Patent Application
20050072491
The present invention relates to hand-held power tools, and particularly to a support fixture for such tools.
Hand-held power tools have been used by woodworkers for many decades. From the day that the power drill replaced the brace and bit, hand-held tools have greatly simplified most woodworking projects and, perhaps most significantly, made woodworking and carpentry within the grasp of the non-professional. Throughout its development, the power drill has been adapted to a variety of woodworking and carpentry tasks, nearly all predicated on replacing the drill bit with a specialized tool. For instance, special bits have been developed for creating different types of holes in a workpiece. Other attachments allow a power drill to act as a screwdriver or sander. Still other attachment bits convert the power drill to a router capable of producing intricate patterns and scrollwork in a workpiece.
Woodworking power tools have evolved from the bulky pistol grip type drill to a more compact, “pencil” type tool. Smaller hand-held tools are available for performing very intricate cuts in a workpiece. Other hand-held power tools and attachments have been developed to allow a held-held drill to function like a coping saw or jig saw. To assist in these functions, templates are frequently provided to guide the woodworker. Initially, a steady hand was the only hope for the woodworker to follow the template, especially when making intricate cuts.
Eventually, attachments were developed that supported the hand-tool and provided a surface for supporting the tool on the workpiece. For instance, U.S. Pat. No. 3,162,221 to Lacey discloses a router attachment that attaches to the working end of a pistol grip drill by way of a split clamp. This attachment freed the woodworker form having to deftly maneuver the bulky drill to perform router operations. The attachment included hand grips on opposite sides of a base plate that interface with the surface of the workpiece. The hand grips allowed the operator to use both hands in a very efficient and effective manner to guide the drill and router bit along the workpiece. While the attachment in the '221 patent maintained the router bit in a fixed vertical position, the router attachment in U.S. Pat. No. 4,102,370 to Vess provided a means for supporting the router bit above the workpiece until it a cut is made. The system of the '370 patent allowed the base of the attachment to remain in contact with the workpiece, even when a cut is not being made.
Many routing cuts are made with a pattern or template. Templates can be used to create finger joints, as disclosed in U.S. Pat. No. 5,584,328 to Grisley, to perform edge cuts, as shown in U.S. Pat. No. 5,685,675 to Beekman, or to create intricate patterns in a workpiece. Of course, the quality of the cut using a template is only as good as the ability of the operator to accurately follow the template. The '328 and '675 patents disclose guide elements that engage and follow the template contour, all the while maintaining the router bit centered with the pattern.
All of these advances have simplified what had once been difficult and time-consuming woodworking tasks. As more and more people become “do-it yourselfers”, the hand-held power tools need to become easier for the operator to manipulate to make accurate and clean cuts.
In one aspect of the invention, a fixture for supporting a hand-held power tool on a workpiece is provided with a base plate for contacting the workpiece, in which the base plate defines an opening for passage of the tool bit therethrough to contact the workpiece. The fixture includes a guide plate supported on the base plate for movement relative to the base plate, and a tool support housing associated with the guide plate. The tool support housing includes a housing body configured to receive the power tool body therein, and defining a tool bore for extension of a portion of the power tool body adjacent the drive spindle therethrough.
A clamping mechanism is provided for fixing the portion of the power tool within the tool support housing, which includes an engagement member supported on the guide plate between the housing body and the guide plate. The engagement member is operable to engage the portion of the power tool body adjacent the drive spindle. The engagement member also defines a bore for extension of the tool bit therethrough. With this tool support housing and clamping mechanism, the power tool is supported at its working end and can be readily engaged to the fixture.
In one embodiment of the invention, a guide apparatus for a hand-held power tool is provided for use with a template on a workpiece. The guide apparatus comprises a base plate having a bottom surface for contacting the workpiece and defining an opening for extension of the tool bit therethrough to perform the operation on the workpiece. The base plate further defines a ledge within the opening. A guide bushing is provided that defines a bore for extension of the tool bit therethrough. The guide bushing includes a support plate configured to be supported on the ledge within the opening and a template guide projecting from the support plate. The template guide is sized to extend beyond said bottom surface of the base plate when the guide bushing is supported on the ledge to contact the template. A locking member is engagable within said opening of the base plate and is configured to bear against the support plate of the guide bushing to maintain the support plate in contact with the ledge of the base plate.
In a preferred embodiment, the template guide of the guide bushing is a hollow cylindrical body. In a further feature, a plurality of guide bushings can be provided, each having a differently configured template guide. For instance, the template guides can have different outer diameters of the hollow cylindrical body to accommodate differently sized templates and create different width routing paths.
