U.S. patent application number 09/268848 was filed with the patent office on 2001-11-08 for parallel arm scroll saw and drive mechanism with visual speed indicator apparatus.
Invention is credited to LEI, XUN.
Application Number | 20010037714 09/268848 |
Document ID | / |
Family ID | 23024765 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010037714 |
Kind Code |
A1 |
LEI, XUN |
November 8, 2001 |
PARALLEL ARM SCROLL SAW AND DRIVE MECHANISM WITH VISUAL SPEED
INDICATOR APPARATUS
Abstract
An arm configuration used in a scroll saw that allows the two
arms to move substantially independently of one another and having
a retaining mechanism which isolates one of the arms if one arm
becomes disengaged from the saw blade or the saw blade breaks. A
speed indicator that allows the user to easily determine the speed
of the saw visually. A drive assembly including a pulley system
that provides for increased torque and the saw to have a wide range
of speeds.
Inventors: |
LEI, XUN; (CHESWICK,
PA) |
Correspondence
Address: |
CAROL I BORDAS
KIRKPATRICK & LOCKHART
1500 OLIVER BUILDING
PITTSBURGH
PA
15222
|
Family ID: |
23024765 |
Appl. No.: |
09/268848 |
Filed: |
March 16, 1999 |
Current U.S.
Class: |
83/783 ;
83/597 |
Current CPC
Class: |
B23D 59/001 20130101;
B23D 49/007 20130101; Y10S 83/01 20130101; Y10T 83/8798 20150401;
Y10T 83/937 20150401; Y10T 83/705 20150401; Y10T 83/081
20150401 |
Class at
Publication: |
83/783 ;
83/597 |
International
Class: |
B26D 007/26 |
Claims
What is claimed is:
1. An apparatus for a saw, said apparatus comprising: a first arm
having a first end and a second end; a second arm having a first
end and a second end; and a link member having a first end
pivotally attached to said first end of said first arm and a second
end slideably attached to said first end of said second arm.
2. The apparatus for a saw according to claim 1, wherein said first
arm and said second arm are substantially parallel to one
another.
3. The apparatus for a saw according to claim 1, further comprising
a saw blade attached to said second ends of said first arm and said
second arm.
4. The apparatus for a saw according to claim 2, further comprising
a member for selectively retaining said first arm relative to a
portion of a saw housing.
5. The apparatus for a saw according to claim 1, wherein said link
member comprises a shaft with a rod at one end and a stop member at
the other end, and wherein said rod is pivotally connected to said
first end of said first arm and said other end of said rod is
slidably affixed to said first end of said second arm by a stop
member attached to said first end of said second arm.
6. The apparatus for a saw according to claim 4, wherein said
retaining member is a hook-shaped member pivotally attached to said
saw housing.
7. The apparatus for a saw according to claim 1, wherein said first
and second arms are fabricated from a composite material.
8. The apparatus for a saw according to claim 7, wherein said
composite material comprises a composite fiber cloth material
impregnated with polymer material.
9. The apparatus for a saw according to claim 8, wherein said fiber
cloth comprises carbon fibers.
10. A scroll saw, comprising: a first arm having a first end and a
second end; a second arm having a first end and a second end; a
link member having a first end and a second end, wherein said link
member first end is pivotally attached to said first arm first end
and said link member second end is slideably attached to said
second arm first end; a blade extending between and connected to
said first arm second end and said second arm second end; a drive
mechanism; a first drive pulley attached to said drive mechanism; a
second drive pulley attached to said second arm; and a drive belt
extending around said first drive pulley and said second drive
pulley.
11. The scroll saw according to claim 10, wherein said first arm
and said second arm are substantially parallel to one another.
12. The scroll saw according to claim 10, further comprising a
drive mechanism speed indicator.
13. The scroll saw according to claim 12, wherein said drive
mechanism speed indicator comprises a transparent cover positioned
over said first and second drive pulleys and having a label with
indicia thereon.
14. The scroll saw according to claim 10, wherein said first and
second arms are made of composite material.
15. The scroll saw according to claim 10, further comprising a
housing member and a retaining mechanism attached to said housing
member for retaining said first arm adjacent a portion of said
housing member when said blade breaks or becomes detached from said
first arm.
