Guiding assembly for a portable power tool

A portable power tool having a sole plate for contacting a workpiece along which a straight line is to be cut has an attachment for the sole plate which includes means for supporting a guiding means which is adjustable with respect to the supporting means to cooperate with a longitudinal guide member releasably attached to the workpiece. The guide member may be angle iron, channel iron, I-beam or other similar configuration conveniently available to a workman and not especially designed to be used with the attachment.

This invention relates to a guiding assembly for a portable power tool, 
such as a circular saw, jig saw, router, or the like and particularly to 
an attachment for such a tool which is conveniently ajustable for use with 
any guide member conveniently available to a workman. 
Heretofore, it has long been the usual practice to cut a straight line 
along a workpiece using as a guide a wooden or metal straight edge against 
which the cutting blade of a portable power tool was aligned. Two 
difficulties with such a guide are that, in the case of a long cut, the 
tool tends to wander or drift away from the straight edge, or the tool may 
slip beneath the guide. To overcome these problems, many artisans have 
designed various types of attachments for portable power tools, the most 
common of which utilizes a rigid member which is adapted to slide along a 
guide member which is releasably attached to the workpiece, for example as 
shown in U.S. Pat. No. 1,911,045. Although such an attachment is 
satisfactory for use with a particular guide having dimensions 
specifically designed to cooperate with the attachment for the power tool, 
such attachments have not found general acceptance since they require a 
workman to have available at all times the specific guide for which the 
attachment is designed. 
To overcome this limitation, I have invented a guiding assembly which is 
adapted for use with and includes any convenient guide member which is 
adapted to be secured to a workpiece in such a way that a leg of the guide 
member extends upwardly from the workpiece, as will be more particularly 
described hereinafter. My guiding assembly includes an attachment for a 
power tool which is fully adjustable in both the lateral and vertical 
directions to enable the attachment to be utilized with such guide 
members, whether they comprise angle iron, channel iron, I-beam or other 
similar configuration. My guiding assembly is easily attached to and 
removed from a portable power tool. It utilizes only a few components, and 
therefore can be inexpensively made. Since the attachment fastens directly 
to the sole plate of a portable power tool, no substantial modification of 
the tool is required. The attachment may be made in whole or in part of 
metal, durable plastic or any other rigid synthetic material, such as 
tempered masonite or the like. 
In a modification of the invention, the distance between the cut to be made 
by the power tool and the guide member which is releasably secured to the 
workpiece can be varied as desired by the use of auxiliary members.

