A brush attachment for a power tool, such as an electric drill, capable of rotating a suitable shaft including an attachment body containing a longitudinally extending chamber and an elongate shaft rotatably mounted in this body and projecting from a rear end thereof. A cam and cam follower mechanism in the chamber convert rotary motion of the shaft into a reciprocating linear motion. There is a shaft mechanism mounted in the body for sliding reciprocating movement only relative to the body and connected to the cam follower. This shaft mechanism projects from a front end of the body. A brush is attached to a front end of the shaft mechanism and reciprocates with this mechanism in the longitudinal direction thereof. The brush attachment can be mounted on the power tool so the attachment body remains stationary relative to the tool when the shaft is rotating.

BACKGROUND OF THE INVENTION 
This invention relates to brush attachments for power tools including an 
attachment designed to convert rotary motion provided by a power tool to 
reciprocating motion. 
Various brush designs intended for cleaning purposes are known and have 
been used for a considerable length of time. These include brushes 
intended for use on various power tools. For example, it is known to use 
large rotating brushes on floor polishing equipment. Often the bristles on 
these brushes are soft and flexible so as not to damage the surface which 
is being cleaned and to provide a shiny finish to the surface. Rotating 
brushes are also known for use in cleaning attachments such as those 
typically used in conjunction with vacuum cleaners. These brushes are used 
to pick up dirt and lint from the surface being cleaned, which is often a 
carpet or rug. 
Very stiff wire brushes are also known for use in certain cleaning and 
abrading operations. For example, wire brushes are known for removing rust 
from metal surfaces or for removing old paint. Generally speaking, wire 
brushes of this type are only used where the strong, metal bristles will 
not damage the surface that is being cleaned. 
The use of machines for sandblasting is also well known for cleaning 
certain surfaces such as brick and stone work as well as metal surfaces. 
Generally speaking, these machines are intended for large cleaning jobs as 
they tend to be relatively expensive and generally require the use of a 
large air compressor. Standard sandblasting techniques can create 
considerable dust and other debris and therefore such cleaning methods are 
normally used outside in an environment where the dust and debris can be 
tolerated. However, sandblasting does have the advantage of providing a 
relatively quick method for cleaning surfaces that are very difficult to 
clean by other methods, such as by brushing and washing. 
Early U.S. Pat. No. 1,007,888 dated Nov. 7, 1911 and issued to P. W. Parker 
describes a special brush device designed for use in association with a 
vacuum cleaner. The brush is rotated by its own electric motor mounted in 
a specially shaped housing. On an extension of this housing is mounted an 
elongate sleeve having a cam mounted at one end. This cam co-acts with a 
further cam which extends around a shaft that is connected to the shaft 
coming from the motor. A coiled spring is connected to the latter cam. At 
the forward end of the first mentioned shaft is an annular brush which can 
be made with stiff wire or fiber. This brush is mounted in the intake end 
of the vacuum tube. The device can be arranged to impart both a 
reciprocatory and a rotary movement to the brush by means of engagement 
between the cams. This known device is said to be suitable for cleaning 
stone, cement and similar surfaces where a slight abrasive action is 
desired. A difficulty with this known device is that it is only designed 
for use in conjunction with a special vacuum cleaner attachment. 
A more recent patent illustrating a mechanism for reciprocating a cleaning 
brush is U.S. Pat. No. 2,671,914 issued Mar. 16, 1954 to R. V. Rucker. 
This specification teaches a mechanism for converting rotary motion to a 
reciprocal lateral motion. It requires the use of a dedicated electric 
motor mounted in a hollow housing that is connected to a handle. The motor 
turns a bevelled pinion gear which rotates a drive gear having a gear 
segment affixed thereto. This gear segment engages a rectangular rack 
causing it first to reciprocate in one direction when its upper teeth are 
engaged and reciprocate in the opposite direction when its lower teeth are 
engaged. This reciprocating rack has a brush affixed thereto. Means are 
also provided for pumping liquid from a reservoir to the brush. 
An object of the present invention is to provide an easy to use brush 
attachment useful for cleaning, particularly the cleaning of surfaces 
where a sandblasting technique would normally be called for. Another 
object of the present invention is to provide a brush attachment that can 
readily be mounted on existing, widely used power tools, such as a power 
drill, thus reducing the cost of the device substantially. The attachment 
is able to selectively either rotate the brush about an axis parallel to 
the bristles or reciprocate the brush in the longitudinal direction of the 
bristles. 
