Abstract:
A combination tool for drilling a bore and countersink for that bore includes a countersink member. The countersink member comprises a longitudinal sleeve with a first end and a second end. The sleeve contains a longitudinal bore through the sleeve from the first end to the second end sized to receive a drill bit. A radial slot through the wall of the sleeve is in communication with the longitudinal bore. The sleeve has a cutting edge connected to the first end of the sleeve. A collar containing a radial bore through its wall is slidably inserted over the sleeve. The radial bore is in communication with the radial slot of the countersink member. A fastening mechanism extends through the radial bore of the collar and slot of the countersink member to engage the drill bit inserted through the longitudinal bore of the countersink member and thus secure the drill bit, countersink member and collar relative to one another.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
   This application claims priority from provisional application No. 60/553,996 filed Mar. 17, 2004, for “Drill Countersink Assembly” by James L. Wienhold, which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   Drill countersinks are known in the art for holding a drill bit, including the exemplary countersink shown in  FIG. 1 . A countersink tool  10  includes a proximal end  12  with a shank  14  and a distal end  16  with a cutting edge  18 . The shank  14  contains an annular groove  20  for connection with an automatic or “quick-release” coupling of a drill chuck or tool holder (not shown). The shank  14  is of any suitable shape for rotatably coupled engagement with a power source, using either a male or female style coupling. Although tool shanks having hex cross-section shapes are shown herein, any shape formed to inhibit rotation of the tool relative to a tool holder or power source will suffice. Likewise, the annular groove  20  formed on the tool shank  14  is not necessary for effective automatic coupling and release of the tool relative to the tool holder or power source. 
   The countersink tool  10  includes a longitudinal bore  22  extending from the cutting edge  18 , the bore  22  being adapted for receiving a drill bit  24  therein. The countersink tool  10  includes a body  27  having an outer wall  28  with a flute  26  formed at the distal end  16 , which includes the cutting edge  18 . The drill bit  24  is held in place within the bore  22  by a set screw  30  which extends through the body  27  to engage the drill bit  24 . Loosening the set screw  30  releases the drill bit  24  to allow an operator to adjust the length L of the bit  24  extending from the bore  22 , and tightening the set screw  30  secures the drill bit  24  within the bore  22  relative to the body  27 . 
     FIG. 2  is a cross-sectional view of holes bored in a board  31  with the prior art countersink tool  10  shown in  FIG. 1 . Step  2 A illustrates the countersink tool  10 , with drill bit  24 , boring a hole  32 , or counterbore, in the board  31  to an approximate depth for flush installation of a screw  34 . The length L of the drill bit  24  extending from the cutting edge  18  of the bore  22  is adjustable to match the screw length. The outer diameter of the countersink, or flute  26 , defines the counterbore diameter. Step  2 B illustrates the hole  32  bored by the countersink tool  10  ready for screw  34  installation. Step  2 C shows an installed screw  34  with a screw head  36  flush with a work surface  37  of the board  31 . 
   Step  2 D shows a hole  35  in which the operator has bored the hole too deep for flush installation of the screw  34 . In some instances the bore hole  32  may be too shallow for flush installation of the screw  34 . Step  2 E illustrates the countersink tool  10 , with drill bit  24 , boring a deeper hole  38  in the board  31  for recessed or covered screw installation. Step  2 F illustrates the resultant hole bored  38  by the countersink in step  2 E. Step  2 G shows an installed screw  34  with a plug  40  inserted in the counterbore to cover the screw  34  and create a plug surface flush with the work surface of  37  of the board  31 . 
   The countersink tool  10  shown and described with respect to  FIGS. 1 and 2  is a single-stage countersink with a single flute. Two-stage countersinks are also known in the art for forming a counterbore having two diameters. In addition, countersinks with more than one flute and/or set screws are also known in the art. 
