Abstract:
A woodworking lathe tool adapted to receive a replaceable, indexable carbide cutting insert. A screw or other fastening means may be employed to releasably fasten a cutting insert, including at least a carbide portion, to the distal end of a tool shank. The tool allows the user to quickly release and index the cutting insert and continue using it as before, extending the useful life of the carbide insert. When all cutting surfaces have been worn, the insert can be replaced, eliminating the inconvenience and cost associated with sharpening tools.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This invention claims priority to U.S. Provisional Patent Application Ser. No. 60/755,139, filed on Dec. 30, 2005, the contents of which are incorporated by reference. 
     
    
     FIELD  
       [0002]     The invention relates generally to a woodworking lathe tool, and more particularly, to a handheld woodworking lathe tool having replaceable, indexable tips.  
       BACKGROUND  
       [0003]     Hobbyists and woodworking professionals use tools, such as chisels and gouges, to shape wooden workpieces as they turn on a lathe. The tools typically have a handle, for comfortable handheld use, and a metal member that extends from the handle and terminates in a shaped tip.  
         [0004]     During normal use, the shaped tip of the metal member frequently becomes dull and must be repeatedly re-shaped or sharpened before continued use. In this manner, the shaped tip eventually wears down in length after repeated sharpenings, until the entire metal member itself must be replaced. The need to repeatedly sharpen tools poses an inconvenience to the user due to the interruption of work, as well as an expense due to the equipment and time needed to shape and sharpen these tools.  
         [0005]     Many processes for shaping wood or other materials involve the removal of material by cutting or similar operations. The tools generally used by home and production lathe shops are made of special steels such as tool steels (e.g., M2) or powdered metals (e.g., PM). Turning and boring tools are available in a wide range of shapes and styles. These tools are commonly known as radius skew, radius scraper, spear point, parting tool, bowl gouge, spindle gouge, roughing gouge, detail gouge, etc. All of these tools need to be continuously re-sharpened and re-honed as they wear through normal use.  
         [0006]     Most of the above-mentioned tools are used for outer diameter (OD) turning or inner diameter (ID) boring. An example of OD turning may occur when forming and/or shaping the outside of a wooden bowl. Typical examples of ID boring may include turning and shaping the inside of a wooden bowl or turning the inside diameter of a wooden pencil cup. Generally, the wood turning tool has a handle or shaft connected to the tool blank. The tool blank is ground or sharpened to meet a variety of specific needs of the wood turner operator.  
         [0007]     In recent years, small carbide inserts (e.g., typically having a screw-on fastening geometry) have been used in certain metal cutting operations. These machining operations utilize turning tool holders or boring bars to hold the carbide inserts. These holders and bars may lock and secure the insert using a Torx® screw. These holders and bars may be held onto the machine by use of a turret (e.g., in CNC operations), or by use of a tool post (e.g., in manual operations). The most common use of these metal cutting holders and bars is in the application of “Swiss type” screw machines or in “near net-shape” part machining.  
         [0008]     Toolholders or boring bars typically used in existing metal cutting operations may not be appropriate for manual wood cutting operations, since they cannot be safely held by hand, for example, in home or small lot production wood turning operations.  
       SUMMARY  
       [0009]     Certain embodiments of the invention include a hand-held woodturning lathe tool adapted to receive a replaceable, indexable carbide tip. The tool may include a longitudinal shank, and may incorporate a set screw or other fastening means to fasten a carbide cutting insert (or carbide-tipped cutting insert) to the distal end of the shank. The carbide insert is designed to last much longer than existing wood turning tools. The invention also extends to the indexable nature of the tip, which allows a user to quickly release and rotate the tip, presenting a new cutting surface for continued use, thereby extending the useful life of the cutting insert. When all cutting surfaces have been worn, the tip can be easily and cost-effectively replaced, eliminating the inconvenience and cost associated with sharpening tools. In certain embodiments of the invention, the cutting insert may employ a symmetrical design that allows reversing the cutting insert, effectively doubling the useful life of the cutting insert.  
         [0010]     Certain embodiments of the invention provide an indexable cutting insert mounted on the tool shank with a fastening screw. In some embodiments, a fastening screw having an internal star-shaped head (e.g., a screw having a hexalobular internal driving feature, such as a Torx® screw) may be used to secure the indexable cutting insert to the tool shank. (A Torx® screw is a screw or bolt that has a special star-shaped pattern in the head, similar to an Allen screw, and requires a specific type of screwdriver or socket to remove. The design may allow for more torque to be put on the head without stripping.) The cutting insert and tool shank assembly are fastened to a tool handle adapted to be held by a woodturning operator. The indexable cutting insert may have several shapes and forms. They are known as DCMT style, VBMT style, RCMT style, grooving style, and threading style, and may be chosen and utilized as job requirements are specified. The indexable inserts may be mounted to the tool shanks with appropriately-sized screws, the shanks then being secured to tool handles, which may be sized to the individual operator&#39;s needs.  
