Abstract:
A tool handle permits selective adjustment of a permitted depth of insertion of a blade therein. The tool handle includes a central bore for reception of a blade through a front opening thereof, and an adjustable stop receivable in the bore, the position of which can be selectively fixed along a longitudinal central axis of the tool handle. So positioned, the stop blocks insertion of the blade beyond a fixed point along the bore selected by the user. As the blade is worn and reground, the stop is moved to a position closer to the front opening of the bore, shortening the degree of blade insertion permitted, and thus allowing a constant distance of blade extension to be maintained. Once adjusted, the blade is securable to the handle, to prevent undesirable movement during use of the assembled tool.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a tool handle, and, more particularly, to a tool handle for receiving a blade member in a manner permitting continuous maintenance of overall tool length irrespective of blade wear. 
     Engraving tools are well known in the art, and consist generally of a spike-shaped blade member which extends from a handle suitably configured for reception in the palm of the hand. Tools of this type are used for a variety of purposes in addition to engraving. For example, engraving tools are use by stone setters to mount diamonds and other stones in a setting. The process is carried out by fitting the stone in a receiving hole formed in the metal support to which the stone is to be mountably secured, and compressing the metal at points along a periphery of the receiving hole to form a series of beads protruding inwardly above, and in contact peripherally with, the stone, thus captively holding the stone in the setting. To maintain precise control while performing this operation, the tool is held in the hand with the handle supported at its base on the heel of the palm, and with the blade supported proximate a terminal end thereof by a suitable extended finger of the same hand in supportive contact therewith. 
     Repeated use of the engraving tool in performance of such tasks results in blade wear, requiring regrinding and a resultant shortening of the blade. This blade shortening adversely affects proper handling of the tool, since the distance that the blade extends forward of the handle is preferably of a constant length selected for ideal comfort and control, predetermined based upon the characteristics of the individual user&#39;s hand. 
     To address this need, a variety of handles are currently available, each permitting the base of a blade to be inserted to different preset depth. Selection of a suitable handle thereby allows incremental control over the overall length of the tool when a blade is inserted therein. In this manner, as a blade is worn, and its length is diminished, a handle permitting a shallower degree of blade insertion is selected to compensate for the decrease in blade length. Although somewhat effective, such solution requires purchase and storage of a plurality of handles, and does not permit continuous blade reception depth adjustment. 
     A tool handle permitting simple and reliable adjustment of an overall tool length when a blade is received therein, and which advantageously permits continuous adjustment of a permitted degree of blade insertion into the handle, would therefore be highly desirable. 
     Accordingly, it is an object of the invention to provide a tool handle which overcomes the drawbacks of the prior art. 
     It is a further object of the invention to provide a tool handle which permits a user thereof to selectively control a permitted depth of insertion of a blade received therein such that the degree of extension of the blade can be adjusted as needed, for example, to maintain constant tool length irrespective of blade wear. 
     SUMMARY OF THE INVENTION 
     In accordance with these and other objects of the invention, there is provided a tool handle for fixed support of a blade member which permits adjustment of a blade reception depth. Such feature allows the degree of blade extension to be user-determined based upon individual need, and permits such selected amount that the blade member extends from the tool handle to be maintained at a constant length irrespective of overall shortening of the blade member due to wear. 
     Briefly stated, the tool handle includes a central bore suited to reception of a blade through a front opening thereof, and an adjustable stop receivable in the bore, the position of which can be selectively fixed along a longitudinal central axis of the tool handle. So positioned, the stop blocks insertion of the blade beyond a fixed point along the bore selected by the user. As the blade is worn and reground, the stop is moved to a position closer to the front opening of the bore, shortening the degree of blade insertion permitted, and thus allowing a constant distance of blade extension to be maintained. Advantageously, although not necessarily, the stop is continuously, rather than incrementally, adjustable. Means for securing the blade to the handle are also provided. 
     In accordance with an embodiment of the invention, there is provided a tool handle in which a central bore extends the entire length thereof, the bore having an opening in both a front and a back face of the tool handle. The central bore is internally threaded for threadably receiving therein a threaded stop member. Means are provided, at a side of the stop facing rearward of the tool handle, for turning the stop to thereby permit adjustment of a longitudinal position thereof along the bore, conveniently in the form of a slot or other configuration adapted to use with an appropriately sized screw-driver insertable into the bore from the back of the tool handle. The side of the stop facing forward of the tool handle advantageously includes centering means for maintaining a fixed position of the inserted end of the blade, conveniently provided as a centrally-formed cylindrical countersunk bore. Securement means are carried on the handle at a location proximal to blade insertion for securing the blade thereto, conveniently provided in the form of a chuck which compressively engages the blade when tightened. 
