Saw guide device

A saw guide for guiding a hand powered saw to make a straight cut at any predetermined angle, the device including a solid guide bar and a saw base pad, to slidably fit over the guide bar, comprised of a different material than the guide bar itself, with the material selected to reduce sliding friction between the guide bar and the base pad.

BACKGROUND OF THE INVENTION 
This invention relates to a saw guide apparatus for hand held power tools, 
with the apparatus specifically constructed to prevent distortion of the 
guide bar during use and further designed to employ a saw base pad 
constructed of a material different than the guide bar which has been 
specifically selected to reduce sliding friction between the guide bar and 
the saw base pad. 
There have been various types of guide apparatuses for power tools having 
blades such as circular saws, sabre saws, and to a certain extent, even 
routers. Typically such units utilize a straight edge guide which is some 
sort of channel member and a carrier shoe adapted to fit over the channel 
member and attach to the power saw itself. 
While such units have met with some degree of success in the marketplace, 
most of the units have certain inherent difficulties. Many of those employ 
very complex mechanical structures which virtually price them out of reach 
in terms of meeting the consumer demand for such saw guide devices. In 
addition, many of those which employ a guide bar comprised of a channel 
shaped U-bracket or the like as the saw guide bar, are subject to easy 
distortion of the guide bar itself during use. Of course, if the guide bar 
is distorted, correspondingly any cuts which are made will also be not 
true since the straightness of the cut is directly dependent upon the true 
straightness of the guide bar itself. Additionally, many of the prior art 
structures employ complex carrier shoes which are attached to the base of 
the power hand tool, with the carrier shoe designed to fit over the guide 
bar. Such carrier shoes are cumbersome, often complex in structure, and in 
most instances are made of metal. The result is that the carrier shoe will 
not smoothly slide along the guide bar and any distortion of the guide bar 
or the carrier shoe will render the unit virtually useless. 
Accordingly, applicant has designed a saw guide which is designed to 
overcome the above enumerated deficiencies of the prior art devices. 
One object of applicant's invention is to provide a saw guide which is very 
simple in structure, and which can be sold at a very economically low 
price. 
Another object of applicant's invention is to provide a saw guide device 
which employs a solid steel guide bar which can be conveniently made from 
cold rolled steel and which is not subject to easy distortion from 
application of pressure over extended periods of use. 
Yet another object of applicant's invention is to provide a saw base pad 
which is constructed of a material different from the material of the 
solid saw guide bar with the material selected to reduce sliding friction 
between the guide bar and the base pad so that the base pad when attached 
to the power hand tool will allow the tool to easily slide along the guide 
bar. 
Yet another object of applicant's invention is to provide an inexpensive 
saw base pad which can be attached to a power tool by pressure sensitive 
adhesive strips. 
A still further object of the invention is to provide an inexpensive 
lightweight guide pad, which can be conveniently adapted for use with a 
variety of different powered hand tools, including sabre saws, circular 
saws, routers and the like. 
The method and means of accomplishing this invention will become apparent 
from the following detailed description of the invention.

