Abstract:
A case mouth chamfer tool utilizes an easily adjustable cutter holder member. The adjustable cutter holder member slides in a dovetail, is adjusted by advancing and retreating a screw, and is held in place by a set screw. The case mouth chamfer tool may be fixed to a micrometer dial threadedly engaging a barrel. A case adapter bearing is fixed to the barrel. The case mouth chamfer tool is adjusted to cut an inside chamfer and the micrometer dial is rotated to adjust the position of the case mouth chamfer tool with respect to the case adapter bearing to precisely adjust the amount of material cut from the case. The case adapter bearing is easily changed to chamfer different cases.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation In Part of U.S. patent application Ser. No. 14/067,531 filed Oct. 30, 2013, which application is incorporated in its entirety herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to chamfering ammunition case mouths and in particular to a camfer tool usable in a motorized adjustable precision micrometer case trimmer. 
     Ammunition cases are generally the most expensive component of ammunition. Many shooting enthusiasts reuse the cases to save money. While such cases may be capable of multiple uses, some cases, especially expensive high power rifle cases, are stretched in each use. When the cases are stretched, the neck of the case (the portion a bullet is seated in), becomes longer and increases the contact surface with bullet, and affects the release of the bullet when the ammunition is filed. Such changes in the release affect the velocity, and thus the consistency of the bullet at long range. 
     To address the case stretching, the cases are often trimmed back to the original length. Both manual and electric trimmers are known. Unfortunately, the known electric trimmers require expensive separate components for each size case. U.S. patent application Ser. No. 14/067,531 address these problems by providing a Micrometer Case Trimmer which merely requires a simple guide bearing for various cases, and a micrometer cutting depth adjustment. The &#39;531 application is incorporated by reference above. 
     While the &#39;531 application provides an excellent solution for case trimming, it does not provide easy chamfering of the case mouth, thus requiring an additional tool. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention addresses the above and other needs by providing a case mouth chamfer tool which utilizes an easily adjustable cutter holder member. The adjustable cutter holder member slides in a dovetail, is adjusted by advancing and retreating a screw, and is held in place by a set screw. The case mouth chamfer tool may be fixed to a micrometer dial threadedly engaging a barrel. A case adapter bearing is fixed to the barrel. The case mouth chamfer tool is adjusted to cut an inside chamfer and the micrometer dial is rotated to adjust the position of the case mouth chamfer tool with respect to the case adapter bearing to precisely adjust the amount of material cut from the case. The case adapter bearing is easily changed to chamfer different cases. 
     In accordance with one aspect of the invention, there is provided an electric case trimmer assembly having a micrometer cutting adjustment. A first cut is made intentionally leaving the case longer than intended. The case is measured, and the micrometer dial is turned a pre-determined number of lines to precisely adjust the case trimmer to trim the case to the correct length. 
     In accordance with another aspect of the invention, there is provided a case chamfering tool. The case chamfering tool includes a base member with a shaft and an adjustable cutter holder member having a dovetail engagement with the base member. The adjustable cutter holder is adjusted to turning a screw having threads engaging the base member and a head cooperating the adjustable cutter holder. The cutter includes three edges and the cutter may be detached and rotated to alternatively use all three of the cutting edges. 
     In accordance with yet another aspect of the invention, there is provided a method for chamfering cases. The method includes installing a case mouth chamfer tool in a micrometer dial of a case chamfering assembly, installing a case adapter bearing for a selected case type into a barrel of the case chamfering assembly, inserting a case of the selected case type into the case chamfering assembly, adjusting the depth of the cutter to almost touch the case mouth, adjusting the cutter laterally to trim a chamber inside the case mouth, adjusting the position of the cutter to cut a small chamfer in the case mouth, attaching the case chamfering assembly to a drill motor, and insert cases into the trimmer with the drill motor running. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein: 
         FIG. 1  is a side view of a case trimming assembly according to the present invention. 
         FIG. 2  is a cross-sectional view of the case trimming assembly according to the present invention taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of the case trimming assembly according to the present invention separated into major components taken along line  2 - 2  of  FIG. 1 . 
         FIG. 4  is a side view of the case trimming assembly according to the present invention with a case ready for insertion into the case trimming assembly. 
         FIG. 5  is a side view of the case trimming assembly according to the present invention with the case in the case trimming assembly. 
