing handle  43  against the arcuate portion  16 . Thus, the table contact piece  45  is moved away from the rear wall  48  to an adjustment position or a temporary fixing position because of the threading engagement of the male thread at the fixing handle  43  with the female thread in the piece  45 . In this case, the fixing handle  43  functions as a base abutment member as well as a fixing mechanism. Further, the table contact piece  45  is spaced away from the front wall  47 , and the fixing handle  43  in threading engagement with the table contact piece  45  is pressed against the arcuate portion  16  because of the reaction force of the spring  46 . In this condition, the relative position among the fixing handle  43 , the table contact piece  45 , and the arcuate portion  16  is fixed. However, the table contact piece  45  is not directly fixed to the frame  42 , but is merely supported within the frame  42  by means of the spring  46 . Therefore, as shown in  FIG. 28 , relative position between the frame  42  and the table contact piece  45  can be changed by rotating the adjustment screw  44  about its axis. In other words, the position of the frame  42  in the angular rotating direction of the turntable  21  relative to the fixing handle  43  and the table contact piece  45  can be finely adjusted, the fixing handle  43  having been immovable in the angular rotating direction because of the intimate contact of the tip end of the fixing handle  43  with the arcuate portion  16 . The fine adjustment can be performed within a length of the front opening  42   a  in the angular rotating direction as shown in  FIG. 28  through which the shaft portion  43 A of the fixing handle  43  extends. In the depicted embodiment, plus minus 2 degrees are set in terms of the angular rotation amount of the turntable  21  for the fine adjustment.  
      In case of the fine adjustment, since the movement of the table contact piece  45  in the tangential direction is provided by the threading engagement between the second female thread  45   b  and the adjusting screw  44 . Therefore, only a small moving amount results in spite of the rotation amount of the knob  44 B. This facilitates the fine adjustment.  
      In this way, rotational position of the turntable  21  relative to the base  11  is roughly set, and then, the rotational position is temporarily fixed by the adjusting screw  43 . Thereafter, fine adjustment is performed by the knob  44 B. Consequently, intended rotational position of the turntable  21  can be promptly and accurately obtained.  
      Upon angular rotation of the turntable  21 , the rotation amount detection unit  51  is moved relative to the outer gear teeth segment  20 . This moving amount is converted into the rotation amount of the first gear set  56  including the first gear  56 A. The rotation angle of the first gear set  56  is amplified at the second gear set  58  and the detected segment  60 , such that the angular rotation of 1 degree of the turntable  21  will cause angular rotation of 72 degrees of the detected segment  60 . Since the disc like detected element  60 B is formed with  100  slits arrayed in a circumferential direction, 20 slits stand for 72 degrees. Further, the detected element  20 B enables detection of a minimum angular rotation of 0.05 degrees for the turntable  21 .  
      Furthermore, the miter saw  1  generates cutting chips during cutting operation. However, the components of the detection unit  51  including the first gear set  56  and the optical sensor  62  are housed in the sealed housing  52 , entry of the cutting chips into the housing  52  can be prevented. Consequently, precise detection of angular rotation of the turntable  21  can result. Thus, the turntable  21  can be moved to a precise angular rotational position by the manipulation to the adjusting screw  44  while observing the angle display at the digital display  131 .  
      After the fine adjustment to the angular rotational position of the turntable  21 , the fixing handle  43  is further clamped. As a result, the spring  46  is compressed, and as shown in  FIG. 29 , the table contact piece  45  is moved to its full fixing position where the table contact piece  45  is in abutment with the front wall  47  projecting from the frame  42 . In this state, relative position between the frame  2  and the table contact piece  45  cannot be changed in spite of the rotation of the adjusting screw  44 , since the table contact piece  45  is tightly pressed against the front wall  47 . Accordingly, the displacement of the frame  42  relative to the arcuate portion  16  is prevented. (The arcuate portion  16  has been integrally with the table contact piece  45  through the fixing handle  43 ). Consequently, the displacement of the turntable  21  associated with the frame  42  relative to the base  11  associated with the arcuate portion  16  does not occur. Thus, the accurate angular rotating position of the turntable  21  can be promptly set and the set angle can be maintained for the angled cutting.  
