U.S. patent application number 11/714981 was filed with the patent office on 2007-07-05 for power miter saw with hinge linkage linear guides.
Invention is credited to Stephen C. Oberheim.
Application Number | 20070151434 11/714981 |
Document ID | / |
Family ID | 37763988 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070151434 |
Kind Code |
A1 |
Oberheim; Stephen C. |
July 5, 2007 |
Power miter saw with hinge linkage linear guides
Abstract
A power miter saw comprises a saw base having a fence for
positioning a work piece, a table rotatably connected to the saw
base; a miter arm assembly for angularly positioning the table
relative to the saw base, a saw blade and motor assembly
operatively connected to the table, a linear guide mechanism
attached to the table and being configured to support the saw blade
and motor assembly and enable movement of the assembly along a
predetermined linear path in either forward or rearward directions,
the mechanism having a horizontal shaft about which the assembly is
pivotable to move a saw blade vertically into and out of cutting
position, the mechanism also having a multiple link hinge pivotally
interconnecting the motor assembly and the table with generally
horizontal shafts that are parallel to one another.
Inventors: |
Oberheim; Stephen C.; (Des
Plaines, IL) |
Correspondence
Address: |
GREER, BURNS & CRAIN, LTD.;Suite 2500
300 South Wacker Drive
Chicago
IL
60606
US
|
Family ID: |
37763988 |
Appl. No.: |
11/714981 |
Filed: |
March 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11284931 |
Nov 22, 2005 |
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11714981 |
Mar 7, 2007 |
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Current U.S.
Class: |
83/581 ;
83/471.3; 83/490 |
Current CPC
Class: |
B23D 45/048 20130101;
Y10T 83/7705 20150401; Y10T 83/7763 20150401; Y10T 83/7768
20150401; B27B 5/208 20130101; Y10T 83/7772 20150401; Y10T 83/7788
20150401; Y10T 83/8773 20150401; Y10T 83/7697 20150401 |
Class at
Publication: |
083/581 ;
083/471.3; 083/490 |
International
Class: |
B26D 5/08 20060101
B26D005/08; B27B 27/06 20060101 B27B027/06 |
Claims
1. A power miter saw comprising: a saw base having a fence for
positioning a work piece; a table rotatably connected to said saw
base; a miter arm assembly for angularly positioning said table
relative to said saw base; a saw blade and motor assembly
operatively connected to said table; a linear guide mechanism
attached to said table configured to support said saw blade and
motor assembly and enable movement of said assembly along a
predetermined linear path between forward and rearward positions
and having a first pivot axis perpendicular to the plane of said
saw blade about which said saw blade and motor assembly is
pivotable to move a saw blade into and out of cutting position;
said mechanism comprising a saw pivot head in which said first
pivot axis is provided, a first multiple link hinge comprising two
hinge links that are pivotally connected together and to said pivot
head and said table with pivot axes that are parallel to one
another and to said first pivot axis; at least one of said pivot
axes comprises an elongated shaft that is supported at opposite end
portions, each end portion having a ball bearing with an inner race
mounted in one of said links, said pivot head and said table, an
outer race mounted in another of said links, said pivot head and
said table and balls positioned between said inner race and said
outer race.
2. A power miter saw as defined in claim 1 wherein said links have
a predetermined width and thickness that substantially inhibits
bending and twisting of said hinge, at least one of said links
having a predetermined width that approximates the length
thereof.
3. A power miter saw as defined in claim 1 wherein said elongated
shaft has a first end portion bearing against the outside of said
inner race and a nut threaded on the opposite end of said shaft
bearing against the outside of said inner race of the other ball
bearing, whereby tightening of said nut causes said inner races of
both ball bearings to be moved toward one another to reduce play in
said ball bearings.
4. A power miter saw as defined in claim 1 wherein said elongated
shaft is located in an aperture in a tongue portion of one of said
links, said pivot head and said table, said saw further comprising
at least one member secured in said tongue portion for contacting
said shaft to prevent any movement of said shaft relative to said
tongue portion.
5. A power miter saw as defined in claim 1 wherein said mechanism
further comprises a second multiple link hinge pivotally
interconnecting said assembly and said table with pivot axes that
are generally parallel to one another and perpendicular to said
first pivot axis.
6. A power miter saw as defined in claim 5 wherein said second
multiple link hinge comprises two hinge links that are pivotally
connected together and to said pivot head and said table by said
pivot axes, a first hinge link having a first end connected to said
table and a second end connected to a second hinge link, said
second hinge link having a first end connected to said pivot head
and a second end connected to said second end of said first hinge
link
7. A power miter saw as defined in claim 6 wherein said first end
of said first hinge link is closer to the plane of the top surface
of said table than said second end, said first and second ends of
said second hinge link being substantially the same distance from
the plane of the top surface of said table.
