Abstract:
The present invention a multi-bit driver comprises a longitudinally oriented housing including a bit chuck at one end; a plurality of tool bits nested within said housing in a retracted position; and bit assemblies including tool bits and being operable to extend said tool bit from said retracted position to said extended position by a single longitudinal motion for selectively extending tool bits to an extended position and retracting said tool bits to said retracted position, such that in the extended position, said tool bits project from said bit chuck and are substantially longitudinally aligned with said housing.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to hand held implements having interchangeable objects which are captured within the implement and selected object extendable from the implement for use.  
         BACKGROUND OF THE INVENTION  
         [0002]    There are presently available on the market place, many forms of multi object and multi-bit devices. An example is in the multi-bit driver where several bits are contained within a hollow handle. When desired to use a particular bit, the handle rear portion is opened by unscrewing a cap for the handle and selecting the needed bit. The selected bit is then placed into a chuck at normally the other end of the handle for use. The disadvantage of this system is that often bits are lost for failure to return the used bit to the hollow handle and often the multi-bit drivers of this type are not used because of the awkwardness of installing and uninstalling bits which are required for particular application.  
           [0003]    There are multi-bit drivers available which provide in one form or another arrangements which minimize or prevent loss of the driver bits. Examples of the prior are devices which have been patented are as follows:  
           [0004]    U.S. Pat. Nos. 4,552,043, 4,552,044, 4,463,788, 4,716,795, 4,716,796, and 5,228,363, all of these patents filed under various titles by the same inventor, Corona et al and describing the hand held multi-bit implement. The Corona type multiple object implements require lowering into position a very long bit, sliding it laterally into position where it can be locked and then urging the bit into a locked position for use. There are a number of specific operations which must be carried out in order to bring the tool bits into operational position and then once again tool bit to its storage position. This type of multi-bit driver, however, does have the advantage that the tool bit cannot be easily lost, as they are non-removable from the handle at all times. The disadvantage of the Corona devices is that they are awkward to use and time consuming to bring the bits into and out of the operational position.  
           [0005]    Other devices which have been patented and have attempted to solve the problem of an easy to use multi-bit driver are found in these following patents:  
           [0006]    U.S. Pat. No. 5,881,615 by Todd Kevin Dahl issued Mar. 16, 1999 under the title Multiple Bit Drivers and Methods.  
           [0007]    U.S. Pat. No. 5,442,982 by Dennis J. Bell issued Aug. 22, 1995 under the title Nesting Pocket Drivers.  
           [0008]    U.S. Pat. No. 5,174,178 issued Dec. 29, 1992 by Horace C. Disston Jr., under the title Selective Tool Handle.  
           [0009]    U.S. Pat. No. 4,924,733 issued May 15, 1990 invented by Archibald M. McKenzie under the title Multiple Bit Driver.  
           [0010]    U.S. Pat. No. 5,265,504 issued Nov. 30, 1993 by Hermann Fruhm titled Cartridge Type Driver.  
           [0011]    All of the above devices attempt to solve the problem of minimizing the loss of the tool bits but yet maintaining an easy to use multi-bit driver which minimizes the time for bringing a tool bit into and out of operation and also decreases the time for selecting one tool bit from another. The above patents all have the disadvantage that the number of operations and the time necessary for bringing the tool bit into operation is quite lengthy and often specially designed tools bits are necessary in order to make these multi-bit drivers functional.  
           [0012]    There is a need for a multi-bit driver which is easily used which allows for a very quick selection of tool bits which prevents the loss of tool bits through misuse and provides for a rugged dependable design.  
         SUMMARY OF THE INVENTION  
         [0013]    The present invention multi-bit driver comprises:  
           [0014]    (a) a longitudinally oriented housing including a bit chuck at one end;  
           [0015]    (b) a plurality of tool bits nested within said housing in a retracted position; and  
           [0016]    (c) an actuating means for selectively extending tool bits to an extended position and retracting said tool bits to said retracted position, such that in the extended position, said tool bits project from said bit chuck and are substantially longitudinally aligned with said housing.  
           [0017]    Preferably wherein said actuating means including said tool bits and being operable to extend said tool bit from said retracted position to said extended position by a single longitudinal motion of said actuating means.  
           [0018]    Preferably wherein said longitudinal motion is effected using a single finger or thumb pressure.  
