Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
i
CA 02372451 2003-O1-31
fa a 2.
Compact Sliding Compound Mitre Saw. g
F1E?sD OF THE INVENTION.
This invention relates to power tools intended to sever long mate-
rials in fiwo pieces for each cut. More particularly, the invention
will have its primary use in woodworking.
i i
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Compact Uliding Compound Mitre haw. Page 3.
BACKGHUUND OF THE ir~TEN'1'ION.
It is known in the art relating to woodworking that the smoothest
cut is obtained when the cutting teeth of the circular saw blade
exit the material at as small an angle as possible. Wood fibres
tend to tear out at the surface when the cutting teeth exit at lar-
ge angles and this problem is unacceptable for accurate finishing
work where appearance is paramount. '1'0 overcome this problem, the
sawblade must enter the flat lying piece of material from above,
and at the same time the circular blade rust be large enough to
complete the cut without having the teeth exit the material at a
large angle. At the same time the blade must be prevented from wob-
bling due to lack of support or due to lack of rigidity in the ma-
chine members controlling the planar motion of the blade, as well
as due to play in any supporting bearings controlling the planar
motion of the blade. '1'o accomodate these demands the existing "com-
pound mitre saw".was created. The saw mechanism is a compact direct
drive unit provided with a very rigid pivot arm, which is provided
v,~ith rugged and accurate pivot means at its far end, which in turn
is rigidly mounted to the surface which suppDrts the material to
be cut. '1'o prevent the material from moving while being cut, a ri-
gid "fence" is provided, against which the material is held by the
human operator; or the material may be clamped in place. '1'o allow
bevel cuts, the pivot means, above, itself is provided with a bevel
pivot means , the axial centerline of which lies on the centerplane
of the saw blade, as well as lying on the spacial extension of the
supporting surface for the material to be cut. 'This ensures that
the saw blade enters the same slot in the supporting surface. 'i'he
bevel pivot means is locked solid during a cut so that any play in
i
CA 02372451 2003-O1-31
compact Sliding compound Mitre Saw. g
pa a 4.
its mechanism is cancelled out in an effort to maintain accuracy of
the cut. To allow angle cute, known as "mitre" cuts in the ~.S.A.~
the supporting surface for the material to be Taut consists normally
in the form of a "rotunda", a rigid horizontal disc, rotatably mourn.
ted in a main table, and locked during a cut. 'j'he vertical axis of
rotation for the rotunda lies approximately under the center of the
saw blade to allow for the same capacity of the cut whether a right
hand or left hand mitre cut is made. 'lhe above fence spans across
the rotunda without contacting it, and is rigidly fastened to the
main table at esoh end, where the main table protrudes sideways
from the rotunda. while all the above accomodations to ensure
"cleanliness" and accuracy of cut, so paramount in finishing work,
have admirably been met in the existing art, the next most impor-
tant asset of the art, compactness and light weight, did not go un-
noticed to woodworkers engaged in other than finishing woodwork,
where rough cute due to fibre breakout are not objectionable. '1'he
problem was that previously existing units did not have enough
cross cut capacity. 'To accomodate this new demand for greatly incre-
ased cross cut capacity, the sliding compound mitre saw was created
in two known forms, In one form, the rotunda is provided with two
horizontal axial bearings, parallel to each other and parallel to
the centerplane of the saw blade. Slideably disposed in said bear-
ings are a pair of rigid steel tubes extending backwards and suppor-
ting the normal conventional bevel pivot boss at the far ends mutu-
ally. 5sid'boss in turn supports the conventional pivot arm pivot
and thus the pivot arm and saw mechanism, with the pivot arm longer
than those on non-sliding saws, to allow for a greater throat depth.
