1. Field of the Invention
This invention relates to novel guide device for cutting through dovetail joints with a router or laminate trimmer and more particularly to a dovetail joint guide device or jig by which through dovetail joints can be easily cut with exceptional accuracy in a very short time. The guide device enables hobbyists to produce professional looking dovetail joints without the need for a large number of templates or complicated procedures. The present guide device also allows a number of dovetail joints to be produced continuously so that a number of cabinet or drawer projects, etc. can be easily accomplished on a scale approaching mass production.
2. Description of the Related Art
Dovetail joints are a professional method of producing adjoining and interlocking joints for cabinets, drawers, etc., by which an incredibly strong joint can be produced. The work of forming dovetail joints for drawers, cabinets, etc., has been long been performed in the art of woodworking and is an eye pleasing sign of fine craftsmanship. There are several methods of making dovetail joints, all of them requiring a number of troublesome steps and adjustments that can introduce inaccuracies into the work. These processes make forming a dovetail joint that is square, strong and elegant a daunting task for all but the most experienced wood workers, both hobbyist and professional alike. To simplify this task, a number of inventors have devised a variety of jigs or guide devices for use with a router, etc. For example, there is the very well known and widely used Keller dovetail template system using various templates or gauges, as seen in several US patents including U.S. Pat. Nos. 4,168,730, 5,139,062 and 5,199,477. However, it is somewhat cumbersome to use and difficult to adjust accurately and it seems to be too delicate for rough use in a workshop. Further, the Keller dovetail system requires special dovetail and straight router bits that can only be used with Keller jigs.
For this reason, a number of patents have been granted for improvements on the Keller system. For example, as shown in
In operation, a number of steps are required for creating the dovetail tails or sockets (into which the dovetail pins will ultimately fit) that entail scribing guide lines, adjusting the router to the proper height, aligning the guide fence, locking the guide fence to the guide bars with several friction fittings, affixing an auxiliary strip to the guide fence, sliding the positioning apparatus past the table router to create a guiding profile, aligning the workpiece using the guiding profile, clamping the workpiece to the guide fence, again sliding the positioning apparatus with the first workpiece past the router, and repeating the last three steps. Fabricating the dovetail pins with this apparatus requires even more steps and repetitions. All of these clamping and cutting steps add inaccuracies to the final product and can be cumbersome to carry out repetitively for a series of joints, making the use of this kind of jig somewhat troublesome for the average hobbyist woodworker.
Another conventional method of making dovetail joints, among others, can be seen in U.S. Pat. No. 6,315,017 to Stottman, shown in
Further, not only are all of these jigs, including the well known Keller jig, troublesome to adjust for accurate joint cuts, they are expensive to replace if damaged. In other words, most other known dovetail jigs suffer from being very complicated, somewhat difficult to adjust accurately and expensive to use maintain over time. There is also a problem of tailboard length. That is, all of these conventional systems require the tailboard to be clamped vertically to the jig, either above or below the worktable. As will be readily apparent, this requires either a tall worktable or a lot of ceiling space when the workpiece is more than about three or four feet in length. Similarly, when the workpiece is clamped to the jig in this fashion, the whole assembly must be moved, a process sure to add difficulty and inaccuracies to the cutting work.
Finally, most of these previous systems require the use of at least two router bits of different shapes, generally a dovetail and straight bit, to cut the tail and pins of the dovetail joint. This requires readjustment of the router after changing of the bits, frequently resulting in not just frustrations in trying to eliminate inaccuracies, but ruined work pieces as well.
To overcome these problems, the present inventor developed a novel guide device or jig for cutting dovetail joints by which extremely accurate dovetail joints can be easily formed without the need for a variety of templates, troublesome measurements or a number of adjustments. This novel guide device can be used with the tailboard flat on the worktable, so that there is no great limitation on workpiece length. Further, this can be accomplished with only the use of the same router bit, normally a straight cut bit, for both the tail and pin cuts. Finally, by first setting the router bit to cut just to the bottom surface of the tailboard, the same setting can be used to cut the pin board as well.
The present invention has been made with a view to solve the problems stated above and its object is to provide a device for cutting dovetail joints and more particularly to a through dovetail joint guide device by which through dovetail joints can be accurately and easily formed.
According to this invention, a guide device or jig for cutting a through dovetail joint is provided which, in one embodiment, includes a rectilinear guide member or template for use in cutting a tail board, hereinafter a tail board template, and another rectilinear guide member or template, for cutting a pin board, hereinafter a pin board template. The tail board template is generally a thin plate or thin plate-like member made of metal or other suitable material, having a series of cutouts or template guides in the shape of an isosceles trapezoid, hereinafter isosceles trapezoidal cutouts, provided longitudinally therein, the narrowest portions or tops of the cutouts in parallel alignment with the top edge of the tail board template and the broadest portions or bottoms of the cutouts in alignment below the tops of the cutouts. The pin board template is also generally a thin plate or thin plate-like member made of metal or other suitable material, having a main body serving as a base or bottom of the template and a series of patterns or fingers in the general shape of an isosceles trapezoid, hereinafter isosceles trapezoidal fingers, of generally the same size and shape of the isosceles trapezoidal cutouts in the tail board, protruding in the same plane from the main body of the pin board template. The isosceles trapezoidal fingers connected to the main body by relatively short rectangular connecting portions or bridges, forming a series of rectangular areas that are open topped between adjacent fingers. An adjustable stopper is also provided for use on the tail board template for setting the depth of the cut in the tail board, i.e. the size of the cut as measured from the joint edge of the workpiece, the stopper also being a thin plate or thin plate-like member made of metal or other suitable material, with a main body serving as a base or bottom of the stopper and a series of patterns or fingers protruding in the same plane from the main body of the stopper and spaced to fit between the trapezoidal cutouts of the tail board template, the stopper being secured in position by normal means such as clamps or, in another modification, by screws, etc. By the use of this stopper, the depth of cut on the tail board can be easily set with no further adjustments necessary, providing, in conjunction with the templates, a fast, accurate and easy means to cut professional looking dovetail joints.