      In this way, the fine adjustment can be performed while the shaft portion  43 A of the fixing handle  43  is in contact with the base  11  (at the temporary fixing position). Accordingly, during fine adjustment, accidental displacement between the base  11  and the turntable  21  due to shock or vibration can be prevented. This enhances accuracy in positioning the turntable  21  at a desired rotational angle position.  
      Next, if the cutting face on the workpiece is to be slanted with respect to the upper surface of the base  11  (hereinafter simply referred to as slant cutting), the circular saw unit  4  is slanted as shown in  FIG. 4 . As described above, the circular saw unit  4  is supported to the tilt section  74 . The clamp shaft  81  is unfastened to release abutment between the slide wall  78  and the tilt motion support  71  so as to allow the tilt section  74  to be tiltable relative to the tilt motion support  71 . Accordingly, the circular saw unit  4  becomes tiltable because of its own weight. With this state, the side surface of the circular saw blade  123  is slanted relative to the upper surface of the workpiece.  
      In the slant cutting at a desired tilting angle, the circular saw unit  4  is maintained at a tilting angle near a desired tilting angle by operator&#39;s hand ( FIG. 30 ). Then, the adjusting knob  94  is rotated to gradually pivotally move the tilt section  74  about an axis of the pin bolt  76  so as to position the circular saw unit  4  at its desired tilting angle. Then, the clamp lever  82  is operated to fix the tilt section  74  to the tilting motion support  71 . Accordingly, accurate positioning is achievable with respect to the tilting angle of the circular saw unit  4 . After fastening the clamp lever  82 , the rotation of the rotation shaft  93  is prevented, since the arcuate gear teeth  92  is immovable.  
      By the pivotal movement of the tilt section  74 , the tilt amount detection unit  101  is moved relative to the arcuate inner gear teeth  77 . The moving amount of the unit  101  is converted into a rotation amount of the first gear  106 A of the first gear set  106 . The rotation angle of the first gear  106 A is amplified at the second gear set  108  and the detected segment  110  such that the pivot angle of 1 degree of the tilt section  74  will cause angular rotation of 72 degrees of the detected segment  110 . Since the disc like detected element  110 B is formed with 100 slits arrayed in a circumferential direction, 20 slits stand for 72 degrees. Further, the detected element  110 B enables detection of a minimum pivot angle of 0.05 degrees for the tilt section  74 .  
      Furthermore, the miter saw  1  generates cutting chips during cutting operation. However, the components of the detection unit  101  including the first gear set  106  and the optical sensor  112  are housed in the sealed housing  102 , entry of the cutting chips into the housing  102  can be prevented. Consequently, precise detection of pivot angle of the tilt section  74  can result. Thus, the tilt section  74  can be pivotally moved to a precise pivot position while observing the angle display at the digital display  131 .  
      After the fine adjustment to the pivot position of the tilt section  74 , the clamp shaft  81  is rotated by the clamp lever  82  so as to fix the tilt section  74  to the tilting motion support  71 . As a result, the accurate tilting posture of the circular saw unit  4  can be promptly set and the set posture can be maintained for the slant cutting at the desired slant angle.  
      Next, a control routine for angle display at the digital display  131  will be described in case of the angled cutting and slant cutting. The detection of the angular rotation amount and the pivot angle can be made by an electrical power supplied from the battery box  132 .  
      When a battery is assembled into the battery box  132 , a control shown in  FIG. 31  is started. Then, the angular rotation angle (Miter) and tilting angle (Bevel) held in a RAM are set to zero (S 1 ). The RAM is a memory accommodated in the microcomputer  142 . Then, the routine proceeds into S 2  where optical pulse count value at the optical sensors  62  and  112  are set to zero.  
      Then, the microcomputer  142  performs detection as to the connection to AC power source (S 03 ). If the AC power source has not been connected (S 03 :No), the routine proceeds into S 7 , where power supply to the digital display  131  is stopped to stop angle display, and the backlight is shut off if the backlight switch  150  had been turned ON for lighting the backlight, and then the routine goes into S 08 . On the other hand, if connection of AC power source is confirmed (S 03 :Yes), the routine is advanced into S 04  where a predetermined angle (the above “0” degree) is displayed and the routine goes into S 05 . In S 05 , judgment is made as to whether or not the backlight switch  150  had been turned ON. If the backlight switch  150  has been rendered ON (S 05 :Yes), the backlight is turned ON (S 06 ), and then the routine is proceeded into S 08 . If the backlight switch  150  had not been turned ON (S 05 :No), the routine proceeds into S 08 .  