           [0019]    Preferably wherein said actuating means connected to said tool bits being operable to retract said tool bits from said extended position to said retracted position by a single longitudinal motion of said actuating means.  
           [0020]    Preferably wherein said longitudinal motion is effected using a single finger or thumb pressure.  
           [0021]    Preferably wherein said actuating means operates to extend said tool bit by longitudinal motion in one direction and retract said tool bit by longitudinal motion in the opposite direction.  
           [0022]    Preferably wherein said longitudinal motion is effected using a single finger or thumb pressure.  
           [0023]    Preferably wherein said actuator means further includes at least one bit assemblies having a flexible bit extension connected to each of said tool bits, said bit extensions for operatively urging said tool bits between said extended and retracted position and for aligning said tool bits with said bit chuck.  
           [0024]    Preferably wherein said actuating means further includes at least one longitudinally aligned actuator channels defined in said housing corresponding to each bit assembly for guiding said bit assemblies slidably along a longitudinal direction.  
           [0025]    Preferably further including a fastening means slidably connecting said bit assemblies to said actuator channels such that said bit assembly is guided slidably along said actuator channel.  
           [0026]    Preferably wherein said fastening means comprises an actuator knob partially projecting externally of said housing for the application of finger pressure thereto, said actuator knob also for connecting a fastener end of said bit assembly to said actuator knob for operatively urging said bit assembly slidably along said actuator channel.  
           [0027]    Preferably wherein said housing including a cone proximate said bit chuck having an interior guide surface for slidably guiding tool bits into alignment with said bit chuck as tool bits are urged into said extended position.  
           [0028]    Preferably further including a guide means for maintaining said bit assemblies separate and nested proximate the inner surface of said housing, and for guiding said bit assemblies as they are urged between the extended and retracted position.  
           [0029]    Preferably wherein said guide means includes permanent magnets mounted in the barrel of said housing for magnetically attracting said tool bits and for maintaining said bit assemblies separate and nested proximate the inner surface of said housing, and for guiding said bit assemblies as they are urged between the extended and retracted position.  
           [0030]    Preferably further including a locking means for locking said tool bit in said extended position.  
           [0031]    Preferably wherein said bit assemblies include a bit extension connected to said tool bit with a connector.  
           [0032]    Preferably wherein said bit extension being flexible in the radial direction and stiffer in the lateral direction. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]    The invention will now be described by way of example only with references to the following drawings in which:  
         [0034]    [0034]FIG. 1 is a partial exploded perspective schematic view of the driver  
         [0035]    [0035]FIG. 2 is an assembled perspective schematic view of the multi-bit driver.  
         [0036]    [0036]FIG. 3 is a perspective schematic view of the bit cartridge.  
         [0037]    [0037]FIG. 4 is a top plan view of the multi-bit driver.  
         [0038]    [0038]FIG. 5 is an end view of the multi-bit driver shown in FIG. 4.  
         [0039]    [0039]FIG. 6 is an end view of the multi-bit driver shown in FIG. 4.  
         [0040]    [0040]FIG. 7 is a bottom plan view of the multi-bit screw driver.  
         [0041]    [0041]FIG. 8 is a top plan view of the multi-bit driver.  
         [0042]    [0042]FIG. 9 is a cross-sectional view of the multi-bit driver shown in FIG. 8, taken along lines  9 - 9 .  
         [0043]    [0043]FIG. 10 is cross-sectional view of the multi-bit driver shown in FIG. 8, taken along lines  10 - 10 .  
         [0044]    [0044]FIG. 11 is a partial exploded perspective view of the multi-bit driver.  
         [0045]    [0045]FIG. 12 is a top plan view of the bit assembly.  
         [0046]    [0046]FIG. 13 is a side plan view of the bit assembly.  
         [0047]    [0047]FIG. 14 is a partial cut away view of the multi-bit driver showing the relationship of the bit assemblies of the barrel.  
         [0048]    [0048]FIG. 15 is a cross-sectional view of the multi-bit driver shown in FIG. 8 taken along lines  15 - 15 .  
         [0049]    [0049]FIG. 16 is a cross-sectional view of the multi-bit driver taken along lines  16 - 16  of FIG. 8.  
         [0050]    [0050]FIG. 17 is a partial exploded perspective schematic view of the presently preferred embodiment of the multi-bit driver.  
