U.S. patent application number 09/929689 was filed with the patent office on 2002-03-28 for plug ejecting hole saw with twist-locking interchangeable saw cups.
Invention is credited to Despres, Roger J..
Application Number | 20020037201 09/929689 |
Document ID | / |
Family ID | 24058853 |
Filed Date | 2002-03-28 |
United States Patent
Application |
20020037201 |
Kind Code |
A1 |
Despres, Roger J. |
March 28, 2002 |
Plug ejecting hole saw with twist-locking interchangeable saw
cups
Abstract
A plug ejecting hole saw includes a saw cup provided at a front
annular edge wall thereof with a plurality of forward protruding
angled cutting teeth, and having at a rear end thereof a circular
base wall having therethrough a non-circular aperture concentric
with the cup. An arbor holder removably attachable to a saw cup of
a selected size includes a collar axially slidably holding
therewithin a central body having a front nose piece which
protrudes axially outward of the collar, the front nose piece
having a transverse cross-sectional shape adapted to be inheritably
received into the saw cup aperture. The nose piece has formed in
longitudinal wall surfaces thereof a pair of diametrically opposed,
longitudinally disposed grooves, each of which longitudinally
slidably holds therewithin a locking tab member urged forward to
abut a separate one of a pair of diametrically opposed, front
transversely disposed web ribs formed in the nose piece axially
inward of the front transverse face of the nose piece. Each
longitudinal groove communicates on one longitudinal side thereof
with a separate one of a pair of transversely disposed grooves
blocked by a forward biased tab member. When the nose piece is
inserted into a saw cup aperture and pushed axially forward, each
tab member is pushed rearward in a longitudinal groove, unblocking
the transverse grooves and thereby allowing the nose piece to be
rotated relative to the saw cup, with peripheral edge walls of the
aperture received in the transverse grooves. With sufficient
relative rotation, the front tab members become axially aligned
with diametrically opposed larger diameter portions of the saw cup
aperture, allowing each tab to be urged forward by a front spring
to a location blocking a transverse groove and thereby preventing
the arbor holder from becoming disengaged from the saw cup. The
arbor holder has a coaxial bore provided with lefthand internal
threads for threadably receiving an arbor having lefthand external
threads, has a rear shank portion adapted to be clamped in a chuck
of a power drill, and has a font collet flange for dampingly
receiving the shank of a pilot drill. The hole saw includes a pilot
drill held in the collet flange. Rotating the saw in a clockwise
sense to cut a hole in a workpiece forms a plug lodged within the
saw cup, while reversing the drill with the saw cup cocked in the
workpiece hole causes the arbor to threadingly advance forward from
the base of the saw cup, thus causing the collet flange to advance
and push the plug from the saw cup.
Inventors: |
Despres, Roger J.; (Fountain
Valley, CA) |
Correspondence
Address: |
Law Offices of William L. Chapin
16791 Sea Witch Lane
Huntington Beach
CA
92649
US
|
Family ID: |
24058853 |
Appl. No.: |
09/929689 |
Filed: |
August 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09929689 |
Aug 14, 2001 |
|
|
|
09517215 |
Mar 2, 2000 |
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Current U.S.
Class: |
408/204 ;
408/226; 408/239A |
Current CPC
Class: |
B23B 51/0453 20130101;
Y10T 408/896 20150115; Y10T 408/957 20150115; Y10T 408/8957
20150115; Y10T 408/907 20150115; Y10T 408/895 20150115; B23B
51/0473 20130101; Y10T 408/8973 20150115; Y10S 408/703 20130101;
Y10T 408/95 20150115; Y10T 408/51 20150115 |
Class at
Publication: |
408/204 ;
408/226; 408/239.00A |
International
Class: |
B23B 051/04 |
Claims
What is claimed is:
1. An adapter for converting a hole saw cup having a right-hand
threaded saw cup bore through a base wall thereof to a
hole-ejecting hole saw comprising; a generally cylindrically-shaped
body having disposed longitudinally therethrough a left-hand
threaded bore, said body having protruding radially outwardly from
a cylindrical wall surface thereof at least a first pair of
longitudinally disposed ribs adapted to penetrate internal threads
of said saw cup bore and thereby retain said body within said saw
cup bore.
2. The adapter of claim 1 further including a transversely
disposed, circular ring-shaped flange at a first rear end of said
body.
3. The adapter of claim 2 wherein said ribs are further defined as
being disposed longitudinally on said cylindrical surface of said
body from said flange to a location rearward of a front transverse
surface of said body.
4. The adapter of claim 3 wherein said ribs are further defined as
having a triangular transverse cross-sectional shape.
5. The adapter of claim 1 further including at a first, rear
transverse end of said body a transversely disposed flange, said
flange having a central generally circularly-shaped portion and a
pair of diametrically opposed, semi-oval shaped wings which
protrude radially outwardly from said central flange portion, said
wings having protruding perpendicularly forward therefrom a pair of
longitudinally disposed, diametrically opposed pins adapted to be
longitudinally insertably received in a pair of apertures through a
base wall of a saw cup.
6. The adapter of claim 5 wherein said ribs are further defined as
being disposed longitudinally on said cylindrical surface of said
body from said flange to a location rearward of a front transverse
surface of said body.
7. The adapter of claim 6 wherein said ribs are further defined as
having a triangular transverse cross-sectional shape.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to saws used for cutting
circular holes through objects made of wood and various other
materials, of the type utilizing a cylindrical saw cup coaxially
fastened to an arbor holding a pilot drill which protrudes forward
of cutting teeth provided on a front annular surface of the saw
cup. More particularly the invention relates to a hole saw which
automatically ejects a plug sawed from a workpiece, in which hole
saw cups of various diameters may readily be interchangeably
mounted on a novel arbor-holder by a twisting, snapping action.
[0003] 2. Description of Background Art
[0004] In U.S. Pat. Nos. 4,741,651 and 5,096,341, the present
inventor disclosed plug ejecting hole saws which utilize a
left-hand threaded mandrel or arbor that holds a pilot drill, the
shank of which is secured in an enlarged diameter flange or collar
located at the front end of the arbor. The arbor is screwed into a
threaded, arbor-holder bore disposed coaxially through a bushing or
thicker portion of a circular disk-shaped base plate which forms
the rear end wall of a cup-shaped saw body which has angled
circumferentially spaced apart cutting teeth in the front annular
end wall thereof. In a hole saw cup of this type, the front,
cup-shaped portion of the saw cup and the thicker rear base plate
or arbor-holder bushing are generally fabricated as separate metal
parts which are brazed together. Thus, this type of hole saw is
sometimes referred to as a "bi-metal" hole saw.