16. The scroll saw according to claim 15, wherein said retaining
mechanism comprises a spring-biased hook-shaped member that is
pivotally mounted to said housing member adjacent said first
arm.
17. The scroll saw according to claim 10, wherein said drive belt
is a highly visible color.
18. The scroll saw according to claim 17, wherein said highly
visible color is selected from the group consisting essentially of
red, florescent green and yellow.
19. A scroll saw comprising: a housing member; a first arm having
first and second ends, said first arm being pivotally supported
relative to said housing member; a second arm having first and
second ends, said second arm being pivotally supported relative to
said housing member; a linkage assembly attached to said first end
of said first arm and said first end of said second arm such that
said first ends of said first and second arms are slidably
interconnected to form a parallel arm assembly; a cutting member
attached to said second ends of said first and second arms and
extending therebetween; and a motor assembly operably attached to
said parallel arm assembly for imparting a reciprocating motion
thereto relative to said housing member.
20. The scroll saw of claim 19, wherein said linkage assembly
comprises a shaft member having a first end pivotally affixed to
said first end of said first arm and a second end slidably affixed
to said first end of said second arm.
21. The scroll saw of claim 19, wherein said motor assembly
comprises: a first drive pulley attached to a motor; a second drive
pulley attached to one of said first arm and said second arm; and a
drive belt received on said first and second drive pulleys and
extending therebetween.
22. The scroll saw of claim 21, wherein said first drive pulley has
a plurality of belt-receiving grooves therein and wherein said
second drive pulley has a plurality of belt-receiving grooves
therein.
23. The scroll saw of claim 22, further comprising a cover attached
to said housing member for substantially covering said first and
second pulleys and said drive belt.
24. The scroll saw of claim 23, wherein at least a portion of said
cover permits viewing of said drive belt on said first and second
drive pulleys while said cover is attached to said housing
member.
25. The scroll saw of claim 24, further comprising a pulley speed
chart on said cover.
26. The scroll saw of claim 25, wherein said pulley speed chart
comprises a reference pulley indicia having a plurality of
reference grooves therein and motor speeds corresponding to each of
said plurality of reference grooves, said reference pulley indicia
disposed on said cover such that the speed of said motor assembly
can be ascertained by determining the drive belt location with
respect to the receiving grooves of one of said first and second
drive pulleys and comparing the drive belt location to the
reference grooves and the corresponding motor speed.
27. The scroll saw of claim 26, wherein said drive belt is
fabricated from a material having a color selected from the group
consisting essentially of red, florescent green and yellow.
28. The scroll saw of claim 19, further comprising a retainer
member affixed to said housing member to retain said first arm
relative to said housing when said cutting member breaks or becomes
detached from said first arm.
29. The scroll saw of claim 28, wherein said retainer member
comprises a hook-shaped member pivotally affixed to said housing
member adjacent said first arm for hooking said first arm
therein.
30. The scroll saw of claim 29, wherein said retainer member is
spring biased relative to said housing member.
31. A scroll saw, comprising: a housing member; a first arm having
a first end and a second end, said first arm pivotally supported
relative to said housing member; a second arm having a first end
and a second end, said second arm pivotally supported relative to
said housing member; a blade attached to said second ends of said
first and second arms and extending therebetween; means for
slidably interconnecting said first end of said first arm to said
first end of said second arm to form a parallel arm assembly; and
means for imparting a reciprocating motion relative to said
parallel arm assembly.
32. The scroll saw of claim 31, further comprising means for
preventing said first arm from reciprocating relative to said
housing when said blade breaks or becomes detached from one of said
first arm and said second arm.
33. A linkage assembly for slidably attaching a first end of a
first arm of a scroll saw to a second arm of a scroll saw, said
linkage assembly comprising: a bracket affixed to an end of said
second arm; and a shaft having a first end attached to the first
end of said first arm and a second end slidably affixed to said
bracket.
34. The linkage assembly of claim 33, wherein said second end of
said shaft slidably protrudes through an aperture in said bracket
and wherein said second end of said shaft has a stop member affixed
thereto to prevent said second end of said shaft from sliding out
of said aperture.
