Convertible zero-clearance circular saw

Abstract

A portable zero clearance circular saw including a motor flame portion with a transverse oriented drive shaft and arbor coupled to the drive shaft, a handle portion with, a hand grip coupled to the motor frame portion aft end, a planar blade deck on a first lateral side, a movable blade shield rotatably mounted coaxial with the drive shaft and having a sidewall with a edge face coplanar with the blade deck, a trigger proximate the hand grip to move the blade shield, and a blade couplable to the drive shaft against the arbor, such that the blade outer surface is flush with the blade deck and blade shield sidewall. The handle portion may be rotatably coupled to the motor frame portion, and may include two laterally disposed blade shield triggers operably coupled to the blade shield via a dual pulley system.

I claim: 
     
         1 . A portable, circular saw adapted to receive a flush mounted circular saw blade, the blade including a central mounting portion having opposed first and second surfaces, and a cutting portion with opposed first and second planar surfaces extending from the central mounting portion to a cutting edge disposed along the blade perimeter, the rotation of the cutting edge defining a blade arc, the saw comprising:
 a. opposed forward and aft ends defining a longitudinal direction;   b. a motor frame portion having opposed forward and aft ends, the motor frame portion including:
 i. a motor connectable to a power source, the motor mounted to the motor frame portion and operably coupled to a drive shaft, the drive shaft projecting from a first lateral side of the motor frame portion, the drive shaft defining a first transverse axis; and, 
 ii. a blade shield axle extending transversely from the motor frame portion first lateral side coaxial with the drive shaft; 
   c. a handle portion coupled to the motor frame portion aft end, the handle portion including a hand grip and a motor actuator to selectively actuate the motor;   d. a blade deck rigidly coupled to the motor frame portion first lateral side, the blade deck including a planar bearing surface;   e. an arbor coupled to the drive shaft, the arbor including a first mounting face adapted to mate to a blade central mounting portion, the distance from the blade mounting face surface to the blade deck planar bearing surface defining a blade offset depth;   f. a lower blade shield movable between a deployed position and a retracted position, the lower blade shield having an arcuate laterally projected sidewall circumscribing a portion of the blade arc from a sidewall first end to a sidewall second end, the arcuate sidewall including a facing edge coplanar with the blade deck bearing surface, the lower blade shield rotatably coupled to the blade shield axle;   g. a base deck extending longitudinally from a forward edge to an opposed aft edge and transversely from a first lateral edge proximal the motor frame portion first lateral side to a second lateral edge, the base deck edges defining a planar bearing surface, the base deck pivotally coupled to the motor frame portion about a second transverse axis and lockable at a plurality of user selectable pitch angles about the second transverse axis to adjust the blade cutting depth, the base deck further pivotally coupled to the motor frame about a first longitudinal axis and lockable at a plurality of user selected bevel angles about the first longitudinal axis.   
     
     
         2 . A circular saw as in  claim 1 , further comprising:
 a. the handle portion rotatably coupled to the motor frame portion aft end to rotate about a second longitudinal axis and lockable at a plurality of user selected rotated positions, the plurality of handle portion user selected rotated positions including at least 0° and 90°.   
     
     
         3 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a first lower blade shield trigger operably coupled to the lower blade shield to move the lower blade shield between the normal deployed position and the retracted position; 
 
     
     
         4 . A circular saw as in  claim 3 , further comprising:
 a. the first lower blade shield trigger mounted to the handle portion proximal the hand grip such that it may be operated by a first thumb of an operator while gripping the hand grip with a first hand.   
     
     
         5 . A circular saw as in  claim 4 , further comprising:
 a. the first blade shield trigger mounted to the handle portion along the first lateral side of the handle portion proximal the hand grip; and,   b. a second lower blade shield trigger operably coupled to the lower blade shield to move the lower blade shield between the normal deployed position and the retracted position, the second lower blade shield trigger disposed along the opposing lateral side of the handle portion from the first blade shield trigger and proximal to the hand grip such that it may be operated by the thumb of an operator while gripping the hand grip with an opposed second hand.   
     
     
         6 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a circular saw blade removably couplable to the blade drive shaft, the blade including a central mounting portion having opposed first and second surfaces wherein the central mounting portion second surface comprises a second mounting face adapted to mate to the first mounting face, a cutting portion with opposed first and second planar surfaces extending from the central mounting portion to a cutting edge disposed along the blade perimeter, the rotation of the cutting edge defining the blade arc; 
 b. wherein, the distance from the second mounting face to the blade first planar surface is equal to the blade offset depth, such that the blade first planar surface is coplanar to the blade deck planar bearing surface. 
 
     
     
         7 . A circular saw as in  claim 6 , further comprising:
 a. wherein the central mounting portion is offset laterally from the circular saw blade second surface.   
     
     
         8 . A circular saw as in  claim 6 , further comprising:
 a. the arbor further including a plurality of fastener receiving holes;   b. the blade central mounting portion having a having a first plurality of mounting apertures, the first plurality of mounting apertures countersunk on the mounting portion first surface, the first plurality of mounting apertures aligned to the fastener receiving holes; and,   c. a plurality of bevel head fasteners to engage the blade to the arbor through the first plurality of mounting apertures and fastener receiving holes, the fastener heads flush with the mounting portion second surface when fully engaged through the first plurality of mounting apertures.   
     