[0005] A novel feature of the inventions disclosed in the
aforementioned patents of the present inventor comprises left-hand
threading of both the outer surface of the arbor and the inner
threaded bore through the saw cup base. With this arrangement, when
the arbor is threaded counterclockwise into the saw cup
arbor-holder bore, as viewed from the front of the saw cup and
pilot drill end of the arbor, the front flange portion of the arbor
advances rearwardly to seat against the inner front wall surface of
the saw cup base. The arbor shank, which protrudes rearwardly from
the saw cup base is then secured in the collet of a power drill.
When the power drill is powered on to turn the pilot drill bit and
saw in the usual clockwise cutting direction, as viewed from the
rear, shank end of the bit, a counterclockwise reaction torque is
exerted on the saw cup teeth by frictional resistance offered by
workpiece in response to the cutting action, tending to further
tighten and secure the arbor flange against the inner surface of
the saw cup base. When the saw cup has penetrated the thickness of
a workpiece such as a door panel, a cylindrically-shaped plug of
workpiece material becomes lodged tightly within the saw cup, and
in prior art hole saws, is difficult to remove from the saw cup.
However, in accordance with the '651 and '341 patents, a plug
lodged within the saw cup may readily be ejected by powering the
drill in a reverse, i.e., counterclockwise direction after a hole
has been bored through a workpiece, while maintaining the saw cup
stationary. Rotating the drill shank and arbor in a
counterclockwise direction by the power drill causes the arbor to
be advanced axially forward within the threaded bore of the saw
cup, and the front flange of the arbor to abut the rear surface of
the plug and eject it forward out of the saw cup bore.
[0006] The above-described plug ejecting feature of hole saws
disclosed in the present inventor's '651 and '341 patents has
provided a highly effective and widely accepted improvement in
bimetal hole saws. Subsequent to issuance of those two patents,
U.S. Pat. No. 5,435,672 was issued for adapters having a left-hand
threaded arbor-receiving bore, and a right-hand external bore. The
adapters were designed to be threaded into right-hand threaded
arbor-holder bores of existing saw cups, thus accommodating
left-hand threaded arbors and permitting the present inventor's
novel plug ejecting function to be accomplished using existing hole
saw cups having right-hand threaded arbor-holder bores. Although
the novel plug ejecting hole saws disclosed in the present
inventor's '651 and '341 patents constituted a substantial
advancement in the art for hole saws having a base provided with a
threaded bore for receiving an arbor, there is another type of
widely employed hole saw cup which heretofore could not utilize the
advantageous plug ejecting construction disclosed in those patents.
This type of hole saw is sometimes referred to as a "Carbon" type,
since it uses hole saw cups fabricated as a unitary structure,
e.g., a deep drawn cup, made from high carbon steel. In this type
of hole saw, the saw cup base is made of relatively thin stock,
thus precluding the use of threaded bore through the base as a
means for attaching the saw cup to an arbor. Instead, this type of
hole saw typically is provided with a non-circular, e.g., a
double-D-shaped central bore through the base of the hole saw cup,
which receives the complementary-shaped, enlarged rear portion of
an arbor which is secured to the base by a threaded fastening
member. The present invention was conceived of to provide a plug
ejecting hole saw which may utilize thin base wall, non-threaded
saw cups of the type described above.
OBJECTS OF THE INTENTION
[0007] An object of the present invention is to provide a plug
ejecting hole saw including an arbor-holder which can be attached
to hole saw cups of various sizes.
[0008] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder which can be secured to
the base of a hole saw cup with non-threaded fastening means.
[0009] Another object of the invention is to provide a plug
ejecting hole saw including a hole saw cup having a right-hand
threaded arbor-securing bore through the base of the hole saw cup,
and an arbor-holder or adapter press fittable into the arbor
securing bore of the saw cup and having through the adapter a
left-hand threaded bore for threadingly receiving an arbor.
[0010] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder which is removably
securable to the base of a non-threaded hole saw cup having an
unthreaded aperture through the base of the hole saw cup for
attaching to an arbor, the arbor-holder having therethrough an
axially disposed left-hand threaded bore for threadingly receiving
an arbor.
[0011] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder which is removably
securable in an unthreaded aperture through the base of a hole saw
cup, without accessing the interior of the hole saw cup.
[0012] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder which is removably
securable to a hole saw cup provided with a non-circular aperture
through its base, the arbor-holder having a front nose piece
insertable forward through the aperture, and locking tabs which
spring forward to lock the arbor-holder axially with respect to the
saw cup when the arbor-holder is rotated with respect to the saw
cup base.
[0013] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder having an outer collar
and inner body disposed axially therethrough, the inner body having
a lefthand threaded bore disposed axially therethrough for
receiving an arbor, a front nose piece slidably holding locking
tabs and circumferential grooves which cooperate to lockingly
engage the base of a hole saw cup when the front nose piece has
been inserted into and rotated in a first direction within an
aperture provided through the base of saw cup, the locking tabs and
grooves being released from locking engagement with the saw cup
base when the collar of the arbor-holder is pulled axially rearward
with respect to the inner body thereof and rotated in the opposite
direction.
[0014] Another object of the invention is to provide a plug
ejecting hole saw including an arbor-holder having an outer collar
which axially slidably holds an inner body having disposed axially
therethrough a left-hand thread for receiving an arbor, the inner
body having a first, front, nose piece snapping lockingly
engageable and releasable within a first size aperture through a
selected one of a first plurality of hole saw cups, and a second,
rear, nose piece releasably engageable within a second size
aperture through a selected one of a second plurality of hole saw
cups.
[0015] Various other objects and advantages of the present
invention, and its most novel features, will become apparent to
those skilled in the art by perusing the accompanying
specification, drawings and claims.
[0016] It is to be understood that although the invention disclosed
herein is fully capable of achieving the objects and providing the
advantages described, the characteristics of the invention
described herein are merely illustrative of the preferred
embodiments. Accordingly, I do not intend that the scope of my
exclusive rights and privileges in the invention be limited to
details of the embodiments described. I do intend that equivalents,
adaptations and modifications of the invention reasonably inferable
from the description contained herein be included within the scope
of the invention as defined by the appended claims.
SUMMARY OF THE INVENTION
[0017] Briefly stated, the present invention comprehends a hole saw
for use with power drills which automatically ejects a
cylindrically-shaped plug produced in cutting a hole through an
object by the drill powered in a first direction, when the power
drill is operated in the opposite direction.