      In S 08 , existence of optical pulse at the optical sensor  112  is detected. Non detection of the optical pulse (S 08 ;No) implies non-rotation of the detected segment  110  formed with the slits  110 C, which implies that the tilt section  74  is not pivotally moved and thus the circular saw unit  4  is not tilted. Therefore, the routine is skipped into an angular rotation angle detection routine starting from S 17  while neglecting the subsequent tilting angle detection routine from S 09  to S 16 . On the other hand, if optical pulse is detected (S 08 :Yes), the routine proceeds into S 09 .  
      In S 09 , tilting direction of the circular saw unit  4  is detected. If the circular saw unit  4  is tilted leftward as viewed from the front of the miter saw  1 , that is, if the tilt section  74  is pivoted relative to the tilting motion support  71  in the counterclockwise direction (S 09 :No), the routine proceeds into S 11  where the pulse numbers corresponding to the tilting angle are added. Then, the routine proceeds into S 12  where an angle to be displayed on the digital display  131  is computed. On the other hand, if the circular saw unit  4  is tilted rightward as viewed from the front of the miter saw  1 , that is, if the tilt section  74  is pivoted relative to the tilting motion support  71  in the clockwise direction (S 09 :Yes), the routine proceeds into S 10  where the pulse numbers corresponding to the tilting angle are subtracted. Then, the routine proceeds into S 12  where an angle to be displayed on the digital display  131  is computed. More specifically, addition or subtraction is made at every 0.05 degrees relative to the angle stored in the RAM in such a manner that detection of 20 pulses at the disc like detected element  110 B amounts to the tilting angle of 1 degree. After the computation of the display angle in S 12 , the routine proceeds into S 13  where the display angle is stored into the RAM.  
      Then, in S 14 , judgment is made as to whether or not the Bevel reset switch  149  is turned ON. The Bevel reset switch  149  is adapted for resetting the tilting angle up to S 13  to zero. If the Bevel reset switch  149  is not turned ON (S 14 :No), the routine proceeds into S 17  in order to start angular rotation angle display routine. On the other hand, if the Bevel reset switch  149  is turned ON (S 14 :Yes), the routine proceeds into S 15  where the optical pulse count value is set to zero, and then the value stored in the RAM is cleared to zero in S 16 . Then, the routine proceeds into S 17 .  
      S 17  through S 25  pertain to process for angular rotation amount display for the turntable  21 . In S 17 , existence of optical pulse at the optical sensor  62  is detected. Non detection of the optical pulse (S 17 ;No) implies non-rotation of the detected segment  60  formed with the slits  60 C, which implies that the turntable  21  is not angularly rotated. Therefore, the routine is returned back to S 03  neglecting the subsequent angular rotation amount display routine from S 18  to S 25 . On the other hand, if optical pulse is detected (S 17 :Yes), the routine proceeds into S 18 .  
      In S 18 , angular rotating direction of the turntable  21  is detected. If the turntable  21  is rotated in counter-clockwise direction as viewed from the top of the miter saw  1  (S 18 :No), the routine proceeds into S 20  where the pulse numbers corresponding to the rotation amount are subtracted. Then, the routine proceeds into S 21  where a rotation angle to be displayed on the digital display  131  is computed. On the other hand, if the turntable  21  is rotated in the clockwise direction as viewed from the top of the miter saw  1 , (S 18 :Yes), the routine proceeds into S 19  where the pulse numbers corresponding to the rotation amount are added. Then, the routine proceeds into S 21  where an angle to be displayed on the digital display  131  is computed. More specifically, addition or subtraction is made at every 0.05 degrees relative to the angle stored in the RAM in such a manner that detection of 20 pulses at the disc like detected element  60 B amounts to the rotation angle of 1 degree. After the computation of the display angle in S 21 , the routine proceeds into S 22  where the display angle is stored into the RAM.  
      Then, in S 23 , judgment is made as to whether or not the Miter reset switch  148  is turned ON. The Miter reset switch  148  is adapted for resetting the rotation angle up to S 22  to zero. If the Miter reset switch  148  is not turned ON (S 23 :No), the routine proceeds into S 03  in order to repeat the above described processing routine. On the other hand, if the Miter reset switch  148  is turned ON (S 23 :Yes), the routine proceeds into S 24  where the optical pulse count value is set to zero, and then the value stored in the RAM is cleared to zero in S 25 . Then, the routine proceeds into S 03  to repeat the above-described processing routine.  