     FIG. 3  is a side view of the prior art countersink tool  10  shown in  FIG. 1  holding a tool bit  24 , and also including an adjustable stop collar  42  attached to the body  27  of the countersink tool  10 . The stop collar  42  is placed around the flute  26  or flutes of the countersink tool  10  to prevent an operator from drilling a counterbore too deep with the countersink tool  10 . The stop collar  42  includes a workpiece engagement surface  43  and a set screw  44  to secure the collar in place along the length of the body  27  of the countersink tool  10 . Loosening the set screw  44  releases the stop collar  42  to permit an operator to adjust its position along the length of countersink tool  10  and tightening the set screw  44  secures the collar  42  in place relative to the body  27 . Thus, the depth of the counterbore is adjustable in two ways, by adjusting the length L of the drill bit  24  extending from the bore  22  with the countersink set screw  30 , and by adjusting the position of the stop collar  42  along the length of the countersink tool  10  with the stop collar set screw  44  (thus fixing a counterbore depth D between the work engagement surface  43  of the stop collar  42  and the cutting edge  18  of the body  27  of the countersink tool  10 , as seen in  FIG. 3 ). 
     FIG. 4  is a cross-sectional view of holes bored in a board  45  by the countersink tool  10  with attached stop collar  42  shown in  FIG. 3 . Step  4 A illustrates the countersink tool  10  fitted with the stop collar  42  boring a hole  46 , or counterbore, in the board  45  to an exact depth for flush installation of a screw  34 . The length L of the drill bit  24  extending from the cutting edge  18  of the bore  22  is adjustable to match the screw length, and the depth D of the counterbore is separately adjustable to match the depth of the screw head. Step  4 B illustrates the hole  46  bored by the countersink tool  10  ready for screw  34  installation. Step  4 C shows an installed screw  34  with a screw head flush with a work surface  48  of the board  45 . Step  4 D illustrates that, in comparison to the hole  35  shown in step  2 D the stop collar  42  aids in boring a hole  46  with a consistent counterbore depth for flush installation of a wood screw. 
   Steps  4 E– 4 G are similar to steps  2 E– 2 G described above with respect to  FIG. 2 . Step  4 E illustrates the countersink tool  10  (with the stop collar  42  removed) boring a deeper hole  50  in the board  45  for recessed or covered screw installation. Step  4 F illustrates the resultant hole  50  bored by the countersink tool  10  in step  4 E, and step  4 G shows an installed screw  34  with a plug  40  inserted in the counterbore to cover the screw  34  and create a plug surface flush with the work surface  48  of the board  45 . 
   BRIEF SUMMARY 
   In one aspect, the present invention is a combination tool comprising a countersink member, wherein the countersink member comprises a longitudinal sleeve with a cutting edge and contains a longitudinal bore through the sleeve to receive the drill bit. A radial slot through the wall of the sleeve is in communication with the longitudinal bore. A collar containing a radial bore in communication with the radial slot of the countersink member is slidably inserted over the sleeve. A fastening mechanism extends through the radial bore of the collar and slot of the countersink member to engages the drill bit inserted through the longitudinal bore of the countersink member. 
   In another aspect, the present invention is an improvement in a countersink assembly for receiving a drill bit, wherein the countersink assembly has a countersink cutting face. The improved countersinking assembly comprises a single fastener mechanism which has a surface which engages a drill bit disposed in the countersink assembly for fixing the operative length of the drill bit. The single fastener mechanism also has a workpiece engagement surface for fixing the operative depth of a bore which can be formed in a workpiece by a countersink which can be formed in the workpiece by the countersink cutting face on the countersink assembly. 
   In another aspect, a method of preparing a countersink tool for use in forming a bore with a tool bit and a countersink at an open end of the bore is provided. First, a drill bit is axially inserted into a longitudinal bore of a countersink tool body so that a desired length of the tool bit extends from a first countersink cutting end of the countersink tool body. Next, a collar having a workpiece engaging surface along the countersink tool body is longitudinally aligned, so that the surface is longitudinally spaced a desired depth from the first countersink cutting end of the countersink tool body. The drill bit, collar, and countersink body are secured together using a single fastener, thereby fixing an operative bore drilling length for the tool bit and an operative countersink depth for the first countersink cutting end of the countersink tool body. 