[0018] A plug ejecting hole saw according to the present invention
includes an arbor-holder removably attachable to a selected one of
a plurality of hole saw cups of various sizes. A main embodiment of
a plug ejecting hole saw according to the present invention
includes an arbor-holder removably attachable to a selected hole
saw cup of the type having a cylindrical cup-shaped body provided
with angled cutting teeth protruding from the front annular surface
of the body, and a relatively thin rear circular base wall having
through its thickness dimension a non-circular aperture for
attachment to an arbor concentrically aligned with the front
annular surface of the body, A preferred arbor attachment aperture
for saw cups according to the present invention has a "double-D"
shaped perimeter formed from diametrically opposed arc segments of
a circle which is concentric with the circular hole saw cup face,
the circle being truncated on opposite sides thereof by a pair of
chords equidistant from and parallel to a diameter which
perpendicularly bisects the arcs. Thus, a preferred arbor
attachment aperture provided through the base of a saw cup
according to the present invention has an inner peripheral edge
wall consisting of a pair of diametrically opposed laterally
symmetric circular arc segments centered at 90-degree and
270-degree locations of a circle, and two diametrically opposed
flat vertical segments centered on zero-degree and 180-degree
locations of the circle.
[0019] A main embodiment of an arbor-holder for use with hole saw
cups of the type having a double-D-shaped arbor-holder aperture
through the base of the saw cup includes an outer cylindrical
housing or collar having therethrough a circular bore which axially
slidably holds a body having cylindrical outer wall surfaces which
fit within the bore. The cylindrical body has a nose piece or boss
which protrudes axially outwardly of the front annular surface of
the collar, the nose piece having a longitudinally or axially
disposed outer surface with an outer transverse cross-sectional
shape similar to that of a double-D-shaped arbor-holder aperture
through a saw cup base, but having a slightly smaller size which
facilitates insertion of the nose piece into the aperture.
[0020] The nose piece has a pair of transversely disposed grooves,
each of which extends radially inwardly into a separate one of two
axially disposed, curved side walls of the nose piece, each of the
grooves having a transverse or outer edge wall located inwardly of
and parallel to the outer transverse edge wall or front face of the
nose piece. The rear or inner edge wall of each of the two
transversely disposed grooves is defined by the front or outer
transversely disposed annular wall surface of the cylindrical body
within the collar.
[0021] Each of the two transverse nose-piece grooves is disposed
circumferentially from a location circumferentially spaced apart
from a junction between a flat and curved side of the
double-D-shaped nose piece. Thus the transverse grooves form a pair
of axial shoulder ribs, which are disposed rearwardly or axially
inwardly from the front transverse face of the nose piece to the
front or outer transverse surface of the cylindrical body. The nose
piece also includes a pair of diametrically opposed,
rectangularly-shaped longitudinal grooves formed in opposite flat
sides of the nose piece, which are disposed rearwardly or axially
inwardly from a transverse plane located axially inwardly or
rearwardly of the front or outer transverse face of the nose piece,
but axially outwards or forward of a transverse plane containing
the front or outer transverse edge walls of the transverse
grooves.
[0022] Each of the two diametrically opposed longitudinal grooves
is centered on a longitudinal plane which bisects the two
diametrically opposed flats of the nose piece. Also, each
longitudinal groove is disposed rearwardly or axially inwardly
through an adjacent transverse groove and extends through the inner
cylindrical body to a location forward of the rear transverse wall
surface of the inner cylindrical body, and penetrates the outer
cylindrical wall surface of the inner cylindrical body. Each
longitudinal groove longitudinally slidably receives a locking tab
support lug having a front locking tab portion which has a length
approximating that of that portion of the longitudinal groove
located in the nose piece, and a radial thickness slightly greater
than that of the radial depth of the groove. Each lug also has a
rear portion of greater thickness than the front tab portion, and
is slidably received within that portion of a longitudinal groove
located within the inner cylindrical body. The rear portion of each
lug is urged axially forward by first spring means comprising a
compression spring, and is limited in forward axial movement by
contact of a retainer pin attached to the lug and slidably received
within a threaded blind bore axially disposed within the collar,
with an end wall of the bore. The arbor-holder also includes second
spring means which resiliently urges the inner cylindrical body of
the arbor-holder rearward or axially inwardly within the
collar.
[0023] When the inner cylindrical body of the arbor-holder is
pushed axially forward or outwardly from the collar against the
resilient force provided by the first spring means, the nose piece
is displaced forward or axially outwardly of the front annular face
of the collar. This displacement causes the front shoulder edges of
the longitudinal tab grooves to move forward of the front
transverse edge walls of the tabs. With the cylindrical inner body
pushed sufficiently far forward within the collar, the rear
transverse edge walls of the transversely disposed grooves are
moved axially outwards or forward of the front edges of the tabs,
unblocking the junctions or passageways between each transverse
groove and the longitudinal tab groove adjacent to it. Also, when
the nose piece is inserted forward into the arbor-holder aperture
of a hole saw cup, contact of the rear surface of the saw cup with
the front surfaces of the tabs pushes each tab rearwardly within
its longitudinal groove against a restoring force provided by a
compression spring. Rearward motion of the tabs unblocks the
transverse grooves, thus allowing portions of the peripheral
aperture edge wall be rotatably received within adjacent transverse
grooves of the nose piece, and thereby allowing the entire arbor
assembly to be rotated clockwise with respect to the hole saw cup.
When the rotation angle approximates forty-five degrees, each of
the two locking tabs springs axially forward in response to spring
forces exerted by the compression springs, into a separate one of
the two radial clearance spaces formed between each nose piece flat
holding a tab, and an adjacent curved inner peripheral edge wall of
the saw cup aperture. In this position, the curved portions of the
nose piece, which have outer longitudinal surfaces spaced farther
apart than the flats of the peripheral wall adjacent the aperture
through the saw cup base, are axially aligned with the peripheral
wall flats. Thus, the peripheral wall flats are retained axially
within the transverse nose piece grooves in this position. Further
clockwise rotation of the arbor-holder with respect to the saw cup
base is limited by contact of an axially disposed nose piece rib
with an intersection between the curved and flat portions of the
peripheral edge wall of the hole saw cup aperture. Counterclockwise
rotation of the arbor-holder relative to the saw cup is limited by
contact of a longitudinal edge of a locking tab with an
intersection between a curved and flat edge wall of the saw cup
aperture. With this arrangement, the saw cup is locked axially and
rotationally to the arbor-holder.
