Motorized circular miter chop saw

A motor operated circular miter chop saw is pivotally mounted on a generally horizontal axle pivot bolt about which it rotates in a vertical plane with the axle pivot bolt being carried by a cast support base structure provided with means allowing lateral adjustment of one end of the axle pivot bolt and vertical adjustment of the other end. Angular orientation of the work piece is provided by an angularly adjustable fence rotatably carried by the cast base support structure with the fence having lugs cooperating with an arcuate slot or groove provided in the cast base support structure. The cast base support structure is also provided with an arcuate slot to provide clearance for the circular saw blade while an adjustable stop is provided carried by the cast support base to preclude the circular saw blade from contacting the cast support base structure. Spring means are also provided for biasing the saw to an upwardly pivoted position.

DESCRIPTION 
Field of the Invention 
This invention relates to powered circular saws and, more particularly, to 
a powered circular saw hingedly mounted to a table having a rotatably 
positionable fence for cutting elongated stock material such as wood to 
length at various reproducable angles. 
BACKGROUND OF THE INVENTION 
In various crafts projects it is useful to be able to accurately cut 
elongated stock material, such as strips of wood, or the like, to length 
and at accurately reproducable angles. For example, in many construction 
projects it is desired to cut strips of wood so that the end cut is 
square, that is perpendicular to the longitudinal axis of the wood strip. 
At other times it is desirable to cut at angles other than 90.degree. such 
as at a 45.degree. angle to enable two such strips to be mitered to 
provide a square or right angle corner joint. Motorized miter saws, in 
which a power driven circular saw is pivotally supported on a support 
member for vertical swinging movement downwardly from a normal inoperative 
rest position towards a work support base structure while also pivotally 
supporting the saw support member on a vertical axis for angular swinging 
movement to preselected angular positions to effect a desired angle 
cutting of the work piece have been previously shown and saws of this type 
are disclosed, for example, in Niehaus et al. U.S. Pat. No. 3,821,918 and 
are commonly referred to as chop saws. A disadvantage of such saws is the 
necessity for pivoting the saw assembly for angular setting and the weight 
and vibration of the saw necessitates that the saw support member be 
rather heavy and closely machined to provide for long life and continued 
accuracy. Among other disadvantages, this necessity makes such 
construction more expensive than might be otherwise desirable. Moreover, 
since the saw blade must descend to a position beneath the work supporting 
surface in order to completely sever the work piece, means must be 
provided to enable the saw to pass through the work supporting surface at 
a number of angular positions which further increases the complexity and, 
accordingly, the cost of such saws. In some saws this is achieved by 
providing a rotating platform which rotates with the saw, further adding 
to the complexity and expense of the machine. If such means are not 
provided, then a disposable work supporting surface, such as a piece of 
scrap wood, must be used beneath the work piece or a movable fence, or the 
like must be provided to enable relative lateral movement of the work 
piece and the saw path, therefore necessitating both the chopping movement 
of the saw and lateral movement of the work piece or saw which results in 
a loss of convenience and a possible lessening of accuracy as well as an 
increase in complexity and expense. 
Without getting into truly massive or welded structures for the work 
support base structure, the most economical basic fabrication method to 
provide the requisite rigidity and strength is to cast the structure of 
metal. While such cast structures are basically inexpensive in comparision 
with a welded structure, a cast structure has the basic inconvenience that 
working surfaces need to be subsequently machined because the surface 
finish produced by processes such as sand casting are generally 
insufficient for work supporting surfaces and are definitely insufficient 
for bearing surfaces about which the chop saw pivots. Moreover, because of 
the limitation of the sand casting process and the contraction of metal 
during cooling following casting, actual dimensions are subject to 
substantially large tolerances which necessitate that critical surfaces 
and the structure defining pivotal axis be subsequently machined and each 
machining operation necessitated by the design generally increases the 
cost of the machine. 
OBJECTS OF THE INVENTION 
Accordingly, it is a primary object of the present invention to provide 
novel and improved miter saws designed, constructed and arranged to 
maximize economy of production while simultaneously maintaining acceptable 
accuracy. 