         [0051]    [0051]FIG. 18 is a perspective schematic view of the presently preferred embodiment of the bit cartridge.  
         [0052]    [0052]FIG. 19 is a top plan view of the bit assembly of the presently preferred embodiment.  
         [0053]    [0053]FIG. 20 is a side plan view of the bit assembly of the presently preferred embodiment.  
         [0054]    [0054]FIG. 21 is a partial cut away view of the presently preferred embodiment multi-bit driver showing the relationship of the bit assemblies and the barrel.  
         [0055]    [0055]FIG. 22 is a top plan view of the presently preferred embodiment of the multi-bit driver.  
         [0056]    [0056]FIG. 23 is a cross sectional view of the presently preferred multi-bit driver shown in FIG. 22 taken along lines  23 - 23 .  
         [0057]    [0057]FIG. 24 is a cross sectional view of the presently preferred multi-bit driver shown in FIG. 22, taken along lines  24 - 24 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0058]    Definition: Tool bits come in a variety of lengths and are normally made of hardened steel and have an hexagonal profile with a variety of driver heads such as Robertson, Phillips, Torx and Allen etc.  
         [0059]    The present invention, a multi-bit driver shown generally as  30  includes the following major components which are depicted in FIGS. 1, 2 and  3 . Multi-bit driver  30  includes housing  31 , cone  34 , collar  36 , bit cartridge  50  which includes bit guide  41 .  
         [0060]    Referring now to FIG. 1, which is partial exploded view of multi-bit driver  30 , housing  31  includes barrel  32 , actuator channel  70 , actuator knobs  72 , external threads  66 , proximate cone end  64  and threads  62 , proximate cap end  60 .  
         [0061]    Housing  31  further includes cone  34  having externally threaded bit chuck  80  at chuck end  39 , internally threaded collar  36 , threadably engaging with bit chuck  80 , internal threads  68 , proximate barrel end  37  as well as locking screws  35 .  
         [0062]    Bit cartridge  50  shown best in FIG. 3 is made up of two major assemblies, namely bit guide  41  which is shown on FIG. 1 and bit assembly  100 .  
         [0063]    As best viewed in FIGS. 3, 12 and  13 , bit assembly  100  includes bit extension  54 , with a fastener aperture  102 , proximate fastener end  53  and a tool bit  52  connected to bit extension  54  with connector  56 . Tool bit  54  is of the type commercially available in the market place and normally would have a locking groove  90  at one end and a driver head  104  at the other end. As depicted in FIGS. 1, 2 and  3 , bit cartridge  50  contains six bit assemblies  100  in this particular arrangement. Fewer or more bit assemblies could be utilized simply by scaling up or down the geometry shown in FIGS. 1, 2 and  3 . In practise, the size of multi-bit driver  30  will limit the upper limit of bit assemblies  100  that are practically feasible in using in multi-bit driver  30  since there are many different driver heads  104  currently on the market, a minimum of four bit assembly  100  seems to be the lower practical limit for the number of driver heads. Having said that, however, there is no reason why multi-bit driver  30  could not be made with only one or two bit assemblies  100  and upwards of  12 ,  16  or  20  bit assemblies  100  except for practicalities of size and function of multi-bit driver  30 .  
         [0064]    Bit guide  41  is best seen in FIG. 1, includes guide support  42  having connected at one end thereof guide  40  and at the other end, end cap  38  having a screw  44  connecting guide support  42  to cap end  38 , wherein cap end  38  has cap threads  46  which are threadably received by threads  62  of cap end  60  of barrel  38 . Bit assemblies  100  are connected to barrel  32  via actuator knob  72  having integrally connected therewith a knob fastener portion  74  for slidably fastening bit assembly  100  to barrel  32  through an actuator channel  70 .  
         [0065]    Guide  40  has in this case six guide faces  43  for receiving slidably thereon bit extension  54  each of which rest on a guide face  43  and can be slidably moved along guide face  43 , as actuator knob  72  is urged along actuator channel  70 .  
         [0066]    Assembly  
         [0067]    Firstly bit assembly  100  is assembled together by fastening bit extension  54  to tool bit  52  using a connector  56 . As shown in the attached diagram connector  56  is a shrink wrap type material that is commercially available which upon applying heat shrinks onto the portion which is within the shrink wrap itself. This is only one method of connecting tool bit  52  to bit extension  54 . Many other methods known in the art can be equally successfully used. Particularly is contemplated molding bit extension  54  which is normally made of a flexible plastic material directly into one end of tool bit  52  which is normally made of a hardened steel material.  