[0024] The inner cylindrical body of the arbor-holder according to
the present invention has through its thickness dimension an
axially disposed bore coaxial with the arbor-holder collar. The
bore has internal left-hand threads adapted to receive an arbor
which may be threaded into the bore through a front opening thereto
in the front or outer face of the nose piece, either before or
after the arbor-holder has been snap-locked into a saw cup as
described above.
[0025] The arbor is provided with a shank which protrudes
rearwardly from the rear surface of the arbor-holder and which is
clamped in the collet of a power drill. A collet flange at the
front end of the arbor-holder holds a pilot drill, and the rear
face of the collet flange seats against the front face of the
arbor-holder nose piece, when the arbor is threadingly tightened in
the arbor-holder bore in a counterclockwise sense, as viewed from
the front of the pilot drill. The rearwardly protruding shank of
the arbor is then clamped in the chuck of a power drill, which is
then powered on to rotate the hole saw in a clockwise sense as
viewed from the shank end of the hole saw, and cut a circular hole
through a workpiece, leaving a cylindrically-shaped plug of
workpiece material lodged within the hole saw cup. The drill is
then angled slightly away from an orientation perpendicular to the
workpiece used to bore the hole, thus slightly cocking the hole saw
cup within the hole cut through the workpiece, and thereby
frictionally lodging the hole saw cup within the workpiece hole.
The power drill is then powered on in a reverse sense to rotate the
arbor in a reverse sense, thus causing the arbor and flange to be
threadingly advanced within the arbor-holder bore, thereby ejecting
the workpiece plug forwardly out from the saw cup body.
[0026] When it is desired to remove the arbor-holder from a saw cup
body, e.g., to install the arbor-holder and arbor in a different
saw cup body, which may be of a different size, the collar of the
arbor-holder is pulled rearwardly from the front nose piece and saw
cup body, thus retracting the locking tabs from the space between
the flat sides of the nose piece and the adjacent curved peripheral
walls of the saw cup aperture. With the locking tabs thus
disengaged from the hole saw cup, the arbor-holder can be rotated
counterclockwise to align the flats and curves of the nose piece
once again with the correspondingly shaped edge walls of the saw
cup aperture, thus allowing the nose piece and entire arbor-holder
to be pulled rearwardly and disengaged from the saw cup body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an exploded perspective view of a plug ejecting
hole saw with snap action saw cup interchangeability according to
the present invention.
[0028] FIG. 2 is a perspective view of the hole saw of FIG. 1.
[0029] FIG. 3 is an exploded rear perspective view of an
arbor-holder according to the present invention.
[0030] FIG. 4 is a front elevation view of the arbor-holder of FIG.
3.
[0031] FIG. 5 is an upper plan view of the arbor-holder of FIG.
3.
[0032] FIG. 6 is a side elevation view of the arbor-holder of FIG.
3.
[0033] FIG. 7 is a rear elevation view of the arbor-holder of FIG.
3.
[0034] FIG. 8A is a partly broken away side elevation similar to
FIG. 6, and showing an arbor and pilot drill installed in the
arbor-holder and showing a front nose piece of the arbor-holder
inserted partially into a saw cup aperture.
[0035] FIG. 8B is a view similar to that of FIG. 8A, showing the
nose piece of the arbor holder fully inserted into the saw cup
aperture.
[0036] FIG. 8C is a view similar to that of FIG. 8B, showing how
the arbor holder of FIG. 8B is removed from a saw cup.
[0037] FIG. 9 is a front elevation view of the articles of FIGS. 8A
and 8B.
[0038] FIG. 10 is a view similar to that of FIG. 9, but showing the
arbor-holder rotated approximately 45 degrees clockwise with
respect to the saw cup, to lockingly engage with the saw cup.
[0039] FIG. 11 is a view similar to that of FIG. 10, but showing
the arbor-holder rotated approximately 90 degrees with respect to
the hole saw cup.
[0040] FIG. 12 is a partly broken perspective away view of the
article of FIG. 1, showing the arbor, adapter, and saw cup thereof
assembled together, preparatory to drilling a hole.
[0041] FIGS. 13-15 illustrate the manner of using the hole saw of
FIG. 1 to drill a hole and eject a plug.
[0042] FIG. 16 is a perspective view of a plug ejecting adapter for
use with hole a saw cup having right-hand threads.
[0043] FIG. 17 is a lower plan view of the adapter of FIG. 16.
[0044] FIG. 18 is a perspective view showing the adapter of FIGS.
16 and 17 partially installed in a saw cup.
[0045] FIG. 19 is a view similar to that of FIG. 18, but showing
the adapter fully installed.
[0046] FIG. 20 is a perspective view of a modification of the
adapter of FIG. 16.
[0047] FIG. 21 is a lower plan view of the adapter of FIG. 20.
[0048] FIG. 22 is a perspective view showing the adapter of FIGS.
20 and 21 installed in the saw cup of FIG. 20.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0049] FIGS. 1-12 illustrate a main embodiment of a plug ejecting
hole saw with twist-locking interchangeable saw cups according to
the present invention, while FIGS. 13-15 illustrate how the hole
saw is used FIGS. 16-22 illustrate an embodiment of the invention
useable with hole saw cups having threaded arbor receiving
bores.
[0050] Referring first to FIG. 1, a plug ejecting hole saw 20 with
twist-locking interchangeable saw cups according to the present
invention may be seen to include a novel arbor holder 21, a saw cup
22 removably fastenable to the arbor-holder, and an arbor 23
holding a pilot drill 24 threadably receivable within a threaded
bore 25 provided through the length of the arbor-holder.
[0051] As shown in FIG. 1, arbor 23 includes a longitudinally
elongated body 26 having a front portion 27 provided with external
left-hand helical threads 28 which extend rearwardly from a front
annular ring-shaped collet flange 29 which clampingly receives the
rear shank 30 of pilot drill 24, as for example, by a set screw 31
tightened into a radial bore 32 in the collet flange, against the
shank of the pilot drill. Arbor 23 also includes an intermediate
unthreaded shank portion 33 which is disposed longitudinally
rearward of front threaded portion 27 of the arbor, and a rear
shank portion 34. Rear shank portion 34 is preferably provided with
longitudinally disposed flats 35 forming a hexagonal cross section
adapted to be clampingly received in the chuck of a power
drill.
[0052] Referring still to FIG. 1, it may be seen that hole saw cup
22 comprises essentially a cylindrical cup-shaped body 36 having a
circular base 37 and a downwardly depending cylindrical shell 38
which may be fabricated as a deep drawn article from relatively
thin-gauge, e.g., 0.030-0.060 inch thick, high carbon steel,
although the exact dimensions, materials, composition and other
such details of the hole saw cup are not essential to the present
invention. Hole saw cup 22 has a plurality of triangularly-shaped
saw teeth 39 which protrude axially outwardly at regular
circumferential intervals from front annular ring-shaped surface 40
of hole saw cup body 36. Teeth 39 may be formed by cutting and
tempering hole-saw cup body 36, or may be fabricated separately as
teeth of a toothed ring which is brazed to the front annular
surface 40 of the saw cup body.
[0053] As shown in FIG. 1, base 37 of hole saw cup 22 has through
its thickness dimension a non-circular aperture 41 concentric with
front annular surface 40 and cylindrical shell 38 of hole saw cup
body 36. Aperture 41 is preferably of a conventional shape adapted
to receive prior-art hole saw arbor-holders. Thus, as shown in FIG.
1, aperture 41 has a "double-D" shaped perimeter wall 42 formed
from a pair of diametrically opposed arc segments 43 of a circle
concentric with front annular surface 40 of saw cup body 36, and a
pair of diametrically opposed straight edge segments 44 which are
chords of the circle, and equidistant from and parallel to a
diameter which perpendicularly bisects the arc segments. Thus, a
preferred arbor attachment aperture 41 through base 37 of hole saw
cup 22 has a peripheral edge wall consisting of a pair of
diametrically opposed, laterally symmetric circular arc segments 43
centered at ninety-degree and two-hundred and seventy-degree
locations, respectively, of a circle concentric with body 36 of the
hole saw cup, and two straight, flat diametrically opposed vertical
segments centered at zero-degree and one-hundred and eighty-degree
locations, respectively, of the circle.
[0054] Referring now to FIGS. 2-7, in addition to FIG. 1, hole saw
20 according to the present invention may be seen to include a
novel arbor-holder 21. As shown in those figures, arbor-holder 21
includes an outer cylindrically-shaped housing or collar 45. Collar
45 of arbor-holder 21 has front and rear transverse faces 46 and
47, respectively, which are perpendicular to the longitudinal axis
of the collar. A circular cross section bore 48 is disposed axially
through collar 45 and has an inner cylindrical wall surface 49
which axially slidably receives outer cylindrical surfaces 51 of an
axially elongated, central locking body 50 received within the
bore.
[0055] As shown in FIGS. 1-3, locking body 50 has a radially outer
portion 52 having a generally cylindrical shape of the same axial
length as collar 45, modified by front and rear pairs 53, 54,
respectively, of longitudinally disposed, relatively deep,
rectangular grooves formed in the outer wall surface 55 of the
locking body, forming therebetween circular arc-shaped cylindrical
quadrant surfaces 51. As may be seen best by referring to FIG. 2
and 3, radially outer portion 52 of locking body 50 preferably has
an axial length equal to that of collar 45. Thus constructed, front
and rear annular surfaces 56 and 57, respectively, of outer radial
portion 52 of locking body 50 are coplanar or flush with front and
rear annular surfaces 46 and 47, respectively, of collar 45.
[0056] As shown in FIGS. 1, 2 and 3, locking body 50 has an inner
radial portion 58 disposed coaxially within outer portion 52, the
inner radial portion having disposed axially therethrough a bore 25
having a left-handed threaded inner surface 60 for threadingly
receiving arbor 23. As may be seen best by referring to FIGS. 1, 2
and 3, inner radial portion 58 of locking body 50 is provided with
a front nose piece or boss 61 having a transversely disposed front
face 62 which protrudes axially outward of front annular faces 56
and 46 of inner body portion 50 and collar 45. Front nose piece 61
has a double-D-shaped transverse cross-sectional shape adapted to
be conformally inserted into aperture 41 through base 37 of hole
saw cup 22. In the preferred embodiment of hole saw 20, locking
body 50 of arbor-holder 21 preferably includes a second, rear,
double-D-shaped nose piece 63 of different size than front nose
piece 61 and having a rear transverse face 64. Rear nose piece 63
is adapted to be conformally inserted into an aperture of different
size than front nose piece 61, enabling the arbor-holder to be used
reversibly with hole saw cups 22 having two different size
arbor-mounting apertures 41. However, as will be made clear in the
ensuing description of the construction and function of hole saw
20, the novel and advantageous advantages of the hole saw may be
achieved with an arbor-holder having a single nose piece.
[0057] Referring now to FIGS. 1-5, it may be seen that a preferred,
double nose piece embodiment of arbor-holder 21 according to the
present invention includes a locking body 50 provided with a
second, rear nose piece 63 having an outer, rear face 64 which
protrudes axially outwardly or rearwardly of rear annular portion
65 of outer body portion 50, and of rear annular surface 47 of
collar 45.
[0058] Referring now to FIGS. 1-6, it may be seen that front nose
piece 61 has a double-D-shaped transverse cross sectional shape.
Thus, front nose piece 61 includes a pair of diametrically opposed,
curved, diametrically opposed side walls 66 disposed longitudinally
between front annular face 62 of the nose piece and front annular
face 56 of outer radial portion 52 of locking body 50. Curved side
walls 66 coincide with a circle concentric with the longitudinal
axis of nose piece 61. Nose piece 61 also includes a pair of flat,
diametrically opposed side walls 67 disposed longitudinally between
front annular face 62 of the nose piece and front annular face 56
of outer radial portion 52 of locking body 50. Flat side walls 67
of nose piece 61 are chords of the circle coincident with curved
side walls 66, and are equidistant from and parallel to a diameter
which perpendicularly bisects the arc segments.
[0059] As shown in FIGS. 1-6, front nose piece 61 of arbor-holder
21 has formed in curved longitudinal side walls 66 thereof a pair
of transversely disposed, rectangular cross section grooves 68
which extend radially inwardly from the outer longitudinal surface
69 of the curved side wall. Each of the two transversely disposed
grooves 68 has a front or outer transverse side wall 70 located
inwardly of and parallel to front face 62 of nose piece 61, forming
therebetween an arc-shaped web 71. Also, each transverse groove 68
has a rear or inner side wall defined by and coextensive with front
annular surface 56 of outer radial portion of locking body 50.
[0060] As may be seen best by referring to FIGS. 3, 5, 6 and 7,
each transverse groove 68 of front nose piece 61 is disposed in a
counterclockwise direction from a location counterclockwise of the
intersection between a curved side wall 66 and flat side wall 67,
thus forming a longitudinal rib web 72, which is disposed
rearwardly or axially inwardly from a front arc-shaped web 71.
Front nose piece 61 also has formed in flat longitudinal side walls
67 thereof a pair of diametrically opposed, longitudinally disposed
rectangular cross section grooves 74. Each longitudinal groove 74
is disposed axially inwardly or rearwardly from a front edge wall
75 located inwardly of and parallel to front face 62 of nose piece
61, forming therebetween a front transversely disposed rectangular
web 76. Preferably, front edge wall 75 of each longitudinal groove
74 is located axially forward or outwardly of front edge wall 70 of
transverse grooves 68.
[0061] Each longitudinal groove 74 has a flat, axially disposed
bottom wall 70 and axially disposed side walls 78 perpendicular to
the base wall. As may be seen best by referring to FIG. 1, each of
the two longitudinal grooves 74 is disposed rearwardly or axially
inwardly from a front web 76 through an adjacent transverse groove
68, and penetrates front annular face 56 and outer cylindrical wall
surface 55 of outer radial portion 52 of locking body 50. Each
longitudinal groove 74 has a rear transversely disposed end wall 79
located forward or axially outwardly of rear annular face 57 of
radial outer portion 52 of body 50, forming therebetween a rear
transversely disposed web 80.
[0062] Referring now to FIGS. 1, 3 and 6, it may be seen that
arbor-holder 21 includes a pair of front locking lugs 81 axially
slidably received within longitudinal grooves 74 in locking body
50. Each front locking lug 81 has the shape of an axially
elongated, rectangular block having a front rectangularly blocked
shaped step portion 82 of reduced height. As will be described in
detail below, front rectangular block-shaped step portion 82 of lug
81 serves to lock front nose piece 61 of arbor-holder 21 within
aperture 41 of hole saw cup 22, and will henceforth be referred to
as a locking tab.
[0063] As shown in FIGS. 1 and 3, each front locking lug 81 has
protruding from the upper surface 83 thereof a longitudinally
elongated and disposed cylindrical retainer pin 84 which protrudes
axially rearward or inwardly of rear transverse surface 85 of the
locking lug. As may be seen best by referring to FIGS. 1 and 3, the
retainer pin 84 of each locking lug 81 is joined to the upper
surface 83 of the locking lug by a thin, axially disposed
rectangular web 86 which depends downwardly from the lower
cylindrical surface of the locking pin.
[0064] Referring now to FIGS. 1 and 3, it may be seen that collar
45 is provided with a pair of diametrically opposed, longitudinally
disposed blind bores 87 which extend axially forward from rear
annular surface 47 of the collar. Each bore 87 is adjacent and
parallel to inner cylindrical wall surface 49 of the collar, and
has a circular outer radial portion 88 adapted to axially slidably
receive a retainer pin 84. Also, each bore 87 has at an inner
radial edge thereof a longitudinally disposed rectangular slot 89
which penetrates the outer circular radial portion 88 of the bore
at an outer radial edge of the slot and which penetrates the inner
cylindrical wall surface 49 of the collar at an inner radial edge
of the slot. Slots 89 are provided to longitudinally slidably
receive webs 86 joining retainer pins 84 to locking lugs 81.
[0065] As may be best understood by referring to FIGS. 1-3, each
front locking lug 81 is preferably installed in arbor-holder 21 by
first positioning the inner block-shaped portion of the locking lug
in the rear portion of a longitudinal groove 74 in locking body 50,
with a helical compression spring 90 bearing against rear wall
surface 79 of the groove and rear wall surface 85 of the locking
lug. Locking body 50 is then positioned coaxially rearward of rear
surface 47 of collar 45 with retainer pins 84 axially aligned with
retainer pin bores 87, and the locking body is inserted axially
forward into bore 48 of collar 45, simultaneously with insertion of
retainer pins 84 into retainer pin bores 87. Forward motion of each
front locking lug 81 relative to front annular surface 46 of collar
45 is limited by contact between front face 93 of a retainer pin 84
abutting a front transverse end wall 94 of a retainer pin bore 87.
Thus limited in forward axial motion, front face 95 of thicker rear
portion 96 of the front locking lug 81 is coplanar or flush with
front annular surface 46 of collar 45.
[0066] Compression spring 90 of front locking lug 81 of
arbor-holder 21 also provides means for spring biasing locking body
50 axially rearwardly within bore 48 of collar, so that front
annular face 56 of radially outer portion 52 of locking body 50 is
coplanar or flush with front annular face 46 of collar 45.
Arbor-holder 21 also includes means for spring biasing locking body
50 axially forward with collar 45. In a preferred embodiment of
arbor-holder 21, the arbor-holder is of a double ended, push-pull
construction having a rear nose piece 63 which protrudes rearward
from collar 45, the rear nose piece being substantially identical
in structure and function to front nose piece 61, but of a
different size for attachment to hole saw cups 22 having an arbor
mounting aperture 41 of different size than those which front nose
piece 61 is adapted to conformally fit within. In this preferred
embodiment, forward or axially outward spring biasing of front
locking body 50 and front nose piece 61 within collar 45 is
accomplished by a pair of rear locking lugs 81R (Rear) and helical
rear locking lug compression springs 90R identical in structure and
function to front locking lugs 81 and springs 90, but which
function in a direction longitudinally or axially opposed to those
of the front locking lugs and springs, as depicted in FIG. 1. In
the preferred, double ended embodiment of arbor-holder 21 depicted
in the figures, saw cup aperture-engaging rear nose piece 63 having
a rear or outer axial face 64 is entirely analogous in structure
and function to front nose piece 61 having a front or outer face
62. Moreover, rear nose piece 63 has associated with it structural
elements that are identical in structure and function to elements
66 through 96 associated with front nose piece 61 and described in
detail above. Thus, the previous discussion of those elements, in
conjunction with the ensuing description of the operation of front
nose piece 61 of arbor-holder 21, will suffice to fully describe
the structure and function of the arbor-holder.