SUMMARY OF THE INVENTION 
The saw guide device of this invention primarily comprises the employment 
of a solid saw guide bar made of cold rolled steel which is capable of 
taking some physical abuse without being distorted from its true 
straightened position and further comprising a saw base pad which is 
adapted to slidably fit over the guide bar for lengthwise sliding along 
the guide bar with the base pad being constructed of a material different 
than the guide bar and selected to reduce sliding friction between the 
guide bar and the base pad. As a result there is no metal to metal sliding 
which is a high friction type of movement and there is no basic tendency 
for the guide bar itself to become distorted during use. 
DETAILED DESCRIPTION OF THE INVENTION 
The following detailed description of the invention is given in connection 
with the employment of a circular saw as a powered hand tool, but it is to 
be understood that other devices such as sabre saws, and routers, may be 
equally employed with the overall concept of the present invention. 
The saw guide device 10 is shown in actual use condition in FIG. 1 mounted 
to a work piece 12 with a circular saw 14 positioned on guide bar 16 with 
the saw making a straight cut 18. The device itself is perhaps best 
illustrated in FIG. 3. Guide bar 14 is comprised of an elongated solid 
steel bar member having a forward end 20 and a rearward end 22. It is 
important that guide bar 16 be of solid metal construction. A solid metal 
guide bar, as opposed to a U-shaped channel member, or a member having an 
upwardly standing guide flange is important to this invention in that such 
other types of guide bars as mentioned herein are subject to easy 
distortion upon application of pressure during use such as they will 
become distorted from the true position. Moreover, a solid length of steel 
is the easiest member to employ in that no special performing operations 
need be conducted. 
Guide bar 16 is attached, near its rearward end 22, to anchor plate 24. The 
attachment of anchor plate 24 to guide bar 16 is by means of a pivot bolt 
threadably received through the aligned aperture 26 of anchor plate 24 and 
aligned aperture 28 of guide bar 16. While the term pivotal has been used 
herein, in FIG. 3 the pivotal fastening means shown is threaded bolt 30 
and wing nut 32. It is, however, to be understood that other fastening 
means which allow pivotal movement of guide bar 16 with respect to anchor 
plate 24 may also be employed. 
At the end of anchor plate 24, which is attached to guide bar 16, anchor 
plate 24 has a protractor index 34 marked about circular edge 36 in order 
to allow movement to predetermine angles. 
At the end of anchor plate 24 opposite protractor index 34 are apertures 38 
and 40 to allow threaded screw clamp 42 and bracket 44 to be attached to 
anchor plate 26 via conventional screw fasteners 46 and nuts 48. In like 
manner, at its rearward end, guide bar 16 has aperture 50 which is 
employed to attach screw clamp 52 via threaded bolt 54 and wing nut 56 to 
guide bar 16. Sighting aperture 58 is provided to allow sighting of angle 
markings on protractor index 34. 
At or near the forward end 20 of guide bar 22 another screw clamp 60 is 
associated with bracket 62 and set screws 64 and 66 in order to allow 
attachment of guide bar 16 to the forward end of work piece 12 as depicted 
in FIG. 1. 
As best seen in FIG. 3, a saw base pad 68 has on its bottom surface 
elongated notch 70 which is of such a dimension that it will matingly 
receive guide bar 16 to allow slidable movement of pad 68 along the 
longitudinal axis of guide bar 16. Positioned on the top surface of base 
pad 68 are a series of pressure adhesive strips 72. It has been found 
convenient to utilize for the pressure adhesive strips 72, the pressure 
adhesive tape material sold by the 3M Company which is used as molding 
adhesive for cars. The material is pressed against the top surface of pad 
68. Positioned over the top surface of the adhesive strip 72 is a paper 
material which is peeled off when the pad is to be attached to the base 74 
(FIG. 1) of circular saw 14. 
An important feature of this invention is that base 68 is comprised of a 
material different than guide bar 16 and that the material is selected to 
reduce sliding friction between guide bar 16 and base pad 68. 
Suitable materials for pad 68 are generally hardened polymeric plastic 
materials often used as metal bearing materials. Examples of suitable 
hardened plastic materials from which base 68 can be made are high density 
polyethylene, nylon, phenolic polymeric materials, polycarbonate polymeric 
materials, teflon and Delrin. Delrin is an acetal resin, is thermoplastic, 
as are the other materials mentioned herein, and is manufactured by E. I. 
duPont de Nemours & Company. Delrin has been utilized for some prototypes 
and been found highly satisfactory. It is therefore preferred. It is 
easily available, reduces sliding friction between the guide bar and the 
base plate 74, and actually runs so smoothly along the longitudinal axis 
of guides bar 16 that it has the feel during movement as if the movement 
is bearing supported. It is also important that the hardened thermosetting 
plastic material be of sufficient rigidity such that it will not easily 
bend and therefore maintain the integrity of the fixed relationship 
between the guide 16 and the base pad 68. All of the materials mentioned 
herein have this capability. It should be understood that there may be 
other hardenable thermosetting plastic materials which meet the criteria 
mentioned herein but have not been specifically enumerated, for example, 
polyvinyl chloride, could perhaps also be employed as well as others. 
In actual operation, the saw guide device of this invention works as 
follows: The edge of anchor plate 24 is placed in abutting relationship 
with one of the edges of work piece 12 and clamped thereto by screw clamp 
42, assuming that wing nuts 32 and 56 are loose, the guide bar 16 is moved 
to the desired angle as indicated on protractor index 34, sighted through 
sight aperture 58 and clamped into position by tightening wing nuts 56 and 
32. Correspondingly, at the outer end or forward end 20 of guide bar 16 it 
can be clamped rigidly into position by means of screw clamp 60 and 
tightening of set screw 64 and 66. Assuming that base plate 68 has been 
attached to the bottom of circular saw 14, the base plate 60 is then 
positioned over guide bar 16 so that notch 70 is in mating relationship 
with guide bar 16. The saw can then be moved freely along longitudinal 
axis of guide bar 16 with sliding friction reduced to a minimum by 
employment of the hereinbefore mentioned materials for saw base pad 68. If 
a unit other than the circular saw is desired for use, other base pads 
fitting the bottom configuration of the saw base 74, or router base or the 
like can be employed with equally satisfactory results. 
Thus, as can be seen, the invention accomplishes all of its stated objects. 
It also provides a unit which has a multitude of variable adjustments for 
the bar itself. In addition, the guide bar itself, being of solid steel 
construction, is not subject to easy distortion and therefore can be used 
for extensive periods of time. 
Certain advantages of the saw guide device of this system are worthy of 
specific mention. First, the unit is entirely portable, of simple 
construction and therefore easy to use. Secondly, the guide bar 16 can be 
used without using anchor plate 24 in the event that a very narrow board 
is being cut. Thirdly, the base 68 can be sold as original equipment along 
with portable hand tools such as a circular saw, sabre saw, or router. 
Fourthly, the saw itself, because of the simplicity of construction of the 
base pad, can be used without the guide, with the base pad attached and it 
will not interfere with the making of a cut. Lastly, and as previously 
mentioned, the guide bar is releaseably attached to the overall device so 
that it can be easily removed and a guide bar of differing length 
substituted therefor.