     
         9 . A circular saw as in  claim 8 , further comprising:
 a. the blade central mounting portion further having a second plurality of mounting apertures, the second plurality of mounting apertures countersunk on the mounting portion second surface, the second plurality of mounting apertures aligned to the fastener receiving holes, the plurality of fasteners engagable through the second plurality of mounting apertures to be flush with the central mounting portion second surface, such that the blade is reversible.   
     
     
         10 . A circular saw as in  claims 1  or  2 , further comprising:
 a. the cross section of the drive shaft defining a shaft diameter; 
 b. the blade shield axle coaxial with and surrounding drive shaft, the blade shield axle having an exterior bearing surface defining an exterior blade shield axle diameter, the exterior bearing surface to rotatably receive a lower blade shield over the blade shield axle; 
 c. the blade shield axle further including an interior bearing surface defining an interior blade shield axle diameter greater than the motor shaft diameter, the blade shield axle interior bearing surface to rotatably receive an arbor first part; 
 d. the arbor further comprising:
 i. a first part comprising a hollow axle to couple over the drive shaft and within the shield axle interior bearing surface; and, 
 ii. a second part extending from the first part, the second part comprising a flange including the first mounting face. 
 
 
     
     
         11 . A circular saw as in  claim 10 , further comprising:
 a. wherein the arbor flange diameter is greater than the blade shield axle outer shaft diameter to retain the blade shield on the blade shield axle.   
     
     
         12 . A circular saw as in  claim 10 , further comprising:
 a. an arbor cap having:
 i. a blade engagement projection to insert into and engage a center mounting aperture through a blade central mounting portion; 
 ii. a surrounding arbor cap flange to go against a blade central mounting portion first surface; 
 iii. an arbor cap center aperture to receive a fastener there through; and, 
   b. a center fastener to engage a blade against the arbor through the center aperture.   
     
     
         13 . A circular saw as in  claim 12 , further comprising:
 a. the arbor cap having a depth dimensioned such that the arbor cap engaged against a blade and the arbor does not protrude past the blade cutting portion first planar surface.   
     
     
         14 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a front deck portion having opposed forward and aft edges and a planar bearing surface extending there between, the front deck portion hingedly coupled proximate the front deck portion aft edge to the base deck proximate the base deck front edge and pivotable about a third transverse axis, the front deck portion lockable at least at a first position, wherein the front deck planar bearing surface is coplanar to the base deck planar bearing surface and wherein the front deck portion forward edge extends forward of the blade arc, and a second position, wherein the front deck planar bearing surface is normal to the base deck planar bearing surface and facing forward. 
 
     
     
         15 . A circular saw as in  claim 14 , further comprising:
 a. the front deck portion further including a locking pin to lock the front deck portion in at least the first or second position and a front deck aperture to access the locking pin, the front deck aperture disposed to align with the locking pin when the front deck portion is in the second position.   
     
     
         16 . A circular saw as in  claims 1  or  2 , further comprising
 a. wherein the blade deck bearing surface extends forward to circumscribe a portion of the blade arc, thereby defining a blade deck interior edge, the distance between the blade arc and the blade deck interior edge defining a blade gap to receive at least a portion of the lower blade shield sidewall in the retracted position. 
 
     
     
         17 . A circular saw as in  claims 1  or  2 , further comprising:
 a. wherein the lower blade shield is biased to the deployed position. 
 
     
     
         18 . A circular saw as in  claim 5 , further comprising:
 a. wherein the first and second blade shield triggers are operable independently from each other.   
     
     
         19 . A circular saw as in  claims 1  or  2 , further comprising:
 a. an electromagnetic brake to electromagnetically lock the motor windings, the brake automatically actuated when the motor trigger is released while the motor is connected to a power source. 
 
     
     
         20 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a hinge block having a first end and opposed second end, the hinge block first end pivotally coupled to the base deck distal from the base deck aft edge along the first longitudinal axis to pivot the base deck around the first longitudinal axis, the hinge block second end pivotally coupled to the motor frame portion at a second transverse axis to pivot the base deck around the second transverse axis; 
 b. dual axes hinge coupler mounted to the base deck proximate the base deck first lateral edge distal from the base deck front edge, the dual axes hinge coupler having a first portion comprising a longitudinal hinge coupling aligned along the first longitudinal axis to pivot the base deck around the first longitudinal axis and a second portion comprising a transverse hinge coupling aligned along a fourth transverse axis; 
 c. a first sliding connector comprising an arcuate track having a first end, a second end, and a first closed channel extending from proximate the first end to the second end, the first end coupled to the dual axes hinge coupler second portion, the first closed channel to slidingly receive a stub axle there through; and, 
 d. a stub axle extending from the first lateral side of the motor frame portion to a free end, the stub axle extending through the first closed channel and having a first selectively releasable compression coupling coupled to the stub axle to lockingly engage against the first arcuate track and motor frame portion. 
 