'Throat depth in the case of machines as described herein, is the
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Compact Sliding Compound Mitre Saw. gage 5.
distance from the edge of the material to be cut nearest to the hu-
man operator, to the vertical obstruction composed by the bevel pi-
vot boss and its upward extending pivot arm pivot tower. 'This full
throat depth cannot be utilized because the bevel pivot boss and pi-
vot arm pivot tower arc toward the human operator against the back-
side of the fence when the rotunda is adjusted for a mitre or com-
pound cut; it is also for this reason that the fence is located well
forward of the bevel pivot boss. Since sliding action causes fibre
breakout at the cut, the operator does not use it to cut finishing
lumber; instead the saw is located above the material and simply
brought down into the material as in conventional saws of this kind,
with only the extra precaution required of holding the handle of the
saw extra securely and firmly to prevent the saw from dumping for-
ward towards the operator. Except for this extra prea~aution,.and for
the extra flexibility of the sliding tubes and any play in the axial
bearings, fmr the sliding tubes, thus creating a greater w potential
for inaccuracy of the cut, the sliding compound mitre saw retains
the primary advantage of the conventional compound mitre saw, namely
the ability to bring the blade down into the material with less
tendency for fibre breakout. In the second known form of the sliding
compound mitre saw, the conventional location for the bevel pivot
boss , that is directly mounted on the backside of the rotunda, is
retained. ~1'his boas is provided with a pair of mutually connected
backward extending and slightly upward pointing arms, at the end of
which a pair of parallel oriented axial bearings is provided; said
bearings axially also parallel to the centerplane of the saw blade.
Disposed slideably in these bearings is a pair of slide tubee~ at
the near end of which a conventional pivot arm pivot is provided.
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Compact Sliding Compound nitre Saw. Page 6.
~'or the rest of a descriptions everything said above for the first
form o~ a sliding compound mitre saw applies.
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Compact Sliding Compound Mitre Saw. Page 7.
SUMMARY OF THE 1NVENT10AT.
'The present invention provides a sliding compound mitre saw having
two primary advantages over the known existing art as described
above, namely~ a pair of slide tubes is provided which do not extend
backward from a ro~bunda, if a rotunda is used, thus providing for a
more compact overall machine while in the rest position; and, sec=
ondly, the axial bearings, disposed on said tubes, and allowing for
the required sliding motion of the saw blades have a rigid relati-
onship geometrically to the center of the saw blade, and by being
located close to said center, are creating less bending moment,
due to the weight of the saw mechanism and due to reaction forces
acting on the saw blade while in use. Zees bendingmoment on said
bearings avoids stiction, allows smaller shorter bearings, and en-
sures greater accuracy of the cut, with any play not magnified by
an ever longer moment arm as is the case with the existing art in
which the saw mechanism is displaced relative to the azial bearings.
'These and other features and advantages of the invention will be
more fully understood from the following description of several
preferred alterriatitre embodiments taken together with the accompa-
nying drawings.
CA 02372451 2003-O1-31
Compact Sliding compound rjitre Saw. page 8.
BRIEF DESCRIPTION OF THE DRAWINGS.
the following definitions apply for the terms used in this disclo -
sure. A "saw" is a etrcular blade mounted on a rotating shaft, the
"arbor", capable of severing, named the "cut", a piece of materi-
al in two pieces, the whole piece being the "cut member". ~1'he arbor
has a gear at one end, which is driven by a pinion gear on the mo-
tor; this arrangement is a "direct drive". The cutting members on
the circumference of the saw are the "teeth", but alternatively may
be abrasives when cutting metals. The spacial extension in line
with the centerplane of the saw is the "plane", or if descriptive
of in-line motion of said plane, is "planar". vertical displacement
of the plane is "chopping", while horizontal displacement in-line
1s "sliding". The housing supporting the arbor and enclosing the
gears is the "gearbox". The horizontal surfaces defining a cut mem-
ber are the "top" and "bottom" while the vertical surfaces are the
"far" and "near" edges, with far and near relating to the location
of the human operator. "Forward" motion means motion towards the
human operator, and ."backward" motion means motion away from said
operator.If a cut is square to all surfaces of the cut member, it
is a "straight" cut. if square to the top and bottom, but not to
the edges, it is a "mitre" cut. If square to the edges, but snot
to the top and bottom, it is a "bevel" cut. If neither square to
top and bottom nor the edges, it is a"compound"cut. '1'he motion of
the saw is limited to circular and planar by machine members. Chop-
p~ng motion is rigidly controlled by a "pivot arm', an approxima-
tely horizontal longitudinal rigid machine member extending back
wards from the gearbox, rigidly attached to same, and provided with
g horizontal axis "pivot arm pivot", parallel to the arbor, at the
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compact Sliding Compound Mitre Saw. gage 9.