8. A power miter saw as defined in claim 6 wherein said pivot axes
of said second multiple link hinge comprises an elongated shaft
that is supported at opposite end portions, each end portion having
a ball bearing with an inner race mounted in one of said links,
said pivot head and said table, an outer race mounted in another of
said links, said pivot head and said table and balls positioned
between said inner race and said outer race.
9. A power miter saw as defined in claim 8 wherein said elongated
shaft has a first end portion bearing against the outside of said
inner race and a nut threaded on the opposite end of said shaft
bearing against the outside of said inner race of the other ball
bearing, whereby tightening of said nut causes said inner races of
both ball bearings to be moved toward one another to reduce play in
said ball bearings.
10. A power miter saw as defined in claim 1 wherein the angle
between said two interconnected hinge links of at least said first
multiple link hinge is less than a threshold angle of approximately
130 degrees to substantially remove toggling.
11. A power miter saw as defined in claim 10 wherein said angle
between said two interconnected hinge links comprises the angle
between said pivot axis interconnecting said hinge links and the
pivot axis on the opposite end of each link.
12. A power miter saw as defined in claim 11 wherein toggling
requires an appreciable additional force to initiate movement of
said saw blade and motor assembly from said extended position to
said retracted position.
13. A power miter saw comprising: a saw base having a fence for
positioning a work piece; a table rotatably connected to said saw
base; a miter arm assembly for angularly positioning said table
relative to said saw base; a saw blade and motor assembly
operatively connected to said table; a linear guide mechanism
attached to said table configured to support said saw blade and
motor assembly and enable movement of said assembly along a
predetermined linear path between forward and rearward positions
and having a first pivot axis perpendicular to the plane of said
saw blade about which said saw blade and motor assembly is
pivotable to move a saw blade into and out of cutting position;
said mechanism comprising a saw pivot head in which said first
pivot axis is provided, a first multiple link hinge comprising two
hinge links that are pivotally connected together and to said pivot
head and said table with pivot axes that are parallel to one
another and to said first pivot axis; wherein the angle between
said two interconnected hinge links of at least said first multiple
link hinge is less than a threshold angle of approximately 130
degrees to substantially remove toggling.
14. A power miter saw comprising: a saw base having a fence for
positioning a work piece; a table rotatably connected to said saw
base; a miter arm assembly for angularly positioning said table
relative to said saw base; a saw blade and motor assembly
operatively connected to said table; a linear guide mechanism
attached to said table configured to support said saw blade and
motor assembly and enable movement of said assembly along a
predetermined linear path between forward and rearward positions
and having a first pivot axis perpendicular to the plane of said
saw blade about which said saw blade and motor assembly is
pivotable to move a saw blade into and out of cutting position;
said mechanism comprising a saw pivot head in which said first
pivot axis is provided, a first multiple link hinge comprising two
hinge links that are pivotally connected together and to said pivot
head and said table with pivot axes that are parallel to one
another and to said first pivot axis, and a second multiple link
hinge comprising two hinge links that are pivotally connected
together and to said pivot head and said table with pivot axes that
are generally parallel to one another and perpendicular to said
first pivot axis; wherein said pivot axes of said first and second
multiple link hinges comprise an elongated shaft that is supported
on opposite ends.
15. A power miter saw as defined in claim 14 wherein said two hinge
links comprise a first hinge link having a first end connected to
said table and a second end connected to a second hinge link, said
second hinge link having a first end connected to said pivot head
and a second end connected to said second end of said first hinge
link
16. A power miter saw as defined in claim 15 wherein said first end
of said first hinge link is closer to the plane of the top surface
of said table than said second end, said first and second ends of
said second hinge link being substantially the same distance from
the plane of the top surface of said table.
17. A power miter saw comprising: a saw base having a fence for
positioning a work piece; a table rotatably connected to said saw
base; a miter arm assembly for angularly positioning said table
relative to said saw base; a saw blade and motor assembly
operatively connected to said table; a linear guide mechanism
attached to said table configured to support said saw blade and
motor assembly and enable movement of said assembly along a
predetermined linear path between forward and rearward positions
and having a first pivot axis perpendicular to the plane of said
saw blade about which said saw blade and motor assembly is
pivotable to move a saw blade into and out of cutting position;
said mechanism comprising a saw pivot head in which said first
pivot axis is provided, a first multiple link hinge comprising two
hinge links that are pivotally connected together and to said pivot
head and said table with pivot axes that are parallel to one
another and to said first pivot axis, and a second multiple link
hinge comprising two hinge links that are pivotally connected
together and to said pivot head and said table with pivot axes that
are generally parallel to one another and perpendicular to said
first pivot axis; wherein said second multiple link hinge comprises
a first link oriented at an angle and having a lower first end
connected to said table with a vertical pivot axis having a first
elongated shaft and a second higher end connected to a first end of
a second link with a vertical pivot axis having a second elongated
shaft, said second link being connected to said pivot head with a
vertical pivot axis having a third elongated shaft; at least said
first and second elongated shafts being supported on opposite end
portions.
