TECHNICAL FIELD

The present invention relates to assistive devices for hand-held power tools In particular, it relates to a conversion tool for use with a hand-held circular saw for easy creation of a table saw equivalent for making long and accurate cuts in large work pieces such as plywood This invention also relates to a conversion tool for use with a hand-held router for creation of a hands-free table top router for accurate use of the router on large work pieces. BACKGROUND ART

Large work pieces such as plywood, particle board, fiber boards and plastic laminates have become common building materials Proper application of these materials usually involves making two or more long cuts in the work pieces Work on large work pieces, especially multiple pieces, is more efficiently performed in a workshop setting having traditional table saws and other more permanently mounted equipment However, it is expensive, difficult and inefficient to move such equipment to a job site For convenience and practical reasons, cuts are usually made on the job site.

As a consequence of the difficulty of transporting table saws and other larger pieces of equipment to job sites, multiple tools and devices have been created in the prior art to assist the on site builder. For example, several saw guides have been developed to help guide the user of a circular saw to make cuts in large work pieces Such devices attach directly to the saw or other tool and two hands are generally required to manipulate the combination tool and guide. Use of such guides also requires a working surface large enough to stabilize or anchor the work piece upon which the cut or other operation will be performed. Valuable time is needed to manipulate each respective work piece into position on which to be worked. The combination of such guides with the saw or other tool can make the combined tool unwieldy to use.

DISCLOSURE OF THE INVENTION

It is a primary objective of the present invention to provide a device to allow better and more efficient use of hand-held power tools It is a further objective of the present invention to provide an improved conversion device for use with hand-held power tools, such as a circular saw, to enable use of the hand held power tool as a stable table top operated tool It is a still further objective of the present invention to provide an improved conversion device for hand-held power tools to allow better and more accurate operation of the power tools on large work pieces A yet further objective of the present invention is to provide an improved conversion device for hand-held power tools which is relatively inexpensive and easily transportable A conversion device for hand-held power tools in accordance with the invention includes a planar elongated arm having at a distal end a saw blade opening for the blade of a circular saw. The saw is fastened to the distal end of the arm using fasteners typically available such as threaded bolts and wingnuts. The saw blade projects through the saw blade hole in the arm A rigid base is securely affixed to a work surface, such as to a thick piece of plywood, typically using threaded fasteners The base is equipped with an upward facing support surface and two threaded fasteners firmly mounted to the base and projecting upwards past the support surface The arm has two oppositely disposed longitudinal slots through which the threaded fasteners pass and are used with nuts to mount the arm on the base The lower surface of the arm is in contact with the support surface of the base and is slidable longitudinally over the base and above the work surface The arm can thus be adjusted to fix the distance between the saw blade and a side facing guide surface on the base according to the dimension of a cut to be made in a work piece Leaf springs mounted on the underside of the arm help the operator hold the work piece to the work surface Measuring indicia on the arm enable easy calculation of the distance between the saw blade and the guide surface. BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 is a perspective view of a conversion device for hand-held power tools in accordance with the invention

FIG 1A is a perspective view of a conversion device for hand-held power tools in accordance with the invention with a circular saw attached to the arm of the device, the device secured to a work surface, and a work piece being fed between the arm and the work surface FIG 2 is a section view of the arm of the conversion device in accordance with the invention taken along section lines 2-2 shown in Fig 1

FIG 3 is a front section view of the base of the conversion device in accordance with the invention taken along lines 3-3 shown in Fig 1

FIG 4 is a side view of the trigger actuating cam of the conversion device in accordance with the invention showing the trigger depressed in the on position

FIG 5 is a side view of the trigger actuating cam of the conversion device in accordance with the invention showing the trigger depressed in the off position

BEST MODE FOR CARRYING OUT THE INVENTION A conversion device for hand-held power tools is described

The conversion device comprises a substantially planar rigid arm 10 and a rigid base 12 as best seen in FIG 1 The base 12 is firmly affixed to a work surface such as a thick piece of plywood using commonly available fasteners passed through holes 14 in the bottom portion 16 of the base 12 In normal operation in the field, the base can be screwed, bolted or even nailed to the work surface, so long as the method of attachment used firmly secures the base to the work surface The base has upwardly projecting sidewalls 18, each sidewall having an upper flange 20 The upper flanges 20 collectively comprise a support surface 22 for the arm 10

The arm 10 is mounted on the base 12 to allow it to slide along substantially its entire length on the support surface 22 of the base 12 Longitudinal slots 24 run substantially the length of the arm 10 Threaded fasteners 26 are firmly mounted to the base and project upwardly through the longitudinal slots 24 In the preferred embodiment, washers 28 on the threaded fasteners 26 spread the load of the arm around the slots 24 The arm 10 includes integral oppositely disposed upwardly projecting lips 30 aJong the entire length of the arm 10 for strength and rigidity The arm 10 further

includes a large hole 32 to make the arm lighter Running the length of the hole 32, oppositely disposed integral longitudinal flanges 34 provide added rigidity and strength to the arm 10.

A saw blade opening 36 is provided at the distal end 38 of the arm 10 A standard circular saw S is attached to the arm 10 at the distal end 38 using commonly available threaded saw mounting fasteners passed up through saw mounting holes 40 Other means for mounting different kinds of circular saws and other tools such as routers may readily be used in other preferred embodiments In the illustrated embodiment, the saw S is mounted to the arm 10 so that its blade B projects below the lower surface 42 of the arm 10 for free rotation Typically the saw blade in operation will dig into the work surface a fraction of an inch as shown in Fig 2

The arm 10, once firmly mounted on the base 12, is cantilevered over the work surface leaving space between the lower surface 42 of the arm 10 and the work surface for insertion of a work piece such as a piece of plywood or fiber board The outer surface of one of the upwardly projecting sidewalls 18 of the base 12 facing the saw blade S forms a guide surface 44 for guiding of a work piece while being passed between the arm 10 and the work surface

In the illustrated embodiment, the arm 10 is equipped with leaf springs 46 disposed below the lower surface 42 of the arm 10 to bias downward against a work piece Measuring indicia 48 are attached to the longitudinal lips 30 of the arm 10 to facilitate measuring distances between the saw blade S and the guide surface 44 of the base 12 Alternatively, a standard rip fence can be attached to the work surface immediately adjacent the guide surface, and the work piece may be guided along the rip fence The arm 10 is drawn away from the guide surface 44 of the base 12, or the rip fence, according to the dimension of a cut to be made in a work piece The disposition of the longitudinal slots 34 allows the arm 10 to rotate slightly radially with respect to the base 12 The user may adjust the radial position of the arm 10 to ensure parallel placement of the saw blade S with the guide surface 44 of the base 12, or the rip fence, to prevent binding of the saw when cutting a work piece A trigger activating cam 50 is provided for attachment to the circular saw S as seen in Fig 1A The cam 50 sits adjacent the trigger in the off position Rotation

of the cam 50 ninety degrees depresses the trigger and activates the saw S for hands- free operation.

There have thus been described certain preferred embodiments of a conversion device for hand-held power tools. While preferred embodiments have been described and disclosed, it will be recognized by those with skill in the art that modifications are within the true spirit and scope of the invention. The appended claims are intended to cover all such modifications.