         [0011]     The indexable cutting insert, shank, and handle may be selected by the woodturning operator (e.g., based on size, shape, and other parameters). The operator&#39;s requirements may change based on the task or the particular machine being utilized.  
         [0012]     As the indexable inserts wear down (e.g., through normal use), the fastening screw may be removed, thereby allowing the insert to be repositioned (i.e., “indexed”) to allow the use of a new cutting edge (e.g., a new or unused corner of the insert). Repositioning or indexing typically involves rotating the cutting insert relative to the tool shank to present a new cutting surface for woodturning. In embodiments having two useable cutting surfaces, for example, indexing the cutting insert might involve rotating the insert approximately 180 degrees (e.g., about an axis aligned with the fastening screw). Other embodiments could employ 3, or 4, or more useable cutting surfaces, which might entail rotating the insert approximately 120 degrees, or 90 degrees, or some other amount, respectively, to present a new or different cutting surface. A new (or different) working edge is thus exposed and ready for use by the woodturning operator with no need for sharpening of the tool. Once all of the useful cutting edges (or corners) have been worn sufficiently, the insert may be replaced and the fastening screw and tool shank re-assembled. The need for sharpening or honing of tool blanks may be greatly reduced or eliminated by use of various embodiments of the invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements:  
         [0014]      FIG. 1  is a top perspective exploded view of a woodturning tool according to an embodiment of the invention;  
         [0015]     FIGS.  2  ( a )-( d ) are top plan views of cutting inserts according to certain embodiments of the invention;  
         [0016]      FIG. 3  ( a )-( b ) are several views of an exemplary cutting insert showing a number of cutting edges or cutting surfaces that may be defined in the cutting insert according to various embodiments of the invention;  
         [0017]      FIG. 4  is a perspective view of a cutting insert according to an embodiment of the invention;  
         [0018]     FIGS.  5  ( a ) and ( b ) illustrate alternate means of indexing an insert according to embodiments of the invention; and  
         [0019]      FIG. 6  is a perspective view of a tool shank for a woodturning tool in accordance with an alternate embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     The following detailed description should be read with reference to the drawings, in which like elements in different drawings are numbered identically. The drawings depict selected embodiments and are not intended to limit the scope of the invention. It will be understood that embodiments shown in the drawings and described below are merely for illustrative purposes, and are not intended to limit the scope of the invention as defined in the claims.  
         [0021]     The woodturning tools according to various embodiments of the invention include a replaceable, indexable, carbide cutting insert (or a cutting insert having one or more carbide cutting surfaces or tips), which improves the performance and longevity of a woodturning tool, while providing convenience to the operator.  
         [0022]      FIG. 1  is a top perspective view of a woodturning tool  10  according to various embodiments of the invention. As shown, tool  10  may have a generally longitudinal handle  20 , which may be made of wood, or of other suitable materials having desired characteristics (e.g., strength, weight, etc.). Handle  20  may be shaped, for example, to provide a comfortable gripping or handling surface for holding in a woodturning operator&#39;s hands. In some embodiments, handle  20  may be shaped differently for right or left-handed operators, but this is not an essential aspect of the invention. Handle  20  may, in some embodiments, have a channel or an opening (such as recess  22 ) formed within in which to support and/or secure tool shank  30 .  
         [0023]     In certain embodiments, handle  20  may include a proximal portion, a central portion, and a distal portion. Recess  22  is formed in the distal portion of handle  20 , and extends longitudinally toward the handle proximal end. Recess  22  may be adapted to conform to the proximal end of tool shank  30 , for example, to provide a stable coupling between handle  20  and tool shank  30 . In many embodiments, it may be desirable for recess  22  to include a cross-sectional shape that minimizes relative rotational movement between tool shank  30  and handle  20 . For example, a square or triangular cross-sectional shape that conforms to a similarly-shaped shank proximal end will tend to reduce or minimize relative rotational movement between the handle  20  and the shank  30 . Recess  22  may be substantially rectangular in cross-section, according to certain embodiments.  
         [0024]     Handle  20  may also include a contoured outer surface, which facilitates hand-held use and operation of woodturning tool  10 . For example, a contoured outer surface of handle  20  may be defined in part by the handle central portion being generally smaller in cross-sectional area than portions of the handle proximal and/or distal portions. More specifically, the handle central portion may have a minimum cross-sectional area that is smaller than a maximum cross-sectional area of the handle proximal portion. Similarly, the handle central portion may have a minimum cross-sectional area that is smaller than a maximum cross-sectional area of the handle distal portion.  