18. A power miter saw as defined in claim 17 wherein said second
link is generally parallel to the plane of the top of said
table.
19. A power miter saw as defined in claim 17 wherein said two hinge
links of at least said first multiple link hinge are pivotally
interconnected by said pivot axis and said hinge is movable when
said saw blade and motor assembly is moved along said predetermined
path between an extended position and a retracted position, the
angle between lines of action through said pivot axes of said
interconnected hinge links being less than a predetermined angle to
prevent toggle action of said hinge.
20. A power miter saw as defined in claim 19 wherein said
predetermined angle is approximately 130 degrees.
Description
[0001] This is a continuation-in-part of Ser. No. 11/284,931 filed
Nov. 22, 2005.
BACKGROUND OF THE INVENTION
[0002] The present invention generally relates to power miter and
abrasive cut off saws.
[0003] Miter saws have been the subject of continued research and
development efforts in the power tool arena for decades, and many
improvements have been made that has resulted in increased ease of
use and productivity. Artisans who install trim carpentry have used
power miter saws for some time and it is well known that wide stock
such as crown molding and the like often requires a miter saw with
either a bigger saw blade or a configuration that enables the blade
to be moved along a horizontal path away and toward the fence of
the miter saw. Such blade moving configurations are generally
marketed as sliding compound miter saws, principally because most
if not all commercially available saws of this type have a sliding
guide assembly comprised of elongated rods that slide in respective
bushings to move the saw blade and motor assembly relative to the
fence of the saw.
[0004] Such sliding guide assemblies are an expensive component of
such miter saws. The current state of the art for such sliding
miter saws includes a linear guide that typically consists of two
of such bushings and rod combinations. These relatively expensive
linear bearings consist of recirculating ball bearings that operate
together with turned, ground, polished and hardened steel rods that
are approximately 40 cm long and 30 mm in diameter. To have minimum
play and deflection of the saw blade and motor assembly, precise
fits are required between the rods and the linear recirculating
ball bearings over the entire linear travel of the rods. The rod
must be made of a high hardness steel to prevent indentation by the
hard steel balls. Such construction is relatively expensive.
[0005] Additionally, an undesirable feature of such bushing and rod
linear guides is that space must be provided behind the saw for the
rods to extend when the saw blade is positioned near the fence.
Because of this space requirement, such a sliding saw cannot be put
next to a wall which results in a larger footprint being occupied
by such a saw. Additionally, these bushings and rod linear guide
mechanisms are susceptible to damage from dirt and grit,
particularly if the saw is a sliding abrasive cut off saw where an
abrasive wheel is used to cut steel and other materials. The
abrasive wheel grinds its way through the steel and produces a
considerable volume of abrasive particles that generally come out
of the back of the saw. These abrasive particles can penetrate into
the ball bushings and damage the bearing. While it is possible to
cover the rods with a bellows or similar cover, the hostile
environment generally leads to degradation of the fabric and
penetration of the ball bushing by the abrasive particles.
[0006] There is a continuing need for improvement in the design and
development of miter and cut-off saws that have linear guide
assemblies.
SUMMARY OF THE INVENTION
[0007] A power miter saw comprises a saw base having a fence for
positioning a work piece, a table rotatably connected to the saw
base; a miter arm assembly for angularly positioning the table
relative to the saw base, a saw blade and motor assembly
operatively connected to the table, a linear guide mechanism
attached to the table and being configured to support the saw blade
and motor assembly and enable movement of the assembly along a
predetermined linear path in either forward or rearward directions,
the mechanism having a horizontal shaft about which the assembly is
pivotable to move a saw blade vertically into and out of cutting
position, the mechanism also having a multiple link hinge pivotally
interconnecting the motor assembly and the table with generally
horizontal shafts that are parallel to one another.
DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a right side perspective view of a first preferred
embodiment of the present invention, particularly illustrating the
saw blade being located in the extended position away from the
fence;
[0009] FIG. 2 is a right side perspective view of the embodiment
shown in FIG. 1, but illustrating the saw blade in a position near
the fence;
[0010] FIG. 3 is a side elevation of the embodiment shown in FIG. 1
with the saw blade in the extended position away from the
fence;
[0011] FIG. 4 is a rear view of the embodiment shown in FIG. 1,
with the saw blade away from the fence;
[0012] FIG. 5 is a right front perspective view of a second
preferred embodiment of the present invention, particularly
illustrating the saw blade being located in the extended position
away from the fence;
[0013] FIG. 6 is a right front perspective view of the embodiment
shown in FIG. 5, but illustrating the saw blade in a position near
the fence;
[0014] FIG. 7 is a side elevation of the embodiment shown in FIG. 5
but illustrating the saw blade in a position near the fence;
[0015] FIG. 8 is a rear view of the embodiment shown in FIG. 5,
with the saw blade in a position away from the fence;
[0016] FIG. 9 is a third preferred embodiment of the present
invention, particularly illustrating the saw blade being located in
the extended position away from the fence;
[0017] FIG. 10 is a side elevation of the embodiment shown in FIG.