Another primary object of the present invention, in addition to the 
foregoing object, is the provision of novel and improved miter saws 
utilizing a cast base structure to which a motor powered circular chop saw 
is pivotally mounted for rotation about a horizontal axis wherein a 
minimum of machining is required to the base structure casting. 
Yet another primary object of the present invention, in addition to each of 
the foregoing objects, is the provision of such a miter saw wherein novel 
and improved mounting means are utilized for mounting the motor powered 
circular chop saw to the base support structure wherein the axis of 
rotation is adjustable in a first direction rotationally in a plane 
generally parallel said work support surface and in a second direction 
rotationally in a plane generally perpendicular said work support surface 
so as to enable accurate orientation of the motor powered chop saw 
relative the base support structure without requiring excessive accuracy 
in the initial fabrication of the cast base support structure. 
Still another primary object of the present invention, in addition to each 
of the foregoing objects, is the provision of novel and improved motor 
powered circular miter chop saws wherein rotation of the motor powered 
chop saw relative to the base is not required for adjustment of angular 
orientation to the work piece to be cut whereby the mounting means between 
the motor powered chop saw and the cast mounting base structure need only 
provide for rotation of the motor driven circular chop saw about a 
horizontal axis for movement of the motor driven chop saw in a vertical 
plane, and thereby enabling novel and improved adjustment means to be 
utilized for adjusting the orientation of the rotational axis of the motor 
driven chop saw relative the cast base support structure. 
Yet still another primary object of the present invention, in addition to 
each of the foregoing objects, is the provision of such motor driven miter 
chop saws wherein the rotational axis for the motor driven chop saw 
relative the cast base support structure comprises means at one end of an 
axle bolt around which the motor powered circular saw pivots for providing 
lateral adjustment thereof and means associated with the other end of the 
axle bolt for providing vertical adjustment thereof whereby accurately 
machined sockets for the two ends of the axle bolt are not required. 
Another and yet still further primary object of the present invention, in 
addition to each of foregoing objects, is the provision in a motor powered 
miter chop saw of the class described of an adjustable stop defining the 
lowermost position of the motor powered circular chop saw relative the 
cast base support structure for precluding the circular saw thereof from 
contacting the cast support base. 
Yet still another and further primary object of the present invention, in 
addition to each of the foregoing objects, is the provision in a motor 
driven circular miter chop saw of the class described of an angularly 
adjustable fence against which a work piece may be positioned to define 
the angle of cut thereof and thereby enabling the angular orientation of 
the chop saw laterally of the cast support base upon which the work piece 
may also be supported to be fixed so that a single arcuate segmental 
recess may be provided for clearance of the circular saw blade to sever 
the work piece at any desired angle by mere lowering pivotal action of the 
chop saw. 
Yet another and still further primary object of the present invention, in 
addition to each of the foregoing objects, is the provision in a motor 
driven circular miter chop saw of the class defined, spring actuated 
detent means on such angularly adjustable fence to define especially 
desirable angular orientation adjustments thereof such as, for example, 
square or 90.degree. cutting (alternatively referred to a 0.degree. of 
miter) and 45.degree. cutting orientations. 
A further and still another primary object of the present invention, in 
addition to each of the foregoing objects, is the provision, in motor 
driven circular miter chop saws of the class defined of novel and improved 
biasing means for biasing the horizontally pivoted chop saw to an upward 
or open position for insertion of an elongated piece under the motor 
driven circular saw blade for cutting. 
Still another and yet still further primary object of the present 
invention, in addition to each of the foregoing objects, is the provision, 
in a motor driven circular miter chop saw of the class defined of locking 
means for the fence to positively maintain the fence aligned in a desired 
angular orientation. 
A yet still further primary object of the present invention, in addition to 
each of the foregoing objects, is the provision, in a motor driven 
circular miter chop saw of the class described having a rotatable fence 
for angularly positioning an elongated work piece, of a arcuate rib or 
plurality of arcuate rib segments depending from the fence engaged with 
and cooperating with a generally arcuate groove provided in the cast base 
support member for guiding such fence around a vertual pivot centered in 
or adjacent the plane of the circular saw blade. 
