Abstract:
Embodiments of an accessory attachment for a rotary power hand tool are disclosed wherein the hand tool is of the type which has a tool housing with a preferably cylindrical nose portion, a motor having a motor drive shaft with a mounting coupling extending forwardly from the nose portion for receiving a drive shaft, the attachment comprising a housing having a first end portion configured to be mounted to the tool housing nose portion and an input shaft for coupling to the motor drive shaft, and having an enlarged second end portion oriented at a right angle relative to the first end portion and also having an output shaft coupled to the input shaft at a right angle relative thereto, a rotary cutting wheel mounted to the output shaft and substantially disposed within said enlarged second end portion, excepting an exposed portion of the rotary cutting wheel for engaging a work surface, an adjustable guide foot pivotally connected to the enlarged second end portion and having a front surface configured to abut the work surface, the guide foot being configured to permit the wheel to extend beyond the front surface, where a position of the guide foot limits a depth of cut of the wheel into the work surface.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is related to CUTTING ATTACHMENT WITH A REMOVABLE COVER FOR ROTARY HAND TOOLS, by David Clarke and Garth W. Prince, filed on even date herewith and given Ser. No. 11/494,117, which is specifically incorporated by reference herein. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to small rotary hand tools, and more specifically to cutting attachments for such rotary hand tools. 
   Undercut saws, or flush cut “jamb” saws, are used to trim door jambs, baseboards and the like, to provide sufficient room to install materials, such as wood flooring, carpeting and tile, underneath the jambs and baseboards. There are many undercut saws on the market, but all known saws are dedicated tools, in that they have few uses other than making the flush cuts for which they were designed. While this exclusive use is welcomed by artisans who use undercut saws on a regular basis and who want a tool that is rugged and dependable, there are many woodworkers and occasional users that would welcome having a tool with multiple uses, including performing flush cuts. 
   Small rotary hand tools of the type that are marketed under the Dremel® and Roto-Zip® brands, for example, typically include a generally cylindrical housing that encloses only a motor with a rotary output shaft extending from the nose end and a nose portion that is configured to connect to various accessories or attachments. This simplicity affords tremendous versatility, because it is capable of performing a multitude of additional tasks depending on the particular accessory attachment that is attached to the tool. 
   Additionally, there has been continued innovation and improvement in the design of accessories for such hand tools, particularly with regard to the attachment of accessories that promote a particular, specialized function of the rotary hand tool. 
   SUMMARY OF THE INVENTION 
   Embodiments of an accessory attachment for a rotary power hand tool are disclosed wherein the hand tool is of the type which has a tool housing with a substantially cylindrical nose portion, a motor having a motor drive shaft with a mounting coupling extending forwardly from the nose portion for receiving a drive shaft, the attachment including a housing having a first end portion configured to be mounted to the tool housing nose portion and an input shaft for coupling to the motor drive shaft, and having an enlarged second end portion oriented at a right angle relative to the first end portion and also having an output shaft coupled to the input shaft at a right angle relative thereto, a rotary cutting wheel mounted to the output shaft and substantially disposed within the enlarged second end portion, excepting an exposed portion of the rotary cutting wheel for engaging a work surface, an adjustable guide foot pivotally connected to the enlarged second end portion and having a front surface configured to abut the work surface, the guide foot being configured to permit the wheel to extend beyond the front surface, where a position of the guide foot limits a depth of cut of the wheel into the work surface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side elevational view of a preferred accessory cutting attachment with an exemplary rotary hand tool; 
       FIG. 2  is a bottom perspective view of the accessory cutting attachment of  FIG. 1 ; 
       FIG. 3  is a bottom perspective view of the accessory cutting attachment of  FIG. 1  without the optional cover; 
       FIG. 4  is a top perspective view of the accessory cutting attachment illustrated in  FIG. 1 ; 
       FIG. 5  is a front perspective view of the accessory cutting attachment illustrated in  FIG. 1  shown with a straight edge guide; 
       FIG. 6  is an exploded front perspective view of the accessory cutting attachment illustrated in  FIG. 1 ; and 
       FIG. 7  is a cross section of a portion of the attachment illustrated in  FIG. 1 , showing the input and output shafts. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Embodiments of the invention include an accessory cutting attachment for a rotary hand tool that promotes a variety of cutting applications. While it is contemplated that the accessory cutting attachment may include mounting features configured to engage a variety of rotary hand tools,  FIG. 1  illustrates an exemplary rotary hand tool, designated generally at  10 , to which the preferred embodiment of the attachment may be coupled. For example, the rotary hand tool  10  may be of the type as those marketed under the Dremel® and Roto-Zip® brands made by the Robert Bosch Tool Corporation of Mount Prospect, Ill. 