far end. The arbor and saw travel through an arc about said pivot
arm pivot during cutting and caused by the human operator. '1'he pi-
vor arm pivot is supported in the top of a vertical "pivot arm pi-
vot tower", which has a second pivot at the bottom end, said second
pivot being the "bevel pivot" and having a longitudinal centerline
which is parallel to the centerplane of the saw, said l~gitudinal
centerline or "aria" closely in line with, or in line with, the sup-
porting surface on the machine for the bottom of the cut member.
Said bevel pivot supported in and by a "bevel pivot boss" and rigi d
1y locked to said boss during a cut. The bevel pivot boss may be dis--
rectly attached rigidly to the support surface for the cut member,
in a conventional machine, or, alternatively, may be rigidly atts..
eked to the far ends of a pair of "slide rails" controlling eliding
motion of the saw, if used. ~y arranging the long axis of the bevel
pivot to lie on both the centerplane of the saw as well as on the
special extension of the support surface, the saw enters said sup
port surface always in the same "slot" regardless of bevel ad3ust-
ment, making for a simpler usage of the machine. if above mentioned
slide rails are deployed in the design of the machine, with the be-
vel pivot boss rigidly attached to the far ends of said rails, a
first arrangement of existing art is arrived at, In this case the
slide rails are axially slideably disposed in a pair of a~d.al bea-
rings, installed rigidly on the bottom of the euppart surface for
the cut member. Alternatively, in a second arrangement of existing
art, the bevel pivot boss is rigidly attached to the backward edge
or near the backward edge, of the support surface for the cut mem-
ber, se is the case with conventional arrangement of the art. howe-
ver, in this ease, the bevel pivot boas is provided with a pair of
CA 02372451 2003-O1-31
Compact Sliding Compound rlitre Saw. rage 10.
upward and backward extending arms, in the top end of which are dis-
posed a pair of axial bearings, with their long axis parallal to
the centerplane of the saw. Supported within these axial bearings
are a pair of parallel slide rails, slideably disposed. Rigidly at-
tached to the forward end of said aliderails is a pivot arm pivot
tower, which in tern supports the pivot arm and gearbox in the con-
ventional manner. In both cases of the existing art of sliding com-
pound mitre saws the pivot arm is longer than in the conventional
arrangement, to create a deeper "throat depth", necessary to acco-
moc~ate the wider lumber for which these saws are intended. "Throat
depth" is the horizontal distance between the near edge of the cut
member and the vertical obstruction created 'by the pivot arm tower.
hut this throat depth cannot be fully exploited because the conven-
tional supporting surface for the cut member is a "rotunda", a flat
horizontally disposed circular disc, provided with a "rotating- wit-
hin-limits" support means, having a vertical axis of rotation which
lies close ~co the center of the saw. Since the pivot arm pivot tower
arcs about the vertical axis of rotation of the rotunda, said tower
moves forward when adjusting the rotunda for a maximum mitre cut,
bringing said tower against the backside of a transversely arranged
"fence", a barrier spanning across the rotunda and rigidly attached
to the "main table", said fence location within the "throat" of the
machine thus limiting the useable portion of the throat depth. ~1'he
fence has the dual function of keeping the cut member safely in pla-
ce during cutting, as well as forming the reference surface for the
degree of ni~~fie cut. The main table form8 the base of the machine,
rotatably-within-limits supporting the rotunda, providing support
for the locking means of the rotunda, and having laterally extending
CA 02372451 2003-O1-31
Yage 11.
