WORKPIECE STABILIZING DEVICE

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure pertains to safety devices for power tool work tables and, more particularly, to a device that guides a workpiece as it moves on the work table and prevents kickback of the workpiece.

Description of the Related Art

Work tables for wood working tools and machines, such as power saws, routers, and the like, generally include a table top on which a workpiece is supported. In many cases, a guide or fence is secured to the table top and extends in the direction of movement of the workpiece for guiding the workpiece with respect to the power tool. As the workpiece is moved on the supporting surface of the table top, it is guided by the fence during a cutting or other wood working operation that is performed on the workpiece. Feather board and other devices are known for pressing the workpiece against the fence during such movement, and various hold-down devices are known for pressing the upper surface of the workpiece to hold the workpiece against the table top. Additionally, table saws utilize pawls mounted on the splitter behind the blade to keep wood that is kicked back from being propelled against the direction of feed. While the foregoing devices have desirable features, they each have their drawbacks.

There is a need for a device that not only prevents kickback of the workpiece during a wood working operation but also enables adjustment of the positioning or hold-down member in longitudinal, lateral, and orthogonal directions relative to the workpiece that enable adjustment in the biasing force of the positioning or hold-down member against the workpiece and that accommodate material of differing widths or thicknesses without needing to adjust the position of the hold-down member.

BRIEF SUMMARY OF THE INVENTION

The present disclosure provides a workpiece guide and anti- kickback device for a work table that not only guides the device alone or in combination with a guide or fence on the work table, but also prevents kickback of the device in a safe and efficient manner.

In accordance with one embodiment disclosed herein, a device for stabilizing a workpiece moving on a work surface is provided, the device having a cam member coupled to the work surface to rotate thereon, the cam member having a bearing surface configured to bear against the workpiece without slipping when the workpiece is moved in a first direction to prevent further movement of the workpiece and to allow the workpiece to slip when the workpiece is moved in a second direction that is opposite to the first direction; and a biasing member coupled to the cam member to urge the bearing surface into contact with the workpiece. In accordance with another aspect of the disclosure, a cam member is provided that has an increasing diameter to a maximum diameter at a lobe and thereafter a decreasing diameter to a minimum diameter. In one embodiment, the cam member has a cross-sectional configuration in the shape of a spiral. In other words, the bearing surface defines a circumference of the cam member with a spiral shape so that the cam member has an increasing effective diameter when the biasing member urges the cam member to rotate the bearing surface in the first direction.

In accordance with another aspect of the present disclosure, the biasing member is coupled to the cam member and urges the cam member to rotate the bearing surface in the first direction to be in constant contact with the workpiece.

In accordance with another aspect of the present disclosure, a base is provided on which is mounted the cam member to rotate about an axis that is substantially perpendicular to the base. Ideally the base is adapted to be attached to the work surface with fasteners that permit adjustment in the

location of the base and the cam member relative to the work surface and, in certain embodiments, relative to a guide on the work surface.

In accordance with another aspect of the present disclosure, the bearing surface on the cam member has sufficient surface area to prevent vertical or orthogonal movement of the workpiece relative to the work surface. In accordance with the present disclosure, a device for stabilizing a workpiece relative to a work surface and a relative guide on the work surface is provided. The device includes a cam member coupled to the work surface to rotate about an axis substantially perpendicular to the work surface, the cam having a circumscribing bearing surface configured to bear against the workpiece to prevent slipping of the workpiece when the workpiece is moved in a first direction that is substantially perpendicular to the axis of rotation of the cam member by urging the workpiece into contact with the guide to prevent further movement of the workpiece in the first direction and to allow the workpiece to slip past the cam member when the workpiece is moved in a second direction that is opposite to the first direction; and a biasing member coupled to the cam member to urge the cam member bearing surface into contact with the workpiece at all times.

In accordance with another aspect of the present disclosure, the circumference of the cam member is defined by the bearing surface to be in the shape of a spiral having an increasing diameter from a minimum diameter to a maximum diameter at a lobe and thereafter reducing to the minimum diameter such that the cam member has an increasing effective diameter when the biasing member urges the cam member to rotate the bearing surface in the first direction..

In accordance with another aspect of the present disclosure, the cam member is rotateably mounted on a base, the base adapted for attachment to the work surface by means of attachment members that permit adjustment in the location of the cam member relative to the guide. As will be readily appreciated from the foregoing, the device of the present disclosure provides workpiece guide and anti-kickback features that

overcome inherent disadvantages of known devices. The present device can be used to press on the side or on the top or on both the side and top surfaces of the workpiece while preventing kickback thereof. The position of the device can be adjusted longitudinally, laterally, and orthogonally relative to the workpiece while the biasing force exerted on the cam member against the workpiece is uniformly provided by a torsion spring.

The base plate provides a mounting point for the spiral cam surface at one edge of the base plate for engaging a side surface of the workpiece on the work table and an adjustment device for moving the base plate relative to the workpiece that includes a lengthwise miter bar slot assembly allowing lengthwise direction of movement of the base along the work table and transverse adjustment slots in the base plate to enable adjustment in the transverse direction, and a pivot that pivotally mounts the spiral cam member to the base plate for pivoting movement. A torsion spring is provided around the pivot and housed within the spiral cam for applying the spiral cam surface against the edge of the workpiece such that it is biased in a direction opposite to a feed direction of the work piece.

In accordance with another aspect of the present disclosure, an assembly for use with a work piece is provided, the assembly including a tool having a work surface; and a system for stabilizing the workpiece moving on the work surface, the system including a cam member coupled to the work surface to rotate thereon, the cam member comprising a bearing surface configured to bear against and stop the workpiece when the workpiece is moved in a first direction to prevent further movement of the workpiece in the first direction and to allow the workpiece to slip when the workpiece is moved in a second direction that is opposite to the first direction; and the system further including a biasing member coupled to the cam member to urge the bearing surface into contact with the workpiece.

In accordance with another aspect of the foregoing embodiment, the system of the assembly further includes a base plate attached to the work surface, the base plate having a first end pivotally attached to the work surface

and a second end having a clamping device formed thereon for clamping the base plate in a selected position on the work surface, the cam member mounted to the base plate to restrict the work piece from moving in a selected direction relative to the base plate and the cam member when the work piece is moving past the cam member.

The present disclosure also provides for a vertical positioning of the device upon the work table fence, rather than upon the table top surface, for holding the workpiece against the table.

The arrangement of the pawls in prior devices is replaced by spiral cams on each side of the splitter that can be fixed on a vertical slot on the splitter with torsion springs around a pivot for each spiral cam member that applies the spiral cam member bearing surface against the surface of the workpiece such that it is biased in a direction opposite to a feed direction of the workpiece. In accordance with another aspect of the present disclosure, a combination workpiece hold-down and anti-kickback device is provided for a router table having a fence against which a workpiece is guided. The device includes a positioning member having a base plate and two spiral cam members mounted thereon with bearing surfaces adjacent one edge of the base plate to engage a side surface of a workpiece on the work table. An opening is provided between the two cams through which the router bit can be raised. An adjustment device for moving the base plate relative to the workpiece is included having a lengthwise miter bar slot assembly allowing lengthwise direction of movement of the device along the work table for adjusting the positioning of the cam member in a lengthwise direction, transverse adjustment slots enable adjustment in the transverse direction, and a pivot that pivotally mounts the cam member to the base plate is provided for pivoting movement. A torsion spring around the pivot and housed within the cam member applies a force against the cam member to urge the bearing surface against the workpiece such that it is biased in a direction opposite to a feed direction of the workpiece.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing and other features and advantages of the present invention will be more readily appreciated as the same become better understood from the following detailed description when taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a top plan view of a workpiece stabilizing device formed in accordance with the present disclosure;

Figure 2 is an exploded side view of the device of Figure 1 ;

Figure 3 is a side view of an alternative embodiment of a workpiece stabilizing device formed in accordance with the present disclosure;

Figure 4 is an exploded end view of the device of Figure 3;

Figure 5 is a top plan view of yet another alternative embodiment of a workpiece stabilizing device formed in accordance with the present disclosure; Figure 6 is an exploded side view of the device of Figure 5; and

Figure 7 is a top plan view of a further alternative embodiment of a workpiece stabilizing device formed in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION Referring initially to Figures 1 and 2, shown therein is one embodiment of a workpiece stabilizing device 10 formed in accordance with the present disclosure to include a base 12 having a cam member 14 rotateably mounted thereon via a pivot bolt 16 that is slidably received through a spacer 18 and thence through an opening 20 in the base plate 12 to be retained in position by a threadably engaged nut 22. A torsion spring 24 is slidably received over the spacer 18, and both the torsion spring 24 and the spacer 18 are received within a central opening 26 in the cam member 14. A fender washer 28 is positioned between the bolt 16 and the top of the cam member 14 to provide a bearing surface. The torsion spring 24 has a first end 30 that

engages an opening 32 in the base 12 and a second end 34 that engages the interior of the opening 26 in the cam member 14.

The cam member 14 has a substantially cylindrical shape when viewed from the top in Figure 1. However, the outer circumscribing wall of the cam member 14 provides a bearing surface 36 that, when viewed from the top, has a spiral shape that defines a lobe 38 on one side. As such, the cam member 14 has an increasing diameter from a minimum diameter portion to a maximum diameter at the peak 40 of the lobe 38 after which it decreases in diameter to the minimum diameter. The cam member 14 is mounted on the base 12 so that the bearing surface extends beyond an edge of the base 12 and the lobe extends further yet beyond the minimum diameter of the cam lobe 14.

The base 12 includes two elongate slots 42 in which are received a lockdown screw 44 that is threadably engaged on an opposite side of the base 12 with a lockdown knob 46. A miter slot bar 48 is provided that includes a longitudinal slot 50 through which the lockdown screw 44 projects to hold the bar 48 against a bottom surface of the base 12. The elongate bar 48 is positioned so that the longitudinal opening 50 is substantially perpendicular to the elongate slots 42 formed in the base 12. The base 12 is adapted to be mounted to a work table 52 having a guide or fence 54 affixed thereto for guiding a workpiece 56 toward the working portion of a power tool (not shown). The bar 48 provides a point of attachment of the device 10 to the work table 52, and the elongate opening 50 enables adjustment about the direction of travel of the workpiece 56, as shown by the arrow 58. The elongate slots 42 allow transverse or lateral adjustment of the base 12 and hence the cam member 14 with respect to the guide 54 and the workpiece 56. Positioning of the device 10 orthogonal to the work table 52 can be accomplished with spacers between the base 12 and the work table 52. The cam member 14 is biased by the torsion spring 24 to rotate in a direction opposite to the feed direction shown by the arrow 58. In the embodiment illustrated in Figures 1 and 2, the cam member 14 is urged to

rotate in a clockwise direction. The bearing surface 36 is configured to provide a nonslip surface such that when the workpiece 56 is moved in a direction opposite to that of arrow 58 it engages the bearing surface 36 and rotates the cam member 14 clockwise so that the effective diameter of the cam member 14 increases, urging the workpiece 56 against the fence 54 and stopping further movement. However, movement with the arrow is permitted by overcoming the force of the cam member 14 and urging the cam member 14 to rotate counterclockwise against the force of the torsion spring 24. Thus, the force of the torsion spring 24 can be selected so that it can be overcome with a small to moderate amount of force placed on the workpiece 56.

Figures 3 and 4 illustrate an alternative embodiment of a workpiece stabilizing device 66 in which elements common to those shown in the first embodiments of Figures 1 and 2 bear the same reference numbers. Here, the cam member 14 is mounted vertically on both sides of the base 12 via the pivot bolt 16, which is threaded on both ends and passes through an opening in the base 12. The pair of cam members 14 mounted on each side of the base 12 are slidably received over a spacer 18 and the torsion spring 24 and retained in position by a pivot knob 70 threadably engaged with the pivot bolt 16. A washer 72 acts as a bearing surface between the cam member 14 and the knob 70. A lockdown hole 68 is provided in the base 12 that, in cooperation with the longitudinal slot 42, enables vertical mounting of the device 66. In this embodiment, a workpiece (not shown) will be held down on the work surface by the cam member 14 and not permitted to be pushed upward or backward or a combination of upward and backward by the blade or tool.

Referring next to the top plan view of Figure 5 and exploded side view of 6, shown therein is yet another embodiment of the present disclosure in which a workpiece stabilizing system 74 utilizes two cam members 14 mounted side-by-side on the base 12. Here, a guard plate 12 is held in position on top of each cam member 14 by the respective pivot bolts 16.

Figure 7 is a top plan view of another embodiment of a workpiece stabilizing system 90 is shown to include a pie-shaped base plate 92 and the cam member 14. Here the base plate 92 has a substantially planar shape with a first end 94 that is defined by the convergence of two sides 96, 98 that in turn extend in an opposite direction to an arcuate end 100. The first end 94 has an opening 102 that enables attachment of the base plate 92 to one end of a mitre slot (not shown) so that the base plate 92 can pivot about the attachment member (not shown) that extends through the opening 102 in the first end 94. A slot 104 is formed in the body 106 of the base plate 92 that is arcuate in shape and limits the pivoting movement of the base plate 92 through interaction with a threaded fastener (not shown) adapted to extend from a supporting surface (not shown) beneath the base plate 92, such as from a mitre bar or through a mitre bar slot (not shown) and into a knob 108. Turning of the knob will result in tightening of the knob against the base plate 92, forcing the base plate 92 against the mitre bar or supporting surface below the base plate 92, firmly securing the base plate 92 into position.

The cam member 14 is adapted to be mounted to the base plate 92 in the opening 110 formed between the arcuate slot 104 and the arcuate second end 100. The opening depth and diameter is adjusted to accommodate the torsion spring (previously described and shown in other views). Thus, positioning of the cam member 14 can be adjusted by pivoting the base plate 92 about the first end 94 and clamping the base plate 92 in the desired position with the single clamping knob 108.

All of the above U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non- patent publications referred to in this specification and/or listed in the Application Data Sheet, are incorporated herein by reference, in their entirety. From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit

and scope of the invention. Accordingly, the invention is not limited except as by the appended claims and the equivalents thereof.