         FIG. 6  is a cross-sectional view of the case trimming assembly according to the present invention with the case in the case trimming assembly taken along line  6 - 6  of  FIG. 5 . 
         FIG. 7  is a side view of the case trimming assembly according to the present invention attached to a drill motor. 
         FIG. 8A  is a side view of the case trimming assembly according to the present invention with the case in the case trimming assembly for a first cut before precision adjustment. 
         FIG. 8B  is a side view of the case trimming assembly according to the present invention with the case in the case trimming assembly for second and latter cuts after precision adjustment. 
         FIG. 9  is a method according to the present invention. 
         FIG. 10A  shows a left side view of a case mouth chamfer tool according to the present invention. 
         FIG. 10B  shows a top view of the case mouth chamfer tool according to the present invention. 
         FIG. 10C  shows a bottom view of the case mouth chamfer tool according to the present invention. 
         FIG. 10D  shows a front view of the case mouth chamfer tool according to the present invention. 
         FIG. 10E  shows a rear view of the case mouth chamfer tool according to the present invention. 
         FIG. 10F  shows a right side view of the case mouth chamfer tool according to the present invention. 
         FIG. 11A  shows a top view of a base member of the case mouth chamfer tool according to the present invention. 
         FIG. 11B  shows a rear view of the base member of the case mouth chamfer tool according to the present invention. 
         FIG. 11C  shows a front view of the base member of the case mouth chamfer tool according to the present invention. 
         FIG. 12A  shows a top view of an adjustable cutter holder member of the case mouth chamfer tool according to the present invention. 
         FIG. 12B  shows a rear view of the adjustable cutter holder member of the case mouth chamfer tool according to the present invention. 
         FIG. 12C  shows a front view of the adjustable cutter holder member of the case mouth chamfer tool according to the present invention. 
         FIG. 12D  shows a left side view of the adjustable cutter holder member of the case mouth chamfer tool according to the present invention. 
         FIG. 13A  shows a left side view of the adjustable cutter holder member attached to the base member in a first cutting position according to the present invention. 
         FIG. 13B  shows a top view of the adjustable cutter holder member attached to the base member in a first cutting position according to the present invention. 
         FIG. 14A  shows a cross-sectional side view of the adjustable cutter holder member attached to the base member in the first cutting position according to the present invention taken along line  14 - 14  of  FIG. 13B . 
         FIG. 14B  shows a cross-sectional side view of the adjustable cutter holder member attached to the base member in a second cutting position according to the present invention taken along line  14 - 14  of  FIG. 13B . 
         FIG. 15  shows a case chamfering assembly according to the present invention. 
         FIG. 16  describes a method for chamfering case mouths according to the present invention. 
     
    
    
     Corresponding reference characters indicate corresponding components throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
     A side view of a case trimming assembly  10  according to the present invention is shown in  FIG. 1 , a cross-sectional view of the case trimming assembly  10  taken along line  2 - 2  of  FIG. 1  is shown in  FIG. 2 , and a cross-sectional view of the case trimming assembly  10  separated into major components taken along line  2 - 2  of  FIG. 1  is shown in  FIG. 3 . The case trimming assembly  10  includes a micrometer dial  12  (or end mill holding portion or tool holding portion), a barrel  14  (or case guiding portion), a case adapter bearing  18 , and an end mill  16 . The end mill  16  is fixedly attached to the micrometer dial  12  using a set screw  17  and the case adapter bearing  18  is fixedly attached to the barrel  14  by a set screw  19 . The end mill  16  includes a cutting face  16   a  for trimming cases. The end mill  16  and case adapter bearing are coaxial with the micrometer dial  12 . 
     The barrel  14  threadedly engages the micrometer dial  12  by threads  20   a  and  20   b , and a third set screw  13  engages a notched ring  22  of the barrel  14 . The end mill  16  is fixedly attached to the micrometer dial  12  and turning the micrometer dial  12  on the barrel  16  advances and retreats the end mill  16  with respect to the barrel  14 . The case adapter bearing  18  includes an outer race  18   a  fixedly attached to the barrel by the set screw  19  and a rotating inner race  18   b  having an inner case contour  18   c . The inner case contour  18   c  is configured for one or more cases  30  (see  FIG. 4 ) and limits the distance a case  30  can be inserted into the barrel  14 . The set screw  13  serves two purposes. The set screw  13  is tightened against the barrel  14  to fix the position of the micrometer dial for repeated trimming, and during adjustment, the set screw  13  contacts sides of the notched ring  22  to limit adjustment of the micrometer ring  12  on the barrel  14 . 
