Cutlery – Cutting tools – Saw
Reexamination Certificate
2000-11-24
2002-06-11
Watts, Douglas D. (Department: 3724)
Cutlery
Cutting tools
Saw
C030SDIG001
Reexamination Certificate
active
06401346
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to hand tools for cutting or sawing. More specifically, the present invention relates to a particular type of handsaw known as a “coping saw”. Coping saws have been in existence for many years and are used primarily by carpenters and other craftsmen for manually cutting curves or angles in wood or other material to create a coped appearance. Coping saws are especially useful in cutting and fitting the crown molding, cove molding and base molding used in many homes and commercial buildings. A typical coping saw is hand operated and has a very narrow linear saw blade which is held, under tension, within a U-shaped frame. Prior art coping saws are similar to hacksaws or fretsaws in that their linear blades must be supported at both ends for proper use. As in most saws, the teeth of a coping saw blade generally have only one sharp edge and will therefore cut in only one direction—typically on the “pull” stroke.
Because of the inherent design and configuration required and necessary for the proper use of a coping saw, it has been difficult, heretofore, to create a useful and effective power driven coping saw. Attempts have been made to produce power driven “reciprocating” coping saws such as the ones disclosed in Keevers, U.S. Pat. No. 5,369,887 and Adomatis, U.S. Pat. No. 4,949,464. However, due to the reciprocating action of the blades, these devices have been only marginally more effective or efficient than manual coping saws. These devices have also been known to bind within the material being cut and merely vibrate back and forth instead of actually cutting or sawing.
Attempts have also been made to produce portable, power driven saws which utilize a continuous or endless blade such as the ones disclosed in Niksich, U.S. Pat. No. 3,621,894 and Schroeder, U.S. Pat. No. 5,363,558. These devices, however, are designed to use a spiral or cylinder-type blade and not the flat and narrow linear blade desired by most craftsmen for use as a coping saw. The Niksich reference discloses a hand held, belt-driven, saw-type power tool wherein the belt and spiral blade travel together around the grooved edge of a C-shaped body. The Schroeder reference discloses a cordless, belt-driven, coping saw having a large U-shaped frame for use with a cylinder-type blade.
The present invention is a modification and significant improvement over prior art, particularly the Schroeder reference, and incorporates unique and novel design features which distinguish the invention over the existing art.
SUMMARY OF THE INVENTION
In view of the foregoing, it is a primary object of this invention to provide a lightweight, ergonomically designed and balanced, hand-held, electric or battery-powered, band-type coping saw, the design and construction of which allows the efficient use of both linear and cylindrical-type band blades.
According to an embodiment of the invention, a powered hand-held coping band saw comprises a balanced, ergonomically designed, handle for housing and controlling a small, but powerful, variable-speed electric motor. The motor operates a gear drive which propels a sprocketed band blade or abrasive cable around and through a specially designed pulley system within a U-shaped uniframe attached to said handle.
An advantage of the present invention is the provision of a powered band-type coping saw having a driving mechanism which allows the blade to be easily and efficiently propelled around and through its U-shaped uniframe in one continuous direction with virtually no vibration.
Another advantage of the present invention is the provision of a powered band-type coping saw having a detachable rechargeable battery pack for portability and extended use.
Another advantage of the present invention is the provision of a powered band-type coping saw having design features that make the device easily maneuverable thereby increasing the effectiveness of the device and thus the efficiency of its user.
Another advantage of the present invention is the provision of a powered band-type coping saw the design of which allows a craftsman or other user of the saw to cut quickly, accurately and at the desired angle.
Another advantage of the present invention resides in the unique and simplistic design of its blade driving mechanism and pulley system.
A further advantage of the present invention is the provision of a powered band-type coping saw the design of which not only allows for the use of linear band blades for coping wooden materials but also allows for the use of abrasive cables for cutting plastic or metallic materials such as conduit or rebar.
A further advantage of the present invention resides in the compact, lightweight unicast housing and frame of the device.
A further advantage of the present invention is the provision of a powered, band-type, coping saw which provides for continuous “pull stroke” operation and which meets and exceeds all safety requirements.
A final advantage of the present invention resides in the easy access to, and the ease of installation and replacement of, the band blade or abrasive cable.
REFERENCES:
patent: 1303809 (1919-05-01), Lofgren
patent: 3621894 (1971-11-01), Niksich
patent: 4949464 (1990-08-01), Adomatis
patent: 5363558 (1994-11-01), Schroeder
patent: 5369887 (1994-12-01), Keevers
patent: 5388334 (1995-02-01), Halsey
May Wm. Randall
Watts Douglas D.
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