35. The linkage assembly of claim 33, further comprising an
attachment rod attached to said first end of said shaft transverse
thereto, said attachment rod having ends rotatably received in a
second bracket attached to said end of said first arm.
36. A speed indicator for ascertaining the speed of a device
powered by a motor assembly that includes at least one drive pulley
that has a plurality of drive-belt receiving grooves therein that
each impart a different speed to a belt when the belt is received
therein, said speed indicator comprising: a reference symbol
juxtapositionly mounted relative to the at least one drive pulley,
said reference symbol having speed indicating indicia thereon that
corresponds to each drive-belt receiving groove in the drive pulley
such that the speed imparted by the drive pulley is ascertainable
by identifying the drive belt receiving groove in which the belt is
received and identifying said speed indicating indicia that
corresponds to that drive belt-receiving groove in which said belt
is received.
37. The speed indicator of claim 36, wherein said reference symbol
is mounted to a cover attached to the device and covering the at
least one drive pulley.
38. A speed indicator for indicating the speed imparted to an
apparatus by a drive arrangement that includes a motor, a first
pulley attached to the motor and having a plurality of
belt-receiving grooves therein, a second pulley having a plurality
of belt-receiving grooves therein and an endless belt received in
one of the grooves in the first pulley and in one of the grooves in
the second pulley, said speed indicator comprising: a pulley
reference chart juxtapositioned relative to the first and second
pulleys, said reference chart having reference pulley indicia
thereon, said reference pulley indicia having a plurality of
reference grooves therein and motor speed indicia corresponding to
each the reference groove, such that the speed imparted to the
apparatus by the drive arrangement is ascertained by identifying
the reference groove that corresponds to the groove of one of the
first and second pulleys in which the endless belt is received in
and identifying said motor speed indicia corresponding to the
reference groove.
39. The speed indicator of claim 38, wherein said reference chart
is affixed to a cover that is located adjacent at least one of the
first and second pulleys and wherein at least a portion of said
cover is transparent.
40. The speed indicator of claim 39, wherein said cover
substantially encloses the first and second pulleys and is
transparent.
41. The speed indicator of claim 38, wherein the belt is fabricated
from material having a color selected from the group consisting
essentially of red, orange, green and yellow.
42. A method for ascertaining the speed of a motor assembly having
at least one drive pulley with a plurality of drive belt receiving
grooves therein, said method comprising: enclosing the at least one
drive pulley having the plurality of drive belt receiving grooves
therein in a cover having at least a transparent portion to permit
viewing of the at least one drive pulley therein and wherein the
cover has a drive pulley speed chart thereon; viewing a drive belt
through the transparent portion; comparing the location of the
drive belt on the at least one drive pulley to a referenced pulley
on the drive pulley speed chart which has a plurality of reference
grooves therein corresponding to motor speeds; and reading the belt
speed corresponding to one of the plurality of reference grooves
which corresponds to the location of the drive belt.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is directed generally to an apparatus
for a saw. More particularly, the present invention concerns an
apparatus for a scroll saw that enables the parallel arms to move
substantially independently of each other and that includes a
retaining mechanism for one of the parallel arms. The present
invention also relates to a drive mechanism and visual speed
indicator that provides increased torque, a wide range of cutting
speeds and allows for the visual determination of the speed of a
saw blade.
[0003] 2. Description of the Background
[0004] One type of conventional scroll saw has two parallel arms
which are fixedly connected to each other at one end by a rear
link. Each parallel arm also has a free end between which a saw
blade extends and is connected thereto. The lower parallel arm is
connected directly to a motor that moves the lower arm and the saw
blade in a reciprocating motion. Because the lower arm and the
upper arm are fixedly connected to one another by the rear link,
the lower arm forces the upper arm to move in a corresponding
manner to that of the lower arm. The disadvantage to this type of
scroll saw is that if the saw blade becomes disengaged from one of
the parallel arms or the saw blade breaks, the upper parallel arm
will continue to move because it is fixedly connected to the lower
parallel arm and, as a result, the broken or detached blade may mar
the workpiece. Furthermore, the parallel arms may move out of sync
resulting in the saw being damaged.
[0005] Conventional saws, drill presses, planers, etc. also
typically include a drive mechanism and speed control apparatus for
controlling the speed of the drive mechanism. One type of drive
mechanism and speed control device employed with a scroll saw
comprises a drive motor that is directly connected to the lower arm
for moving the arms in a reciprocating motion. A speed control is
employed to regulate the speed of the drive motor. The speed
control is manually operable by virtue of an on/off dial knob,
wherein indicia representing speed measurements is displayed around
the knob. In most scroll saw applications, the range of speed of
the motor is generally between 400 revolutions per minute (rpm) and
1600 rpm. The user's choice of motor speed is dependent upon the
workpiece material and the type of cut to be made. The disadvantage
of this type of drive mechanism and speed control device is that
the user is limited to a small range of speed which constrains the
type of cut that can be made and the type of workpiece material
that can be used. Furthermore, the dial setting, which is usually
in small print, can be difficult for the user to read, especially
during operation of the saw.
[0006] Accordingly, there is a need for a scroll saw that has arms
that move substantially independently of one another and that
isolates the movement of one of the arms if an arm becomes
inadvertently disengaged from the saw blade or the saw blade
breaks. There is another need for a drive mechanism and visual
speed indicator that is easily observed during operation and that
enables the saw to make various cuts on a variety of workpiece
materials. There is still another need for a drive mechanism and
visual speed indicator that can be easily observed and employed on
a myriad of other driven devices, tools, etc.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides an arm configuration for a
saw having spaced apart arms with a blade extending between and
connected to the free ends of the arms and a link member extending
between and connected to the other ends of the arms, wherein the
arm configuration is constructed to allow the arms to move
substantially independently of one another.
[0008] The present invention provides a scroll saw having two
parallel arms that move substantially independently of one another
such that if the saw blade breaks or becomes disengaged from the
upper parallel arm, the motion of the upper parallel arm may be
stopped to prevent marring of the workpiece or damage to the saw. A
link member extends between and connects the distal ends of the two
parallel arms and a saw blade extends between and is connected to
the proximate ends of the two parallel arms. The link member is
pivotably attached to one of the two parallel arms and is slideably
attached to the other of the two parallel arms.
[0009] The present invention also includes a mechanism that will
retain the upper parallel arm if the upper parallel arm becomes
disengaged from the saw blade or the saw blade breaks thus,
preventing the upper parallel arm from marring the workpiece or
damaging the arm configuration. The upper arm retaining mechanism
can take the form of a hook-shaped member which is spring loaded
and pivotally mounted adjacent the upper parallel arm.
[0010] The present invention further provides a drive mechanism and
visual speed indicator which allows for easy verification of the
speed of the saw, increased torque and the ability to cut a variety
of materials and make a variety of cuts. The drive mechanism and
visual speed indicator may be a motor and drive pulley assembly
having a transparent pulley cover, wherein the drive belt is highly
visible. The user can verify the speed of the pulleys by comparing
the position of the drive belt on the pulleys with a speed chart
placed on the saw.
[0011] The present invention further provides the arm configuration
to be sized and proportioned to comfortably maneuver and accept a
large workpiece. The space between the two parallel arms of the
scroll saw which accepts the workpiece is unobstructed and large
enough to maneuver and accept a variety of sized and shaped
workpieces.
[0012] The present invention further provides that the two parallel
arms are made from a composite material. The composite material may
be a composite fiber cloth material impregnated with polymer
material, wherein the fiber cloth may be carbon fibers.
[0013] The present invention solves problems experienced with saws.
Those and other advantages and benefits of the present invention
will become apparent from the description of the preferred
embodiments hereinbelow.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0014] For the present invention to be understood and readily
practiced, the present invention will be described in conjunction
with the following Figures, wherein:
[0015] FIG. 1 is a perspective view of a scroll saw employing one
embodiment of the present invention;
[0016] FIG. 2 is a front view of the scroll saw shown in FIG.
1;
[0017] FIG. 3 is a front elevational view of the parallel arm
configuration and a portion of the motor and drive pulley assembly
of the scroll saw shown in FIG. 1;
[0018] FIG. 4 is a front elevational view of the link member, the
upper bracket and the lower bracket of the scroll saw shown in FIG.