It is a feature of the present invention that the saw is constructed 
primarily from relatively inexpensive castings eliminating a number of 
parts from conventional construction and requiring a minimum of machined 
parts maximizing economy of manufacture while yet providing an accurate 
and durable tool. 
The invention resides in the combination, construction, arrangement and 
disposition of various component parts and elements incorporated in 
improved motor driven circular miter chop saws constructed in accordance 
with the principles of this invention. The present invention will be 
better understood and objects and important features other than those 
specifically enumerated above will become apparant when consideration is 
given to the following details and description which, when taken in 
conjunction with the annexed drawing describes, discloses, illustrates and 
shows a preferred embodiment or modification of the present invention and 
what is presently considered and believed to be the best mode of 
practicing the principles thereof. Other embodiments and modifications may 
be suggested to those having the benefit of the teachings herein, and such 
other embodiment or modifications are intended to be reserved, especially 
as they fall within the scope and spirit of the subjoined claims. 
SUMMARY OF THE INVENTION 
In accordance with the present invention a motor operated circular miter 
chop saw is pivotally mounted on a generally horizontal axle pin or bolt 
about which it rotates in a vertical plane with the axle bolt being 
carried by a cast support base structure provided with means allowing 
lateral adjustment of one end of the axle bolt and vertical adjustment of 
the other end thereof enabling inexpensive and easy adjustment for 
manufacturing tolerances in the cast support base structure. Angular 
orientation of the work piece is provided by an angularly moveable fence 
rotatably carried by the cast base support structure with the fence having 
lugs cooperating with an arcuate slot or groove provided in the cast base 
support structure. The cast base support structure is also provided with 
an arcuate slot extending perpendicular the chop saw axle bolt to provide 
clearance for the circular saw blade, the blade being aligned with the 
arcuate slot by the axle bolt adjustment means while an adjustable stop is 
provided carried by the cast support base to preclude the circular saw 
blade from contacting the base of the arcuate clearance slot in the cast 
support base structure. Detent means are provided for locating the 
rotatable fence structure for work piece cut off at a right angle or 
90.degree. (sometimes referred to as 0.degree. of miter) as well as at 
45.degree. right and left orientation. Lock means are also provided for 
firmly locking the fence in a desired orientation, whether in the detent 
position or any position therebetween and biasing means are provided for 
biasing the chop saw to an upward position enabling insertion of an 
elongated work piece therebeneath. 
While the saw described is primarily intended for the cutting of soft 
material such as wood, utilizing a wood cutting blade, it is intended that 
this application also cover similar devices provided with metal cutting 
blades, abrasive discs, and the like, for cutting and facing diverse 
materials.

DETAILED DESCRIPTION OF THE INVENTION 
With reference now to the drawing, there is shown and illustrated a motor 
operated circular miter chop saw constructed in accordance with the 
principles of the present invention and designated generally by the 
reference character 10. The miter saw 10 comprises a cast base structure 
designated generally by the reference character 12, a motor driven 
circular saw structure designated generally by the reference character 14 
rotatably carried on a pivot assembly generally designated by the 
reference character 16 mounted with the cast base structure 12 and a 
rotatable fence structure designated generally by the reference character 
18 rotatably carried by the cast base structure 12 for limited rotational 
movement about a vertual pivot located or adjacent the plane of the 
circular saw blade 20 of the motor driven circular saw 14. In addition, 
biasing means generally designated by the reference character 22 are 
provided for biasing the circular saw 14 in an upward direction towards an 
open position whereat the circular saw 14 is generally spaced above the 
cast base portion structure 12 for the insertion of an elongated work 
piece therebetween to rest on a work supporting surface 24 defined by the 
top surface of the cast base portion 12 and against the work supporting 
face 26 on the fence structure 18 generally perpendicular the work 
supporting surface 24. A generally arcuate depression or clearance slot 28 
is provided in the cast base structure 12 in general alingment with the 
circular saw blade 20 to enable the circular saw blade 20 to pass through 
the plane of the work supporting surface 24 as the saw is lowered against 
the force of the biasing means 22 to cut the work piece. The fence 
structure 18 is also provided with a generally central slot 30 to provide 
clearance for the saw blade for the same purpose, the slot being wide 
enough to accommodate the saw blade even at the extreme of the fence 
rotation. Adjustable stop means 32 are also provided for limiting the 
downward pivoting chop motion of the motorized circular saw 14 to prevent 
the circular saw blade 20 from contacting the bottom of the saw clearance 
groove 28 or the fence structure 18 rearward of the saw clearance slot 30. 