         [0025]     Tool shank  30 , shown in  FIG. 1 , is typically a longitudinal member having a proximal end and a distal end. Tool shank  30  may be adapted to be operatively coupled to handle  20 . For example, the proximal end of tool shank  30  may be sized and shaped to achieve a compression fit, or other suitable coupling mechanism, within recess  22  of handle  30  in certain embodiments of the invention. Tool shank  30 , when coupled to handle  20 , extends longitudinally from handle  20  to provide an exposed portion adapted to receive a cutting insert  50 , as shown in  FIG. 1 . Tool shank  30  may be formed of metal (e.g., steel), and may be shaped to include rounded and/or angled surfaces, depending on the intended application, for example. In some embodiments, the shank may be ¼, ⅜, or ½ round or square in cross-sectional shape, for example without limitation.  
         [0026]     Tool shank  30  may include a shaped portion  36  at or near the shank distal end, the shaped portion adapted for a certain type of cutting or shaping process. The shaped portion  36  may further include a landing surface  33  and one or more sidewalls  34  near the shank&#39;s distal end adapted to receive an insert  50 . In preferred embodiments, the shaped portion  36  may be shaped to substantially match the shape of insert  50  to provide a stable mounting arrangement. In some embodiments, the shaped portion  36  may comprise first and second sidewalls  34  that together form a shaped edge to the landing surface  33 , which may provide a stable mounting arrangement for mating the cutting insert  50  with tool shank  30 . The stability of this mounting arrangement may be enhanced, for example, in embodiments where the sidewalls  34  substantially conform to a portion of cutting insert  50 . In some embodiments, the shaped edge formed by first and second sidewalls  34  may be substantially “V”-shaped to conform to certain cutting inserts. Shank  30  may further include threaded aperture  32  disposed in the landing surface  33  of the shaped portion  36 , the threaded aperture being adapted to receive a fastening screw  40  placed through opening  52  in cutting insert  50 , for holding insert  50  to shank  30 . In certain embodiments, fastening screw  40  may be used in conjunction with washer  42  to provide additional support for securing cutting insert  50  to shank  30 . In some preferred embodiments, fastening screw  40  may have a hexalobular internal driving feature (i.e., an internal star-shaped head), such as found in Torx® brand screws.  
         [0027]     FIGS.  2  ( a )-( d ) show top plan views of insert  50  according to certain embodiments of the invention.  FIG. 2 ( a ), for example, shows an insert  50  having substantially symmetrical shaped cutting surfaces  51  and  53 . Thus, while cutting surface  51  is made available for use in woodturning, cutting surface  53  mates with (e.g., conforms to the shape of) shaped portion  36  of tool shank  30  (see  FIG. 1 ). In use, the insert  50  of  FIG. 2 ( a ) may be indexed (i.e., rotated to provide a different cutting edge or surface) when cutting surface  51  has worn down sufficiently, for example, by removing the fastening screw  40  of tool  10  ( FIG. 1 ) and rotating insert  50  approximately 180 degrees. Cutting surface  53 , having a substantially similar type of cutting surface as surface  51 , can be used to continue a given operation, without having to re-sharpen any part of the tool  10 . After indexing the insert  50 , cutting surface  53  is now available for woodturning, while cutting surface  51  now mates with the shaped portion  36  of tool shank  30 . ( FIG. 1 ).  
         [0028]     FIGS.  2  ( b ) and ( c ) show alternate embodiments of cutting insert  50  which may provide the ability to index the insert  50  in order to present a different type of cutting edge or surface for a different type of woodturning operation, for example.  FIG. 2  ( b ) shows an insert  50  with a single rounded edge  54 .  FIG. 2  ( c ) shows an insert  50  with two rounded edges  56 . In some embodiments, the two rounded edges  56  of  FIG. 2  ( c ) need not be the same, providing potentially even more flexibility to an operator. The rounded edges  54  and  56  may include a variety of shapes and sizes. In some embodiments, edges  54  and  56  may be substantially circular, being defined by a radial dimension, for example. In some embodiments, a radial dimension of edges  54  and  56  may include ½″, ⅜″, and ¼″ radii, and may further include edges with increments of 1/64″ or 1/32″ in radius therebetween.  
         [0029]      FIG. 2  ( d ) is a plan view of an alternate embodiment of cutting insert  50 . The embodiment of  FIG. 2  ( d ) is a cutting insert  50  having more than two cutting surfaces available. For example, the particular embodiment illustrated in  FIG. 2  ( d ) includes four cutting surfaces  51 ,  53 ,  55 , and  57 . Such an embodiment may be indexable by rotating the cutting insert  50  in increments of about 90 degrees, for example. Of course, minor variations of this embodiment are contemplated, such as using different numbers of cutting surfaces or having different types of cutting surfaces, and such variations would be deemed to fall within the scope of the invention as claimed herein.  