[0067] Referring again to FIGS. 1-3, it may be understood that each
of the two front locking lugs 81 is preferably installed in
arbor-holder 21 by inserting retainer pins 84 of each front locking
lug axially forward into a blind retainer pin bore 87, forward
axial motion of each front locking lug being limited by contact of
the front face 93 of the retainer pin with front transverse end
wall 94 of a retainer pin bore 87. Rearward axial motion of each
front locking lugs 81 is limited by compression of spring 90
against rear transverse end wall 79 of longitudinal groove 53/74 in
which the locking lug is axially slidably received. Preferably, as
shown in FIG. 7, a set screw 98 is threaded into the entrance of
each front locking lug retainer pin bore 84 after arbor-holder 21
is assembled, to exclude entrance of dust or other foreign matter
Into the bore.
[0068] It may be understood by referring to FIGS. 1 and 3 that each
of two rear locking lugs 81R is preferably installed in
arbor-holder 21 by inserting retainer pins 84R of each of the rear
locking lugs axially forward into a blind retainer pin bore 87R,
forward axial motion of each rear locking lug being limited by
contact of the rear face 99R of the retainer pin with front
transverse end wall 94R of a retainer pin bore 87R. Rearward axial
motion of each rear locking lug 81R is limited by contact of font
face 93R of retainer pin 84R with a set screw 98R threaded into the
entrance of each rear locking retainer pin bore 87R after
arbor-holder 21 is assembled.
[0069] As will be made clear in the description of the operation of
arbor-holder 21 presented below, attachment of the arbor-holder to
a saw cup entails insertion of nose piece 61 of the arbor-holder 21
into aperture 41 of a hold saw cup 22, and axial inward or rearward
motion of locking tabs 82 while inner locking body 50 is held
axially fixed within collar 45. Immobilization of inner locking
body 50 relative to collar 45 during this step may be accomplished
simply by applying a forward restraining force on the rear nose
piece of arbor-holder 21, or the shank of an arbor 23 protruding
rearwardly from the arbor-holder, e.g., by the palm of a hand
grasping the collar to install the arbor-holder in a saw cup body.
Preferably, however, arbor-holder 21 is provided with integral
means for resisting axial motion of inner locking body 50 relative
to a collar 45 when locking lug bias springs 90 are axially
depressed in response to axially inward motion of locking tabs 82.
Thus, as shown in FIGS. 1 and 3, collar 45 of arbor-holder 21
preferably has a threaded bore 100 which is disposed radially
between outer cylindrical wall surface 101 and inner cylindrical
wall surface 49 of the collar. A ball 102 within bore 100 is urged
radially inwardly into a dimple 103 formed in the outer cylindrical
wall surface of inner locking body 50 by a compression spring 104
disposed within the bore and retained therein by a set screw 105.
Thus constructed, axial motion of inner locking body relative to
collar 45 is resiliently resisted with a force adjustable by
adjusting compression in spring 104 by turning set screw 105.
Operation Of The Invention
[0070] The novel functional characteristics of hole saw 20
according to the present invention may be best understood by
referring to FIGS. 7-13.
[0071] Referring now to FIGS. 7-13, arbor-holder 21 of hole saw 20
is shown with threaded intermediate shank portion 33 of an arbor 23
threaded into threaded bore 25 through the arbor-holder. As is also
shown in FIGS. 7-13, the flat and curved portions of the
longitudinal side walls of front nose piece 61 are axially aligned
with corresponding flat and curved side walls of aperture 41
through base 37 of hole saw cup 22, and the nose piece pushed
forward into the saw cup arbor-mounting apertures. During this
installation step, axially inward or rearward motion of nose piece
61 with respect to collar 45 is prevented by a radial force exerted
on locking body 50 of the nose piece by compression spring 104 and
ball 102, or by preventing axial motion of shank 34 of arbor 23,
e.g., by pressing the palm of a hand against the rear surface of
the shank.
[0072] As shown in FIG. 8A, inserting front nose piece 61 of
arbor-holder 21 sufficiently far into hole saw cup arbor attachment
aperture 41 causes rear surface 106 of hole saw cup base 37 to
contact and press front locking tabs 82 axially rearwardly or
inwardly within longitudinal locking tab grooves 74. As shown in
FIG. 8A, axially inward motion of locking tabs 82 causes the front
edge walls 107 of the locking tabs to be pushed rearward or axially
inwardly of rear edge walls of transverse grooves 68, as shown in
FIG. 8B, thus unblocking and extending the effective
circumferential extent of each transverse groove counterclockwise
to an axially disposed rib which is located counterclockwise of
longitudinal groove 74, from the former limit formed by a clockwise
longitudinal edge wall of locking tab 82. The increased effective
length of each transverse groove 68 permits front nose piece 61 of
the arbor-holder to be rotated counterclockwise with respect to
hole saw cup body, as viewed from the front of the arbor-holder and
saw cup and shown in FIG. 9. This rotation is enabled by the web
portion of aperture 41 of saw cup base 37 being slidably received
within that portion of longitudinal groove 74 comprising an
extension of transverse groove 68, and which is normally blocked by
locking tabs 82 urged forward by locking lug springs 90.
[0073] As shown in FIG. 10, when nose piece 61 of arbor-holder 21
has been rotated about 45 degrees with respect to its axially
aligned initial position with respect to aperture 41 of hole saw
cup 22, radial clearance space between flat portion 67 of nose
piece 21 and curved inner peripheral edge wall 43 of the aperture
becomes sufficient to allow forward axial motion of locking tabs 82
into the clearance spaces. Further counterclockwise motion of nose
piece 61 within aperture 41 of saw cup 22 is limited to about 221/2
degrees by contact of a counterclockwise longitudinal rib 72, with
the intersection between the opposed curved 43 and straight 44
peripheral aperture edge walls 72 of aperture 61. Moreover,
clockwise rotation of arbor-holder 21 with respect to hole saw cup
22 is limited to about 221/2 degrees by abutting contact between
the clockwise edge of a locking tab 82 and an intersection between
a curved peripheral wall 43 and a straight peripheral wall 44 of
aperture 41, that intersection located clockwise of a second
longitudinal nose piece rib 72. Thus installed, saw cup 22 is fixed
against axial movement with respect to front nose piece 61 of
arbor-holder 21 by front rear edge walls of transverse nose piece
grooves 68 embracing perimeter wall 42 of saw cup aperture 41,
against counterclockwise rotation of the arbor-holder relative to
the saw cup by a longitudinal nose piece rib 72 abutting the
aperture perimeter wall, and against clockwise rotation by a
locking tab 82 abutting the aperture perimeter wall.
[0074] FIGS. 13-15 illustrate how hole saw 20 according to the
present invention is used to cut a hole through a workpiece and
eject a workpiece plug from the saw.