     In an alternative embodiment in accordance with the invention, a tool handle permits user adjustment of blade insertion depth without the need for secondary adjustment tools. Like the above embodiment, a threaded stop is threadably received in a threaded bore in the handle, however the means provided on threaded stop for selectively moving same in a direction along a longitudinal tool axis are provided in the form of longitudinal slots which slidably receive arms of an advancement member rotatably mounted to the handle. Terminal ends of the arms are retained for rotation of the advancement member about a fixed axis. A locking nut is provided which threadably engages a threaded portion of the advancement member, and which, when tightened against the forward end of the handle, prevents rotation of the advancement member relative handle  31 . When the threaded stop is to be relocated along the longitudinal tool axis, use of a secondary adjustment tool is thereby obviated. To effect adjustment, the user simply loosens the locking nut, which then permits rotation of the advancement member, and which in turn rotates the threaded stop. When a desired longitudinal stop position is reached, the locking nut is tightened against the handle, prohibiting continued undesirable rotation during use of the engraving tool. 
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  is a cross-sectional side view of an engraving tool employing a tool handle in accordance with an embodiment of the invention, illustrating blade insertion prior to experiencing wear; 
     FIG. 1 b  is a cross-sectional side view of the engraving tool of FIG. 1, illustrating blade insertion after shortening of the blade due to wear adjusted to maintain constant overall tool length; 
     FIG. 2 is a cross-sectional side view of a tool handle in accordance with another embodiment of the invention, employing an alternative chuck which permits accommodation of a wide range of blades having various diameters; 
     FIG. 3 is a cross-sectional side view of an engraving tool employing a tool handle in accordance with yet another embodiment of the invention, in which adjustment of blade reception depth is adjustable by rotation of an integral advancement member relative the handle; and 
     FIG. 4 is a cross-sectional view taken on line IV—IV of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the figures, and in particular FIG. 1 a , an engraving tool employing a tool handle in accordance with an embodiment of the invention is depicted, the engraving tool generally designated  10 . Engraving tool  10  includes a handle  1  of suitable shape for comfortable reception in the hand of a user. A blade  2 , which as shown, typically includes a forward portion  2   a  suitably configured for performing a stone setting operation, and a shaft portion  2   b  for securement of same to handle  1 . Handle  1  includes a tool reception bore  3   a  disposed along a longitudinal tool axis A, having an opening in a forward end of handle  1  to permit reception of shaft portion  2   b  of blade  2  therein. In addition to reception bore  3   a , handle  1  is provided with a threaded bore  3   b  also aligned with longitudinal tool axis A and communicative with reception bore  3   a . Threaded bore  3   b  has an opening in a rearward end of handle  1  to permit threaded reception of a threaded stop  4 . Means are provided for selectively locating threaded stop  4  along longitudinal tool axis, conveniently in the form of a slot  4   a  formed in a side thereof facing rearward of handle  1 , to permit turning thereof in a desired clockwise or counterclockwise direction to effect travel along the longitudinal path by a screwdriver blade (not shown) inserted through the opening of threaded bore  3   b . When blade  2  is inserted into reception bore  3   a , as shown in FIG. 1 a , a terminal end thereof bottoms against threaded stop  4 . The position of threaded stop  4  along longitudinal tool axis A therefore determines the depth of permitted insertion of blade  2  in handle  1 . 
     Once inserted, blade  1  is secured in the handle conveniently by structure carried at a forward end of handle  1  defining a chuck portion  5 . The configuration of chuck portion  5  may be of any suitable conventional design employed for like purpose, such as any of the many keyless chuck designs commonly used for retaining a drill bit in a drill. In the depicted example, chuck portion  5  includes external threads  5   a  for threadably engaging a threaded compression member  6 . One or both of external threads  5   a  or the threads comprising threaded compression member  6  are tapered threads such that inward pressure is exerted on chuck portion as threaded compression member  6  is advanced along external threads  5   a . A series of slots (not shown) are cut longitudinally through chuck portion  5  to permit inward compressive deformation thereof in response to tightening of threaded compression member  6 . When threaded compression member  6  is sufficiently tightened, the inward walls of reception bore  3   a  in the region of chuck portion  5  firmly engage shaft portion  2   b  of blade  2 , holding it securely in place. 
     Since shaft portion  2   b  extends freely into threaded bore  3   b  of handle  1  and is unsupported therein, means are advantageously provided for securing the terminal end of shaft portion  2   b  contacting threaded stop  4  to prevent possible undesirable wobbling thereof when working pressure is applied to a terminal end of forward portion  2   a  of blade  2 . Such securement means are advantageously provided in the form of a central cutout  4   b  which, in the depicted embodiment, is advantageously of conical shape to provide self-centering of the terminal end of shaft portion  2   b  regardless of its precise thickness. 