9 with the saw blade in the extended position away from the
fence.
[0018] FIG. 11 is another side elevation of the embodiment shown in
FIG. 9, with the saw blade near the fence; and
[0019] FIG. 12 is a rear view of the embodiment shown in FIG. 9,
with the saw blade located away the fence;
[0020] FIG. 13 is a perspective view of the right side of a fourth
preferred embodiment, with the blade and motor assembly in an
extended and lowered position;
[0021] FIG. 14 is a perspective view of the left side of the fourth
preferred embodiment, with the blade and motor assembly in a
retracted and lowered position;
[0022] FIG. 15 is a right side view of the fourth preferred
embodiment, with the blade and motor assembly in an extended
position;
[0023] FIG. 16 is a right side view of the fourth preferred
embodiment, with the blade and motor assembly in the retracted and
lowered position;
[0024] FIG. 17 is a left side view of the fourth preferred
embodiment, with the blade and motor assembly in the extended and
lowered position;
[0025] FIG. 18 is a top view of the fourth preferred embodiment,
with portions removed to illustrate the vertically oriented hinge
linkage; and
[0026] FIG. 19 is a detailed plan view, partially in section,
illustrating the construction of one of the pivot connections that
are utilized in the fourth preferred embodiment.
DETAILED DESCRIPTION
[0027] Four embodiments of the present invention are shown and
described herein, with the each of the embodiments having a
multiple hinge linkage that is designated herein as a horizontal
hinge linkage that interconnects the saw blade and motor assembly
to the table of the miter saw. It should be understood that while
it is referred to herein as a generally horizontal hinge linkage,
the several shafts of the linkage may not always be exactly
horizontal, and may have a pivot axis that can vary up to about 30
degrees in either direction from exact horizontal. However, it is
preferred that the axes be in a substantially horizontal
orientation when the saw is set at a zero degree bevel position.
Regardless of the bevel angle or the orientation of the surface on
which the saw is supported, the shafts are preferably substantially
parallel to the arbor shaft in which the blade is mounted and
therefore substantially perpendicular to the plane of the saw
blade.
[0028] The horizontal hinge linkage is utilized rather than an
elongated rod and bushing configuration and provides increased
stiffness to undesired movement of the saw blade arising from
structural deflections during cutting operations. Two of the three
embodiments also have a vertical hinge linkage for maintaining the
elevation of the saw pivot head (to which the saw blade and motor
assembly is attached) constant during movement of the saw blade and
motor assembly away and toward the fence during a cutting
operation. A third preferred embodiment utilizes the horizontal
hinge linkage together with a single rod and bushing arrangement
whereby the rod and bushing arrangement also maintains a constant
elevation of the saw pivot head as the saw blade and motor assembly
is moved toward and away from the fence during a cutting operation.
It should be understood that the saw blade and motor assembly 22 is
pivotable about a saw pivot that is part of the saw pivot head,
which is attached to the horizontal hinge linkage. The saw blade
and motor assembly can be pivoted up out of contact with a work
piece or moved down into contact with a work piece during a cutting
operation as is conventional for miter saws.
[0029] Such hinge linkages have a cost advantage compared to
conventional bushing and rod guides because they have a simpler
construction, which may comprise as few as two generally planar
shaped linkages that are connected together by shafts that may
preferably incorporate rotary bushings or low cost ball bearings
and which are also linked to the support frame of the rotatable
table as well as to the saw pivot head. Tight tolerance fits
between hinge components are relatively easier to achieve using low
cost ball bearings that are preloaded in the axial direction so
that nearly all axial and radial play is removed. In contrast,
conventional bushings and sliding rod systems require expensive
manufacturing processes to ensure that the outside surface of the
rod is precise over its entire length. Another advantage of the use
of hinge linkages is that their stiffness characteristics are
determined primarily from the width of the hinge linkages as
measured along the pivot, i.e., shaft axis. Thus, increased system
stiffness can be achieved by making the hinge larger and this is
generally less expensive than using larger rods and bushings.
[0030] As previously mentioned, the horizontal hinge linkage pivots
around axes that are parallel to the cutting plane of the blade and
therefore provides increased stiffness along the axis of rotation
of the saw blade and because of this desirable characteristic, the
length of the hinge shafts is greater than other shaft lengths such
as those used in the vertical hinge linkage. The structural
stiffness is very important to the quality of cuts made by the saw.