Compact Aiding compound r'~itre haw.
swings" which have upper surfaces flush with the upper surface of
the rotunda, providing additional support for the cut member. The
"handle" is an attachment, rigidly mounted on the gearbox opposite
the pivot arm, which the operator grips firmly to bring the saw
down and through the cut. "Counter balance bias means" is a flexi-
ble force means, constantly acting, of enough strength to keeep the
saw mechanism suspended in the highest possible position allowed by
"travel stops" on the pivot arm pivot, said travel stops limiting
the upper and lower position of the saw, the lower position designed
to provide for maximum overall cutting capacity of the saw. The axis
of rotation is the "long Axis". 'lhe generic name for a complete saw
of the kind described is a "sliding pivot arm saw", since all combine
ne the motion of an arc provided by a pivot arm with the ability, if
desired, to move the saw linearly. The complete package of saw and its
its drive is the "saw mount". The combined ability of a mitre and a
bevel cut makes the complete saw a "sliding pivot arm compound mitre
saw"; if bevel cut ability is excluded, the saw is a "sliding pivot
arm mitre saw". Just like the long axis of the bevel pivot lies on
both the centerplane of the saw as well as on the spatial extension
of the support surface for the cut member, to ensure that the saw
always enters the same clearance slot in the said support surface,
regardless of bevel adjustment, so does the vertical axis of rotati-
on for the rotunda lie on the centerplane of the saw as well as on
the spatial extension of the working face of the vertical fence, to
ensure that the saw always enters the same clearance slot in said
working surface of the fence, regardless of mitre adjustment. laid
clearance slot in the fence creates a left "wing" and a right wing
CA 02372451 2003-O1-31
Compact Sliding Compound Mitre Saw. rage 12.
of the fence, said wings tied rigidly together by a horizontally
lying , crescent shaped, "fence bridge".
BRIEF DESCRIPTION OF THE DRAWINGS, ( Continued.)
FIG.1 is a simplified cross section, vertically taken, of the first
form of the existing art.
FIG. 2 is the same as above, of the second form of the existing art.
In both cases, the stroke of the sliding rail system has been incre-
ased from known embodiments to accomodate the cutting of a 2 inch by
14 inch size cut member, with drawings made to scale for better comv~-
parison purposes.
F1G. 3 is a plan view of the embodiment of Fig. 2, to clarify the
relationship between the components making up a typical embodiment
of the known existing art.
CA 02372451 2003-O1-31
rage 13 .
Compact 511ding Compound Mitre Saw.
FIG. 4 is a vertical cross section, taken on the centerplane of the saw,
showing
y the main novel fe~ure of the invention, namely two cantilevered rigidly
mounted
slide rails attached at their backward ends to a vertical extension of the
bevel
pivot, the bevel pivot tower, and provided with a pivot arm carriage,
slideably
'mounted on the fixed slide rails, form which the saw unit is suspended via a
con-
ventional pivot arm rigidly attached to the gearease of the direct drive. This
embodiment has also many of the advantages of the convaritional radial arm
saw.
FIG. 5 is a cross section, of the novel pivot arm carriage having outboard
linear
axial bearings slideable mounted on fixed cantilvered slide rails, also
showing
the carriage clearance , in this case 3~ inches, in the 45 degrees bevel
position,
in phantom outline, all taken on a plane labelled A A in Fig. 4. It is
understood
that normally dimensional relationships, even if novel, do not affect
patentability,
but in the case of tools like sliding compound mitre saw, component
relationships
p~"ticularly dimension wise, effect marketability greatly, since compactness
is a
prime prerequisite for postable tools; p~tability is the key and any serious
pro-
trusions are a detrim~t. In this vinvention, the slide rails do not protruele
be-
yond the envelop size required to complete the cut. All figures are drawn to
scale
and for the identical capacity of 14 inches wide materials
FIG. b_ is three views of a means to provide elevating. ~ ability for the
slide rails
in order to provide for a greater range of partial depth cuts than is possible
for
the eanbodiment of Fig. 4.