         [0068]    In order for multi-bit driver  30  to work properly, bit assemblies  100  must have certain properties. Firstly, bit extension  54  must be made of a resiliently flexible material which allows for elastic bending of bit extension portion  54 . In this regard, many plastics are suitable including poly propylene, nylon, TEFLON, vinyl and like plastic materials. Secondly, bit extension preferably has memory properties which ensures that tool bit  52  is always delivered to bit chuck  80  in similar orientation to ensure it is aligned properly and is slidably received through bit chuck  80 . It is also possible to use metals including spring steel and/or spring aluminum as possible materials for bit extension  54 . As already mentioned, connector  56  is of a shrink wrap type, however, directly molding bit extension  54  to tool bit  52  and/or integrally manufacturing bit extension  54  together with tool bit  52  is also a possibility, particularly if both bit extension  54  and tool bit  52  are made of the same material.  
         [0069]    As best shown in FIG. 11 once bit assemblies  100  have been assembled, they are loaded into barrel  32  as shown in FIG. 11. Bit assemblies  100  are urged through cap end  60  of barrel  32  and are longitudinally aligned with an actuator channel  70  in barrel  32 . In this manner, bit assemblies  100  are nested etui distant around the interior circumference of barrel  32  and in this case  6  bit assemblies are shown to be inserted into barrel  32 . Note that preferably each bit assembly  100  has a slight angular bend namely angle theta  108  as shown in FIG. 13. At connector  56  where tool bit  52  is connected with bit extension  54 , the angle theta is approximately 20° which has been found to work best in practise. Angle theta  108  can range from 1° to 45°, however, the preferred angle is 20°. Angle theta  108  is incorporated into bit assembly  100  in order to keep head end  112  of bit assemblies  100  proximate the inner diameter of barrel  32  and to prevent tool bit  52  from impinging on one another while loaded in barrel  32 . Angle theta  108  is also required to ensure tool bit  52  is aligned longitudinally with receiving channel  89  when it enter bit chuck  80 . From FIGS. 3 and 11 you will see that assemblies  100  are installed into barrel  32  such that the head end  112  of tool bits  52  are projecting outwardly toward to the interior diameter of barrel  32 .  
         [0070]    Once bit assembly  100  has been inserted far enough into barrel  32  such that fastener aperture  102  lines up with an actuator channel  70 , bit assembly  100  is then slidably fastened to barrel  32  by inserting an actuator knob  72  having a knob fastener  74  which as shown is of the split collar type, in order to fasten bit assembly  100  to barrel  32 . Note that bit assembly  100  is free to slidably move along actuator channel  70  by urging knob fastener  74  longitudinally upward or downward along actuator channel  70 . Knob fastener  74  of actuator knob  72  passes through actuator channel  70  defined in barrel  32 , as well as through fastener aperture  102  defined in bit extension  54 , wherein fastener aperture  102  is dimensioned so that as fastener  74  passes through fastener aperture  102  it locks extension  54  to knob fastener  74 .  
         [0071]    Once bit assemblies  100  are in place, and fastened into placed with knob fastener  74 , bit guide  41  can now be inserted through cap end  60  of barrel  32 . Guide  40  is connected to guide support  42  in such a manner so as to allow guide  40  to rotate independently of guide support  42  while threading end cap  38  into threads  62  at cap end  60 .  
         [0072]    With guide  40  in place, the bit extension  54  of bit assemblies  100  are in slide able engagement with guide faces  43  of guide  40  as they are urged along actuator channel  70 . Guide  40  serves to maintain bit extension  54  in their proper position longitudinally aligned with actuator  70  and also ensures to keep bit assemblies  100  nested outwardly adjacent the inner diameter of barrel  32 .  
         [0073]    As best shown in FIGS. 9 and 10, cone  34  can now be threadably installed onto external thread  66  of barrel  32  and subsequently locking screw  35  can be installed to ensure that cone  34  does not rotate or turn on external thread  66  but rather remains in a stationary position.  
         [0074]    Once cone  34  is in place, steel ball  82  is placed into a counter sink  81  located in bit chuck  80  and collar  36  is threadably attached to chuck end  39  until tapered surface  84 , makes contact with steel ball  82 . This completes the assembly of multi-bit driver  30 .  