Without the requisite structural stiffness, it is common for the
saw blade to deflect out of the desired cutting plane on an
intermittent basis which can result in one or more cut
discontinuities or jagged cut portions, rather than a continuous
smooth cut at the desired angle.
[0031] Another advantage of the hinge linkage is that it has
greatly reduced sensitivity to dirt and grit because the bearing
surfaces of a hinge linkage are not exposed but are contained
within a ball bearing or short rotary bushing. Such ball bearing or
rotary bushings can be relatively easily sealed compared to a rod
and bushing system where the entire rod is a critical bearing
surface and therefore has to be sealed with a large accordion or
bellow shaped fabric or other type of cover which is often easily
damaged.
[0032] Turning now to the first preferred embodiment shown in FIGS.
1-4, the miter saw, indicated generally at 10, has a generally
circular base 12 with an attached fence 14, which base supports a
rotatable table 16 that has a miter arm control assembly, indicated
generally at 18, for adjusting the rotational position of the table
for setting the miter angle of work piece that would be placed on
the table 16. A saw blade and motor assembly, indicated generally
at 20, is operatively connected to the table 16 by a linear guide
mechanism, indicated generally at 22. The saw blade and motor
assembly 20 has an electric motor 24 that is operatively connected
through a gear mechanism, not shown but located within housing
portion 26 that drives a saw blade 28. A handle 30 enables an
operator to move the blade and motor assembly 20 into and out of
engagement with a work piece that may be placed on the table 16
adjacent the fence 14. The blade and motor assembly 20 is pivotable
about a saw pivot shaft 32 that is connected to a saw pivot head 34
to which the linear guide mechanism 22 is attached. The blade and
motor assembly 20 is shown in FIG. 1 to be in a position where the
blade is moved to its extended position away from the fence 14 and
lowered into cutting position were a work piece placed on the table
16. During operation, an operator places a work piece on the table
16, brings the handle 30 down into cutting position either before
or after activating the motor 24 and then pushes the handle 30
toward the fence 14 to have the blade 28 cut the work piece. At the
end of the cut, the blade and motor assembly 20 would be
essentially in the position shown in FIG. 2 where the bottom reach
of the blade 28 is generally coextensive with the fence 14.
[0033] The linear guide mechanism 22 of the first preferred
embodiment shown in FIGS. 1-4 is designed so that the miter saw has
a dual bevel operation, rather than a single bevel operation,
meaning that the bevel angle can be adjusted either right or left
from the normal zero angle or position wherein the plane of the
blade 28 is perpendicular to the plane of the top surface of the
table 16. The blade and motor assembly 20 as well as the linear
guide mechanism and rotate about a bevel pivot shaft 36, with the
linear guide mechanism having a support frame 38 with a generally
cylindrical end portion 40 to which the bevel pivot shaft 36 is
connected to. The shaft 36 extends through an opening in an
enlarged extension 42 of the table 16. Thus, the end portion 40 can
rotate relative to the extension 42 and be supported by the shaft
36. The support frame 38 is preferably a casting that has a lower
flange 44, an upper flange 46 as well as vertically oriented
flanges 48 and 50.
[0034] A horizontal hinge linkage is comprised of links 52 and 54
which have adjacent ends connected together by a shaft 56. The saw
pivot head 34 has a pair of spaced flanges 58 as well as a single
flange 60 located below the flanges 58. The link 54 has its
opposite end connected to the flanges 58 by a shaft 62. Similarly,
the opposite end of the link 52 is connected to the vertical
flanges 48 and 50 by a shaft 64. As previously mentioned and while
not specifically illustrated, the shafts 32, 62, 56, 64, 78 and 82
are preferably of the type which utilize rotary bushings or low
cost ball bearings so that they are freely rotatable and will have
an extended useful life.
[0035] As is best shown in FIGS. 1 and 2, the link 52 has a
generally L-shaped side configuration with the transverse extension
66 having the aperture in which the shaft 56 is located. This
permits the two links 52 and 54 to be folded together in a
generally parallel arrangement as shown in FIG. 2 when the blade
and motor assembly 20 is moved into its final cutting position
where the blade is adjacent to the fence 14. As is best shown in
FIG. 4, the width of the links 52 and 54 is relatively large and
therefore the shafts 56, 62 and 64 that interconnect the links 52
and 54 with one another and with the saw pivot head 34 and support
frame 38 are relatively long. This contributes to the desirable
stiffness of the linear guide mechanism which substantially
reduces, if not eliminates, any movement by the blade out of the
cutting plane which can result in poor quality cutting. Stated in
other words, the extremely wide links and their coupling to the saw
pivot head and support frame 38 results in high rigidity reducing
torsional and linear deflection of the saw blade away from its
intended cutting plane which is very desirable from a cut quality
standpoint.