Detent means designated generally by the reference character 34 are 
provided to quickly and easily locate the fence structure 18 rotatably in 
any of several preferred positions such as, for example, perpendicular the 
plane of the saw blade 20 and at 45.degree. angles right and left thereof 
by cooperation with either a central cup detent 36 or either of to offset 
cup detents 38 offset 45.degree. from the central detent 36. A pair of 
locking means designated generally by the reference character 40 are also 
provided for positively locking the fence structure 18 in a desired 
angular orientation. 
In addition to the upper work supporting surface 24, the cast base 
structure 12 further comprises a pair of side walls 42, a front wall 44 
and a rear wall 46, each depending therefrom with laterally outwardly 
extending feet 48 being integral with the lower edges of the walls 42, 44 
and 46 at the four corners for supporting the miter chop saw 10 on a 
table, or the like. Mounting apertures 50 are provided in each foot 48 to 
enable the miter chop saw 10 to be fastened in position. Projecting 
generally rearwardly of the rear wall 46 of the cast base structure 12 and 
forming an integral part thereof, there is provided a generally U-shaped 
channel portion 58 having a rear wall 60 generally parallel of the rear 
wall 46 and a pair of side wall portions 62 generally parallel the side 
walls 42 and extending upwardly above the plane of the work supporting 
surface 24 to define a pair of mounting ears forming a part of the 
circular saw mounting means 16. The adjustable stop means 32 is carried by 
the rear wall 60 and comprises a threaded stud 64 threadedly engaged 
through a threaded aperture 66 provided through the rear wall 60 so that 
the forward end of the threaded stud may be adjustably extended into the 
U-shaped channel 58 and a lock or jam nut 68 is provided to lock the 
threaded stud 64 in the desired position. 
As heretofore pointed out, the circular saw structure 14 is pivotally 
mounted, and the support means 16 therefore comprises a pin or pivot bolt 
70 extending through the side walls 62 and adjustably mounted therein so 
as to be adjustable in a first direction rotationally in a plane generally 
parallel said work support surface and in a second direction rotationally 
in a plane generally perpendicular said work support surface as will be 
hereinafter described and through a bore 72 extending through a boss 74 
integrally formed with a blade guard and motor supporting casting 76 
forming the main supporting structure of the circular saw structure 14. 
The blade guard casting 76 has an electric motor 78 mounted to one side 
thereof for driving the circular saw blade 20 and carrying a handle 
portion 80 for enabling the circular saw assembly 14 to be controlled, 
i.e., lowered for cutting action and raised slowly with the biasing means 
22. The blade guard casting 76 is generally open on the side thereof 
opposite the motor 78 and is closed by means of a generally flat sheetlike 
cover plate 82 held in position as by means of screws 84 passing through 
the cover plate 82 and threadedly engaged in threaded holes suitably 
provided in the blade guard casting 76. The cover plate 82 can therefore 
be removed, as necessary, for removal and replacement of the circular saw 
blade 20 as required. 
Integrally formed with the blade guard casting 76 generally on the opposite 
side of the mounting boss 74 there is provided generally downwardly 
extending crank arm 86, the rearward edge 88 of which may engage the 
inward end of the threaded stud 64 of the adjustable stop means 32 to 
limit the pivotal movement of the blade guard casting 76 and, therefore, 
of the circular saw assembly 14. The distal end portion of the crank arm 
86 is pivotally connected, as by means of a pin 90 to a control rod 92 
pulled by an actuating spring 94 to therewith define the biasing means 22. 
