This invention relates to systems and methods for manufacturing an 80% (partially unfinished) firearm receiver, with a high rate of success with improved quality, by an unskilled user.
A market exists for incompletely/partially manufactured firearm lower receivers. A firearm lower receiver is unregulated until a minimum level of manufacturing is completed. This level is typically known as “80%”. Firearm lower receivers completed to this level are typically referred to as “80%” lower receivers. These firearms must then be completed by the end user to be operable. In a typical configuration the lower receiver is cast and/or forged and is partially machined, with certain aspects of the inner slot (in which the trigger mechanism resides) remaining uncut. The finishing task cuts this remaining slot with appropriate dimensions and accuracy.
The completion of these lower receivers can be time consuming and quality results may be difficult to achieve with prior art. In accordance with the prior art, the technique for finishing the receiver can place a rotary power tool in a position that is effectively too far away from the lower receiver. As such this prior art technique can produce poor results and broken tooling. Additionally, the prior art technique can involve placement of a rotating tool in direct contact with guiding areas of a jig, which can result in premature wear.
It would be desirable to provide a jig assembly that effectively reduces the unsupported distance between the rotary power tool and the 80% lower receiver and that avoids direct contact between the rotating tool and its guiding features.
This invention overcomes the disadvantages of the prior art by providing a device that reduces the distance between the lower receiver and the rotary power tool and by using additional features to guide the rotary tool instead of placing it in direct contact with any of the plurality of guiding features. An improved jig for manufacturing a firearm lower receiver is comprised of a power tool mount; an adapter; a guide plate with plate screws; a rear support with mounting screws; a front support; and at least one carriage with at least one locating pin. A guide plate is disposed around and below the top surface of a lower receiver and is mounted to the carriage(s) in conjunction with a rotary power tool adapter. The jig is a universal fitment. The jig includes a bearing to support a rotary tool and is constructed and arranged to provide for use of at least one guiding feature to facilitate in the guidance of the rotary tool without placing the rotary tool in direct contact with any of a plurality of guidance features for firearm lower receiver manufacturing. A removable locating pin is situated in a location along the front and rear takedown pin holes of a firearm receiver that is not threaded and is provided with at least one of a pull, a string or other handle for firearm lower receiver manufacturing.
The invention description below refers to the accompanying drawings, of which:
The primary function of a jig is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. In
As described herein, the lower receiver 116 includes a buffer mount 117 for receiving a buffer assembly within the shoulder stock at one end, and the front surface of the magazine well 119 at the other. As defined herein, the buffer mount 117 is at the “rear” end of the lower receiver, while the magazine well 119 is at the “front” end of the lower receiver. As presented in
Note that the carriage plate 114 is provided with three drill guide holes, 132, 134, 136, along its side for the location of and drilling of appropriate diameter pin holes into the lower receiver 116. These guide holes are used to guide and align a drill bit to bore desired holes into the lower receiver side. By way of non-limiting example drill guide hole 132 is a guide hole for a hammer pivot/pin hole, for the subsequent mounting of an assembly that retains the hammer mechanism within the lower receiver. Drill guide hole 134 is a guide hole for a trigger pivot/pin hole, for the later mounting of a trigger pivot/pin to retain the trigger mechanism. Drill guide hole 136 is a guide hole for a selector/safety pivot hole, for the subsequent mounting of a selector/safety lever. These carriage guide holes provide for the accurate and precise placement of the pin holes and are constructed so that an unskilled user can properly place the pivot/pin holes for completion of the assembly of a functioning lower receiver. Holes can be provided on each of opposing carriage plates to drill each side of the receiver in an embodiment. In alternate embodiments holes are provided on one side and the drill passes through both sides of the receiver. The thickness of the carriage plate(s) and close tolerance of the hole to the drill shaft is sufficient to ensure minimal skew or wobble as the drill passes into the receiver side.
The rotary power tool mount 103 is adapted to receive an appropriately sized and shaped rotary power tool 102, as described further below. The rotary power tool retains an appropriate rotary tool 104 in accordance with various embodiments. The term “rotary tool” shall be taken broadly herein to mean any one of a variety of rotating cutting elements that can be mounted removably (or permanently) within a chuck or arbor of the rotary power tool 102. For example a two-flute or four-flute end mill of appropriate diameter (for example, a ¼ inch diameter, or another appropriate diameter between (e.g.) ⅛ inch and ½ inch) can be mounted within the rotary power tool. The mill can include a cutting end and a shaft that is free of cutting surfaces. The shaft is adapted to confront the jig so as to avoid cutting its sides while the cutting end is adapted to reside within the receiver so as to cut the appropriate slot(s) in conjunction with the jig's outline(s). The rotary tool 104 can be constructed from a variety of high-strength materials, such as high-speed steel, tungsten carbide, etc.
As shown, the rear support 110 is threaded into lower receiver 116 via the receiver's rear buffer mount (a large round hole at the rear of the receiver in which a buffer assembly normally resides when assembled into a firearm). Front support 118 is placed between two mounting ears on the lower receiver 116 before an easily removable locating pin 704 inserted through the mounting ears of the lower receiver 116 and through the hole in the front support 118. Illustratively, the front support 118 resides where the front pivot/takedown pin between the upper and lower receiver on a complete firearm normally resides. The pivot hole in this arrangement has been drilled by the supplier of the 80% receiver, and is, thus available for use in mounting the front support via pin 306. As with other receiver holes and structures relied upon to engage the jig assembly, they are reliably located by the manufacturer using sophisticated tooling so that the jig accurately and repeatable mounted to the lower receiver 116, and the corresponding cutting performed by the user is equally reliable and accurate.
After mounting the front support 118, a guide plate 108 is then placed atop the assembly by aligning the holes in the guide plate 108 with the threaded holes in the front support 118, the threaded holes in the rear support 110, and the threaded holes in both the left and right carriages 302 and 114 respectively. The guide plate 108 has a thickness TC1 of between ⅜ and up to ½ inch and a length LC1 of approximately 8 inches (±0.5 inches). The adapter plate 122 has a thickness TC2 of approximately ½ inch and a length LC2 of approximately 4 inches (±0.5 inches). In other embodiments, these thicknesses and widths can vary greater or lesser, depending on the materials used. Once aligned, carriage-to-guide plate screws 106 are inserted through the guide plate 108 and tightened to connect the carriages 114 and 302 to the guide plate 108. The rear support-to-guide plate screws are inserted through the holes in the guide plate 108 and tightened into the rear support 110. The front support-to-guide plate screws 120 are inserted through the guide plate 108 and tightened into the front support 118. These screws 120 can be sheet-metal screws or flat head screws (for example, a #8-32 flat head screw) and the hole(s) in the front support 118 can be sized to receive such screws. The carriage screw 304 is threaded to a corresponding female thread in the left carriage 302 and continued through a threaded hole in the right carriage 114. Illustratively, both the left carriage 302 and right carriages 114 are threaded so if the assembly is placed into the jaws of an external vice or other clamp, it will tend to resist deformation that could damage the lower receiver 116 sandwiched therebetween. The screw 304 can have a recessed drive head (e.g. hex, star, etc.) so that it avoids interference with a clamping jaw (if any). The above thus defines the full set of components of the jig assembly, which are connected either directly or indirectly to the lower receiver 116.
The illustrative jig assembly is depicted as retaining a rotary power tool 102 in the power tool mount 103, but it is contemplated that the power tool can be a non-rotary tool. The jig provides for the use of at least one of the various guiding features (for example, left carriage 302) to be utilized to aid in the guidance of a power tool 102 without placing the tool in direct contact with any guiding feature.
Note that a wide variety of rotary power tools can be employed in association with an embodiment of the jig assembly—for example a small router, drill, hand piece of a flexible-shaft unit or Dremel®-style tool. The rotary tool can be cordless or powered by (e.g.) wall current via a power cable.
The following is a description further views and representations of the assembled jig assembly 100 and corresponding rotary power tool (102) arrangement.
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As described above, the left carriage plate 302 is also provided with three drill guide holes, 632, 634, 636, for the location of and drilling of pivot/pin holes into the lower receiver 116 that are aligned with the right carriage holes 132, 134 and 136, respectively and define the same dimensions. In embodiments in which a pin/pivot defines different diameters on each side, or is eccentric the diameter or placement of the left carriage hole can vary relative to that of the right carriage hole.
In use, the rotary power tool 102 and mount 103 and adapter 122 are placed on top of the guide plate 108 and assembled, as described above, to form the jig. The guide pins 908 are placed into the guide cavities 1202 located within the guide plate 108. The rotary tool 104 protrudes by a predetermined length from adapter 122 so as to interface with the lower receiver 116 situated below guide plate 108. The geometry of the walls of the lower receiver are generally vertical, with the walls of each side parallel to each other up and down and front to back. This geometry provides an opportunity for the unskilled user to complete the machining of the receiver and the performance of the machining tools is optimized by the stability of the jig. The rotary power tool 102, adapter 122, rotary tool 104, guide pins 908, and connecting screws 904 and 906, are then guided within the guide cavities 1202. The location of the guide pins 908 and guide cavities 1202 are placed as to locate the rotary tool 104 in a predetermined location within the lower receiver 116 to achieve the desired results without placing the rotary tool 104 in direct contact with any components other than the lower receiver 116, thus reducing premature wear. Window 920 is a cutout slot at the rear of adapter 122 and provides visual and physical access to the lower receiver during machining operations, as well as preventing contact with the buffer mount 117.