     A side view of the case trimming assembly  10  with a case  30  ready for insertion into the case trimming assembly  10  is shown in  FIG. 4 , a side view of the case trimming assembly  10  with the case  30  in the case trimming assembly  10  is shown in  FIG. 5 , and a cross-sectional view of the case trimming assembly  10  with the case  30  in the case trimming assembly  10  taken along line  6 - 6  of  FIG. 5  is shown in  FIG. 6 . Windows  24  allow viewing the contact of case  30  with the end mill  16  and allows trimmed material to escape from the barrel  14 . The case  30  is manually inserted by a user until the case  30  rests against the inner case contour  18   c  of the case adapter bearing  18 . When the case mouth  30   a  encounters the end mill cutting face  16   a  before the case  30  is seated against the inner case contour  18   c , material is cut from the case mouth  30   a  until further advance of the case  30  into the barrel is stopped by the inner case contour  18   c.    
     A side view of the case trimming assembly  10  attached to a drill motor  40  is shown in  FIG. 7 . The entire case trimming assembly  10 , with only the exception of the rotating inner race  18   b  of the case adapter bearing  18 , is rotated by the drill motor  40 . The user holds the case  30  and inserts the case  30  into the rotating case trimming assembly  10 . 
     A side view of the case trimming assembly  10  with the case  10  in the case trimming assembly  10  for a first cut before precision adjustment is shown in  FIG. 8A  and a side view of the case trimming assembly  10  with the case  30  in the case trimming assembly  10  for second and later cuts after precision adjustment is shown in  FIG. 8B . The first cut is made with the micrometer dial turned counter clockwise as far as possible, but turned back clockwise to align a dial mark  12   a  with a closest barrel mark  14   a . There is preferably a single dial mark  12   a  and preferably a multiplicity of evenly spaced apart barrel marks  14   a . The number of barrel marks may vary, but a relationship between the angular spacing of the barrel marks  14   a  and the threads  20   a  and  20   b  (see  FIG. 3 ) is preferably known and used as a basis for adjusting the micrometer dial  12  on the barrel  14 . For example, in a preferred embodiment, turning the micrometer dial  12  to align the dial mark  12   a  with and adjacent barrel mark  14   a , advances or retreats the micrometer dial  12  0.002 inches on the barrel  14 . 
     After making a first cut, the length of the trimmed case  30  is measured, and the micrometer dial is adjusted on the barrel to provide the desired precision cut. 
       FIG. 9  is a method according to the present invention. The method includes installing a case adapter bearing for a selected case type into a barrel of the case trimmer assembly at step  100 , turning a micrometer dial of the case trimmer assembly counter clockwise until a stop is reached at step  102 , turning the micrometer dial of the case trimmer assembly clockwise to align a micrometer dial mark with a first barrel mark at step  104 , attaching the case trimmer assembly to a drill motor at step  106 , with the drill motor running, inserting a case of the selected case type into the case trimmer assembly against an end mill of the case trimmer assembly at step  108 , trimming excess material from the case at step  110 , removing the trimmed case from the case trimmer assembly at step  112 , measuring the length of the trimmed case at step  114 , turning the micrometer dial clockwise to adjust the position of the end mill with respect to the case adapter bearing at step  116 , with the drill motor running, inserting a case of the selected case type into the case trimmer assembly at step  118 , and trimming excess material from the case at step  120 . 