[0036] As best shown in FIG. 4, the link 52 is not a solid
construction, but has side walls 68 and end walls 70 with cross
braces 72 provided to provide increased overall strength for the
link. The link 54 is similarly constructed as is shown in FIG. 1,
it also having similarly configured side walls, end walls and cross
braces. The hinge links 52 and 54 are preferably die cast aluminum
but can be steel stamping if desired.
[0037] The vertical hinge linkage is located below the horizontal
hinge linkage and it comprises links 74 and 76 which have adjacent
ends connected together by a vertical shaft 78. The links 74 and 76
are not as wide as the horizontal hinge links 52 and 54 for the
reason that their functionality is to maintain the elevation of the
saw pivot head 34 constant during movement of the blade and motor
assembly 20 toward and away from the fence 14. Elevational
deflections are not as critical for a miter saw cut quality for the
reason that the work piece is generally being completely cut
through.
[0038] The narrower links 74 and 76 are vertically displaced from
one another which requires the elongated vertical shaft 78 to
extend to interconnect them. The link 74 is located between the
horizontal flanges 44 and 46 and is pivotally connected to these
flanges by a shaft 80. Similarly, the link 76 has spaced flange
portions that are connected to the flange 60 by a shaft 82. As is
shown in FIG. 1, the flange 60 is located beneath the near flange
58 and the flanges 44 and 46 are also located beneath the vertical
flanges 48 and 50, and the shaft 78 that interconnects the links 74
and 76 extends away or to the left side of the saw (as viewed from
the handle 30) so that when the vertical and horizontal linkages
are folded together as shown in FIG. 2, little if any portion of
the links extend outside of the width of the flanges 48 and 50.
This is significant in that changing of the bevel angle of the
blade and motor assembly 20 can be accomplished in either the left
or right direction and the hinge linkages will not interfere with
the dual bevel adjusting capability.
[0039] It should also be apparent from FIG. 2 that when the blade
and motor assembly 20 are moved as far toward the fence 14 as is
possible, the linkages do not extend in any rearward direction
beyond the original position end of the support frame 38. This
enables the miter saw to be placed near a wall, for example, and be
fully operational, unlike many conventional sliding rod and bushing
configurations of compound miter saws.
[0040] A second preferred embodiment is shown in FIGS. 5-8 and have
many similar components as the embodiment shown in FIGS. 1-4. In
the following description, components that are labeled with the
same numbers as those shown and described with regard to the first
preferred embodiment are substantially similar in their design,
configuration and operation and therefore will not be described in
detail. Components with reference numbers having a prime or double
prime designation are similar to those that are identified with
regard to the embodiment shown in FIGS. 1-4, but may have some
structural differences which are apparent or which will be
generally described. or which will be given different numbers than
those illustrated in FIGS. 1-4.
[0041] The second preferred embodiment is indicated generally at
100 in FIGS. 5-8 and has many similarities to the first preferred
embodiment, but while the first embodiment is a dual bevel
configuration saw, the second embodiment saw 100 is a single bevel
configuration. The links 74' and 76' are connected together by a
shaft 78' that is not as long as the shaft 78 of the first
preferred embodiment, because the links 74' and 76' are vertically
adjacent one another rather than being spaced apart. Also, the link
76' is at an elevation that is substantially similar to the
elevation of the link 54' and therefore unable to fold toward the
link 52'' and 54'. Thus, the connection between link 74' and 76'
extends outwardly away from the links 52' and 54'. Because of the
outward extension, particularly when it is folded as shown in FIGS.
6 and 8, the links interfere with other portions of the saw 100
when the saw would be pivoted in the counterclockwise direction as
shown in FIG. 8. Therefore, the single bevel operation of this
second preferred embodiment is in the clockwise direction as shown
in FIG. 8.
[0042] A third preferred embodiment of the invention is the saw 110
that is shown in FIGS. 9-12 is less detail than the embodiments of
FIGS. 1-8. Saw 110 has a horizontal hinge linkage comprising links
52'' and 54'' that are interconnected and operate substantially
similar to those described in the embodiments of FIGS. 1-8. The saw
pivot head 34'' has a slightly different configuration and the end
of the link 54'' is connected to the saw pivot shaft 32 which is
also journaled in the saw pivot head 34''. An elongated rod 112 is
journaled in a bushing (not shown but located in the upper end of
support frame 38) and maintains the saw pivot head 34'' at a
constant elevation as the blade and motor assembly 22 moves the
blade 28 toward the fence 14. Only one rod 112 is provided for the
reason that control of the saw blade cutting plane is provided by
the horizontal hinge linkage, as is the case with the other
embodiments shown in FIGS. 1-8, and the only function that is
performed by the rod 112 is to keep the pivot head 34'' at a
constant elevation during operation. In this regard, the blade and
motor assembly 20 is shown in its retracted position in FIGS. 9 and
10 and in the cutting position in FIG. 11 where the blade 28 is
adjacent the fence 14. In the position shown in FIG. 11, it is
apparent that the rod 112 will extend beyond the rear surface of
the support frame 38'' which requires a larger footprint in that it
would not be possible to place the saw 110 with the support frame
38'' located close to a wall or other similar surface. Thus, while
this embodiment does not have the space advantages of the first and
second preferred embodiments, this embodiment has the advantage of
controlling the saw blade cutting plane by a generally horizontal
hinge as is achieved in all embodiments and only one rod and
bushing combination is required which provides a cost benefit
compared to conventional arrangements which have a pair of rod and
bushing configurations.