1;
[0019] FIG. 5 is a side elevational view of the link member, the
upper bracket and the lower bracket of the scroll saw shown in FIG.
4;
[0020] FIG. 6 is a partial sectional view of the link member shown
in FIG. 4 taken along line 6-6 in FIG. 4;
[0021] FIG. 7 is an exploded view of the motor and drive pulley
assembly of the scroll saw shown in FIG. 1;
[0022] FIG. 8 is a top view of the scroll saw shown in FIG. 1 with
the table removed and with a pulley speed chart label of the
present invention shown in chain line;
[0023] FIG. 9 is a top view of the pulley cover and speed chart
label shown in FIG. 8 with the pulleys of the motor and drive
pulley assembly shown in chain line;
[0024] FIG. 10 is a side elevational view of a portion of the
scroll saw shown in FIG. 1 with the retaining mechanism of the
present invention in a disengaged position;
[0025] FIG. 11 is the side elevational view of the portion of the
scroll saw shown in FIG. 10 with the retaining mechanism in an
engaged position;
[0026] FIG. 12 is an exploded view of the retaining mechanism and a
portion of the housing covering the upper parallel arm of the
scroll saw shown in FIG. 1; and
[0027] FIG. 13 is a partial longitudinal sectional view of the
portion of the housing that the retaining mechanism is pivotably
connected thereto.
DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention will be described below in terms of a
scroll saw. It should be noted that describing the present
invention in terms of a scroll saw is for illustrative purposes and
the advantages of the present invention may be realized using other
structures and technologies that have a need for an arm
configuration, wherein the arms can move substantially
independently of each other and/or a drive mechanism with a speed
indicator which provides a quick and easy method of visually
determining the device's speed.
[0029] It is to be understood that the Figures and descriptions of
the present invention have been simplified to illustrate elements
that are relevant for a clear understanding of the present
invention, while eliminating, for purposes of clarity, other
elements and/or descriptions thereof found in a typical scroll saw.
Those of ordinary skill in the art will recognize that other
elements may be desirable in order to implement the present
invention. However, because such elements are well known in the
art, and because they do not facilitate a better understanding of
the present invention, a discussion of such elements is not
provided herein.
[0030] FIGS. 1 through 3 illustrate a scroll saw 10 of the present
invention substantially comprising a housing 12, a table 14, a
parallel arm assembly 16, a conventional blade 20, a motor and
drive pulley assembly 22, a hold down bar 24 and a hold down foot
26. The scroll saw 10 is also generally depicted in co-pending U.S.
design patent application Ser. No., ______ being filed concurrently
with the present application and entitled Scroll Saw, the entire
disclosure of which is hereby incorporated by reference.
[0031] An exemplary parallel arm assembly 16 of the present
invention, shown in greater detail in FIGS. 3 through 6,
substantially comprises an upper arm 28, a lower arm 30 and a link
member 32 connected to and extending between the end 29 of the
upper arm 28 and the end 31 of the lower arm 30, both of which are
distal to the saw blade 20. The upper arm 28, the lower arm 30 and
the link member 32 are sized and proportioned such that a
relatively large workpiece can be maneuvered and accepted within
the opening 27 defined by the upper arm 28, the lower arm 30 and
the link member 32. In this embodiment, the horizontal length from
the saw blade 20 to the portion of the housing 12 that houses the
link member 32 is approximately twenty (20) inches. The skilled
artisan will appreciate, however, that such distance can be
advantageously sized to provide the saw with the desired
capabilities without departing from the spirit and scope of the
present invention.