         [0030]     In some embodiments of the invention, the cutting inserts  50  may be described using terminology from metalworking or machining industries. Such descriptions may include, but are not limited to the following: RCMT 32, RCMT 43, DCMT 21.5, CCMT 21.5, and VBMT 21.5. These descriptions may provide a shorthand way to describe the overall shape of the cutting inserts, as well as the angles of the cutting surfaces on such inserts.  
         [0031]      FIG. 3  ( a ) shows a side perspective view of insert  50  showing a number of edges  60 ,  62 ,  64  that may define one or more cutting surfaces in insert  50 . In some embodiments, edge  60  (i.e., the front-most cutting surface) may have an angle defined therein, typically to provide clearance for cutting operations. The angle may range generally from about 5 to 15 degrees from vertical, and in more preferred embodiments of the invention, the angle of edge  60  may range from about 7 to 11 degrees from vertical. Similarly, edges  62  and  64  may have an angle defined therein according to certain embodiments, the angles also ranging from 7 to 11 degrees from vertical.  
         [0032]      FIG. 3  ( b ) is a top plan view of exemplary cutting insert  50 , showing edges  60 ,  62 , and  63 , which collectively form a first cutting surface  66 . Similarly,  FIG. 3  ( b ) shows edges  64 ,  65 , and  68 , which form a second cutting surface  67 . As noted above, a woodturning operator may index the cutting insert  50  by rotating it (e.g., approximately 180 degrees about opening  52 ) to present a different cutting surface to a wooden workpiece. This may be done either because a first cutting surface becomes worn (e.g., in embodiments where the first and second cutting surfaces are of a substantially similar type), or because a different type of cutting surface is needed for a particular woodturning operation (e.g., in embodiments where the first and second cutting surfaces are of a different type).  
         [0033]      FIG. 4  illustrates an alternate embodiment of the invention in which insert  50  may be formed of a metal body portion  58  (e.g., steel), and may include carbide portions  70  forming carbide cutting surfaces. The carbide cutting surfaces may be shaped and angled to provide the desired cutting characteristics.  
         [0034]     FIGS.  5  ( a ) and ( b ) illustrate alternate means of indexing an insert  50 . In  FIG. 5  ( a ), a preferred method of indexing insert  50  involves rotating insert  50  substantially 180 degrees (e.g., either clockwise or counter-clockwise, as indicated by “CW/CCW” in  FIG. 5  ( a )) to present a new cutting edge to a workpiece. For example, the cutting insert  50  is rotated in a plane that is substantially parallel to the landing surface  33  of tool shank  30  ( FIG. 1 ), according to a preferred embodiment.  FIG. 5  ( b ) shows an alternate method of indexing insert  50  which involves turning insert  50  over to present the opposite surface of insert  50 . This method may or may not be suitable, depending on the particular cutting application and/or on the presence and nature of edges  60 ,  62 , or  64  ( FIG. 3 ), if applicable.  
         [0035]      FIG. 6  is a perspective view of an alternate embodiment that may provide additional support for fastening a cutting insert to the tool shank  30 . In the embodiment shown in  FIG. 6 , the shaped portion  36  of tool shank  30  has recessed portions  38  formed between sidewalls  34  and landing surface  33 . Recessed portions  38  may facilitate mating of the cutting insert with the shaped portion  36  of tool shank  30 , and may thereby provide additional support or stability to a cutting insert releasably fastened therewithin.  
         [0036]     Various specific embodiments of the invention may include the following, all of which are deemed to fall within the scope of the appended claims:  
         [0037]     1. Woodturning tool  10  having cutting insert  50  adapted for general purpose roughing and semi-finishing to size and shape. This tool may be a right handed tool, for example, by providing a suitable shape to handle  20  of tool  10 .  
         [0038]     2. Similar to above, except adapted for left-handed use.  
         [0039]     3. Tool  10  having insert  50  adapted for blending radii and finishing cuts. This embodiment of tool  10  is adapted to produce a smooth finish to a wooden workpiece.  
         [0040]     4. Tool  10  having insert  50  adapted for forming shallow groove widths, notches, etc., as ground on the insert.  
         [0041]     5. Similar to 1 above, except the insert  50  may have a larger nose radius.  
         [0042]     In certain embodiments of the invention, a woodturning system or kit may provide an operator the ability to readily switch between the above configurations and/or provide additional cutting configurations.  
         [0043]     Thus, embodiments of a WOODTURNING TOOL are disclosed. One skilled in the art will appreciate that the present invention can be practiced with embodiments other than those disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation.