Note: Descriptions are shown in the official language in which they were submitted.
CA 02243746 1998-07-22
CORNER UNDERCUT JAMB SAW
BACKG ROUND OF THE INVENTION
Field of the Invention:
This invention relates generally to powered saws, and
more particularly to a saw for removing enough wood from the
lower end of door jambs to enable installation of flooring
products such as ceramics, carpets, vinyl tile and hardwood,
for example.
Description of the Prior Art:
There is currently on the market, an undercut saw
marketed by Crain Cutter Co., Inc. of Milpitas, California
under the Model No. 800. This saw is useful to cut away the
lower end of outer corners of door jambs immediately above a
sub-floor, to provide sufficient space to insert finish
flooring materials. Another saw which we have heard a
little about is a "door trimmer" by Janser Inc. of Benton
Harbor, Michigan. But we do not believe that these saws are
useful for interior corners. Prior to the present
invention, it was necessary to use a hand saw or chisel at
inside corners or use shoe molding to cover up the finished
flooring at inside corners. So there has been a need for a
better way to undercut door jambs. This invention addresses
that need.
CA 02243746 1998-07-22
SUMMARY OF THE INVENTION
Described briefly, according to a typical embodiment of
the present invention, a powered cutter is supported on a
carriage which is mounted on a guideway supported to enable
moving the machine around on a horizontal surface such as a
sub-floor of a building. The cutter-to-floor spacing is
adjustable. A cutter guard is affixed to the guideway and
shaped to admit the machine to an inside corner of a
building room. The cutter is normally disposed in a
retracted rest position behind the guard but can be advanced
into position ahead of the guard when the guard is
positioned adjacent or against a door jamb or the like and
the carriage is pushed toward the door jamb to advance the
cutter into cutting position. Immediately upon release of
the advancing force, the cutter is resiliently returned to
retracted protected position.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a side elevational view of the corner undercut
jamb saw according to the present invention.
Fig. 2 is a top plan view thereof.
Fig. 3 is a front end view thereof.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to
the embodiment illustrated in the drawings and specific
language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope
of the invention is thereby intended, such alterations and
further modifications in the illustrated device, and such
further applications of the principles of the invention as
illustrated therein being contemplated as would normally
occur to one skilled in the art to which the invention
relates.
Referring now to the drawings in detail, a guideway base
plate 11 is generally rectangular in configuration but with
a pointed front portion having a forwardly-opening U-shaped
notch llS centered on the longitudinal center line of the
base. The base is supported at three points 12, 13 and 14
by adjusting foot assemblies, each of which, in the
illustrated embodiment, includes a 1/4-20 bolt 16, an
assortment of washers 17 and a stop nut 18 threaded on the
top of the bolt. The selection and thickness of the washers
and their location between the bolt head 19 and the bottom
llB of the base 11 determines the spacing between the base
and the sub-floor or other support surface 21. It thereby
determines the spacing between the saw blade 22 and the
surface 21. Therefore, if surface 21 is the sub-floor of a
room, the spacing established by the adjustable feet
determines the space between the sub-floor and the bottom of
a door jamb 23 after it is cut at line 24 by the saw blade.
Alternatively to the washer stack, threaded holes can be
provided in the plate 11 and jamb nuts screwed onto the bolt
above and below the plate and tightened against the plate
after the desired adjustment is made by threading the bolt
16 up or down in the plate. Other alternatives may be
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employed. The use of the three feet assures that there will
be no rocking of the machine as the cut is made, even if the
floor 21 is not perfectly level and smooth.
Base plate 11 has two parallel upstanding guide flanges
26 and 27, the top edges of which lie in a plane that is
parallel to the plane of the bottom llB of the plate 11.
These flanges serve both as guideways and supports for a
carriage which is in the form of slide 31 which is
rectangular and includes two parallel downturned flanges 32
and 33 located immediately inboard and in slip-fit
relationship to the flanges 26 and 27, respectively. Slide
runners are provided in the form of narrow, downwardly
facing surfaces 34 and 35 of the slide immediately outboard
the guide flanges 32 and 33, respectively, and bearing on
the top edges 26T and 27T of the guide flanges 26 and 27,
respectively. Therefore, the slide 31 can readily slide
back and forth in the directions of arrows 36 and 37,
respectively, in Fig. 1. The slide is retained on the base
flanges 26 and 27 by brackets 38 and 39, respectively, which
have an inverted L-shape, the downwardly extending legs
thereof being fastened to the flanges 26 and 27 by five
screws 41, each.
A nose guard or blade guard 42 is made of a piece of
metal that has an upstanding flange serving as a wall which
makes an angle of 90~ as viewed from the top. The base 42H
of the guard extends rearwardly from the wall and has a
U-shaped notch 42S opening to the rear and aligned with the
forwardly opening U-shaped notch between the edges llL and
llR (Fig.2) in the base 11. The guard base is fastened to
the top of base 11 at opposite sides of the notches by
screws such as 44, and is mounted so that the bisector of
the corner angle and the notches is at the center line 43 of
the machine. This enables the machine to be moved into an
inside corner of building room walls as represented by the
two corner jamb pieces 23A and 23B. It should be
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recognized, of course, that the angle can be even sharper,
if desired, to facilitate undercutting jamb boards that are
disposed at an angle less than gOo. But the travel of the
saw blade 22, as will be seen, is so significant that it is
capable of undercutting jambs all the way through the jambs
even though the included angle between the two jamb boards
is less than 90~.
Power for the saw is provided by a power unit 46
including an electric motor, handle and gear head assembly
which, in the illustrated example, is a MILWAUKEE BRAND
electric polishing machine, Model No. 55-40, manufactured by
the Milwaukee Electric Tool Corporation of Brookfield,
Wisconsin, 53005 U.S.A. Because that machine is not
marketed for usage as a saw, we provide a special arbor 47
which has a threaded central aperture whereby the arbor is
screwed onto the polisher output spindle and up tight
against a shoulder thereon. The saw blade 22 is mounted on
the arbor, and secured thereon by a tapered flat head screw
48 with an allen socket in the head and 5/8-10 thread
screwed into the threaded central aperture in the arbor.
The taper centers the blade on the spindle axis. The blade
is non-rotatably pinned to the arbor by two number 10-32 set
screws parallel to and on opposite sides of the spindle axis
50. The saw blade is a standard 5.5 inch diameter
carbide-tipped blade drilled to receive the setscrews. The
blade is spaced slightly below the bott~m llB of the base
11 .
The spindle and arbor of the polisher require clearance
as the saw blade is advanced from the position shown by the
solid line 22 in Figs. 1 and 2, to the dotted line position
shown in Fig. 2 where it is fully advanced. Therefore, the
base is provided with notch llS beginning in base 11 behind
the spindle and extending forward and open at the front.
Similarly, the base 42H of the blade guard has the
rearwardly-opening notch 42S beginning near the front of the
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guard and extending to the rear and in registry with the
base notch llS, and through which the blade 22 can be seen
in Fig. 2. This combination of notches provides an open
path for the blade mounting arbor as it is moved forward
from the rest position shown by the solid circular
representation of the saw blade to the position shown by the
dashed circular representation of the saw blade.
A generally L-shaped back stop 51 fastened to base 11
near the rear end of the base and engageable by the rear end
of the slide flange 33, limits the rearward travel of the
carriage relative to the base 11. The p~wer unit is
constantly urged toward a rest position against the back
stop by a tension spring 52 whose rear end is hooked to a
post 53 screwed into the plate 11 below the machine handle
46H. The front end of the spring is hooked at 54 in a hole
in slide 31 or to a post projecting down from the bottom of
slide 31.