[0032] The upper and lower arms 28 and 30 are made from a graphite
composite material and are hollow along their lengths. A composite
material is that constructed of a matrix material reinforced by a
fibrous material. The composite material used to produce the upper
and lower arms 28 and 30 of the present invention comprises a
composite fiber cloth impregnated in a matrix of a
temperature-cured resin-derived polymer. The composite material is
a carbon fiber cloth impregnated in a cured epoxy resin. The
thickness of the wall of the hollow upper and lower arms 28 and 30
is substantially uniform. The composite material upper and lower
arms 28 and 30 of the present invention can be produced by a
conventional blow-mold manufacturing process known to those of
ordinary skill in the manufacturing art. Such a process is
typically used to manufacture familiar items such as tennis
rackets. Accordingly, one of ordinary skill advised of the shape
and intended function of the finished product could produce the
product by a conventional blow molding process without undue
experimentation. The composite material of the upper and lower arms
28 and 30 is described in further detail in U.S. patent
applications Ser. Nos. 08/870,886 and 09/041,980, the entire
disclosures of which are hereby incorporated by reference. Those of
ordinary skill in the art will further appreciate, however, that
arms 28 and 30 may be fabricated from other suitable materials,
such as, for example, iron, steel, etc.
[0033] The saw blade 20 is releasably attached to the proximate end
33 of the upper arm 28 and the proximate end 35 of the lower arm 30
by any known means. A blade tensioning apparatus, generally
designated as 37, can releasably attach the blade 20 to the
proximate end 33 of the upper arm 28. A blade clamp mechanism 41
can releasably attach the blade 20 to the proximate end 35 of the
lower arm 30. The blade tensioning apparatus 37 and the blade clamp
mechanism 41 are disclosed in greater detail in U.S. Pat. Nos.
5,363,733 and 4,681,006, the entire disclosures of which are hereby
incorporated by reference. Those of ordinary skill in the art will
further appreciate, however, that other blade tensioning apparatus
and blade clamp mechanisms may be used in the present
invention.
[0034] Referring to FIG. 6, the link member 32 substantially
comprises a shaft 38 having a rod 39 traversely attached at the
first end portion 34 of the shaft 38. Specifically, the rod 39 has
a substantially cylindrical threaded opening 43 that transverses
the center portion of the longitudinal axis of the rod 39. The
opening 43 receives the first end portion 34 of the shaft 38 which
is also threaded and fixedly connects the rod 39 to the shaft 38.
The rod 39 has a second threaded opening 47 that is substantially
cylindrical, and positioned concentric with the longitudinal axis
of the rod 39. The second opening 47 receives a set screw 59 which
further fixedly connects the rod 39 to the shaft 38. The set screw
59 prevents the connection between the shaft 38 and the rod 39 from
loosening due to the reciprocating motion of the arms 28 and
30.
[0035] A bushing 49 is connected on each end of the rod 39 by a
slide fit. Bushings 49 have recesses 51 that receive the ends of
rod 39 and allow for the rod 39 to rotate relative to the bushings
49. The bushings 49 are received within circular bores 65 of the
upper bracket 44 by a press fit. See FIGS. 3 and 4. The upper
bracket 44 further defines a rectangular opening at 67, shown in
hidden lines, that receives the distal end 29 of the upper arm 28.
The rectangular opening is sized and proportioned to correspond to
the upper arm distal end 29. The distal end 29 of the upper arm 28
is fixedly connected to the upper bracket 44 by two screws (not
shown).
[0036] As seen in FIG. 6, the second end portion 36 of the shaft 38
is slideably received by opening 45 of a cylindrical bar 69. The
opening 45 transverses the longitudinal axis of the bar 69 at its
center portion. The opening 45 expands to form a larger portion 71
that receives the stop member 40 of the link member 32 such that a
ledge 75 is formed. The ends of the bar 69 are each received by a
cylindrical cavity 81 defined by bushings 83. Bushings 83 are
rotatably connected to the bar 69 with a slide fit, and fixedly
connected to the lower bracket 48 by being press fitted in the
circular bores 85 of the lower bracket 48. See FIGS. 3 and 4. As
with the upper bracket 44, the lower bracket 48 has a rectangular
opening at 91, shown in hidden lines, that receives the lower arm
30. The lower arm 30 is fixedly connected to the lower bracket 48
by two screws (not shown). It will be appreciated that the
slideable and rotatable connections of the link member 32 to the
lower and upper arms 30 and 28, respectively, can take many other
forms.
[0037] As seen in FIGS. 1-3, the upper arm 28 is pivotally
supported relative to the housing 12 at 50 by collar 54 and a pivot
bolt 56. The collar 54 is a circular collar that is received on the
upper arm 28 and is attached thereto by the pivot bolt 56. The
pivot bolt 56 extends through the collar 54, the housing 12 and the
upper arm 28. The head portion of the pivot bolt 56 projects from
the housing 12, as shown in FIG. 1 at 50, and the threaded portion
of the pivot bolt 56 engages a tapped hole (not shown) in the
housing 12. The pivot bolt 56 defines an axis about which the upper
arm 28 pivots relative to the housing 12. The lower arm 30 is also
pivotally connected to the housing 12 at 52 by collar 55 and a
second pivot bolt 56. The collar 55 is U-shaped such that the lower
arm 30 extends between the two legs of the U-shaped collar 55 and
the pivot bolt 56 clamps the two legs together. The pivot bolt 56
also extends through the housing 12. The head portion of the pivot
bolt 56 projects from the housing 12, as shown in FIG. 1 at 52, and
the threaded portion of the bolt 56 engages a tapped hole (not
shown) in the housing 12.
[0038] A bellows 53 is fixedly disposed within the housing 12 and
attached to the lower arm 30 by a bellows collar 93 and a fastener
57. The bellows collar 93 comprises a U-shaped member that fits
around the lower arm 30 such that the legs of the U-shaped member
extend downward and are clamped together by fastener 57. The
fastener 57 is a screw which extends through a lip (not shown) of
the bellows 53 and the legs of the U-shaped member, wherein the
screw is held in this position by a nut (not shown). As the lower
arm 30 moves up and down, the bellows 53 causes a flow of air to be
pumped through an air nozzle (not shown) that is used to blow saw
dust away from the workpiece during cutting thereof.
[0039] The motor and drive pulley assembly 22, shown in greater
detail in FIGS. 7 through 9, substantially comprises a motor 58, a
driven pulley 60, a drive pulley 62 and a drive belt 64. The motor
58 is a single phase alternating current (AC) induction motor;
however, a direct current (DC) variable speed motor could also be
used. The motor 58 is connected to the drive pulley 62 by shaft 63.
The driven pulley 60 has a bearing housing 68 that houses the
bearings (not shown) upon which the driven pulley 60 rotates. The
driven pulley 60 and the drive pulley 62 are made from cast
iron.
[0040] The drive belt 64 extends around both the driven pulley 60
and the drive pulley 62 and is a highly visible color such as
yellow, red or florescent green. The driven pulley 60 is connected
to shaft 61 which is further connected to an eccentric shaft 87.
The longitudinal axis of the eccentric shaft 87 is offset from the
longitudinal axis of shaft 61. The eccentric shaft 87 is connected
to the lower arm 30 by the drive collar 66, shown in FIG. 3, and a
fastener (not shown). This connection between the shaft 61,
eccentric shaft 87 and the drive collar 66 is similar to the
crankshaft in an automotive engine, which converts the rotation of
a shaft into the linear movement of a piston. The use of this
pulley system generates more torque than those DC variable
induction motors that are commonly used on other scroll saws.
[0041] A transparent cover 70 having a label 72 is placed over the
driven pulley 60 and the drive pulley 62. The label 72, shown in
FIGS. 7 through 9, has a speed chart thereon that is centrally
disposed on the cover 70 such that the user can quickly determine
the speed of the driven pulley 60 by identifying the position of
the drive belt 64 with respect to the driven pulley 60 and
comparing this with the speed chart on the label 72. The range of
speed of the driven pulley 60 in this example is between 400 rpm
and 2000 rpm. The label 72, shown in FIG. 9, illustrates a
reference pulley 73 with several grooves 77 and a speed in
revolutions per minute (rpm) corresponding to each of the several
grooves 77. Specifically, the user visually identifies which groove
of the driven pulley 60 that the drive belt 64 is positioned within
and compares this to the corresponding groove 77 and speed on the
label 72 to identify the speed of the driven pulley 60. It should
be kept in mind that the label 72 can take many other forms than
that illustrated such as being placed at another location on the
scroll saw 10.
[0042] In operation, the motor 58 is powered by an appropriate
power source (not shown) such that the motor 58 rotates the drive
pulley 62 and the rotation is transferred to the driven pulley 60
by the drive belt 64. The driven pulley 60 then transfers the
rotation to the lower arm 30 via the shafts 61 and 87 which
converts the rotational motion into an up and down motion pivoting
the lower arm 30 about 52 which results in the reciprocating sawing
motion of the saw blade 20. The saw blade 20 then cuts the
workpiece (not shown) and moves the upper arm 28 in a corresponding
up and down motion such that the upper arm 28 pivots at 50. The up
and down motion of the upper arm 28 is transferred to the link
member 32 at the pivotal connection between the link member 32 and
the upper arm 28, discussed above. The rod 39 is able to rotate
approximately two (2) degrees to allow for the pivoting motion of
the upper arm 28. The slideable connection between the lower arm 30
and the link member 32 at the lower arm distal end 31 allows for
the link member 32 to slideably engage the lower bracket 48 such
that the up and down motion of the link member 32 does not
substantially affect the motion of the lower arm 30. As a result of
this slideable connection between the link member 32 and the lower
arm 30, the arms 28 and 30 can move substantially independently of
one another. Thus, the scroll saw 10 is not damaged and the
workpiece is not marred if the saw blade 20 is disengaged from the
upper arm 28 or lower arm 30 or if the saw blade breaks.
[0043] FIGS. 10 through 13 illustrate a retainer, designated
generally as 74, that retains the upper arm 28 within the housing
12 if the saw blade 20 breaks or is disengaged from the upper arm
28. The retainer 74 comprises a hook member 76 and a torsion spring
member 78. The hook member 78 has a hook portion 90 and a pin
member 92. The pin member 92 has a boss 94 with a threaded recess
96 for receiving a screw 98. The boss 94 extends through an opening
100 in the housing 12 and the screw 98 is threaded into opening 96
thereby attaching the hook member 76 to the housing 12. The pin
member 92 extends through opening 101 in the housing 12. The
torsion spring 78 has a biasing arm 102 and several coil portions
104 which define a cylindrical opening 106 through the torsion
spring 78. The torsion spring 78 is attached to the housing 12 by a
screw 85. The screw 85 extends through a flat washer 81, a spacer
79, the opening 106 of the torsion spring 78 and is threadably
received in threaded recess 108 in the housing 12. As can be seen
in FIG. 13, the flat washer 81 and the spacer 79 are received
within the opening 106 of the torsion spring 78.
[0044] After the hook member 76 and the torsion spring 78 are
attached to the housing 12, as described above, the biasing arm 102
engages the pin member 92 of the hook member 76 to bias the hook
member 76 into the position shown in FIG. 10. If the saw blade 20
becomes disengaged from the upper arm 28 or if the blade breaks,
the upper arm 28 may continue to reciprocate due to momentum. The
upper arm 28 moves upwardly in the direction of arrow A, shown in
FIG. 10. The upper arm 28 then engages the hook portion 90 of the
hook member 76 which pivots about the longitudinal axis C of the
screw 98 and allows the upper arm 28 to continue into the recess 80
defined by the housing 12. The hook member 76 is then forced in the
direction opposite to arrow A into its original position by the
biasing arm 102 of the torsion spring 78 such that the hook member
76 now holds the upper arm 28 within the housing 12 and prevents it
from moving downward where it could potentially result in marring
of the workpiece.
[0045] Thus, the present invention represents a vast improvement
over prior scroll saw arrangements. The unique arrangement of the
present invention's arms enables the motion of the upper arm to be
controlled to prevent damage to the workpiece should the blade
break or become disengaged from one of the arms. The present
invention is also well suited to accommodate and cut relatively
large workpieces. In addition, the novel speed indication device of
the present invention cannot only be advantageously employed in
connection with scroll saws, but it can also be advantageously used
in connection with any similarly arranged motor/pulley drive
arrangement for a variety of different machines.
[0046] Those of ordinary skill in the art will recognize, however,
that many modifications and variations of the present invention may
be implemented without departing from the spirit and scope of the
present invention. The foregoing description and the following
claims are intended to cover all such modifications and
variations.
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