         [0075]    In Use  
         [0076]    As best shown in FIGS. 10 and 14, multi-bit driver  30  is utilized as follows. With all of the six bit assemblies  100  installed into barrel  32  and nested equally around the interior circumference of barrel  32 , tool bit  52  can be selected from retracted position  93  for use by slidably urging actuator knob  72  longitudinally along actuator channel  70 .  
         [0077]    As shown in FIG. 14 as actuator knob  72  is moved with simple finger pressure longitudinally along actuator channel  70  such that, head end  112  and/or driver head  104  of tool bit  52  makes contact with guide surface  110  of cone  34 . Tool bit  52  is guided into and enters chuck receiving channel  89 . As actuator knob  72  continues to be urged upwardly along actuator channel  70 , tool bit  52  slidably moves along guide surface  110  thereby flexing bit extension  54  as tool bit  52  moves closer to chuck receiving channel  89 . Finally, tool bit  52  enters chuck receiving channel and is aligned with longitudinal axis  99  of housing  31 . Tool bit  52  should be substantially aligned longitudinally with housing  32  in order to be able to usefully employ multi-bit driver  30 .  
         [0078]    Tool bits  52  normally have an exterior hexagonal profile and chuck receiving channel  89  has a cooperating hexagonal opening. The flat longitudinally aligned bit extension sliding along guide faces  43  on guide  40  serve to align tool bit  52  exactly with chuck receiving channel  89  such that tool bit  52  is easily and slidably received within chuck receiving channel  89  anytime it is urged towards chuck receiving channel  89 .  
         [0079]    By continuing to urge knob fastener  74  upwardly, tool bit  52  passes through chuck receiving channel  89  until locking groove  90  aligns with steel ball  82  located in counter sink  81  in bit chuck  80 . At this point tool bit  52  is aligned with longitudinal axis  99 , and is in the extended position  97 .  
         [0080]    In order for tool bit  52  to slidably and easily pass through receiving channel  89 , collar  36  is eased off and/or threadably moved forward along bit chuck  80 , such that tapered service  84  does not contact steel ball  82  and is free to move upwardly within countersink  81 .  
         [0081]    Once locking groove  90  aligns with steel ball  82 , collar  36  is threadably engaged and rotated onto bit chuck  80  until tapered surface  84  of collar  36  engages with steel ball  82  forcing it downwardly into countersink  81  so that steel ball  82  makes contact with locking groove  90 , thereby locking tool bit  52  rigidly and securely into chuck receiving channel  89 .  
         [0082]    At this point, tool bit  52  is ready to be used and driver head  104  can be pushed and urged against any fastener head in the traditional manner.  
         [0083]    To select another tool bit  52 , collar  36  is threadably eased away from steel ball  82 , thereby allowing steel ball  82  to move upwardly within countersink  81 , thereby releasing steel ball  82  from locking groove  90  and tool bit  52 . Actuator knob  72  is urged backwardly along actuator channel  70  retracting tool bit  52  back into barrel  32  of housing  31 .  
         [0084]    Subsequently another tool bit  52  can be selected in the same manner described above and urged forwardly up actuator channel  70  to be put into the working position in chuck receiving channel  89  as described here above.  
         [0085]    Description of the Presently Preferred Embodiment  
         [0086]    Referring now to FIGS. 17 through 24 which depict the presently preferred embodiment namely, multi-bit driver  230 , the concept of multi-bit driver  230  is analogous to the concept of multi-bit screw driver  30  with some modifications as will be described here below.  
         [0087]    Referring first of all to FIG. 17, multi-bit driver  230  includes the following major components, namely barrel  232 , cone  234  having collar  36 , actuator knob  72 , end cap  238  and bit assemblies  100  including bit extension  54 , connector  56  and tool bit  52 . Note that this presently preferred embodiment, namely multi-bit driver  230  has eliminated the bit guide  41 , comprising of guide  40  and guide support  42 . Bit guide  41  functions to maintain bit assemblies  100  nested circumferentially equally around the inner portion of barrel  32  and to keep the bit assemblies  100  nicely separated within barrel  32 . Bit guide  41  has essentially been replaced with magnets  202  which are located as shown in the FIGS.  17 - 24 .  
