Gear cutting – milling – or planing – Milling – Randomly manipulated – work supported – or work following device
Reexamination Certificate
2000-07-11
2002-09-03
Howell, Daniel W. (Department: 3927)
Gear cutting, milling, or planing
Milling
Randomly manipulated, work supported, or work following device
C144S136950, C144S154500, C408S112000, C408S24100G, C409S206000
Reexamination Certificate
active
06443676
ABSTRACT:
FIELD OF THE INVENTION
This invention pertains generally to hand-held power tools, such as spiral cutting tools, and accessories therefore, and more particularly to adjustable depth guides for setting the depth of cut to be made by such power tools.
BACKGROUND OF THE INVENTION
A spiral cutting tool is a hand-held power tool having an electric motor that rotates a spiral cutting tool bit at high speeds. A spiral cutting tool bit includes a sharp cutting edge that is wrapped in a spiral around the axis of the bit. The spiral cutting tool bit is designed for cutting perpendicular to the axis of the bit. The electric motor that drives the bit is enclosed in a motor housing. The motor housing is generally cylindrical in shape, with the spiral cutting tool bit extending from one end of the motor housing along the axis of the housing. A spiral cutting tool is used to remove material from a work piece by moving the rotating spiral cutting tool bit through the work piece in a direction perpendicular to the axis of rotation of the bit. A spiral cutting tool is conventionally operated by grasping the motor housing with one or both hands, turning on the electric motor to begin high speed rotation of the spiral cutting tool bit, plunging the spinning spiral cutting tool bit into a work piece, such as a piece of wood, and then moving the cutting tool bit through the work piece in a direction perpendicular to the axis of the spiral cutting tool bit by moving the motor housing in a direction parallel to the plane of the work piece while keeping the axis of the motor housing generally perpendicular to the work piece surface.
Precise control of a cut being made by a spiral cutting tool, or any other hand-held power tool, is dependent upon the tool operator maintaining a firm grasp on the tool. Various methods have been employed to ensure that an operator maintains a firm grip on a hand-held power tool. With extended and continuous operation, the motor housing of a spiral cutting tool can become warm, and cutting tool vibrations may cause an operator's hands and arms to become fatigued. Extended and continuous use of a spiral cutting tool by grasping the motor housing can, therefore, become uncomfortable, reducing the ability of the operator to control precisely the cut being made. U.S. Pat. No. 5,813,805, issued to Robert K. Kopras, describes a detachable handle for spiral cutting tools and other similar hand-held power tools. The detachable handle provides for extensive continuous use of the power tool while maintaining operator comfort and cutting tool control. The handle may be attached securely to the spiral cutting tool when the tool is to be used for extended periods of time, or generally to enhance the operator's comfort and control in using the spiral cutting tool. The handle may be removed from the tool, for example, when the spiral cutting tool is to be used in tight quarters wherein the handle might become an obstacle to precise control of the spiral cutting tool. The handle is removably secured to the spiral cutting tool by threaded knobs that are inserted through mounting holes in the ends of the handle and tightly threaded into threaded holes formed in handle lugs extending from the motor housing. The threaded knobs are preferably designed so that the detachable handle may be secured tightly to the handle lugs by hand, without the need for a wrench or other tool. The detachable handle also features compartments formed therein for holding various spiral cutting tool accessories, such as extra spiral cutting tool bits and a wrench for securing the bits to the spiral cutting tool.
To set the depth of a cut to be made by a spiral cutting tool, or other hand-held power tool, the tool is typically provided with a depth guide. The depth guide typically includes a depth guide base, which is attached to the power tool housing via one or more depth guide shafts. The depth guide shafts are attached to the power tool housing so as to be slidably movable with respect thereto, thereby allowing the depth guide base to be moved into positions of various distances from the tool, to set various cut depths. A locking knob is typically provided as part of the depth guide which, when tightened, typically by hand, prevents movement of the depth guide shafts and, therefore, movement of the base portion of the depth guide with respect to the tool. To set a depth of cut using such a depth guide, the locking knob is first loosened, to allow movement of the depth guide shafts. The depth guide base is then moved into the desired position to establish the desired depth of cut by moving the depth guide shafts relative to the power tool housing. Markings may be provided, e.g., on the depth guide shafts or on a mechanism attached thereto, to assist in establishing the correct desired cut depth. When the depth guide base is positioned in the desired position, the locking knob is manually tightened, to prevent further movement of the depth guide shafts, and, therefore, of the depth guide base. When locked into position, the bottom of the depth guide base provides a surface which is placed against a work piece to be cut, with a cutting bit extending below the surface by a desired amount corresponding to the depth of cut.
Cutting debris, such as sawdust, can accumulate in the base of a conventional depth guide, around the point of a cut, as the tool to which the depth guide is attached is used to make a cut. The accumulated debris can obscure the point of the cut, i.e., the point where a cutting bit enters a work piece, thereby interfering with accurate use of the tool.
What is desired is a depth guide for setting the depth of cut of a spiral cutting tool, or similar hand-held power tool, which is more easily and rapidly operable than conventional depth guides as described above. What is also desired is a device for removing effectively cutting debris from the base of a depth guide for a hand held power tool.
SUMMARY OF THE INVENTION
The present invention provides a depth guide for setting the depth of cut of a spiral cutting tool, or similar hand-held power tool, which automatically locks into a desired position to set the depth of a cut without requiring manual operation of a locking knob or similar structure. The depth guide is released from the locked position by actuation of a release switch. Thus, a depth guide in accordance with the present invention is more easily operable than conventional hand-held power tool depth guides. A depth guide in accordance with the present invention may be mounted in a handle of a hand-held power tool, such as a detachable handle, for mounting the depth guide to a housing of the tool.
An automatic locking depth guide in accordance with the present invention includes a base portion, a depth guide shaft attached to the base portion, and an automatic locking and release mechanism coupled to the depth guide shaft. The automatic locking and release mechanism allows limited sliding movement of the depth guide shaft, automatically prevents movement of the depth guide shaft when the shaft is moved into a desired position to set a desired depth of cut, and releases the shaft from the locked position, to allow motion of the depth guide shaft, in response to the actuation of a release switch. By moving the depth guide shaft in extending and retracting directions, the depth guide base is moved away from and toward a hand-held power tool to which the depth guide is attached, thereby adjusting the depth of cut to be made by the tool. In accordance with the present invention, the depth guide shaft is preferably biased into an extended position, e.g., by a compression spring. The automatic locking and release mechanism preferably includes a mechanism for automatically locking the depth guide shaft into a locked position by preventing movement of the depth guide shaft in an extending direction while allowing movement of the depth guide shaft in a retracting direction. A depth adjustment mechanism for setting one or more depths of cut is provided for preventing movement of the depth gu
Foley & Lardner
Howell Daniel W.
Roto Zip Tool Corporation
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