[0075] Referring first to FIG. 13, arbor 23 of hole saw 20 is shown
clamped in the chuck B of a power drill A, and the drill powered on
to rotate the arbor of arbor-holder 21 and hole saw cup 22 in a
clockwise sense to bore a circular hole C through a workpiece D,
e.g., a wooden door panel, and thus lodging a cylindrically-shaped
plug E cut from the workpiece within the bore of the saw cup.
[0076] As shown in FIG. 14, the longitudinal axis of drill A and
hole saw 20 are then cocked at an angle with respect to a
perpendicular to the longitudinal axis of hole C, lodging the outer
surface of hole saw cup 22 against the inner peripheral wall
surface of hole C. Then, as shown in FIG. 15, drill A is powered to
turn hole saw 22 in a counterclockwise direction. This action
causes left-hand threaded arbor 23 to threadingly advance outwardly
from the threaded bore of arbor-holder 23, thus advancing collet
flange 29 and plug E out from the bore of saw cup 22.
[0077] Arbor-holder 21 may be readily removed from a hole saw cup
22 and attached to a different hole saw cup, by first grasping
collar 45, and pulling axially rearwardly, as shown in FIG. 8C.
This action retracts locking tabs 82 axially inwardly within
longitudinal nose piece grooves 74 from transverse grooves 68, thus
allowing collar 45 to be rotated ninety degrees clockwise to align
the contours of front nose piece 61 with those of saw cup aperture
41, thus permitting the arbor-holder to be pulled rearward to
remove the nose piece from the aperture.
[0078] If it is desired to attach arbor-holder 21 to a hole saw cup
22 having a different size aperture 41, arbor 23 may be threaded
into rear nose piece 63, as shown in FIG. 2, whereupon the rear
nose piece may be inserted into the aperture, and the arbor-holder
attached to the different size hole cup and used exactly as
described above.
[0079] In a modification of the plug ejecting hole saw described
above, the arbor holder and arbor could both be provided with
right-hand threads, thus providing all of the advantages of the
basic embodiments described above, including quick
interchangeability of different size saw cups, without the plug
ejecting capability.
[0080] FIGS. 16-22 illustrate adapters for converting non-plug
ejecting hole saws with right-hand internal arbor threads into plug
ejecting hole saws having left-hand internal threads adapted to
receive left-hand threaded, plug-ejecting arbors.
[0081] FIG. 16 shows a plug ejecting adapter 110 for a hole saw cup
F having a right-hand threaded bore G for receiving a right-hand
threaded arbor (not shown). As shown in FIG. 16, adapter 110
comprises a cylindrical body 111 having at a first, rear end
thereof a transversely disposed, circular ring-shaped flange 112 of
larger diameter than the body. Body 111 has disposed through its
length a left-hand threaded bore 113. Body 111 also has protruding
radially outwardly from cylindrical surface 114 thereof a plurality
of longitudinally disposed, circumferentially spaced apart axial
ribs 115. As shown in FIG. 16, each rib 115 courses axially forward
from front annular surface 116 of flange 112, to a location
rearward of front annular surface 117 of body 111. As shown in FIG.
17, each rib 115 preferably has a triangular cross-section adapted
to cut through threads H of threaded bore G through saw cup F, when
adapter 110 is press-fitted into the saw cup bore.
[0082] Referring now to FIGS. 17 and 18, it may be seen that a
front portion 118 of cylindrical wall surface 114 of adapter 110
forward of front transverse ends 119 of ribs 115 has a diameter
slightly less, e.g., 0.001 inch, less than the minimum inner
diameter of threaded bore G of saw cup F. Thus, as shown in FIG.
18, when force is applied to rear annular surface 120 of adapter
flange 112 to drive body 111 of adapter 110 partially into bore G,
bore 113 through the adapter is aligned with bore G. Then, when
adapter 110 is pressed fully into bore G of saw cup F, as shown in
FIG. 19, front annular surface 116 of rear adapter flange 112 seats
on rear annular surface J of saw cup F. In this position, ribs 115
of adapter 16 fit tightly into longitudinally disposed grooves cut
into saw cup threads H, by driving the adapter into the saw cup
bore, thus tightly gripping the ribs and securing the adapter to
the saw cup, which may then be used with a left-hand threaded plug
ejecting arbor in the manner described above.
[0083] FIGS. 20-22 illustrate a modification 120 of adapter 110.
Modified adapter 120 is particularly well adapted for use with hole
saw cups of larger diameter, requiring larger drive torques. FIGS.
20 and 21 show a plug ejecting adapter 120 for a hole saw cup F,
having a right-hand threaded bore G1 for receiving a right-hand
threaded arbor (not shown). As shown in FIG. 20, hole saw cup F1
has through rear base wall K1 thereof a pair of apertures L1
located on diametrically opposed sides of saw cup bore G1.
[0084] As shown in FIGS. 20 and 21, modified adapter 120 includes a
cylindrical body 121 having at a first rear end thereof a
transversely disposed flange 122. Flange 122 has a central circular
portion 123 of larger diameter than body 121, and a pair of
diametrically opposed, semi-oval-shaped wings 124 which protrude
radially outwardly from the central circular portion of the
flange.
[0085] Modified adapter 120 also has a pair of parallel engagement
pins 125 which protrude axially forward from front annular surface
126 of flange 122. As shown in FIG. 20, pins 125 are preferably of
about the same length as body 121 of adapter 120, are of smaller
diameter than apertures L1 through saw cup base K1, and are axially
alignable with the apertures. Body 121 of adapter 120 has disposed
through its length a left-hand threaded bore 133. Body 121 also has
protruding radially outwardly from cylindrical surface 134 thereof
a plurality of longitudinally disposed, circumferentially spaced
apart axial ribs 135. As shown in FIG. 20, each rib 135 courses
axially forward from front annular surface 126 of flange 122, to a
location rearward from front annular surface 137 of body 121. As
shown in FIG. 22, each rib 135 preferably has a triangular
cross-section which is adapted to cut through threads H1 of
threaded bore G1 through saw cup F1, when adapter 120 is
press-fitted into the saw cup bore.
[0086] Adapter 120 is installed in saw cup F1 in exactly the same
manner as adapter 110 is installed in saw cup body F and described
above. Thus installed, engagement pins 125 are received in
apertures L1 through rear base wall K1. With this arrangement,
large torques between adapter 120 and saw cup F which might
dislodge ribs 135 from bore G1 of the saw cup are prevented from
doing so by pins 125 held in apertures L1 and thereby preventing
relative rotation between the adapter and saw cup.
* * * * *