A support fixture for a hand-held power tool is provided that comprises a base plate for contacting the workpiece and defining an opening for passage of the tool bit therethrough. The fixture also includes a guide plate supported on the base plate for movement relative to the base plate, the guide plate having means for supporting the hand-held power tool with the tool bit aligned with the opening. In one feature of the invention, the base plate is formed of a substantially transparent material. This transparent material permits visualization of the workpiece or template on which the base plate rest during operation of the power tool.
It is one object of the invention to provide a fixture for supporting a hand-held power tool on a workpiece. It is a further object to provide the fixture with a mechanism permitting ready and simple engagement of the power tool to the fixture. Yet another object is to provide a guide arrangement for integration with a template that is easily mounted to the fixture.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains.
In accordance with one embodiment of the invention, a plunge router support fixture 10 is depicted in
To allow the user/operator to easily depress the guide plate assembly, and to control the movement of the support fixture 10, a pair of hand grips 25, 27 are provided. The hand grips can include a snap-on cap 26, 28, respectively, as shown in
To increase the accuracy of these depth adjustments, the support fixture 10 is provided with a depth marker 30 that is supported vertically from the base plate. The marker 30 is preferably removable and replaceable. In the preferred embodiment, the depth marker 30 is supported by a boss 31 formed in the base plate and a slot 32 in the guide plate assembly (so the guide plate assembly can slide relative to the marker 30). Preferably, the boss 31 forms a slight pressure fit with the depth marker 30 so that the marker cannot be easily dislodged.
The base plate 12 defines a guide edge 34 that integrates with certain guide components depicted in
Alternatively, the guide component can be a circle guide 45. The circle guide 45 is mounted to the support fixture 10 using the same guide rods 40 described above. The circle guide includes a centering bore 47 through which extends a nail 46 that is driven into the workpiece to establish the center point for rotation of the router support fixture 10.
In another aspect of the router support fixture 10 of the present invention, a limit stop assembly 48 is provided to limit the downward movement of the guide plate assembly 14. As best shown in
Preferably, the base plate 12 and the guide plate assembly 14 are formed substantially of a high strength plastic material. In addition, the tool support housing and guide bushing components are also preferably formed of a plastic material. The guide posts 16 are preferably formed of metal to improve wear resistance as the guide plate assembly translates up and down along the posts. In one embodiment of the invention, at least the base plate 12 is formed of a substantially transparent material. This transparent material will permit a generally unobstructed view of the working area as the power tool performs its cuts in the workpiece.
In one important feature of the invention, a tool support housing 60 is provided within the guide plate assembly 14 that is used to carry the operating end of the power tool when the tool is supported by the router support fixture 10. The tool support housing 60 includes a clamping mechanism for clamping the tool to the support housing. In a preferred embodiment, this clamping mechanism includes an engagement member in the form of an overthrow nut assembly 62 that can be used to readily engage the working end of the tool within the support housing 60, as described in more detail herein.
In a further important feature of the invention, a guide bushing collar 68 is defined in the base plate 12, as shown in
Yet another aspect of the invention contemplates means for mounting accessories to the router support fixture 10. In accordance with one embodiment, dovetail accessory mounts 74 are defined on the perimeter of the guide plate assembly 14, as best seen in
Details of one embodiment of the overthrow nut assembly 62 can be seen in
The support body 80 defines a guide recess 84 concentric about the tool bore 82 on the underside of the body. The recess terminates in a bearing face 86 that is directly abutting an overthrow nut 88. The nut 88 includes a threaded tool bore 90 that is configured to mate with the threaded end of the housing of the tool R. Most hand-held tools include a threaded portion of the tool housing adjacent the drive spindle, such as the threaded portion T shown on the tool R in
As explained above, the tool R is oriented within the housing 60 so that the shaft lock button B of the tool R is accessible through the window 61. In this orientation, the bit of the tool R can be replaced while the tool is supported within the router support fixture 10. The operator can simply depress the shaft lock button B while loosening the collet nut of the tool R. The old bit can be removed and new bit inserted into the collet of the router tool R, with the assembly tightened by again accessing the shaft lock button B through the window 61.
The overthrow nut 88 includes a guide collar 92 at the top of the nut that is sized for rotating engagement within the guide recess 84 of the support body 80. A bearing flange 94, disposed beneath the guide collar 92, is sized for rotating engagement relative to the bearing face 86 of the support housing and the interior of a retainer cup 100 used to trap the bearing flange 94. The exterior of the nut 88 preferably defines wrench engagement surfaces 96, such as a hex head configuration. The wrench 76 described above is preferably configured to engage the hex surfaces 96 to tighten or loosen the overthrow nut 88. However, the engagement surfaces 96 are most preferably sized to accommodate manual rotation of the overthrow nut 88 to connect the router tool R to the support housing 60.
The overthrow nut assembly 62 is configured to allow free rotation of the overthrow nut 88. Thus, the assembly 62 includes a retainer cap 100 that interfaces with the support body 80 to trap the overthrow nut. The retainer cap 100 defines a bore 102 through which the overthrow nut 88 extends, as shown in
The tool support housing 60 and overthrow nut assembly 62 is depicted in
In another embodiment, the housing 60 is kept as a stand-alone component. Thus, as shown in
The overthrow nut assemblies 88 and 115 of the present invention provide a substantial advantage over prior tool attachments. In prior attachments, a clamp is used to clamp onto the body of the power tool. In plunger type tools, the power tool may not be clamped to the attachment, the attachment relying instead on gravity to hold the tool on the support. With the present invention, the hand-held power tool R can be easily connected to or disconnected from the router support fixture. The working end of the tool can be easily inserted into the support housing 60 with the threaded portion of the tool aligned with the overthrow nut 88. The tool is fixed to the support fixture by simply rotating the overthrow nut from beneath the guide plate assembly 14.
A further important feature of the invention resides in the guide bushing collar 68 and associated guide components. In particular, as shown in
The guide bushing defines a bit bore 126 through which the tool bit extends. A support plate 128 is concentrically defined around the bit bore and is configured to rest on the support ledge 122 of the guide bushing collar 68. The guide bushing 70 is held in place by a bushing plug 72. In the preferred embodiment, the bushing plug 72 includes a threaded collar 130 that mates with the internal threads of the guide bushing collar 68. A pair of fingers 134 project upward from the plug 72 for manual engagement.
As shown in
As mentioned above, the guide plate assembly includes a number of dovetail mounts 74. These mounts are configured to support different accessories associated with the particular woodworking project. One such accessory is shown in
In the preferred embodiment, the flexible support 144 is a flexible armored cable connecting the light source 142 to the power source 146. For instance, the flexible support can be in the form of a “gooseneck” cable or a wrapped cable of known design. The light source 142 is preferably an LED, while the power source is preferably a disc battery, such as a lithium ion or a NiCad battery. The power source 146 can include an “on/off” switch for energizing the light source.
The side disposed dovetail mounts are particularly well suited for support a light accessory, such as the accessory 140 shown in
Another benefit of the accessory 140 of the present invention will be appreciated with reference to
In the illustrated embodiment, the accessory 140 is a light source. Other types of accessories are contemplated provided they can be kept in a small and light enough package so as not to interfere with the use of the hand-held tool R and the router support fixture 10. Moreover, the accessory preferably is provided with its own power source, where necessary, to avoid the need for wires and plugs to connect to an external power source. For instance, the accessory can be configured as a directional source of air to help clear the working area of wood chips and dust. In this case, the light 142 at the free end of the accessory can be replaced with a nozzle, while the flexible support 144 can be in the form of a flexible conduit. The power supply 146 can include a fan, such as a piezo fan, capable of sufficient air flow to clear the working area of debris. Alternatively, the power supply can be replaced by a squeeze bulb that can be rapidly depressed to generate a burst of air at the free end of the accessory.
One benefit of the accessory 140 is exemplified by its ability to be mounted to the power tool itself. It is contemplated that mating dovetail mounts can be provided on various components in the woodworking workshop. For instance, the carrying case for the power tool can be provided with dovetail mounts on its exterior so that the carrying case and light accessory can be combined to form an independent light source.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected. For instance, while the illustrated tool R is a rotary power tool, other tools are contemplated.
Furthermore, while the support fixture 10 of the illustrated embodiment is configured for use in connection with a hand-held router, the support fixture can be used with other hand-held power tools. For instance, the same support fixture can be used as a drill press where the power tool R is a drill.
In the preferred embodiment, the overthrow nut assembly 62 is configured to engage a threaded portion T on the body of the power tool R. Thus, the assembly includes a nut 88 that is internally threaded to mate with the threaded portion of the tool. However, other engagement mechanisms are contemplated, provided they are capable of easy manual manipulation. For instance, a collet or similar clamping arrangement can be implemented in lieu of the overthrow nut.
Furthermore, in the preferred embodiment, the arrangement for mounting the accessories to the support fixture or to the body of the power tool contemplates a dovetail engagement. In an alternative embodiment, the dovetail engagement can be replaced by a suitable male-female mounting feature capable of a tight fit or press fit engagement.