   Generally, as illustrated in  FIG. 1 , the rotary hand tool  10  is a powered rotary hand tool of the type that includes a generally cylindrical housing  12  preferably made of a rugged, impact resistant plastic material and having a substantially cylindrical nose portion  14 . Enclosed within the housing  12  is a motor (not shown) that drives a motor output shaft  16  that extends through and from the nose portion  14 . A detachable handle  18  is also optionally provided with the hand tool  10 . 
     FIGS. 1-7  illustrate an accessory cutting attachment, designated generally at  20 , according to a preferred embodiment of the invention. The preferred cutting attachment  20  includes features promoting coupling of the cutting attachment with the rotary hand tool  10 . Advantageously, the preferred cutting attachment  20  also includes a variety of features enabling a user to perform a multitude of cutting applications. For example, when coupled to the rotary hand tool  10 , the preferred cutting attachment  20  may be used for various undercutting applications, including door jamb cutting, as well as trim and base board cutting for a predetermined adjustable depth, for example as much as approximately ¾ inch. Additionally, the preferred cutting attachment  20  includes features that promote use of the cutting attachment as a circular saw when used in a vertical or other angled orientation. 
   More particularly, the preferred accessory cutting attachment  20  includes an attachment housing, designated generally at  22 , having a coupling end  24  configured to couple with the rotary hand tool  10 , and an enlarged cutting end, indicated generally at  26 , disposed at a generally right angle to the coupling end  24 . 
   The attachment housing  22  is preferably composed of a rugged, impact resistant plastic material and having an output shaft  28  and an input shaft  36  that are interconnected by gears as shown in  FIG. 7 . The output shaft  28  is configured to drive a rotating tool, such as a rotary saw wheel or blade, indicated generally at  30 . For example, the attachment housing  22  may include nylon, ABS, or polypropylene, preferably 33% glass-filled nylon. Preferably, the cutting attachment  20  includes two halves that matingly engage one another in a clamshell engagement to form the single attachment housing  22 , though it is contemplated that the attachment housing may be made of a greater or lesser number of parts. 
   The coupling end  24  of the attachment housing  22  is generally cylindrical in shape, and includes a generally circular opening that is sized and configured to snugly and matingly receive cylindrical nose portion  14  of the rotary hand tool  10 . To maintain engagement of the attaching housing  22  to the rotary hand tool, the coupling end  24  also preferably includes a locking mechanism, such as an annular band clamp  32  disposed around an outer circumference thereof. The annular band clamp  32  also preferably includes a cam lock  34  such that the band clamp  32  may be tightened around the outer circumference of the coupling end  24  and then locked into the tightened position. 
   Coupling of the drive shaft  16  of the rotary hand tool  20  to the input shaft  36  of the cutting attachment  20  may be accomplished in a variety of ways. For example, a drive nut may be coupled to the motor drive shaft  16  which has a hexagonal or square opening that engages a suitable coupling on the input shaft  36  in a manner that assured non slipping rotation, but sliding decoupling when the attachment is removed from the tool  10  as is known to those of ordinary skill in the art. Alternatively, the input shaft  36  of the cutting attachment  20  may have a square or other noncircular configuration. In this manner, the rotary hand tool  10  and cutting attachment  20  are mechanically coupled, with the motor output shaft  32  of the rotary hand tool, and input shaft  36  of the cutting attachment properly aligned. 
   The enlarged cutting end  26  of the attachment housing  22  is preferably configured to provide a variety of tasks, such as undercutting, flush-cutting, as well as operating as a circular saw when the cutting attachment  20  is used in a vertical or other angled orientation. 