FIG. 7 is a cross section taken on the centerplane of the circular saw, of the
pre
y (erred emboduaent of the invention, with the fixed slide rails on the
opposite side
of the direct drive unit. This allows the saw to be raised to any position
desired.
FIG. 8 is a plan view of the embodiment of Fig. 7~ labelled B H in Fig. 7.
FIG. 9 is a cross section taken on the long vertical plane of the saw and
labelled
A A in Fig. 7
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Compact Sliding CoMpound Mitre Saw. gage 140
DESCRIPTION OF THE PREFERRED EMBODIMENTS.
Turning now to FIG. 4. there is shown a vertical cross section, taken
an the centerplane of saw 12, of a preferred embodiment of the invea~tion.
Sliding
~~compound mitre saw 10 includes a saw t ' 11, a circular saw 12, a rigidly
attached ( to saw mount .~ 11,) pivot arm 13, a pivot arm pivot 14, a pivot
arm
carriage 15, slideably mounted on cantilevered forward pointing rigidly
attached
slide rails 20 via outboard mounted integrally attached linear axial bearings
31,
having downward oriented ears to pick up pivot arm pivot 14 in a manner which
al,'~
lows true planar travel within limits for saw 12 only. Counter balance spring
means 33 is strong enough to lift the saw assembly to the high rest position
shown in phantom outlines while chop travel limit stops 35 prevents saw 12
from p~etrating the support surface for cut meber 19 beyond an optimum depth.
From the high rest position the saw must be brought down, by pushing handle
36, to a level whereby the top surface of saw mount 11 3ust slides underneath
the free forward ends of slide rails 20, at which level this embodiment has a
3~ inch ma,~dmum capacity, which is also the maximum capacity of the 10 inch
dia.
saw blade shown, Unlike known existing art in some cases, the invention
therefo-
re does not reduce the capacity of the saw blade. Similarly, when the saw is
ad-
3ust~1 for a ma~d.mum bevel of 45 degrees, saw carriage 15 clears the working
sur-
face by 3~ inches, as shown in phantom outline in Fig. 5. Returning now to
Fig. 4
slide rails 20 are press fitted in the top end of pivot arm tower 3?, which is
approximately symmetrically disposed above bevel pivot ring 38, which may
rotate
within limits about bevel pivot 16, which has an axis of rotation or long axis
which lies on the centerplane of saw 12 as well as lying on the spacial
extension
of the working surface of the saw, This ensures that saw 12 always enters or
pe-
netrates said working surface in the same clearance slot. ~_Pivot arm tower 3?
is manually locked rigid to the working surface by tightening screw clamping
means 1?~ which is prevented from being loosened too far by a locknut on pivot
16 as shown. Bevel pivot ring 38 mates with and engages a matching machined
planar surface on bevel pivot boss 18~ which is rigidly attached to rotunda2l.
Said rotunda is a round hat-like structure, with a flat circular top surface,
the working surface of the saw for supporting cut meanber 19, and has an
integral
clearance channel for saw 12 for all situations, clearance channel 41; circum-
ferential side wall 42 has a machined bottom edge which acts as a planar
bearing
23, engaging a matching radial plane surface in main table 24, the base for
the
machine. Rotunda 21 may rotate within limits about rotunda pivot 22, supported
CA 02372451 2003-O1-31
Compact Sliding Compound Mitre Saw, gage i~
in ce3~trsl pivot boss 45~ and is locked to ioain table 24~ after ad3ustment
for
mitres by rotunda lock 25. The long saris of rotunda pivot 22 lies on the
center~
plane of saw 12 as well as lying on the ~pacial extension of the working face
of
fence 26~ which fence spans across the rotunda with its ends rigidly attached
t0
'. the le~~t wing 29 and right wing 30 of main table 24, The axis location for
rotun
da pivot 22 ensures that saw 12 always enters the same clearance slot in fence
26 ; this slot divides fence 26 in a left wing 27 and a right wir:g 28~ which
are
rigidly connected together by fence bridge 28A; refer briefly to Fig. 5 for
cla-
rity, Pivot arm carriage 15 is prevented fry running off slide rails 20 by sli-
de rail end stop 32. Phantom outline 39 is the saw in the high rest position
while phantom outline 40 is pivot arm carriage 15 in the 45 degree bevel
positi-
on. All figures in this disclosure show embodiments sized for a capacity of 14
inches of width for cut member 19' and are drawn to scale for comparison
purposes.