It is a further object of the invention to provide a unique brush 
construction that is particularly suited for cleaning in a manner that 
might be considered similar to sandblasting. This unique brush attachment 
employs tough, flexible bristles which are capable of restoring themselves 
substantially to their original shape after repeated bending. The bristles 
of the brush can vary in length from long, centrally located bristles, to 
shorter bristles located at two opposite sides of the brush. 
In the preferred embodiment of the brush, there is a brush body which is 
generally rectangular with a central longitudinal axis and the long 
bristles extend along this longitudinal axis. In one preferred embodiment 
of the brush, the bristles are made of a stiff, wavy polypropylene or 
nylon material. 
SUMMARY OF THE INVENTION 
According to one aspect of the invention, a brush attachment for a power 
tool capable of providing rapid reciprocating motion in a desired 
direction comprises a brush body having a front surface and tough, 
flexible bristles having their inner ends firmly mounted in this brush 
body so as to cover an area on the front surface this area having a 
centerpoint. The bristles are capable of restoring themselves 
substantially to their original shape after repeated bending. The bristles 
taper in length from long, centrally located bristles to shorter bristles 
located at opposite extremities of the brush located on opposite sides of 
the centerpoint. The taper is substantially even from the centerpoint of 
the area to the opposite extremities. There are also means for connecting 
the brush body to a power tool. 
According to another aspect of the invention, a brush attachment for a 
power tool capable of rotating a suitable shaft includes an attachment 
body containing a longitudinally extending chamber and an elongate shaft 
rotatably mounted in this body and projecting from a rear end thereof. 
There is a mechanism in the chamber for converting the rotary motion of 
the shaft into a reciprocating linear motion in the direction of the 
elongate shaft. In addition, a shaft mechanism is mounted in the body for 
sliding reciprocating movement only relative to the body and is connected 
to the converting mechanism. This shaft mechanism projects from a front 
end of the body. A spring is mounted at one end of the attachment body and 
engages a shaft mechanism. The spring is adapted to drive the shaft 
mechanism rapidly in a forwards direction as part of the reciprocating 
linear motion. A brush is attached to a front end of the shaft mechanism 
and is adapted for reciprocating motion with the shaft mechanism in the 
longitudinal direction thereof. There are also means for detachably 
mounting the brush attachment on the power tool so that the attachment 
body remains stationary relative to the power tool when the shaft is 
rotating. 
According to a further aspect of the invention, a power tool for cleaning 
or abrading a surface or structure includes a power tool mechanism having 
a motor and means for controlling the operation of this motor and an 
elongate rotatable shaft mounted in this mechanism and operatively 
connected to the motor for rotation. There are also means for converting 
the rotary motion of the shaft into a reciprocating motion and a shaft 
mechanism capable of reciprocating movement relative to the power tool 
mechanism and connected to the converting means. There are means for 
slidably mounting the shaft mechanism s that the shaft mechanism 
reciprocates only relative to the mounting means. A brush is attached to 
the front end of the shaft mechanism and is adapted for reciprocating 
motion with the shaft mechanism in the longitudinal direction thereof. The 
brush has bristles that cover an area of the brush, this area having a 
centerpoint, and vary in length from long, centrally located bristles to 
shorter bristles located at opposite extremities of the brush located on 
opposite sides of the centerpoint. 
In one particular preferred embodiment, there are additional means provided 
for reciprocating the brush with a lighter, shorter stroke, rather than 
the full, normal reciprocating motion. 
Further features and advantages will become apparent from the following 
detailed description taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates a preferred form of brush attachment 10 designed and 
constructed for use with a power tool 12 capable of rotating a suitable 
shaft. The illustrated power tool is a standard portable electric drill 
having a handle 14 and an operating trigger or button 16. As is well know, 
these drills can be provided with an electrical cord for attaching the 
drill to a power source or they can be provided with a suitable internal 
battery that provides a source of power for a period of time before it 
needs to be recharged. The front end of the drill is provided with a 
standard chuck mechanism 18 which is usually adjustable to fit a number of 
drill bit sizes and which can be tightened by means of a suitable key (not 
shown) to secure the drill bit in the drill for rotation. 