      Incidentally, the process from S 17  to S 25  for the rotation angle displaying routine can be executed prior to the process from S 08  to S 16  for the pivot angle displaying routine. Alternatively, consequential steps S 08  to S 16  and another consequential steps S 17  to S 25  can be performed almost simultaneously through a multi-task processing.  
      The above-described processing is always executed as long as an electric power is supplied from the battery box  132  even if a main AC power source is not connected, and therefore, angular rotation amount of the turntable  21  and the tilting angle of the circular saw unit  4  can be always recognized. That is, those angles in the former cutting operation can be maintained. In other words, the miter saw  1  can be promptly operated without initial adjustment of the rotation angle and the tilting angle when the AC power source is connected if these angles for the former cutting operation is still available for the subsequent cutting operation. Further, an electric power level supplied from the battery box  132  is dependent on the power storage amount in the battery in the battery box  132 . If the storage amount becomes vacant, the power supply will be stopped. In order to avoid this problem, a control can be made to shut off the power supply from the battery box  132  and to start power supply from the AC power source to the control circuit when the AC power source is connected. This control can also be made to start power supply from the battery box  132  if the AC power source is then disconnected.  
      A miter saw according to a second embodiment of the present invention will next be described with reference to  FIGS. 45 and 46 . In the miter saw  181  according to the second embodiment, a tilt support portion  184  integrally extends from a turntable  183 . A support section corresponding to the support section  3  includes a holder section  185 , a slide section  186 , and a saw unit support section  187 . Further, the second embodiment provides an adjustment unit corresponding to the adjustment unit  41  of the first embodiment, and a tilt amount fine control unit corresponding to the tilt amount fine control unit  91  of the first embodiment.  
      A pivot axis of the holder section  185  is aligned with a slit  191   a  of a slit plate  191  at a neck table section  190  of the turntable  183 . Further, a pivot axis of the holder section  185  is coincident with an upper surface of the turntable  183 . The slit  191   a  is adapted to allow a circular saw blade  192  to be inserted therein when a circular saw unit  189  is moved toward the turntable  183 .  
      The holder section  185  is pivotally movable relative to the turntable  183  and is supported to the tilt support portion  184  provided integrally with the turntable  183 . A pivot posture of the holder section  185  is changed and fixed relative to the tilt support portion  184 . The holder section  185  has an upper end portion provided with a slide guide portion  186 A.  
      The slide section  186  has guide bars (not shown) movable in frontward/rearward direction and slidably supported by the slide guide portion  186 A. The saw unit support section  187  is provided at, a front end of the guide bars. The circular saw unit  189  is pivotally movably supported to the saw unit support section  187  through a support pin  188 . Thus, by the sliding movement of the slide section  186  relative to the holder section  185 , the circular saw unit  189  having the circular saw blade  192  is moved in the frontward/rearward direction at a position above the base  182  and the turntable  183 . In such a miter saw  181 , the angular rotation of the turntable  183  and the tilting motion of the circular saw unit  189  can be performed in the manner similar to the foregoing embodiments. That is, the second embodiment includes components those corresponding to the digital display  131 , the optical sensors  62 ,  112 , the motor, and the microcomputer  142  of the first embodiment.  
      A laser oscillator  201  is provided at the support section, i.e., at the saw unit support section  187  provided at the slide section  186  for irradiating a laser beam on to a workpiece  1001  mounted on the turntable  183 . The saw unit support section  187  has a front surface  187 A at which a laser emitting surface of the laser oscillator  201  is exposed. The laser oscillator  261 , the digital display  131 , the optical sensors, motor and the microcomputer are all supplied with electric power from a single AC power source. Further, the laser oscillator  201  is movable in the axial direction of the circular saw blade  192  by a axial position adjusting mechanism (not shown).  