[0043] A fourth preferred embodiment is shown in FIGS. 13-19 and is
indicated generally at 200. Many of the components are similar to
the embodiment 10 so that where reference numbers are the same as
the description of the FIG. 1 embodiment, such components and their
functionality are very similar if not identical. Components with
reference numbers above 200 are sufficiently different from
analogous components of the other embodiments to warrant separate
numbers or are new in the fourth preferred embodiment.
[0044] This embodiment also has a generally circular base 12 with
an attached fence 14, which base supports a rotatable table 16 that
has a miter arm control assembly, indicated generally at 18, for
adjusting the rotational position of the table for setting the
miter angle of a workpiece that would be placed on the table 16. A
saw blade and motor assembly, is also indicated generally at 20, is
operatively connected to the table by a linear guide mechanism,
indicated generally at 202. The saw blade and motor assembly 20 has
an electric motor 24 that is operably connected through a gear
mechanism (not shown), but located within the housing portion 26
that drives a saw blade 28. A handle 30 enables the operator to
move the blade and motor assembly 20 into and out of engagement
with a workpiece that is placed on the table 16 adjacent the fence
14. The blade and motor assembly is pivotable about a saw pivot
shaft 32 that is connected to saw pivot head 204. When the handle
30 is lowered by an operator, the blade 28 will be lowered into its
cutting position and as shown in FIG. 13, it slightly penetrates a
slot 206. The pivot head 204 has a pair of spaced flanges 208 that
extend upwardly and which are attached to a first horizontal link
210 by pivot connection shaft 212. The first horizontal link 212 is
connected to a longer link 214 by pivot connection shaft 216. The
link 214 has its lower end portion connected to a vertical support
18 by pivot connection shaft 220. The link 214 has a generally
transverse extension 222 at its upper end portion which facilitates
articulation of the links 212 and 214 relative to one another. In
this regard, the width of the link 212 is narrower than the width
of the extension 222 so that the link 212 can nest within the
extension 222. As is best shown in FIG. 16, when the blade and
motor assembly 20 is in its retracted position, the link 214 is in
a generally vertical orientation. It should be appreciated that the
shaft 212, 216 and 220 are oriented parallel to one another and
substantially perpendicular to the plane of the blade 28. The links
212 and 214 are relatively wide and the thickness of them is
substantial so that they resist bending which would detrimentally
affect the quality of the cut by the blade 28.
[0045] The vertical support 218 is integrally formed with a support
frame 224 that is generally cylindrically shaped. A bevel pivot
shaft 226 supported by an extension 228 of the table 16 enables the
support frame 224 and vertical support 218 to pivot for the purpose
of providing bevel cuts. The vertical support 218 also has a side
mounting structure 230 with a tongue portion 232 for supporting an
angled link 234 that is connected to the tongue portion by a pivot
connection shaft 236. The upper end of the link 234 is connected to
another link 238 by pivot connection shaft 240. The link 238 has
its other end connected to a tongue portion 242 that is part of the
pivot head 204 by a pivot connection shaft 244.
[0046] As with the embodiment shown in FIG. 1, the vertical shafts
236, 240 and 244 maintain the elevation of the pivot head 240
substantially constant relative to the table 16. The width and
thickness of the links 234 and 238 are comparable to the links 212
and 214. However, the amount of possible bending of the links 234
and 238 is not as critical as bending that could occur with the
links 212 and 214 inasmuch as the quality of a cut is generally not
affected by vertical movement of the blade during extension and
retraction because the blade penetrates the slot 206 during most
cutting operations. As is evident from the drawings, and
particularly FIGS. 13 and 15, the links 234 and 238 are not solid
but are preferably cast of aluminum and have reinforcing ribs 246
that extend across the interior of the links to impart additional
strength. While not as clearly shown, the construction of the links
210 and 214 are similar in that they have reinforcing ribs that are
also cast with the links.