     Operation of engraving tool  10  will now be described with reference to FIGS. 1 a  and  1   b . FIG. 1 a  depicts blade  2  having minimal wear installed in handle  1 . Stop  4  is adjusted to provide desirable extension of blade  2  from handle  1  suited to the user&#39;s preference. In the depicted example, once adjusted, an overall tool length is indicated by the distance D. A blade contact side of threaded stop  4  is a distance d from the rearward end of handle  1 . After continued use and subsequent regrinding, the length of forward portion  2   a  of blade  2  is shortened, as shown in FIG. 1 b . Longitudinal adjustment of threaded stop  4  permits the user to maintain a constant value for the overall tool length, i.e. distance D. To accomplish same, threaded compression member  6  is loosened about chuck portion  5 , restoring slidable freedom of movement to blade  2 , and threaded stop  4  is advanced along longitudinal tool axis A by clockwise rotation (assuming right-handed threads) thereof by a screwdriver blade inserted into threaded bore  3   b . As shown in FIG. 1 b , to maintain constant overall tool length as distance D, threaded stop  4  is moved to a longitudinal position in which a blade contact side of threaded stop  4  is a new distance d′ from the rearward end of handle  1 . Once the new setting is attained, threaded compression member  6  is tightened sufficiently about chuck portion  5  to effect blade-securing compression. 
     It is noted that chuck portion  5  in the above embodiment is integral with handle  1 , thus requiring that handle  1  be fabricated from a suitably resilient material, for example, metal or plastic, to permit proper operation of the blade securement means. Alternatively, a chuck mechanism analogous in design and function with that of the above described embodiment can be fixed to the handle, permitting its fabrication using a material differing from that of the handle, and without departure from the intended scope of the invention. For example, the handle could be fashioned from wood, and a metal chuck could be fixably received thereon, such as, for example, in press fit engagement. 
     Turning now to FIG. 2, an alternative embodiment of an engraving tool (blade not shown) employing a handle design in accordance with the invention is shown generally at  20 . Engraving tool  20  is of analogous construction with the preceding embodiment of FIGS. 1 a  and  1   b , and differs only with respect to the chuck mechanism comprising the blade securement means. As such, threaded stop  4  is threadably received in a threaded bore  3   b ′ formed in a handle  1 ′ for movement along a longitudinal axis A′ of engraving tool  20 . Handle  1 ′ also includes a reception bore  3   a ′ adapted to receive a removable chuck  25  in closely conformed fit about a shaft portion  25   a  thereof. Chuck  25  further includes a central bore  25   b  through which a blade is receivable, advantageously in a minimal clearance fit, and a slotted head portion  25   c  which shoulders against a forward end of handle  1  at the opening of reception bore  3   a ′. Slotted head portion  25  includes longitudinal slots (not shown) which permit inward movement of slotted head portion  25  when compressive force is applied thereto. A threaded compression member  26  is threadably engagable with a threaded front portion  27  carried on handle  1 ′. Threaded compression member  26  includes an angled shoulder  26   a  which compressively engages a corresponding angled front portion  25   d  of chuck  25  when threaded compression member  26  is tightened thereagainst. Continued tightening causes chuck  25  to be inwardly deformed, compressing same against a blade (not shown) inserted therein. By making chuck  25  a separate member receivable on handle  1 ′, a variety of chuck sizes, i.e. chucks having different diameter central bores, can be made available to fit a wide variety of blade diameters. Referring now to FIGS. 3 and 4, an engraving tool employing a handle design in accordance with an advantageous embodiment of the invention is depicted, the engraving tool generally designated  30 . Engraving tool  30  includes a handle  31  in which blade  2  is fixably receivable by means of a chuck arrangement functioning analogously with either of the above described embodiments (for purposes of illustration, the example in FIG. 3 is shown as employing the chuck design of the embodiment of FIG.  2 ). Handle  31  includes a threaded bore  31   a  requiring an opening only in a forward side of handle  31 . A threaded stop  34  is threadably received in threaded bore  31   a . Means are provided on threaded stop  34  for selectively moving same in a direction along a longitudinal tool axis A″, provided in the form of longitudinal slots  34   a  (advantageously two or more), seen best in FIG.  4 . An advancement member  33  is rotatably mounted to handle  31 , conveniently through a bearing  35  located at a forward end of handle  31 , and includes a reception bore  33   a  through which blade  2  is receivable. Advancement member  33  includes a series of arms  33   b  which, when same is received in mounted position, extend the length of threaded bore  31   a , and which correspond with and are configured to pass freely through longitudinal slots  34   a  in threaded stop  34 . Terminal ends of arms  33   b  are retained for rotation of advancement member  33  about a fixed axis conveniently by a straight end bore  31   b  formed in handle  31 , and which is of matching diameter to that of advancement member  33 . A locking nut  36  is provided which threadably engages a threaded portion  33   c  of advancement member  33 , and which, when tightened against the forward end of handle  31 , prevents rotation of advancement member  33  relative handle  31 . 
     By virtue of such design, when threaded stop is to be relocated along longitudinal tool axis A″, the requirement of a secondary adjustment tool is obviated. Rather, the user simply loosens locking nut  36  which then permits rotation of advancement member  33  by gripping same at a forward end thereof. Rotation of advancement member  33  in turn rotates threaded stop  34  since arms  33   b  are slidably received through longitudinal slots  34  formed in threaded stop  34 , and moves same in a direction along longitudinal tool axis A″ dependent upon a rotational direction. When a desired position is reached, locking nut  36  is tightened against handle  31  to prohibit undesirable rotation during use of engraving tool  30 . 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.