   The above summary is not intended to describe each disclosed embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify illustrative embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be further explained with reference to the attached figures, wherein like structure is referred to by like numerals throughout the several views. 
       FIG. 1  is a side view of a prior art countersink tool. 
       FIG. 2  is a cross-sectional view of holes bored in a substrate with the prior art countersink shown in  FIG. 1 . 
       FIG. 3  is a side view of a prior art countersink tool with an adjustable collar mounted thereto. 
       FIG. 4  is a cross-sectional view of holes bored in a substrate with the prior art countersink shown in  FIG. 3 . 
       FIG. 5A  is a side view of a countersink assembly of the present invention with a stop collar in a first position. 
       FIG. 5B  is a side view of the countersink assembly shown in  FIG. 5A  with the stop collar in a second position. 
       FIG. 5C  is a cross-sectional view of the countersink assembly taken along line  5 C of  FIG. 5A . 
       FIG. 5D  is a cross-sectional view of the countersink taken along line  5 C of  FIG. 5A . 
       FIG. 6A  is a side view of another embodiment of the countersink assembly of the present invention with a stop collar in a first position. 
       FIG. 6B  is a side view of the countersink shown in  FIG. 6A  with the stop collar in a second position. 
       FIG. 6C  is a side view of the countersink member of the countersink assembly shown in  FIG. 6A . 
       FIG. 6D  is a cross-sectional view of the countersink assembly taken along line  6 D of  FIG. 6A . 
       FIG. 6E  is a cross-sectional view of the countersink taken along line  6 D of  FIG. 5A . 
   

   While the above-identified drawing figures set forth several embodiments of the invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the present invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art which fall within the scope and spirit of the principles of this invention. 
   DETAILED DESCRIPTION 
     FIGS. 5A and 5B  are side views of one embodiment of my inventive countersink assembly  55 , which comprises a countersink  60  and stop collar  62  assembly of the present invention. The countersink  60  and stop collar  62  assembly includes a single set screw  64  for adjusting a length L 1  of a drill bit  66  extending from the countersink  60  and adjusting the position the stop collar  62  along the length of the countersink  60 . The adjustable stop collar  62  is movable between a first position (shown in  FIG. 5A ) and a second position (shown in  FIG. 5B ), but may be secured in place at any point there between. The position of the stop collar  62  along the countersink  60  thus determines a depth D 1  of the countersink which may be formed by the countersink assembly  55  (compare depth D 1  in  FIG. 5A  with depth D 1  in  FIG. 5B ). 
   The countersink  60  comprises a tubular sleeve  68  which includes a longitudinal bore  70  extending from a cutting edge  72 , the bore  70  adapted for axially receiving a drill bit  66 . A flute  74  forms an outer wall  76  of the bore  70 , which includes an open ended radial slot  78 . The radial slot  78  is aligned to extend substantially perpendicular to the longitudinal axis of the sleeve  68 . The radial slot  78  extends completely through the sleeve  12  such that the radial slot  78  communicates with the longitudinal bore  70 . The drill bit  66  is an ordinary twist drill bit commonly used in the art. 
   The stop collar  62  comprises a cylindrical wall  80  with the inner diameter being nominally larger than the outer diameter of the outer wall  76  of the countersink  60  (See  FIG. 5C ). The stop collar  62  has a workpiece engagement surface  67  and a radial bore  82  for reception of a fastener to secure the collar  62  about the countersink  60  and drill bit  66 . In one embodiment, the bore  82  is threaded to receive the set screw  64 . The stop collar  62  is positioned about the sleeve  68  such that the open ended slot  78  receives the set screw  64 . The set screw  64  is movable along the slot  78  as the stop collar  64  is moved between the first position (shown in  FIG. 5A ) and the second position (shown in  FIG. 5B ). 