The major components of the brush attachment 10 of the present invention 
which are illustrated in FIG. 1 include a brush 20, an attachment body 22, 
a suitable coil spring 24, and a brush locking hub 27. The mechanism for 
mounting the brush attachment on the power tool is also shown in FIG. 1. 
These mounting means can selectively cause the attachment body 22 to 
either rotate or remain stationary relative to the power tool When the 
shaft, which is inserted in the chuck mechanism 18, is rotated. The 
mounting mechanism includes an elongate lever member 26 and a bracket 28 
which is rotatably mounted on an elongate shaft 30, which is a shaft whose 
end 31 is inserted in the chuck mechanism 18. The lever member 26 is 
pivotally connected to the bracket and is adapted for engagement with the 
power tool as shown in FIG. 1. 
In the illustrated preferred embodiment, the lever member has connected 
thereto a strap 32 which is preferably elastic. At each end of the strap 
are Velcro*-type fasteners 34 and 36 which are provided to secure the 
strap tightly around the power tool in the manner illustrated in FIG. 1. 
It will be appreciated that because the strap is elastic and because of 
the use of the Velcro-type fasteners, the brush attachment of the 
invention can be secured to a variety of power drills of different makes. 
Furthermore, the lever member can be provided With an adjustable pin 38 
that is slidable in a slot 40. The projecting end of this pin is inserted 
in any suitable hole, slot or opening formed in the side of the power 
drill in order to provide a positive, mechanical engagement that prevents 
the lever member from being rotated about the side of the drill. 
Turning now to the construction of the attachment body 22, this body is 
preferably cylindrical and made of a suitable metal such as steel. It can 
have a knurled outer surface to permit it to be gripped easily. Extending 
most of the length of the body is a longitudinally extending, cylindrical 
chamber 42. Closing the rear end of this chamber is a cylindrical cup 
member 44, which fits into the recessed end of the body 22. This member is 
secured in place by screw 45 shown in FIG. 5. An integral, cylindrical 
extension 46 projects from the front end of the body and has a central 
passageway 48 formed therein. A spring seat 50 is formed where this 
extension 46 meets the wider main portion of the body 22. The rear end of 
the aforementioned spring 24 engages the main body 22 at this point. 
Extending into the attachment body 22 is the aforementioned shaft 30 which 
has a reduced front end portion at 52. A collar thrust washer 54 is 
mounted in the cup member 44 and the shaft 30 is rotatably mounted in the 
washer 54. On the inside of the chamber 42 and next to the washer 54 is a 
spring thrust washer 56 against which rests the rear end of a coil spring 
58, the purpose of which is described hereinafter. Mounted for rotation 
with the shaft 30 is a spiral cam member 60. The spring 58 engages a small 
shoulder formed on the shaft 30, thereby biasing the shaft and the spiral 
cam member towards the position shown in FIG. 2. 
The brush attachment 10 is provided with means in the chamber 42 for 
converting the rotary motion of the shaft 30 into a reciprocating motion 
and, in particular, a reciprocating linear motion. The converting means 
includes the aforementioned cam member 60 and a cam follower 64, 
preferably in the form of a roller. This cam follower is mounted in a yoke 
portion 66 which is part of a shaft mechanism 68. The yoke portion 66 is 
located in the chamber 42 and slidable in a groove 70 formed in a wall of 
this chamber. The engagement between this yoke portion 66 and the groove 
70 prevents rotation of the shaft mechanism relative to the body 22. As 
shown in FIG. 2 to 4, the shaft mechanism 68 extends through the 
passageway 48 and projects forwardly out of the body 22. The locking hub 
27 is attached to the front end of this shaft mechanism. 
The preferred brush attachment 10 includes a manually operated engaging 
member for selectively causing the converting means, i.e. the cam 60 and 
the cam follower 64, to either operate or not operate upon rotation of the 
shaft 30. It will be understood that if the converting means is not 
operating, the brush of the attachment is simply rotated, Which motion may 
be desired for some cleaning operations. The preferred illustrated 
engaging member is a dog 72 pivotally and slidably mounted on the bracket 
28. A suitable recess 74 is formed in the rear end of the attachment body 
22 and, in particular, in the cup member 44 as shown in FIG. 2. The dog 72 
can be pushed into the recess 74 which prevents the body 22 from rotating 
with the shaft 30. This in turn prevents the shaft mechanism 68 from 
rotating which causes the cam follower 64 to move along the spiral cam 
member 60 until it reaches the top or rear end of the spiral cam member as 
shown in FIG. 2. This action causes the coil spring 24 to be compressed so 
that when the cam follower 64 is suddenly released at the end of the 
spiral path, the shaft mechanism 68 is driven forwardly quickly and with 
considerable force by the spring 24. 
