Abstract:
A drill chuck having an adjustable depth stop to control an amount by which a tool bit, such as a drill or a screwdriver bit, is inserted into the drill chuck. The adjustable depth stop can include a spring, such as a conical spring, that can be coupled to a spindle of the chuck.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Patent Application No. 60/654,848 filed Feb. 18, 2005, the disclosure of which is hereby incorporated by reference. 

   FIELD OF THE INVENTION 
   The present invention generally relates to drill chucks and more particularly to a drill chuck having an adjustable depth stop to control an amount by which a tool bit, such as a drill or a screwdriver bit, is inserted into the drill chuck. 
   BACKGROUND OF THE INVENTION 
   Tool bits, especially twist drills, are frequently manufactured at different lengths, where the relatively shorter lengths are typically associated with bits of relatively smaller diameters or sizes. With twist drills, for example, small diameter drills tend to be somewhat flexible during use so that relatively long ones will have a tendency to wander or break when employed by the typical operator in a hand drill. When chucking a relatively short twist drill, it is often times necessary to hand position its shank to the jaws of the chuck to guard against contact between the tips of the drill flutes as well as to ensure that a sufficient amount of the drill body extends from the jaws of the chuck. Accordingly, there remains a need in the art for an improved drill chuck having an adjustable depth stop to control an amount by which a tool bit is inserted into the drill chuck. 
   SUMMARY OF THE INVENTION 
   In one form, the present teachings provide a chuck having a spindle supporting a plurality of jaws that are adapted to engage a shank of a drill. The chuck can also include a resilient member that is coupled to the spindle and located rearwardly of a front end of the jaws. The resilient member is operable for biasing a drill bit inserted into the chuck in a direction outwardly away from the spindle 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a side view in partial section of a drill/driver having a drill chuck constructed in accordance with the teachings of the present invention; 
       FIG. 2  is a perspective view of a portion of the drill chuck of  FIG. 1  illustrating the chuck attachment screw and the height adjusting spring in greater detail; 
       FIG. 3  is a top plan view of a portion of the drill chuck of  FIG. 1  illustrating the head of the chuck attachment screw; 
       FIG. 4  is a top plan view of a portion of the drill chuck of  FIG. 1  illustrating the height adjustment spring; 
       FIG. 5  is an exploded perspective view of a portion of another drill chuck constructed in accordance with the teachings of the present disclosure which specifically illustrates an alternative construction of the chuck attachment screw, the height adjusting spring and a means for coupling the chuck attachment screw and the height adjustment spring; and 
       FIG. 6  is a partial longitudinal section view of the portion of the drill chuck of  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIG. 1  of the drawings, a drill/driver  8  that is illustrated to be drivingly associated with a drill chuck  10  constructed in accordance with the teachings of the present invention. The drill/driver  8  can be constructed in a conventional manner and can include an output shaft  12  with a threaded aperture  14 . 
   The drill chuck  10  can be any type of drill chuck (e.g., keyed, keyless, impacting) and except as otherwise described herein, the drill chuck  10  can be conventional in its construction and operation. Accordingly, further details concerning key-type, keyless-type and impacting drill chucks may be found with reference to U.S. Pat. Nos. 3,810,642; 5,330,204 and 6,247,706, all of which are hereby incorporated by reference as if fully set forth herein. 
   The drill chuck  10  can generally include a spindle  20 , a plurality of jaws  22 , a nut  24 , a chuck attachment screw  26  and a height adjustment spring  28 . The spindle  20  may be fixedly but removably coupled to the output shaft  12  through threaded engagement of the chuck attachment screw  26  to the threaded aperture  14  in a conventional and well known manner. The jaws  22  can extend through the spindle  20  and can be threadably engaged to the nut  24  in a conventional and well known manner. 
   The height adjustment spring  28  can be any type of suitable spring or spring-like (i.e., resilient) member. With additional reference to  FIGS. 2 through 4 , the height adjustment spring  28  is a conical compression spring having a radially-inwardly extending tab  30  and is configured to engage the head  32  of the chuck attachment screw  26  in the particular provided. More particularly, the head  32  includes a groove  36  into which the tab  30  is received, while one or more coils  28   a  of the spring  28  are wrapped about the head  32  to maintain the spring  28  in a fixedly but removably coupled condition with the head  32 . 
   The height adjustment spring  28  will tend to deflect in response to the weight of a drill  40  that is inserted into the drill chuck  10 . The resilient nature of the height adjustment spring  28  tends to space the end  40   a  of the drill  40  away from the head  32  of the chuck attachment screw  26  so that the front end of the shank  42  of a relatively small diameter drill  40  can be roughly aligned to the front end of the jaws  22  while the end  40   a  of a relatively larger and heavier drill, which will typically have a longer length shank, will lie closer in proximity to the head  32  of the chuck attachment screw  26 . The relatively weak height adjustment spring  28  can be easily overcome by the operator if a different spacing between the end  40   a  of the drill  40  and the head  32  of the chuck attachment screw  26  is desired. 
   While the height adjustment spring  28  has been described herein as being attached to a chuck attachment screw, those of ordinary skill in the art will appreciate from this disclosure that the invention, in its broader aspects, may be constructed somewhat differently. For example, the screw or feature to which the height adjustment spring  28  is coupled may be connected or formed directly on the output spindle of the drill/driver, such as in a situation where the spindle is hollow and internally threaded to engage male threads that are formed on the output spindle. Furthermore, it will be appreciated that an intermediate structure may be employed to couple the height adjustment spring  28  to the spindle as is shown in  FIGS. 5 and 6 . In this regard, the tab  30  may be inserted to or encased in a plastic material that forms the intermediate structure  100 , while the intermediate structure  100  may be sized to be at least partially received into an aperture that can be formed in the spindle, the output spindle or the head  32  of the chuck attachment screw  26  (e.g., the hex shaped socket  102  in the head  32  of a socket head cap screw) as appropriate. In the particular example provided, the tab  30  is inserted into a hole  104  in the intermediate structure  100 , at least one coil of the conical coil spring  28  is wrapped about (engaged to) the intermediate structure  100 , and the intermediate structure  100  is press-fit into the socket  102  in the head  32  of the chuck attachment screw  26 . 
   While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the foregoing description and the appended claims.