In another embodiment, two threaded posts are attached adjacent to either edge of at the sides of the top of the tail board template in an area above the narrowest portions or tops of the trapezoidal cutouts, and the stopper is provided with two rectangular openings extending parallel and adjacent to either edge near the bottom of the stopper, at a position corresponding to the threaded posts, the rectangular openings fitting over the threaded posts so that the stopper can be fixed to the tail board at an appropriate position.
In a further embodiment, at least two rectangular windows are provided, one on each side of the series of trapezoidal cutouts, an uppermost portion of each rectangular window being in parallel alignment with the broadest portions of the trapezoidal cutouts, the windows being adapted to accept a scrap piece from a workpiece so that the stopper can be adjusted to run up against the bottom edge of the scrap piece and firmly secured to the template 1, as will be described in detail below
In another related embodiment of the invention, both the tail board template and the pin board template comprise two thin plates or thin plate-like members respectively, each member being a mirror image of the other. That is, the tail board template comprises two thin plate-like members with mutually symmetrical quadrilateral apertures or cutouts provided longitudinally therein, wherein the same side of each cutout is not parallel to the opposite side. By flipping one of the guide members over and sliding the quadrilateral cutouts longitudinally over the set of quadrilateral cutouts in the bottom guide member, the size of the resultant cutout can be adjusted while still retaining the relative isosceles trapezoidal shape, as explained in more detail below. Similarly, the pin board template comprises thin plates or thin plate-like members with mutually symmetrical fingers of a generally triangular pattern connected to the main body of the member by thin rectangular bridges. Again, by flipping one of the thin plate-like members over and sliding the fingers over the fingers on the bottom thin plate-like member, the size of the rectangular areas between the fingers and the distances between each finger can be adjusted, so that a generally isosceles trapezoid shape can be formed by the outline of the fingers.
A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description of the invention and accompanying drawings which set forth illustrative embodiments in which the principles of the invention are utilized.
a and
a and
a and
a and
Preferred embodiments of a guide device for cutting through dovetail joints according to this invention will be described hereunder with reference to the drawings.
In
The operation of this embodiment will be described below. First, the operation for cutting the tail board will be explained. As also shown in
Next, the operation for cutting the pin board will be described. As seen in
As can be understood from the brief description above, a through dovetail joint, as seen in
The operation of the stopper 15 will be explained in conjunction with
In this way, the depth of the tail board cut can be simply and accurately set to the width of the workpiece 13, i.e. the pin board. The board is then cut as in the first embodiment.
In a further embodiment of the invention as seen in
Another advantage of the present device as mentioned above is the need to only use one router bit for all the cuts. Specifically, since the templates of the present device are made of a thin material such as metal or plastic, the only requirement for a router bit is the use of a template guide or pilot bearing to run along the edges of the fingers or cutouts of the templates. This is concretely shown in
Also, as mentioned above, by first setting the router to cut just to the bottom of the tail board or workpiece 12, as seen in
Although the above embodiments allow a woodworker and hobbyist to make accurate dovetail joints repeatedly with very few adjustments, each of the templates are limited to one size, hence allowing only one size of joint to be cut for each template. Even though the templates are fairly inexpensive as they only require simple machining or casting work to produce, stocking a large number of templates of different sizes can be prohibitive to a hobbyist.
Accordingly, in another embodiment of the present invention, adjustable templates are provided, as shown in
With this embodiment, the pairs of respective mirror image templates are laid upon each other facing in reverse directions longitudinally, and slid back and forth until the desired size is reached, making the cuts smaller or wider. The templates can then be appropriately clamped to each other and used in the same fashion as in the above embodiments.
In a further embodiment of the invention, as seen in
As mentioned above, the present device can be used with both hand held and table mounted routers. Examples of using table top routers for both the pin board and tail board are shown in
As can be seen from the above, the present guide device for cutting through dovetail joints greatly facilitates the process of cutting both tail boards and pin boards without the use of multiple fences, t-squares, numerous measurements, adjustments, etc. as in the conventional devices. The present invention also makes it possible to use a single router bit without any adjustments of router bit cutting depth, etc., outside of those needed to cut the workpiece easily, as the device does not depend on router bit cutting depth for accurate cuts. This allows reductions in both time spent making drawers, etc., and in the number of inaccuracies that are inherently introduced with conventional methods. It provides even hobbyist woodworkers with a tool that allows the cutting of dovetail joints that are crisp, accurate and flush, resulting in joints with a surprisingly professional appearance. The device is also very compact, comprising essentially two thin plate-like templates, with size being regulated only by the width of the joints to be produced, so that storage is much less of a problem than encountered by using conventional devices. Further, with use of the mirror image templates, only one device is needed for a variety of joint sizes, a versatility that can be appreciated by hobbyists with limited resources and/or space.
It is understood that various details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation, the invention being defined by the claims.