         [0088]    Referring to FIGS.  18 , one will see that the presently preferred bit cartridge  250  includes end cap  238 , actuator knob  72 , bit extension  54 , connector  56 , tool bit  52  and has eliminated bit guide  41  which is comprised of guide  40  and guide support  42 .  
         [0089]    Referring now to FIGS. 19 and 20 which illustrate bit assembly  100  which remains essentially unchanged being comprised of bit extension  54 , connector  56  and tool bit  52  and having a fastener aperture  102  in one end of bit extension  54 .  
         [0090]    Referring now to FIG. 21, showing schematically the bit assemblies  100  located within barrel  232 , I will now explain the difference in operation between the current multi-bit driver  230  and the previous multi-bit screw driver  30 .  
         [0091]    Referring now to FIG. 21, bit assembly  100  is urged along longitudinal direction  204  by applying finger pressure to actuator knob  72  which is operatively connected to the fastener aperture  102  of bit extension  54 . As actuator knob  72  is urged along actuator channel  70 , it in turn urges tool bit  52  longitudinally along the inside of barrel  232  until tool bit  52  exits out of bit chuck  80  of barrel  232 . One skilled in the art will notice that bit extensions  54  are flexible in one direction and therefore, conforms to forces in that direction imparted upon bit extension  54 . Bit assembly  100  is kept nested along barrel wall  206  by the attraction forces between magnets  202  and metallic tool bit  52  as it is being extended and retracted out of barrel  232 . Magnets  202  preferably are of the permanent magnet type. Looking to FIG. 21 for example, the upper bit assembly  100  is nested closely to barrel wall  206  because of the attraction between tool bit  52  of bit assembly  100  and magnet  202 . In this manner as the bit assemblies are extended and retracted out of barrel  232 , they are kept separate and apart and kept from interfering with each other because of the attraction caused by magnet  202  with each individual tool bit  52 . There is an individual magnet  202  for each individual tool bit  52  being placed in barrel  232 . As discussed above, preferably there are six tool bits  52 , meaning  6  bit assemblies  100  nested around the inner diameter of barrel  232  which must be kept separate and apart and prevented from interfering with each other as they are being extended and retracted. In every other manner, multi-bit driver  230  operates in the same manner as multi-bit screw driver  30  does as described above. The major differences being that the bit guide  41  is no longer present, namely former parts guide  40  and guide support  42  are no longer necessary and have been replaced by magnets  202 .  
         [0092]    Referring now to FIGS. 23 and 24 which are cross-sectional view taken along  23 - 23  of FIG. 22 and  24 - 24  of FIG. 22 respectively, one will see that the bit guide  41  components, namely guide  40  and guide support  42 , are no longer present within the interior of barrel  232  as in the previous embodiment, namely multi-bit screw driver  30 . Bit extension  54  is flexible in radial direction  177  and stiffer in lateral direction  179 .  
         [0093]    Furthermore, it will be understood by persons skilled in the art that bit assembly  100  as shown comprised of three major components, namely bit extension  54 , connector  56  and tool bit  52 , may in fact be manufactured from one single integral piece. For example, bit assembly  100  may be made of one continuous metal component having a flexible end corresponding to bit extension  54  which is flattened and has spring like qualities and not requiring any kind of a connector  56  in that the bit extension  54  and the tool bit  52  are integrally made of one component. In addition, there are any number of other combinations that are possible to produce bit assembly  100 , the important factor being that the bit extension  54  section being flexible in nature in order that it can move along the interior portion of cone  34  as the bit assembly  100  is urged longitudinally along longitudinal direction  204 .  
         [0094]    Preferably, bit assembly  100  is flexible in the radial direction and not flexible in the lateral direction to prevent interference of the bit assemblies with each other within barrel  232 . Therefore, the preferred flat cross sectional shape of bit extension  54  as shown in the Figures.  
         [0095]    Bit assembly  100  must be flexible enough to allow tool bit  52  to move along the inner surface of cone  234  and/or cone  34  in order that tool bit  52  would enter into receiving channel  89  of bit chuck  80  of cone  234  or  34 . The bit extension  54  of bit assembly  100  must, however be stiff enough to urge the tool bit  52  through the receiving channel  89 .  
         [0096]    It should be apparent to persons skilled in the arts that various modifications and adaptations of this structure described above are possible without departure from the spirit of the invention the scope of which defined in the appended claim.