   To this end, the enlarged cutting end  26  of the attachment housing  22  includes a blade guard, indicated generally at  40 , configured to operationally enclose a substantial portion of the rotary cutting wheel  30 . While it is contemplated that the blade guard  40  may be unitary with the enlarged cutting end  26  of the attachment housing  22 , for purposes of illustration, the blade guard is shown and described as being releasably secured to a nose portion  42  of the enlarged cutting end, such as via a band clamp  44  and cam lock  46 . It is further contemplated that alternative locking mechanisms, such as a snap-fit or frictional engagement, may be provided in place of the band clamp  44  and cam lock  46  without departing from the scope of the invention. 
   The blade guard  40  is preferably bowl-shaped, with a concave portion  48  for containing the rotary cutting wheel  30  therein. A generally ring-shaped collar  50  extends upwardly from a surface of the blade guard  40  opposite the receiving portion to engage the nose portion  44  of the enlarged cutting end  26 , and it is around this collar  50  that the band clamp  44  and cam lock  46  are preferably secured to releasably secure the blade guard to the enlarged cutting end. 
   The rotary cutting wheel  30  is dome-shaped, having a preferably smooth, but segmented annular flange  52  disposed around an outer circumference thereof and having a cutting edge  54 . The rotary cutting wheel  30  is designed to cut through wood and small nails, and is preferably a segmented abrasive wheel having tungsten carbide bonded to its perimeter surface, but not on either face. 
   The rotary cutting wheel has an offset center hub portion  56 , which allows a mounting flange  58  having a preferably integral hexagonal nut portion  60  to be recessed in the rotary cutting wheel. The configuration of the rotary cutting wheel  30  enables the attachment  20  to make flush cuts in a work surface. 
   It is contemplated that the cutting attachment  20  may be operated at any angle between those designations known to those skilled in the art as “vertical” and “horizontal,” where “horizontal” refers to operation of the cutting attachment during undercutting and flush cutting applications where the cutting plane of the wheel is horizontal and the wheel is flush cutting a vertical surface such as a baseboard of a wall, for example. Vertical then means the cutting plane of the wheel is generally perpendicular to a horizontal surface. 
   The preferred cutting attachment  20  also preferably includes additional features to promote depth of cut adjustment, such as a pivoting foot, designated generally at  62 . Advantageously, the preferred pivoting foot  62  promotes a smooth, easy and user-friendly mechanism to determine and maintain a desired depth of cut. The pivoting foot  62  is preferably configured to be pivotably coupled to the blade guard  40  to permit the user to determine and maintain the desired depth of cut. 
   As illustrated in  FIGS. 1-6 , the pivoting foot  62  is preferably an elongated member  64  having an elongated extension  66  extending from one end thereof, with the extension having a curved slot  67 . At an end of the elongated member  64  opposite the one end having the elongated extension  66 , a mounting bracket  68  is provided to fixedly couple the pivoting foot  62  to the blade guard  40 . The mounting bracket  68  is secured to the blade guard  40  via a fastener  70 , which may include a variety of fasteners, such as a shoulder rivet, a plain rivet with a shaft retainer, a threaded connection or any number of cylindrical-type fasteners, to name a few. The fastener  70  securing the mounting bracket  68  to the blade guard  40  serves as a pivoting point for the pivoting foot  62 , whereas the elongated extension  66  is configured to be selectively moveable with respect to the blade guard. By selectively pivoting the pivoting foot  62  about the pivot point defined by the mounting bracket  68 , a user may determine the desired cutting depth. 
   More particularly, at maximum depth of cut, the elongated member  64  is configured to be generally parallel to a generally squared end  72  of the blade guard  40 . The blade guard  40  preferably includes a curved channel  74  that is correspondingly configured to promote sliding reciprocation of the elongated extension  66  therein, where the elongated extension may be removably secured into a desired position via engagement of a wing nut  76  or other fastener at a particular position along a length of the curved slot  67 . It should be understood that the wing nut  76  can be a bolt with a wing configuration with the bolt being screwed into a nut structure secured in the blade guard  40 , or a threaded bolt may be secure in the blade guard  40  and extend through the slot  67  and a wing nut  76  can be screwed onto the bolt. In either configuration, the size of the wing nut should be sufficient so that when it is tightened, it will engage the extension  66  and hold it in place. At the maximum depth of cut position, the elongated extension  66  will have the wing nut  76  at the extreme lower end  78  of the curved slot  67 . 