Turning now to FIG. 5~ there is shown a cross section labelled A A
in Fig. 4~ showing the relationship of the numbered components relative to saw
12 and rotunda 21. The above description of the numbered components applies.
It
should be noted that on occasion the sliding compound mitre saw is used with
the
pivot arm in a locked partially raised position in order to cut a slot of con-
stant depth in the material. The embodiment of the invention as shown in Fig's
4 and 5 to scale may readily be used for such purposes by installing a 6 inch
saw blades which gives a 2 inch gap btween the bottom edge of the blade and
the
decks with the saw in the highest sliding position. If this is deemed insuffi-
cient from market studies .pivot arm. tower 37 may be made taller by a small
amounts or readilg lends itself to incorporate a linear elevating device at
the
manufacturing lever which will have additional market appeal. A pref erred
embo-
diment of such a modification is shown in FIG. 6~ and is designed to be
unobstru-
sive and simple to manufacture. - Pivbt arm tower 37 is horizontally split in
two
halves bevel pivot ring 38 and elevating pivot arm. tower 43. Each is provided
with suitable cast in place bosses to accomodate two elevating guide rods 44
and
elevating screw 46. Guide rods 44 are press fitted in their bosses in the.
lower
half of pivot arm tower 37, while the they are precision slideably disposed in
four bosses integral with the upper half. Said lower half is provided with a
ver-
tical cast in place threaded sleeve betwaen the guide rods to engage elevating
screw 46, which is provided with two collars preventing any linear travel of
the
screw in its hole in the upper half of pivot arm tower 37.
Turning now to FIG. 7~ there is shown a cross section of the preferred
embodiment
of the inventions taken on the cesZterplane of the saws except for the slide
rails
j
CA 02372451 2003-O1-31
Compact Sliding Compound Mitre Saw, Page 16,
°and pivot arm carriage, for which a sideview in the same direction as
the rest of
the drawing is shown. The description and numerals given for Fig. 4 applies
except
as follows: slide rails 20 are in a stacked arrangement on the side of
circular saw
~12 on the opposite side of a~~r.mount 1l. This has the advantage over the
eutbodiment
of Fig. 4 of allowing saw mount 11 to be raised to any position desired within
lime
mits~ and be locked in a raised position by adjusting a screw in chop travel
limit
stop 35. This makes limited depth cuts simple. Pivot arm 13 is pivotably
mounted on
an outboard extension of pivot arm carriage 15, which simply comprises a pair
of
sleeves for mounting linear axial bearings 31~ said sleeves connected together
by
an integral web and having an outboard mount for pivot arm pivot 7.1,.~ as
shown in
Fig. B. In addition to theeadvantage described above this embodiment has the
advan-
tage of allowing a robust bridges slide rail end stop 32~ to rigidly connect
the
ends of slide rails 26 together for improved overall:°i~igidity of
linear guidance
means for carriage 15.
The inventive concepts need not use rotunda 21, which may be an
integral part of main table 2t~. To enable mitre cuts, fence 26 may be
provided
with a vertical axis to allow it to rotate 3.n a horizontal plane. An
invention
to place that axis on the centerplane of saw 12 as well on the spatial
extension
of the working face of the fences is the subject of a sepzrate patent
applicati-
on by this inventory with the advantage already explained, Similarly, bevel pi-
vot 16 may be eliminated for application rot requiring the ability to cut
bevels,
Accordingly while the invention has been disclosed by reference to specific
pre-
ferred ~bodiments~ it should be understood that numerous changes could be made
within the scope of the inventive concepts disclosed, accordingly the
invention
is not intended to be limited by the disclosures but rather to have the full
sco-
pe permitted by the language of the following claims.