The control rod 92 extends through an aperture 96 provided in the rear 
wall 46 and the rearward end portion of the spring 94 bears against the 
rear wall 46 generally surrounding the control rod 92. The spring 94 is 
maintained under compression at the forward end portion by a thrust washer 
98 annularly mounted on the control rod 92 adjacent the forward end 
portion of the spring 94 and the thrust washer 98 is held in position by a 
thrust nut 102 installed on a threaded end portion 104 of the control rod 
92 and, in turn, locked in position by means of a jam or lock nut 106. 
As will be apparent, the tension applied to the control rod 92 by the 
compression spring 94 tends to rotate the crank arm 86 in a clockwise 
direction as seen in FIG. 4 thereby biasing the circular saw assembly 14 
to an upward, open position. 
The axle pin or pivot bolt 70 is provided with a nut 108 holding it axially 
in position and passes through the saw guard casting hub 72, both side 
walls 62, as well as four bearing washers 110, two washers being 
positioned on each side of a pair of thickened generally rectangular 
bosses 112 and 114 formed with, respectively, and extending generally 
upwardly from, each of the two side walls 62. The righthand end of the 
axle bolt 70 is vertically adjustable in the thickened boss 114 on the 
righthand side wall 62 while the lefthand end of the axle bolt 70 is 
horizontally adjustable within the thickened boss 112 on the lefthand one 
of the walls 62. Hence, the circular saw blade 20 may be aligned with the 
arcuate saw clearance slot 28 and to be perpendicular the work support 
surface 24. As shown in more detail in FIG. 4, the thickened portion 114 
of the righthand one of the side walls 62 is provided with a generally 
U-shaped recess 116 elongated in the vertical direction within which the 
axle or pivot bolt 70 is positioned and the axle bolt 70 is vertically 
adjusted therewithin by means of a compression spring 118 beneath the axle 
bolt 70 and an adjusting screw 120 passing downwardly through a hold down 
strap 122 attached to the thickened portion 114, as by means of a pair of 
cap screws 124. A lock or jam nut 126 is provided to hold the adjusting 
screw 120 in position. 
At the lefthand end, the axle bolt 70 is retained in position by a hold 
down strap 128 held in position by a pair of cap screws 130 and an 
aperture 132 elongated in a horizontal direction is provided which is 
larger than the axle bolt 70 permitting the axle bolt 70 to be at least 
laterally adjustable therewithin and a further plate 134 is provided 
having an aperture 136 which is a close fit around the axle bolt 70. The 
plate 134, in turn, is provided oversize horizontally elongated apertures 
138 enabling it to be affixed adjustably sideways on the lefthand side 
wall 62, as by means of cap screws 140. 
The work supporting surface 24 of the cast base structure 12 is provided 
with an arcuate groove 142 for guiding the fence structure 18. Through the 
base of the groove 142 the cast base structure 12 is also provided with an 
arcuate slot 144 through which a pair of carriage bolts, or the like, 146 
are provided as part of the locking means 40 for locating the fence 
structure 18 in a desired angular orientation. The slot 144 subtends about 
275.degree. so that the fence 18 may be rotated at least 45.degree. each 
side of center. Cooperating with the carriage bolts 146 are a pair of 
sleeves 148 and crown nut portions 150 which, when tightened on the 
carriage bolts 146 are effective to lock the fence structure 18 in a 
desired angular orientation. The fence structure 18 further comprises a 
generally semicircular base portion 152 provided with angular degree 
markings and there is also provided on the cast base structure 12 an 
indicator means 154 adjacent the periphery of the semi-circular portion 
152. It will be noted that the indicator means 154 and the angular degree 
markings are offset from the angle of the fence face 26 so as not to be 
obscured by the blade guard 14. The fence is also provided with at least 
one depending boss 158 riding in the groove 142 to guide the fence 
structure 18. Preferably, three bosses are provided about 90.degree. 
apart. The detent means 34 comprises a detent ball 160 held in a socket 
162 also holding a detent spring 164 provided in a detent bracket 166 
mounted to the cast base support structure, as by means of cap screws 168.