      As shown in  FIG. 45 , a laser light  201 A can be irradiated onto an upper surface of the workpiece  1001 . The laser light  201 A providing a triangular laser beam region generates a linear laser line  201 B at an intersection between the triangular laser beam region and the upper surface of the workpiece  1001 . Since the laser oscillator  201  is laterally movable in interlocking relation to the lateral movement of the circular saw blade  192 , the linear laser line  201 B can also be laterally movable on the work-piece  1001  in interlocking relation to the lateral movement of the circular saw blade  192 . Further, since the position of the laser oscillator  201  is adjustable in the axial direction of the circular saw blade  192  by the axial position adjusting mechanism (not shown), the linear laser line  201 B can be located within a width defined between loci of opposite side surfaces of the circular saw blade  192 , or can be located outside of the width but close to the width.  
      With the arrangement, the linear laser line  201 B can be irradiated within the width of the circular saw blade  192  irrespective of the angularly rotational position of the turntable  183 , tilting position of the circular saw blade  192 , or frontward/rearward position of the circular saw  192 , because the angular rotating angle of the laser light region  201 A relative to the base  182  is coincident with the angular rotating angle of the circular saw blade  192  relative to the base  182 , and because the laterally tilting angle of the laser light region  201 A is coincident with the laterally tilting angle of the circular saw blade  192 , and because the frontward/rearward movement of the laser light region  201 A occurs concurrently with the frontward rearward movement of the circular saw blade  192 .  
      In the same manner, the linear laser line  201 B can be irradiated immediately outside of but along the width of the circular saw blade  192  by adjusting the axial position adjusting mechanism.  
      In other words, the circular saw blade  192  can be always moved within a region of or in parallel with the laser light region  201 A regardless of the tilting posture of the circular saw blade  192  or regardless of moving phase thereof toward and away from the turntable  183 , so that the circular saw blade  192  can always be seated on the linear line  201 B. Accordingly, intended cutting operation can be easily performed by aligning the linear laser line  201 B with the intended cutting line.  
      Further, the saw unit support section  187  accommodating therein the laser oscillator  201  is tiltingly moved in interlocking relation to the circular saw blade  192 . Therefore, the laser light  201 A is also tiltingly moved at a tilting angle the same as that of the circular saw blade  192 . As shown in  FIG. 46 , a cut-marking line  1001 D is drawn on a surface  1001 C of the workpiece, the surface  1001 C being in confrontation with the holder section  185 . The laser oscillator  201  is configured so that the laser light  201 A irradiates the surface  1001 C.  
      For angled cutting along the cut-marking line  1001 A, as shown in  FIG. 45 , the turntable  183  is angularly rotated so as to align the linear laser line  201 B with the cut-marking line  1001 A. After the alignment, the user simply pivotally moves the circular saw unit  189  toward the turntable  183 , after the frontward/rearward movement of the circular saw unit  189 , if any. The above-described adjustment unit ( 41 ) can effectively perform the fine alignment.  
      For the slant cutting along the cut-marking line  101 D, the circular saw unit  189  is laterally tiltingly moved so as to align the linear laser line  201 B with the cut-marking line  1001 C. After the alignment, the user simply pivotally moves the circular saw unit  189  toward the turntable  183 , after the frontward/rearward movement of the circular saw unit  189 , if any. The tilt amount fine control unit ( 91 ) can effectively perform the fine alignment.  
      Since the laser oscillator  201  generates the laser line, the user can accurately and easily recognize the angle of the cut-marking line already drawn on the surface of the workpice. Therefore, subsequent cutting operation can be smoothly performed.  
      According to this modification, since the circular saw unit  189  is movable in frontward/rearward direction, a workpiece having a greater size in frontward/rearward direction can be cut.  
      The miter saw according to the present invention is not limited to the above described embodiments, but various modifications may be conceivable.  
       FIG. 32  shows a first modification pertaining to the adjustment unit  41 , wherein like parts and components are designated by the same reference numerals and characters as those shown in the foregoing embodiments. In the first modification, a single spring  152  is interposed between a table contact piece  151  (corresponding to the table contact piece  45 ) and the front wall  47  instead of two springs  46 . This modification can reduce components or parts that constitute the adjustment unit  41 .  
      A second modification pertaining to the adjustment unit is shown in  FIGS. 33 through 35 . The arcuate portion  16  of the base has a lower surface at its outer peripheral side, and the lower surface is formed with gear teeth  153  facing downward. A frame  154  of the turntable is provided with a support portion  154 A extending downward therefrom, and a female thread extending frontward/rearward is formed in the support portion  154 A. The shaft portion  43 A of the fixing handle  43  is threadingly engaged with the female thread. By rotating the fixing handle  43  about its axis in one direction, the tip end of the fixing handle  43  is brought into abutment with the arcuate portion  16  so as to fix the position of the frame  154  relative to the arcuate portion  16 .  