Referring to FIG. 1, a portable power tool, such as the circular saw 1 
shown, a jig saw, router, or the like, has a cutting blade 2 which is 
adapted to rotate through a sole plate 3 of the tool to cut a workpiece 4. 
In order to cut a straight line across the workpiece, particularly in the 
case of long cuts to be made, an attachment 5 is secured to the sole plate 
3 of the power tool by fasteners, such as threaded bolts 6, as will be 
more fully described hereinafter. A guide member in the form of an angle 
iron 7 is releasably secured at opposite sides of the workpiece to the 
workpiece by clamps 8. A straight line cut is made across the workpiece by 
engaging the attachment 5 with upstanding leg 9 of the angle iron to 
provide a guiding assembly at one side of the workpiece and moving it in 
the direction of the guide member across the workpiece. 
A preferred attachment as shown in FIG. 2 comprises a supporting means 
including a longitudinal channel 10 having a rectangular cross section. 
The channel 10 may be made of metal, plastic, or other rigid material. 
There are holes 11 in opposite top face 12 and bottom face 13 at both ends 
of the channel. A guiding means comprising an angle 14 is attached to the 
top face 12 such that slots 15 in a first leg 16 of the angle at both ends 
of the channel are aligned with the holes 11 in the channel. Threaded 
bolts 6 are inserted from below the sole plate through the holes 11 in the 
channel and through the slots 15 in the first leg of the angle. Each bolt 
preferably has a washer 17 and bolt assemblies are secured by wing nuts 18 
threaded to the bolts. The angle 14 also has a depending or second leg 19 
which extends substantially parallel to a side face 20 of the channel and 
the space 21 between the second leg 19 and the side face 20 of the channel 
is adjusted by moving the angle 14 relative to the channel. After the 
appropriate distance is established the wing nuts 18 are tightened to 
secure the relative positions of the elements of the attachment. The space 
21 between the inside of the second leg 19 and the face 20 of the channel 
is selected in accordance with the width of a guide member to be engaged 
therebetween. 
The guide member may be, as shown in FIGS. 1 and 2, an angle iron 
comprising L-shaped longitudinal member 7 having an upstanding leg 9 which 
is slidably received in the space 21 between the channel and the second 
leg 19. The maximum width of leg 9 of the angle to be engaged therebetween 
is limited only by the maximum distance that the inside of the depending 
leg 19 and the channel face 20 can be spaced. This, of course, depends 
upon the width of the first leg 16 and the length of the slots 15 therein. 
A similar embodiment of the attachment is shown in FIG. 3, except that in 
this embodiment the first leg 16 of the angle is vertically spaced from 
the top face 12 of the channel by a plurality of shims 22 which may be in 
the form of strips or washers. The shims include holes 23 whereby bolts 6 
can extend through them and the shims can be secured by the bolts and wing 
nuts in an integral unit. By adjusting the attachment vertically, it is 
able to engage one leg 24 of an I-beam guide member, such as an ordinary 
carpenter's level 25. Lateral adjustment of the attachment is accomplished 
in the same manner as described with respect to FIG. 2 and need not be 
repeated. It is apparent from a consideration of FIGS. 2 and 3 that the 
preferred attachment according to the present invention is adjustable both 
laterally, that is, to increase or decrease the width of the attachment 
and vertically, that is, to increase or decrease the height of the 
attachment with respect to the plane of the workpiece to accommodate any 
guide member which is conveniently available to a workman at a job site. 
To facilitate acceptance of the longitudinal guide members such as angle 
iron 7 (in FIG. 1), the entry end 26 of the second leg 19 of angle 14 is 
smoothly curved or bent outwardly away from the line of the cut to be 
made. The lowermost portion of the leg 19 is bent slightly greater than 
the uppermost portion thereof. 
In a further embodiment of the invention, where it is desirable to increase 
the distance of the cutting blade or tool from the guide member releasably 
secured to the workpiece, or for use with certain power tools which do not 
have a continuous sole plate along the edge adjacent the cutting blade or 
tool, I propose to use an auxiliary plate 27 either alone or in 
combination with extension arms 28 as shown in FIG. 4. The main elements 
of the attachment are as previously described and comprise a channel 10 of 
rectangular cross section, a shim or shims 22 if necessary, and an angle 
14 having a first leg 16 and depending or second leg 19, all secured to 
the auxiliary plate and/or to the extension arms by threaded bolts 6. The 
bolts 6 extend upwardly through holes 11 in the channel and shims and 
through the slots 15 in the angle 14. The unit includes washers 17 and 
wing nuts 18 threaded to the bolts. The extension arms 28 are fastened to 
the sole plate by conventional fasteners 29. To prevent the auxiliary 
plate 27 from shifting with respect to the sole plate 3 of the power tool 
it may be necessary to utilize more than one fastener in either the 
auxiliary plate or the sole plate or both on a single extension arm. 
Utilizing the arrangement shown in FIG. 4, it is possible to place the 
attachment on the opposite side of the power tool from the cutting blade, 
a convenience which may be desirable for certain cutting activities. In 
addition, such an arrangement on the opposite side from that shown in FIG. 
1 can and does improve visibility of the cut being made and is 
particularly helpful for persons who wish to work with the left hand. 
In a still further embodiment of the invention, as shown in FIG. 5, an 
auxiliary plate 27 having an area greater than the sole plate of the power 
tool is bolted to the sole plate in four locations, only two of which are 
shown in the Figure. Such an arrangement provides additional rigidity over 
the arrangement shown in FIG. 4, since the rigidity of the auxiliary plate 
does not depend upon extension arms, but rather the plate is securely held 
to the sole plate and acts as a large sole plate. The auxiliary plate and 
extension arms shown in FIGS. 4 and 5 may be made of metal or plastic, 
however, it is also contemplated that these components be made of a rigid 
synthetic material, such as tempered masonite, which has good sliding 
capability. 
In many portable power tools, the plane of the sole plate is adjustable 
relative to the plane through the cutting blade to enable workpiece edges 
to be chamfered. If the attachment of the present invention is located on 
the side of the sole plate nearest the cutting blade, the attachment may 
be easily removed to permit chamfering by simply removing the holding 
bolts in the sole plate. If the attachment is on the opposite side of the 
sole plate, it will not interfere with adjustment of the cutting blade. 
It is apparent that although the saw is shown in a position so as to make a 
straight cut parallel with an edge of the workpiece, the guide member may 
be located in any position across the workpiece to enable any sort of 
straight line cut to be made, including mitered joints. 
The invention is particularly useful for cutting long workpieces, for 
example panels of 4 .times. 8 feet and greater in which, heretofore such 
straight cuts have not been made without some sort of guiding means and 
for the tool. However, although such means was desirable, a workman 
generally was either unable or unwilling to carry with him a guide member 
sufficiently long to enable the straight line cut to be made. 
As previously stated, the elements of my guiding assembly may be made of 
metal, preferably aluminum, or of a rigid synthetic material, such as 
plastic, or particularly with respect to the auxiliary plate and extension 
arms, of a tempered masonite or the like. 
Having described presently preferred embodiments of the invention, it is to 
be understood that the invention may be otherwise embodied within the 
scope of the appended claims.