Woodworking – Work guide
Reexamination Certificate
2001-08-03
2003-05-06
Bray, W. Donald (Department: 3725)
Woodworking
Work guide
C033S497000, C033S832000, C033S430000, C033S471000, C083S435140, C083S468700, C083S468300, C083S468000, C083S467100, C269S303000, C269S315000
Reexamination Certificate
active
06557601
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to woodworking equipment, and in particular to an apparatus for precisely orienting and maintaining a workpiece in a predetermined position relative to a cutting tool.
2. Description of Related Art
Operations associated with the cutting, drilling, and shaping of wood or other materials with power tools require the workpiece to be positioned accurately relative to the tool in order to achieve the desired results. In certain applications, the positioning of the workpiece is accomplished through the use of a “fence” which is positioned relative to the tool. In some applications, a table saw, for example, the fence may be aligned along the cutting axis of the tool to achieve a substantially straight cut as the workpiece is guided through the saw blade when one edge of the workpiece is maintained in abutting relationship with the fence. In other applications, a miter saw or drill press, for example, the fence may be used, by maintaining one edge of the workpiece in abutting relationship with the fence, to assist in holding the workpiece in a fixed position while the tool passes through the workpiece.
Another positioning device used in connection with a fence is a mechanical stop. Typically, the stop is slidably or removably mounted on the fence with a portion extending down the face of the fence to a point at or near the base of the fence. While the fence is used to position the workpiece in one dimension relative to the tool, the stop allows the workpiece to also be positioned relative to the tool in a dimension along the axis of the fence. When used with a miter head on a table saw, for example, the stop permits positioning of the workpiece such that the workpiece may be cut to a particular length. When used with a router table and fence, for example, the stop may be positioned to stop the workpiece at a predefined position such that the router cut is made only a predefined amount along the axial dimension of the workpiece.
One shortcoming of existing mechanical positioning devices is that they have typically not been capable of providing the accuracy required for many applications. The positioning devices are often large and made of heavy steel to increase accuracy by reducing the amount of mechanical flex in the positioning devices themselves. Their size and weight make these devices cumbersome and difficult to use. Further, despite their size and weight, these devices are still not sufficiently accurate for precision applications.
A shortcoming associated with mechanical stops is that they are typically designed to interface with a particular fence and cannot be used with fences for other tools, or if the fence configuration is modified. For example, in many woodworking operations, it is desirable to connect an auxiliary fence to the face of the existing fence. Most mechanical stops cannot be used together with an auxiliary fence. Some fence manufacturers have attempted to overcome that shortcoming by configuring the fence to permit positioning of the mechanical stop in different locations perpendicular to the face of the fence depending on whether an auxiliary fence is installed. These stop/fence combinations still have the inherent shortfall that the mechanical stop is designed only to interface with a particular fence.
A number of positioning jigs have recently been designed in order to improve the positioning process. For instance, U.S. Pat. No. 4,793,604 granted to Christopher L. Taylor (hereinafter referred to as “the Taylor '604 patent”) discloses a universal precision positioning jig adapted for precision positioning of a workpiece with respect to a woodworking tool, such as a table saw, router table, drill press, or other tool. The Taylor '604 patent includes a fixed lower body member and a moveable upper body member, each having mounted thereon a series of tooth-like projections formed into elongated racks. The upper body member is provided with a mount for a fence and is moveable with respect to the fixed lower body member. The racks are meshed together by the tightening of a knob threaded through the middle of the upper and lower body members. The knob is tightened after the fence has been properly positioned to prohibit movement of the upper and lower body members relative to each other during the cutting operation. This, in turn, fixes the position of the fence.
The toothed rack meshing system was further improved upon in U.S. Pat. No. 5,195,730 (hereinafter referred to as “the Taylor '730 patent”), also granted to Christopher L. Taylor. The Taylor '730 patent discloses a fixed based and a carriage, the carriage being moveable with respect to the base. Toothed racks such as those taught in the Taylor '604 patent are also used. One toothed rack is mounted on the carriage and a complementary toothed rack is mounted on the base. The carriage rides in slots on the base and is spring loaded to prevent meshing of the toothed racks until positioning is completed. A cammed clamping lever attached to a rod running through the carriage and base clamps the carriage and the base together, thereby locking and intermeshing the toothed racks to set the carriage position.
One improvement in the art resulting from the Taylor '604 and '730 patents is the use of calibrated templates slidably mounted in slots on the carriage. A cursor above the. templates measures the position of the carriage with respect to the cutting blade. Formulas are printed on the templates in order to produce complicated cuts such as dovetail joints or box joints. Using these templates, woodworkers can quickly create intricate wood products previously attainable only by experienced professionals.
The intermeshing teeth on the toothed racks of the Taylor '604 and '730 patents are set at intervals of {fraction (1/32)} of an inch, and provide fully repeatable positioning with a precision of {fraction (1/32)} of an inch. The accuracy and rapidity of positioning with the Taylor designs constitutes a substantial improvement in the art. U.S. Pat. No. 5,716,045, which also issued to Christopher L. Taylor (the “Taylor '045 patent”), further improved upon the previous Taylor patents by combining a micropositioning feature with the toothed racks.
Some mechanical stops include pivotal features that allow a portion of the mechanical stop providing support for the workpiece to pivot between a work position and a standby position. In the work position, the stop is configured to engage and position the workpiece along the fence relative to the cutting tool. The stop can be rotated into the standby position such that it no longer engages the workpiece.
U.S. Pat. No. 5,337,641 issued to Duginske discloses a stop and fence combination for woodworking applications. The stop is slidably positionable along the length of the fence using a bolt
ut combination with the nuts located within a T-slot along the top of the fence. The stop is configured such that it may be rotated up and away from the fence so that the fence may be used without the stop while the stop remains connected to the fence.
U.S. Pat. No. 5,768,966, which also issued to Duginske, discloses a fence geometry that permits the rotatable stop from the '641 patent to be used when an auxiliary fence is attached to the face of the main fence. The '966 patent accommodates the auxiliary fence by adding a second T-slot adjacent to and parallel to the T-slot of the '641 patent. When the stop is used without an auxiliary fence, the stop is connected to the fence using the T-slot further from the fence face. When the stop is used with an auxiliary fence, the stop is connected to the fence using the T-slot nearer the fence face.
One shortcoming associated with rotatable stops is the mechanical flex associated with pivotable parts. This flex, under some circumstances, can reduce the positioning accuracy of the stop. Another shortcoming is evident when using a pivotable stop in conjunction with a mitered workpiece. A mitered work
Bray W. Donald
Hilton Robert C.
Taylor Design Group
Thompson & Knight LLP
Wynne Richard
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