      An adjustment member  155  is disposed over the shaft portion  43 A, and rides over the support portion  154 A. A spring  156  is disposed over the shaft portion  43 A and interposed between a front surface of the support portion  154 A and the adjustment member  155  for urging the adjustment member  155  frontward. The adjustment member  155  has a rear end integrally provided with a gear wheel  155 A meshedly engageable with the gear teeth  153 . The adjustment member  155  has a front end integrally provided with a knob  155 B.  
      Fine adjustment for the rotational position of the turntable  21  using the adjustment member  155  will be described. After the turntable  21  having the frame  154  is rotated to a position near the predetermined rotation angle, the adjustment member  155  is pressed rearward to allow the gear wheel  155 A to be meshingly engaged with the gear teeth  153 . While maintaining this meshing engagement, the knob  155 B is rotated about its axis to perform fine control. Then, the fixing handle  43  is fastened, so that the position of the frame  154  relative to the arcuate portion  16  is fixed at the desired rotational position of the turntable  21 .  
      Because of the meshing engagement between the gear wheel  155 A and the gear teeth  153 , the turntable  21  is not angularly rotatable relative to the base  11  unless the adjustment member  155  is rotated. Further, since the gear ratio of the gear wheel  155 A to the gear teeth  153  is small, angularly rotating amount of the turntable  21  can be small in spite of the several rotations of the adjustment member  155 . This facilitates fine adjustment.  
      A third modification pertaining to a fine adjustment to the tilting angle will be described with reference to  FIG. 36  wherein like parts and components are designated by the same reference numerals as those shown in  FIGS. 18 . A spring  164  is interposed between a fine adjustment knob  163  and a clamp lever  161  for normally urging the fine adjustment knob  163  rearward through a spacer  162 , so that the slide wall  78  of the tilt section  74  is urged toward the tilt motion support  71 . Thus, friction force is generated between the slide wall  78  and the tilt motion support  71 .  
      If the intimate contact of the slide wall  78  to the tilt motion support  71  is released upon unfastening the clamp lever  161 , the circular saw unit  4  is urged to be tiltingly moved due to its own weight. However, this tilting motion due to the own weight can be restrained because of the friction force still imparted between the slide wall  78  and the tilting motion support  71  by the biasing force of the spring  164 .  
      Further, free rotation of the fine adjustment knob  163  is restrained because of the biasing force of the spring  164  is imparted on the knob,  163 . Accordingly, a tilting movement of the tilt section  74  is also restrained since the tilt section  74  is connected to the fine adjustment knob  163  through the rotation shaft  93 . Thus, tilting motion of the circular saw unit  4  due to its own weight can be restrained. This means that it is unnecessary to manually support the circular saw unit  4  at a given posture by user&#39;s hand during fine adjustment to the tilting angle of the circular saw unit  4 . This facilitates the fine adjustment.  
      A fourth modification pertaining to a fine adjustment to the tilting angle will be described with reference to  FIGS. 37 and 38 . A shaft support  169  is rotatably supported in a peripheral side of the turntable at a position below the tilt section  74 . A fine adjustment shaft  167  has one end connected to the shaft support  169 , so that the fine adjustment shaft  167  is pivotally movable about an axis of the shaft support  169 . The fine adjustment shaft  167  has an intermediate portion formed with a worm  166  selectively engageable with the arcuate gear teeth  92 . The fine adjustment shaft  167  has a free end integrally provided with a fine adjustment knob  168 . A stop  170  extends from the peripheral side of the turntable so as to limit the pivotal movement of the fine adjustment shaft  167  in a direction away from the arcuate gear teeth  92 .  