   Both the drill bit  66  and stop collar  62  are held in place within the bore  70  by the set screw  64 . Set screw  64  contains a hexagonal cavity  63  to allow reception of an allen wrench for securing the set screw  64  within the threaded bore  82 . Loosening the set screw  64  releases the bit  66  to allow an operator to adjust the length L 1  of the bit  66  extending from the bore  70  from the cutting edge  72 , and releases the stop collar  62  to allow an operator to adjust its position along the length of countersink  60  (and thus to adjust the depth D 1  of the screw head countersink to be formed from the work engagement surface  67  of the stop collar  62  to the cutting edge  72  of the countersink  60 ). As seen in  FIG. 5C , tightening the set screw  64  secures the bit  66  within the bore  70  and secures the collar  62  in place relative to the countersink  60 . Thus, with manipulation of a single fastener (e.g., a set screw), the relative positions of the effective drill bit length and screw head countersink depth can be fixed. The drill bit, countersink, and collar are fixed relative to one another by the single fastener and manipulation step. 
   The countersink  60  is attached to a shank  84 . The shank  84  contains an annular groove  86  for connection with an automatic or “quick-release” coupling of a drill (not shown). The shank  84  is of any suitable shape for rotatably coupled engagement with a power source, using either a male or female style coupling. Although shown as having hex cross-section shape, any shape formed to inhibit rotation of the tool relative to a tool holder or power source will suffice. Likewise, the annular groove  86  formed on the tool shank  84  is not necessary for effective automatic coupling and release of the tool relative to the tool holder or power source. In one embodiment, the shank  86  contains a longitudinal bore  87  (shown in phantom) concentrically aligned with the longitudinal bore  70  of the countersink  60 . This allows shank  86  to receive a portion of drill bit  66  which provides further adjustment for hole depth L 1  when using the drill countersink assembly  55 . 
     FIG. 5C  is a cross-sectional view of the countersink  60  and stop collar  62  assembly shown in  FIG. 5A , as taken along line  5 C— 5 C in  FIG. 5A  and  FIG. 5D  is a cross-sectional view of the countersink  60  alone shown in  FIG. 5A , as taken along line  5 C— 5 C in  FIG. 5A . As illustrated, in one embodiment the countersink  60  is semi-circular in cross section, with the stop collar  62  being circular in cross section (other shapes would suffice, so long as the collar is moveable longitudinally along the countersink). The drill bit  66  is also typically circular in cross section and fits into the corresponding longitudinal bore  70  of the countersink  60 . Set screw  64  extends through a cooperatively threaded radial bore in the stop collar  62  and has an end surface  64   a  which engages and hold drill bit  66  against the countersink  60 . 
     FIGS. 6A and 6B  are side views of another embodiment of my inventive countersink assembly  85  which comprises a countersink  90  and stop collar  92  assembly. The countersink  90  and stop collar  92  assembly includes a single set screw  94  for adjusting a length L 2  of a drill bit  96  extending from the countersink  90  and adjusting the position of the stop collar  92  along the length of the countersink  90 . The adjustable stop collar  92  is movable between a first position (shown in  FIG. 6A ) and a second position (shown in  FIG. 6B ). In addition, the countersink  90  is movable along the length of the drill bit  96  to adjust the length of the bit  96  for drilling. The position of the stop collar  92  along the countersink  90  thus determines a depth D 2  of the countersink which may be formed by the countersink assembly  85  (compare depth D 2  in  FIG. 6A  with depth D 2  in  FIG. 6B ). 