[0047] Additional structural strength is provided with the fourth
preferred embodiment for the reason that the link 234 has spaced
flanges 248 that fit around the tongue 232 and the shaft 236 is
thereby supported at both ends rather than an overhung load
connection. The double-ended support provides a stronger connection
that imparts an increased strength to the linkage. Similarly, the
upper end of the link 234 has a tongue 250 and the link 238 has a
pair of spaced flanges 252 in which shaft 240 is secured. The shaft
240 is therefore also supported at opposite ends which is a
stronger connection. The other end of the link 238 also has a pair
of flanges 254 that support both ends of the shaft 244.
[0048] It should be understood that the angle of the link 234
relative to the vertical shaft 236 is such that the link 234 does
not interfere with or contact the extension 228. If the tongue
portion 232 is located higher than as shown, the angle of the link
234 would necessarily be less, i.e., more toward horizontal. It
should be understood that the length of the vertical support 218
may be increased so that the location of the tongue 232 may be
changed so that it may be at the same height above the table 16 as
the shafts 240 and 244. In other words, the link 234 may be
horizontally oriented just as is the link 238. However, if this is
done, there is an issue of the saw being undesirably top heavy.
Another consideration is that the angle between the links 210 and
214 as determined by the line of action between a line extending
through shafts 212 and 216 relative to the line of action through
shafts 216 and 220 identified as angle .theta. in FIG. 17 as well
as the angle through the vertically oriented shafts 236, 240 and
244 marked as angle .theta. in FIG. 18 should be less than
130.degree. to prevent a toggle action of the links. The toggle
action is defined herein to mean an increased necessary force to
push the blade and motor assembly 20 from its extended position as
shown in FIGS. 13, 15 and 18 toward the retracted position. If a
toggle action is experienced, a greater noticeable and appreciable
force is required to start the movement. If the angles of the links
are less than 130.degree., such toggle action is not
experienced.
[0049] It is desirable that the linear guide mechanism 202 very
little unnecessary movement or play in the pivot connections that
would or could result in decreased cut quality by the saw. While
this is more important with the pivot connections of the links 210
and 214 relative to the pivot head 204 and vertical support 218, it
is also important with regard to the pivot connections of the links
234 and 238. For this reason, it is preferred that the pivot
connections utilize ball bearings on both ends of the shafts.
Referring to FIG. 19 which is exemplary and diagrammatic, a link
214 is shown with the shaft 216. It passes through an aperture 256
and has one end portion 258 that bears against an inner race 260 of
a ball bearing, indicated generally at 262 that also has an outer
race 264 and a plurality of balls 266. The other ball bearing 268
also has an inner race 270, an outer race 272 and a plurality of
balls 274. A nut 276 is threaded on the end of the shaft 216 and is
tightened so as to pull the inner races 260 and 270 toward one
another which offsets the inner and outer races of each ball
bearing relative to one another and takes any play or looseness out
of the ball bearing which prevents the ball bearings from
contributing to looseness that would create a deterioration of the
quality of the cut. Also, a pair of cap screws 278 is provided in
apertures 280 in the link 210 and are tightened to bear against the
shaft 216 and lock it from rotation or other movement relative to
the link 210. Therefore, with the immobilization of the shaft 216
as well as the removal of any play in the ball bearings 262 and
268.
[0050] Because of the design of the linear guide mechanism 202,
there is a natural tendency for the blade and motor assembly 20 to
gravitate toward the extended position. To counteract this
tendency, it is therefore preferred to have at least one spring or
other biasing mechanism provided to neutralize this tendency. In
this regard, a torsion spring in one of the pivot connections may
be provided or a tension spring interconnecting the link 214 with
the pivot head 208 may be used, for example.
[0051] Also during transport, the blade and motor assembly 20 may
undesirably move from one position to another which can be somewhat
hazardous to a carrier and it is desirable to have a locking
mechanism that prevents unwanted movement while it is being
carried. In this regard and referring to FIG. 17, an elongated
slotted member 280 having a pivot connection 282 to the link 214
and a handle 284 associated with the pivot head 204 may be
provided. If the blade and motor assembly 20 is placed in its
extended position such as shown in FIG. 17, the knob 284 can be
tightened to hold the saw in this position during transport.
[0052] A desirable attribute of the fourth preferred embodiment is
particularly illustrated in FIG. 16 wherein the blade and motor
assembly 20 is in its retracted position and the link 214 is
substantially vertical. Since the link 214 does not extend
rearwardly beyond the vertical support 218, it can be appreciated
that the saw 200 can be placed very close to a rear wall or the
like without impairing the normal operation of the saw.
[0053] While various embodiments of the present invention have been
shown and described, it should be understood that other
modifications, substitutions and alternatives are apparent to one
of ordinary skill in the art. Such modifications, substitutions and
alternatives can be made without departing from the spirit and
scope of the invention, which should be determined from the
appended claims.
[0054] Various features of the invention are set forth in the
following claims.
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