      Normally, the fine adjustment shaft  167  is in abutment with the stop  170 , so that the worm  166  is disengaged from the arcuate gear teeth  92  as shown in  FIG. 37 . If the circular saw unit  4  is to be tiltingly moved to a desired tilting angle position, the fine adjustment shaft  167  is pivotally moved toward the arcuate gear teeth  92  so as to engage the worm  166  with the arcuate gear teeth  92  as shown in  FIG. 38 , after the circular saw unit  4  is tiltingly moved to a position near the desired tilting angle position. By this engagement, tilting posture of the circular saw unit  4  can be maintained. Then, the fine adjustment knob  168  is rotated about its axis so that the arcuate gear teeth  92  is moved about the axis of the pivot bolt  76 . The movement of the arcuate gear teeth  92  implies the tilting movement of the tilt section  74  about the axis of the pivot bolt  76 . Thus, the tilting angle of the circular saw blade  123  can be subjected to fine adjustment. Then, the clamp lever  82  is fastened to fixely secure the tilting angle.  
      Since the fine adjustment knob  168  is movable to the engagement position in meshing engagement with the arcuate gear teeth  92  and to a non-engagement position in out of engagement therefrom, the worm  166  is only engaged with the arcuate gear teeth  92  when the fine tilting angle control is required. In other words, resistive force is not applied when the circular saw unit is tiltingly moved prior to the fine adjustment.  
      A fifth modification pertaining to a fine adjustment to the tilting angle will be described with reference to  FIG. 39 . An arcuate elongated slot  171  is formed longer than that of the elongated slot  79 , so that the tilt section  74  can be tiltable to the angle of about 45 degrees in both clockwise and counterclockwise directions. Thus, the circular saw unit  4  can be tilted to about 45 degrees in rightward and to 45 degrees in leftward.  
      A sixth modification pertaining to a fine adjustment to the tilting angle is shown in  FIG. 40 . According to the modification, an arcuate elongated slot  171 ′ is positioned along an outer peripheral edge of the tilt section  74 .  
      A seventh modification pertaining to a tilting amount detection unit is shown in  FIGS. 41 and 42 . A tilting amount detection unit  172  includes a housing  172 A in which rotation shafts  174  and  178  are rotatably supported. A shaft support  179  is attached to the housing  172 A for rotatably supporting a rotation shaft  176 .  
      A first gear set  173 , a second gear set  175  and detected segment  177  are coaxially mounted on the shafts  174 ,  176 ,  178 , respectively. Geometrical relationship among the rotation shafts  174 , 176 , 178  is such that a line connecting the rotation shafts  174  and  178  is assumed to be a base line of a triangle, and the rotation shaft  176  is at an apex of the triangle. The shaft support  179  is movable in a direction perpendicular to the line connecting the rotation shafts  174  and  178  and perpendicular to the rotation shaft  176  as shown by arrows Al and A 2 . Further, the shaft support  179  can be fixed to the housing  172 A by screws  180 . An optical sensor  180  is provided beside the detected segment  177 .  
      For assembly, the shaft support  179  is urged in the direction A 1  (toward the line connecting the rotation shafts  174  and  178 ) so as to maintain meshing engagement of the second gear set  175  with the first gear set  173  and the detected segment  177 . Then, the screws  180  are fastened to fix the shaft support  179  to the housing  172 A. With this arrangement, any rattling among the first gear set  173 , the second gear set  175  and the detected segment  177  does not occur. Accordingly, accurate rotation amount of the detected segment  177  in response to the rotation of the first gear set  173  can be obtained, thereby enhancing detection accuracy at the optical sensor  180 . A modification is conceivable to the seventh modification such that the shaft support  179  is not fixed to the housing  172 A, and a biasing member such as a spring is provided for biasing the shaft support  179  in the direction A 1 .  
      An eighth modification pertaining to a tilting amount detection unit is shown in  FIG. 43 . According to this modification, the spring  105  in the tilting amount detection unit  101  ( FIG. 19 ) is dispensed with. The tilting amount detection unit  101  is pivotally moved about the axis of the pin  113  so as to meshingly engage the first gear  106 A with the arcuate inner gear teeth  77 . Then, the screw  114  is fastened to maintain the meshing engagement without rattling. Thus, the position of the tilting amount detection unit  101  can be fixed relative to the arcuate inner gear teeth  77 , thereby accurately detecting the tilting angle of the tilt section  74  relative to the tilting motion support  71 .  