   The countersink  90  is a multi-flute countersink, as seen in  FIG. 6C . The countersink comprises a sleeve  100  which includes a longitudinal bore  102  extending from a distal cutting edge  104  to a proximal end  105 , which is adapted for receiving the drill bit  96 . Flutes  106  form a distal portion of an outer wall  108  of the bore  102 , which includes a close ended radial slot  110  in communication with the longitudinal bore  102 . When the assembled ( FIGS. 6A and 6B ), the stop collar  92  is positioned about the countersink  90  such that the close ended slot  110  is aligned with a set screw  94  that is threadably received in the stop collar  92 . The set screw  94  is movable along the slot  110  as the stop collar  92  is moved between the first position (see, e.g.,  FIG. 6A ) and the second position (see, e.g.,  FIG. 6B ). In the illustrated embodiment, the drill bit  96  is a taper-point drill bit commonly used in the art. The stop collar  92  and set screw  94  are similar in structure and function to those previously described as stop collar  62  and set screw  64 . In this embodiment, a proximate end  97  of the drill bit  96  directly attaches the countersink assembly  85  to a drill chuck. 
   Both the drill bit  96  and stop collar  92  are held in place within the bore  102  by the set screw  94 , which has an end surface  94   a  for the engaging the drill bit  96 . Loosening the set screw  94  releases the drill bit  96  so that an operator can move the countersink  90  relative to the drill bit  94  to adjust the length L 2  of the bit  96  extending from the bore  102 . Likewise, loosening the set screw  94  also releases the stop collar  92  to allow an operator to adjust its position along the length of countersink  90  (and thus adjust the depth D 2  of the screw head countersink to be formed from a work engagement surface  93  of the stop collar  92  to the cutting edge  104  of the countersink  90 ). As seen in  FIG. 6D , tightening the set screw  94  secures the bit  96  within the bore  102  and secures the collar  92  in place relative to the countersink  90 . Thus with manipulation of a single fastener (e.g., a set screw), the relative positions of the effective drill bit length and screw head countersink can be fixed. The drill bit, countersink, and collar are all fixed relative to one another by the single fastener and manipulation step. 
     FIG. 6D  is a cross-sectional view of the countersink  90  and stop collar  92  assembly shown in  FIG. 6A , as taken along line  6 D— 6 D in  FIG. 6A , and  FIG. 6E  is a cross-sectional view of the countersink  90  alone shown in  FIG. 6A , as taken along line  6 D— 6 D in  FIG. 6A . In this embodiment, the countersink  90  cross section is the majority of a circle (approximately 270 degrees), and the collar  92  is circular in cross section (other shapes will suffice, so long as the collar is movable longitudinally along the countersink). The drill bit  96  is typically circular in cross section and mates with the corresponding longitudinal bore  102  of the countersink  90 . Set screw  94  extends through a cooperatively threaded radial bore in the collar  92  to engage and hold drill bit  96  against the countersink  90 . The slot  110  is smaller than the slot  78  that illustrated in  FIGS. 5A–5D  leaving more material for countersink  90 . This adds to the structural integrity of wall  108  of the countersink  90  allowing for multiple flutes  106  which provide multiple cutting surfaces for cutting edge  104 . 
   The present invention is a countersink having a single fastener that an operation manipulates to secure and adjust a drill bit held by the countersink and a stop collar attached to the countersink. The improved countersink simplifies use by an operator and manufacture of the countersink. A single fastener countersink allows an operator to bore either flush or deep holes without adding or removing a part from the countersink. The countersink includes fewer parts for simplified manufacturing. Current countersinks are sold without stop collars, which may be purchased separately and attached to the countersink for use. The present invention is sold as a single unit, thereby lowering the cost, improving efficiency in the field and reducing lost parts. 
   With the above disclosed countersink assembly tool, a method of preparing a countersink tool for use in forming a bore with a tool bit and a countersink at an open end of the bore is provided. First, a drill bit is axially inserted into a longitudinal bore of a countersink tool body so that a desired length of the tool bit extends from a first countersink cutting end of the countersink tool body. Next, a collar having a workpiece engaging surface along the countersink tool body is longitudinally aligned, so that the surface is longitudinally spaced a desired depth from the first countersink cutting end of the countersink tool body. The drill bit, collar, and countersink body are secured together using a single fastener, thereby fixing an operative bore drilling length for the tool bit and an operative countersink depth for the first countersink cutting end of the countersink tool body. 
   Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.