The extended position of the shaft mechanism 68 is illustrated in FIG. 3 
where the spring 24 is fully extended and the cam follower 64 is at its 
forward most position about to engage again the spiral cam member 60. It 
is important to note that in this forwardmost position the front end of 
the shaft 30 is still seated firmly in pilot hole 76 formed in the shaft 
mechanism. Thus, the shaft 30 is properly supported at all times and there 
is not undue wear and tear on the thrust Washer 54. Another preferred 
feature is the provision of a rubber washer 78 at the forward end of the 
chamber 42. This washer helps to cushion the shock of the shaft mechanism 
68 striking the forward end of the chamber and helps to reduce the noise 
of operation. 
The construction of the bracket 28, the lever member 26 and the dog will 
now be further described with reference to FIG. 5. Two locking collars 80 
are clamped on the shaft 30 on opposite sides of the bracket 28 so as to 
prevent axial movement of the bracket. The bracket 28 forms two parallel 
support arms 82 which are connected together by means of a pivot pin 84. 
As shown in FIGS. 4 and 5, the lever member 26 is pivotally mounted on the 
pivot pin 84 and the dog 72 is slidably mounted thereon. The dog 72 can be 
operated by pushing on a rearwardly extending portion 86 which is held in 
the position shown in FIG. 2 by means of a screw 88. A rubber washer 
clamped by the head of the screw 88 helps to hold the dog 72 in the 
desired position. 
The brush 20 includes means for connecting the body 90 of the brush to the 
power tool and, in particular, to the remainder of the brush attachment 
10. The preferred illustrated connecting means comprises a metal shaft 92 
which extends perpendicularly from a rear surface 93 of the brush body. 
The shaft 92 is connected to the brush attachment by insertion into a 
central passageway 94 located in the front end of the shaft mechanism 68. 
There are means for securing the shaft 92 in the passageway 94. In 
particular, near the front end of the shaft mechanism 68 there is an 
opening for receiving and accommodating a locking ball 96. This ball is 
held in place by the aforementioned locking hub 27 which itself is secured 
to the forward end portion of the shaft mechanism 68 by transversely 
extending pin 98. The pin 98 can be inserted through holes 100 formed in 
opposite sides of the hub 27. The locking ball 96 fits into a recess 102 
formed near the end of shaft 92. It will be appreciated that the shaft 92 
can be removed from passageway 94 by pushing the hub 27 against the action 
of the coil spring towards the body 22. This inward motion of the hub 
permits the ball 96 to move radially outwardly into the wider end region 
104 of the central passageway that extends through the hub 27. 
Turning now to the construction of the brush itself, the brush 20 comprises 
a large number of tough, flexible bristles 108 which have their inner ends 
firmly mounted in the brush body 90 by any suitable, known means. The 
bristles cover at least a substantial portion of the front surface 110 of 
the brush body. Because the bristles are intended to strike hard against a 
surface to be cleaned by means of a linear movement perpendicular to the 
surface to be cleaned, the bristles should be capable of restoring 
themselves substantially to their original shape after repeated bending 
and flexing. The bristles should also be arranged in the manner shown in 
FIG. 9, that is, they should vary in length from long centrally located 
bristles 112 to shorter bristles 114 located at two opposite sides of the 
brush. The reason for having bristles that vary in length in this manner 
is to prevent the brush in use from simply bouncing in an ineffective 
manner off the surface being clean or abraded. With the described 
arrangement, the bristles will not all strike the surface at the same time 
but will in fact strike the surface at various times during the course of 
the outward movement of the brush. This system assists greatly in the 
operation of the present brush attachment and makes it a very effective 
cleaning device that operates in a manner that might be considered similar 
to sandblasting. Thus, the end of each bristle in the brush as it strikes 
the surface to be cleaned, acts like a small particle of sand thrown 
against the surface by rapidly moving air. 