      A modification pertaining to a tilting amount detection unit will be described. A low output and low power consumption motor (not shown) is drivingly coupled to the rotation shaft  111  or  178  of the detected segment  110  or  177  so that positive rotation force is imparted on the shaft  111  or  178 . By the rotation force, the rotation shafts  107 ,  109  or  174 , 176  are urged to be rotated. However, since the first gear  106  or  173  is engaged with the arcuate inner gear teeth  77 , and since rotation torque of the motor is extremely small, the detected segment, the first gear set and the second gear set are not rotated. Still however, because of the application of the rotational force by the motor, no rattling occurs between engaging regions. Further, even if relative movement occurs between the arcuate inner gear teeth  77  and the tilting amount detection unit  101  by the tilting motion of the tilt section  74 , the motor does not affect the relative movement, since the output of the motor is extremely small. Furthermore, because of the employment of the low power consumption motor, power from the battery box  132  can be used for energizing the motor even if the main power source is not connected.  
      The above-described modifications to the tilting amount detection unit are also available for the rotation amount detection unit  51 . Further, in the above-described embodiments, gears are used for transmitting rotation to the detected segment. Here, friction wheels can be used instead of the gears for amplifying and transmitting rotation.  
      A ninth modification pertaining to a control circuit is shown in  FIG. 44 . In the control circuit shown in  FIG. 24 , the battery box  132  is provided for continuously measuring rotation amount of the turntable  21  and tilting amount of the circular saw unit  4 . However, in the control circuit shown in  FIG. 44 , the battery box  132  is dispensed with. In the latter case, if the turntable  21  is angularly rotated or the circular saw unit  4  is tiltingly moved while the AC power source is disconnected, computation of such angle cannot be made in the microcomputer  142 . Even if the AC power source is connected thereafter, the rotation amount and tilting amount is unknown. To avoid this problem, a notice as to the necessity of zero resetting can be displayed on the digital display  131 . After the turntable  21  is set to zero angle position, and after the circular saw unit  4  is set to zero angle position in response to the notice by the display  131 , Miter reset switch  148  and the Bevel reset switch  149  are pressed for initialization. Then, the turntable is angularly rotated or the circular saw unit  4  is tiltingly moved.  
      Further, the set position of the battery box  132  is not limited to within the semi-circular recess  24 , but can be disposed at the lower surface of the base  11 .  
      In the second embodiment, a mirror can be disposed at the front surface  187 A of the saw unit support section  187  so as to confront with the surface  1001 C ( FIG. 46 ) of the workpiece  1001 . Normally, the user is positioned at a front side of the miter saw  181  for cutting operation. If the mirror is not provided, the user must walk toward the rear side of the miter saw  181  so as to observe the surface  1001 C in order to acknowledge the alignment between the linear laser line  201 B with the cut-marking line  101 D. However, because of the provision of the mirror, the user can acknowledge the alignment state from the front side of the miter saw  181 , because the mirror can shows the alignment state.  
      Further, in the second embodiment, the linear laser line  201 B is positioned within the width of the circular saw blade  192 , the width being defined between opposing moving loci of the opposite side surfaces of the blade  192 . However, the width of the linear laser line  201 B in the axial direction of the circular saw blade  192  can be increased so that the linear laser line  201 B is positioned exceeding over the width defined between opposing moving loci of the opposite side surfaces of the blade  192 . Alternatively, an adjusting mechanism can be provided to the laser oscillator  201  so as to control the width of the linear laser line  201 B. Furthermore, the liner laser line  201 B can be positioned outside of the width defined between opposing moving loci of the opposite side surfaces of the blade  192  but along the width.  
      In the second embodiment, the slide section  186  is provided. However, the slide section  186  can be dispensed with. Further, in the second embodiment, the digital display  131  can be dispensed with, or other type of a digital display can be provided.  
      Further, the laser oscillator  201  in the second embodiment can be provided in the above-described various modifications.  
      Further, in the second embodiment, the laser oscillator  201  is accommodated in the saw unit support section  187 . However, the accommodating position is not limited to the saw unit support section  187 . Instead, the laser oscillator  201  can be disposed at other position such as at the circular saw unit  189  (for example, near the handle or near the saw blade cover), or at the holder section  185 .  
      Further, AC power source is used as a power source of the laser oscillator  201  in the second embodiment. However, a battery accommodated in the miter saw can be used as a power source of the laser oscillator  201 .  
      Further, various combinations are conceivable with respect to the above-described modifications. Further, various modification can be effected on the slide type miter saw  181 .