The power unit is mounted to the slide 31 at the front
and rear. At the front, a triangular plate 61 fastened to
the top of the slide 31 by two cap screws 62, is fastened to
the bottom of the motor gear case 46F at the front 61F by a
screw extending up into the gear case from the bottom of the
plate 61. Near the rear end of the motor, there is a
U-shaped bracket 63 which is fastened to the top of the
slide 31 by screws 64 (Fig. 3) extending up through the
slide and threaded into the horizontal ~ort-ion 63H of the
bracket 63. Upstanding arms 63U of the bracket 63 are
connected both to the motor housing at the rear and to side
bracket plates 66 and 67. The connection of the bracket 63
to the side plates 66 and 67, is made by two special studs,
one on each side and which pass through the plates 66 and 67
and the upstanding arms 63U at each side of the motor
housing. The attachment includes the stud 68 having the nut
69 outside plate 66 and nut 70 inside the upstanding bracket
arm 63U which is hidden behind the downwardly extending leg
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71L of the handle mounting bracket in Fig. 3. The threaded
body of the stud passes freely through apertures in the side
mounting plate 66 and the upstanding bracket arm 63U and
into a recess in the side of the motor housing where the
original housing tie bolt head normally resided. The same
construction is provided with stud 73 at the opposite side
of the motor housing. Both studs 68 and 73 are internally
threaded with a number 10-32 thread. A through bolt or
screw 74 threaded throughout its length, extends all the way
through stud 68 and the motor housing and stud 73. Its
threaded reception in the studs, and the-abutment of the
inner ends of the studs in the recesses in the motor
housing, enable tightening the studs against the motor
housing to hold it together just as it was originally held
together by the through bolt that was removed to enable
adaptation to the present invention. The outer ends of the
studs can be slotted, if desired, to facilitate turning them
in on the screw 74 and thereby tightening the studs against
the motor housing. The nut 69 threaded onto stud 68 is
tightened against the side plate 66, and the nut 70 threaded
onto the stud 68 is tightened against the inside face of the
arm 63U of mounting bracket 63 affixing the bracket 63 and
the side plate 66 together. The same construction is
provided at the other arm of bracket 63 and side plate 67.
The same kind of construction is provided near the bottom of
each of the arms 63U with the studs, throug~ bolt or screw,
nut and washer assembly 76.
At the front of the side bracket plates 66 and 67, they
are connected to the motor body by bolts 81 (Fig. 3)
threaded into the gear case, with suitable spacer nuts 82
between the inside faces of the plates 66 and 67, and the
outside faces of the gear case. The threaded holes in the
gear case are those already provided for mounting a handle
on the left hand or right hand side of the machine when it
was used as a polisher.
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A handle 83 is fastened by bolt 84 to the horizontal
portion of the handle mounting bracket 71, the downward~y
projecting legs 71L of which are fastened to the inside
faces of plates 66 and 67 by three number 10-32, round head
screws 86 with washers and nuts 87 on the inside face of the
side plates 66 and 67.
In the use of the invention, a determination is first
made as to whether or not the sub-floor on which the machine
is to be operated, is hard and smooth enough for the bolt
heads 19 of the adjustable foot assemblies to be slided on
it smoothly. If not, or if the jambs are being undercut
prior to placement of underlayment, a piece of plywood or
underlayment material 88 can be placed under the feet for
the machine feet to rest on it in the same position as the
piece 88 is maneuvered around on the sub-floor to place the
machine in the orientation desired for undercutting jambs.
In any case, the feet are adjusted by the appropriate
selection of washers to place the top of the saw blade at
the desired level above the sub-floor to accommodate the
insertion of finished flooring tile, wood, carpet or other
material. Then the machine is pointed toward the surface to
be undercut and moved to position the blade guard 42 at or
near the vertical surface of the door jamb or wall molding.
Then the saw blade is started by pulling the trigger under
handle 46H and the blade is advanced by pushing the power
unit forward toward the wall, advancin~ the blade into the
door jamb or wall molding and moving the machine around the
door jamb as needed to provide the desired undercut. Then,
when the cutting is complete within the range of motion of
the blade, the handle is released and the power unit returns
under the urging of the spring 52 until the rear end of the
slide flange 33 engages the upwardly extending abutment
surface 51S of the back stop 51. The total travel of the
slide 31 on the base 11 from the forwardmost position of the
blade shown by the dotted outline 22 in Fig. 2 and where the
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angled front end of the bracket 61 (Fig. 2) is immediately
behind the upturned wall of the blade guard 42, to the
normal rest position where the rear end of guide flange 33
abuts the stop 51S, is approximately 2-5/8 inches.
From the foregoing description, it can be readily
recognized that practice of the invention can be made with
different brands of power units, electrically or otherwise
powered, with circular or other cutters, and the mountings
thereof to the carriage will be different, depending upon
the specific construction of the power unit. Cutter height
adjustment can be done otherwise than with the illustrated
screws, nuts and spacers. Also, of course, apparatus
tailor-made throughout to function according to the present
invention, can be provided. Therefore, while the invention
has been illustrated and described in detail in the drawings
and foregoing description, the same is to be considered as
illustrative and not restrictive in character, it being
understood that only the preferred embodiment has been shown
and described and that all changes and modifications that
come within the spirit of the invention are desired to be
protected.