As shown in FIG. 8 and 9, the preferred brush body is generally rectangular 
with a central longitudinal axis extending parallel to each of the long 
sides 116. The long bristles 112 extend along this longitudinal axis. The 
preferred material for the bristles is nylon, most preferably nylon 612, 
but polypropylene is another usable material. Nylon 612 is an excellent 
material for the bristles as it has the qualities of superior flexibility, 
excellent abrasiveness, good impact qualities, and resistance to 
chemicals. It also absorbs very little, if any, water. Polyethylene UHMW 
is another excellent bristle material in that it does not absorb water and 
it has superior impact qualities. The preferred form of bristle is a 
bristle having a short wavy appearance and it is believed that such 
bristles have a better cleaning ability. In one preferred embodiment of 
brush constructed in accordance with the invention, the fiber size used 
was 0.016 inch and the average fiber length for the complete brush was 
approximately 7/8ths inch. The surface area covered by the bristles was 
approximately 1 square inch. In determining the preferred fiber size and 
fiber length for the bristles and the strength of bristles to be used, one 
must take into consideration the strength of the spring 24. The larger and 
stronger the spring 24 is, the stronger the bristles should be made so 
that they can withstand the driving force acting on them. 
In one preferred embodiment of the present brush attachment, the coil 
spring 24 was made of carbon steel and had a wire diameter of 0.092. The 
outside diameter of the spring was 1.055 inch while the inside diameter 
was 0.875 inch. This spring had a free length of 1 7/8th inch and could 
deflect or contract approximately 50% of its free length. This steel 
spring was suitable for use with the specific type and size of bristles 
detailed above. 
FIG. 4 of the drawings illustrates what occurs when the shaft 30 is rotated 
in the reverse direction indicated by the arrow X in the figure. FIG. 3 
illustrates the fully extended position of the brush attachment wherein 
both the spring 24 and the shaft mechanism 68 are fully extended. If the 
shaft 30 is rotated clockwise, the cam follower 64 will immediately 
commence to engage the spiral cam 60 causing compression of the spring 24. 
However, if the shaft 30 is rotated counterclockwise, the cam follower 
will first become disengaged entirely from the spiral cam 60 and then, 
upon a complete rotation of the spiral cam, will engage the bottom surface 
of the spiral cam at 120. If the body 22 is gripped so that it cannot 
rotate, further counterclockwise rotation of the shaft 30 will cause the 
cam follower to move the spiral cam rearwardly in the chamber and to 
compress the small coil spring 58. This also results in the attachment 
body 22, the shaft mechanism 68 and the brush being moved a short distance 
forwardly relative to the shaft 30. This continues until the cam follower 
again disengages from the spiral cam member at the position illustrated in 
FIG. 4 when the body 22 and the brush are again driven rearwardly under 
the action of the spring 58. It will thus be appreciated that in the 
reverse direction and provided that the body 22 is held against rotation, 
the preferred brush attachment of the invention is able to cause the brush 
20 to reciprocate lightly a short distance (relative to the much longer 
stroke provided by rotating the shaft 30 in the opposite direction). In 
this way, the preferred brush attachment of the invention is able to 
provide two different types of reciprocating strokes for cleaning 
purposes. The stroke that would be chosen depends upon the particular 
requirements of the cleaning job, i.e. whether a strong cleaning and 
abrading action is required or only a light cleaning action. If the body 
22 is not prevented from rotating, the brush will simply rotate when the 
shaft 30 is rotated in the reverse direction. 
If desired, a rubber sleeve can be placed over the coil spring 24 so that 
the spring will not be exposed. The provision of such a sleeve will help 
to prevent fingers or other body parts from being pinched by the spring 
action. 
It will also be understood by those skilled in this art that the brush 
attachment 10 described and illustrated herein can, if desired, be 
incorporated as an integral part of a power tool. In other words, a power 
tool could be constructed in which the input shaft 30 is permanently 
connected to a drive motor. Furthermore, if a cleaning tool having a brush 
with no rotary action is desired, the body 22 can simply be an integral 
extension of the housing in which the drive motor is mounted and arranged. 
Although such a dedicated power tool might have less versatility, in that 
it could not be used for other purposes such as normal drilling, such a 
tool might be less expensive to manufacture than the total cost of a 
separate power tool such as a power drill and a separate brush attachment 
constructed as described herein. 
It will be apparent to those skilled in this art that various modifications 
and changes are possible and can be made to the brush, brush attachment 
and power tool described herein without departing from the spirit and 
scope of this invention. Accordingly, all such modifications and changes 
are intended to be par of this invention.