     A left side view of a case mouth chamfer tool  50  according to the present invention is shown in  FIG. 10A , a top view of the case mouth chamfer tool  50  is shown in  FIG. 10B , a bottom view of the case mouth chamfer tool  50  is shown in  FIG. 10C , a front view of the case mouth chamfer tool  50  is shown in  FIG. 10D , a rear view of the case mouth chamfer tool  50  is shown in  FIG. 10E , and a right side view of the case mouth chamfer tool  50  is shown in  FIG. 10F . The case mouth chamfer tool  50  holds a cutter  58  used to chamfer mouths of ammunition cases. The cutter is held in a groove  56   a  in the top of an adjustable cutter holder member  56 . A set screw  59  is tightened against the cutter  58  to hold the cutter in the groove  56   a . The adjustable cutter holder member  56  includes a dovetail base  56   b  which slides in a dovetail slot  54   a  in a base member  54  and is adjusted by turning a screw  62  engaging both the base member  54  and the adjustable cutter holder member  56 . The adjustable cutter holder member  56  is held in position after adjustment by a second set screw  60  in the base member  54 . The base member  54  includes a shaft  52  having a flat  52   a . The case trimmer assembly  10  (see  FIG. 1 ) may be converted to chamfer case mouths by replacing the end mill  16  with the case mouth chamfer tool  50 , held in place by the set screw  17 . 
     A top view of a base member  54  is shown in  FIG. 11A , a rear view of the base member  54  is shown in  FIG. 11B , and a front view of the base member  54  is shown in  FIG. 11C . The base member  54  includes a small female threaded passage  55   b  and a larger unthreaded passage  55   a . The passages  55   a  and  55   b  are coaxial and sequential, the passage  55   a  reaching from the exterior about half way into the base member  54 , and passage  55   b  continuing through the base member  54 . The top of the passage  55   a  opens into the dove tale slot  54   a . The base member  54  and shaft  52  share a centerline CL. The dovetail slot  54   a  is preferably perpendicular to the centerline CL. 
     A top view of an adjustable cutter holder member  56  is shown in  FIG. 12A , a rear view of the adjustable cutter holder member  56  is shown in  FIG. 12B , a front view of the adjustable cutter holder member  56  is shown in  FIG. 12C , and a left side view of the adjustable cutter holder member  56  is shown in  FIG. 12D . 
     A left side view of the adjustable cutter holder member  56  attached to the base member  54  in a first cutting position is shown in  FIG. 13A , a top view of the adjustable cutter holder member  56  attached to the base member  54  in the first cutting position is shown in  FIG. 13B , a cross-sectional side view of the adjustable cutter holder member  56  attached to the base member  54  in the first cutting position taken along line  14 - 14  of  FIG. 13B  is shown in  FIG. 14A , and a cross-sectional side view of the adjustable cutter holder member  56  attached to the base member  54  in a second cutting position taken along line  14 - 14  of  FIG. 13B  is shown in  FIG. 14B . A screw  62  engages threads in the passage  55   b  and a head  62   a  of the screw  62  partially resided in a recess  56   c  in the bottom of the adjustable cutter holder member  56 . Thus turning the screw  62 , advances or retreats the screw  62  into the base member  54 , and also translates the adjustable cutter holder member  56  with respect to the base member  54 , thereby adjusting the position of the cutter  58 . The set screw  60  (see  FIG. 10F ) holds the position of the adjustable cutter holder member  56 . 
     The cutter  58  includes three cutting edges  58   a ,  58   b , and  58   c , and the cutter  58  may be detached and rotated to alternatively use all three of the cutting edges. The cutting edges are angled to cut the chamber in the case mouth. 
     A case chamfering assembly  51  is shown in  FIG. 15 . The case chamfering assembly  51  is a combination of the case trimming assembly  10 , replacing the end mill  16  with the case chamfering tool  50 . The barrel  14  may include a large window  24   a  allowing easier lateral adjustment of the cutter  58 . When assembled, the windows in the barrel  14  allow access to the screw  68  to laterally adjust the cutter  58  and to the set screw  59  to hold the position of the cutter  58 . 
     A method for chamfering case mouths according to the present invention is described in  FIG. 16 . The method includes installing a case mouth chamfer tool in a micrometer dial of a case chamfering assembly at step  200 , installing a case adapter bearing for a selected case type into a barrel of the case chamfering assembly at step  202 , inserting a case of the selected case type into the case chamfering assembly at step  204 , adjusting a depth of the cutter to almost touch the case mouth at step  206 , adjusting the cutter laterally to trim a chamber inside the case mouth at step  208 , adjusting the position of the cutter to cut a small chamfer in the case mouth at step  210 , attaching the case chamfering assembly to a drill motor at step  210 , and insert cases into the case chamfering assembly with the drill motor running at step  212 . Step  208  may further include turning a barrel of the case chamfering assembly to align windows in the barrel with a cutter lateral adjustment screw and a cutter holding set screw. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.