   The wing nut  76  may be loosened or removed to permit reciprocation of the slot extension  66  relative to the wing nut and the curved channel  74  until the pivoting foot  62  is placed in the desired position to obtain the desired depth of cut. The wing nut  76  is then replaced and/or tightened to lockingly secure the position of the pivoting foot  62  relative the blade guard  40 . 
   The elongated member  64  is preferably configured to have an outwardly facing planar surface that is configured at a lower edge  80  to expose the rotary cutting wheel  30 . More particularly, the lower edge  80  includes an opening or aperture to permit extension of the rotary cutting wheel  30  therethrough when the pivoting foot  62  is coupled to the enlarged cutting end  26 . Accordingly, as depth of cut is adjusted, increasingly larger portions of top and bottom surfaces of the rotary wheel  30  are exposed via the lower edge  80  of the elongated member  64 , thereby promoting correspondingly increasingly larger depths of cut, as determined by the user. 
   In this manner, the pivoting foot  62  permits the user to determine and maintain a depth of cut from a range of depths, such as from 0″ to a maximum of approximately ¾″. Advantageously, the outwardly facing planar surface of the pivoting foot  62  may also serve as a stable and secure base during operation of the cutting attachment  20  as a vertical or otherwise angled circular saw. In other words, the cutting attachment  20  may be used as a circular saw. 
   The pivoting foot  62  may also be optionally configured to include a straight edge guide, indicated generally at  82 , which advantageously promotes the accurate cutting of long, straight cuts when the cutting attachment  20  is used in the vertical orientation where there is a guide surface against which the edge guide can follow. 
   More particularly, the pivoting foot  62  may include a slotted bracket  84  in which to releasably secure the straight edge guide  82 . The slotted bracket  84  is generally rectangular in shape, with a generally rectangular passage  86  therethrough. 
   It is contemplated that the slotted bracket  84  may be configured to receive a straight edge guide such as the straight edge guide  82  shown in  FIG. 5 . When provided, the straight edge guide  82  includes a generally rectangular, elongated member  88  that is configured to fit in the rectangular passage  86  of the slotted bracket  84  and be slidable with respect thereto. An orifice  90  disposed within the rectangular passage  86  is configured to receive a threaded fastener (not shown) that can be tightened when the straight edge guide  82  is properly positioned. Thus, the elongated member  88  may be slidably moved within the rectangular passage  86  until the desired position is achieved, at which point the fastener is tightened within the orifice  90  and holds the straight edge guide  82  in the desired position. 
   The straight edge guide  82  also preferably includes an alignment member, indicated generally at  92 , for alignment with an edge of the work piece to be cut. For example, when the cutting attachment  20  is used in the vertical position, a generally planar surface  94  of the alignment member  92 , which is oriented to be generally parallel with the annular flange  52 , abuts the work piece to guide the rotary cutting wheel  30  in a linear cutting path parallel to the planar surface of the alignment member. 
   The preferred cutting attachment  20  may also optionally include a removable cover, designated generally at  96 , to protect the user from injury when the cutting attachment  20  is operated in the vertical orientation. The cover, indicated generally at  96 , and the blade guard  40  are configured to engage one another such that the cover and blade guard at least partially sandwich the rotary cutting wheel  30  therebetween. The preferred cover  96  includes a pair of diametrically opposed hooks  98  extending upwardly from a surface of the cover oriented to face the rotary cutting wheel  30 , as well as a locking member  100  extending upwardly from the surface of the cover oriented to face the rotary cutting wheel toward an outer edge thereof, and at a position intermediate the pair of hooks  98 . 
   In the closed position, the hooks  98  engage correspondingly configured locking orifices (not shown) disposed in the blade guard  40 , and the locking member  100  releasably clamps an outer circumference of the blade guard. On an external surface  102  of the cover  96 , corresponding to the location of the locking member  100 , is a release button  104  which, when depressed, releases the clamping force of the locking member, thereby permitting the user to quickly and easily disengage the cover  96  from the blade guard  40 . 
   While various embodiments of the present invention have been shown and described, it should be understood that other modifications, substitutions and alternatives are apparent to one of ordinary skill in the art. Such modifications, substitutions and alternatives can be made without departing from the spirit and scope of the invention, which should be determined from the appended claims. 
   Various features of the invention are set forth in the following claims.