     
     
         21 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a hinge block having a first end and opposed second end, the hinge block first end pivotally coupled to the base deck distal from the base deck aft edge first longitudinal axis to pivot the base deck around the first longitudinal axis, the hinge block second end pivotally coupled to the motor frame portion at a second transverse axis to pivot the base deck around the second transverse axis; 
 b. the base deck further comprising a dual axes coupler disposed proximate the first lateral edge to couple the base deck to the motor frame portion, the dual axes coupler having a first portion comprising a longitudinal rotatable coupling aligned along the first longitudinal axis to pivot the base deck around the first longitudinal axis and a second portion comprising a transverse rotatable coupling aligned along a fourth transverse axis; and, 
 c. a second sliding connector comprising overlapping first and second arcuate portions:
 i. the first arcuate portion having a first end coupled to the hinge block distal from the hinge block first end, and a second end; 
 ii. the second arcuate portion having a first end coupled to the base deck distal from the base deck aft edge and distal from the base deck first lateral edge, a second end, and a closed channel extending from proximal the second arcuate portion first end to second arcuate portion second end; and, 
 iii. a second selectively releasable compression coupling to selectively lockingly engage the first and second arcuate portions against each other. 
 
 
     
     
         22 . A circular saw as in  claims 1  or  2 , further comprising:
 a. the bevel angle continuously adjustable within a range of approximately +65° to approximately −10°, wherein the base deck bearing surface oriented normal to the blade arc defines 0°. 
 
     
     
         23 . A circular saw as in  claims 1  or  2 , further comprising:
 a. a dust cover removably couplable to the saw to substantially enclose the blade arc. 
 
     
     
         24 . A circular saw as in  claim 23 , the dust cover further comprising:
 a. an aft cover portion, a lower blade cover portion, and a front cover portion;   b. the aft cover portion removably mountable to the blade deck and covering a portion of a mounted blade;   c. the blade cover portion removably mountable to the lower blade shield and rotatably coupled to the aft cover portion coaxial with the first transverse axis such that the blade cover portion moves with the lower blade shield;   d. the front cover portion removably mountable to the base deck proximal the base deck forward edge and movable with the base deck.   
     
     
         25 . A circular saw as in  claims 1  or  2 , further comprising:
 a. the motor further including a first brush access port on the motor frame portion first lateral side; 
 b. the blade deck further including a first aperture aligned with the first brush access port to provide access to a motor brush. 
 
     
     
         26 . A circular saw as in  claim 3 , further comprising:
 a. a double pulley rotatably coupled to the motor frame portion first lateral side at a fifth transverse axis, the double pulley including a first sheave having a first diameter and a second sheave having a second diameter smaller than the first diameter;   b. a first cable operably coupling the first lower shield trigger to the first sheave; and,   c. a second cable operably coupling the second sheave to the lower blade shield.   
     
     
         27 . A circular saw as in  claim 17 , further comprising:
 a. a center lever disposed between the first and second lower blade shield triggers, the center lever including a transversely oriented bridge portion, first and second legs extending from opposing ends of the bridge portion to first and second leg ends, and opposed first and second tabs extending transversely from the bridge portion opposed ends, the center lever first and second legs pivotably coupled to the handle portion coaxially to the first and second lower blade shield triggers on a sixth transverse axis, the first and second tabs overlapping the first and second lower blade shield triggers, respectively, such that either the first or second lower blade shield trigger will engage against its respective tab to move the center lever when the respective trigger is depressed;   b. a double pulley rotatably coupled to the motor frame portion first lateral side at a fifth transverse axis, the double pulley including a first sheave having a first diameter and a second sheave having a second diameter smaller than the first diameter;   c. a first cable operably coupling the center lever to the first sheave; and,   d. a second cable operably coupling the second sheave to the lower blade shield.   
     
     
         28 . A circular saw as in  claim 26 , further comprising:
 a. a biasing spring coupled between the motor frame portion and the lower blade shield to bias the lower blade shield toward the deployed position.   
     
     
         29 . A circular saw as in  claim 27 , further comprising:
 a. a biasing spring coupled between the motor frame portion and the lower blade shield to bias the lower blade shield toward the deployed position.   
     
     
         30 . A circular saw blade removably mountable to a zero clearance circular saw having a motor coupled to a drive shaft, a blade deck including a planar bearing surface, and a first mounting face coupled to a drive shaft, the distance from the first mounting face to the blade deck bearing surface defining a blade offset depth, the saw blade comprising:
 a. a central mounting portion having opposed first and second surfaces wherein the central mounting portion second surface comprises a second mounting face adapted to mate to the first mounting face;   b. a cutting portion having opposed first and second planar surfaces extending from the central mounting portion to a cutting edge disposed along the blade perimeter, the rotation of the cutting edge defining the blade arc;   c. wherein, the blade central mounting portion is offset laterally from the blade cutting portion second surface and the distance from the second mounting face to the blade cutting portion first planar surface is equal to the blade offset depth, such that the blade cutting portion first planar surface is coplanar to the blade deck planar bearing surface when mounted to the saw.