In operation, the user places carriages 114 and 302 in a vise or other clamping device to hold steady. The protrusion depth of the rotary tool 104 is set using indices 1102, 1104, 1106. In practice, this is done by placing rotary tool 104 within the indices and aligning to the appropriate hash mark for the required milling step and moving the rotary power tool adapter 122 into contact with the edge of guide plate 108 therefore setting the protrusion depth to the appropriate hash mark relative to the bottom surface of adapter 122
The assembled rotary power tool 102, mount 103, rotary tool 104, adapter 122 and guide pins 908 are engaged with the guide plate 108 and guide cavities 1202. When the assemblies are placed atop each other with guide pins 908 within guide cavities 1202 the rotary power tool is switched on and rotary tool 104 begins to rotate at a high rate of angular velocity. The user grasps either the rotary power tool 102, mount 103 or adapter 122 and slide the adapter 122 along the guide plate 108. The protruding guide pins 908 contact the walls of the guide 1202 preventing rotary tool 104 from milling into the incorrect locations. This task is continued until guide pins 908 have been translated through the entire guide cavities 1202 removing all the material that rotary tool 104 has contacted within the lower receiver 116. The rotary power tool 102 is then switched off and the rotary tool 104 is allowed to come to rest. The assembled rotary power tool 102, mount 103, rotary tool 104, adapter 122 and guide pins 908 are then lifted off of the guide plate 108. The rotary tool 104 is then placed back into indices 1102, 1104, 1106 to adjust the protrusion depth to the next hash mark of the respective index. When the depth is properly set, the assembled rotary power tool 102, mount 103, rotary tool 104, adapter 122 and guide pins 908 are re-engaged with guide plate 108 and guide cavities 1202. The same procedure is followed to remove this material with rotary tool 104 from lower receiver 116. This procedure is similarly followed until all material is removed from lower receiver 116. Chips can be removed periodically during each cutting task using a vacuum or by rotating the receiver and jig assembly upside down.
In order to guide rotary 104 properly in lower receiver 116 to allow for proper function, guide cavities 1202 have additional cavities contained within them. For example, the entire guide cavity 1202 is milled to a depth greater than 1/16 inch but less than ⅛ inch. A further reduced area within guide cavity 1202 is milled to a depth greater than ⅛ but less than 3/16 inch. Yet another area within the reduced area is milled to a depth greater than 3/16 inch. This allows for two reduced area cavities within the larger guide cavity 1202. Guide pins 908 can be interchanged with varying lengths to allow for the assembled rotary power tool 102, mount 103, rotary tool 104, adapter 122 and guide pin 908 unit to be engaged in either the full guide cavities 1202 or within the reduced area cavities within guide cavities 1202. If a guide pin 908 has a length greater than zero but less than ⅛ of an inch, it would guide within the entire guide cavities 1202. If a guide pin 908 has a length greater than ⅛ but less than 3/16 of an inch, similarly it would guide within the reduced area within the guide cavities 1202. Finally, if a guide pin 908 has a length greater than 3/16 of an inch it would be guided within the cavity within the reduced area cavity which is within the guide cavities 1202. With this arrangement, the assembled rotary power tool 102, mount 103, rotary tool 104, adapter 122 and guide pins 908 can guide the rotary tool 104 to various shapes within the lower receiver by interchanging the guide pins 908 length.
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Initially, prepare your router for milling by installing the universal router adapter 5. If using a variable speed router, start router on slowest speed and gradually increase speed until optimal milling results are achieved. Generally speaking, this will equate to speed “2” to speed “4” on most variable models with “1” to “10” speed adjustments. Do not insert or remove router while it is spinning. Move router smoothly in a clockwise manner, do not mill in straight lines for extended periods. Avoid abruptly pulling the end mill or exerting excessive force to move the end mill. Apply WD-40 liberally while milling to reduce excess heat. Remove chips whenever necessary.
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At block 1802, clamp jig assembly in the vise by the guide plate 1 so right side plate is facing up and ensure that the assembly is level. Use a rag or cardboard between the vise and guide plate to prevent damage to the top surface of the guide plate.
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At block 1808, unclamp jig assembly from vise and flip it over so the left side plate is facing up and re-clamp by the guide plate 1. Ensure that assembly is level. Use a rag or cardboard between the vise and guide plate to prevent damage to the top surface of the guide plate.
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One advantage of the presently described jig assembly or assemblies is they do not require the user to completely disassemble the jig assembly to remove or mount an 80% lower receiver.
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It should be clear that the above-described jig for manufacturing a firearm lower receiver is a universal fitment and facilitates in the guidance of the rotary tool without placing the rotary tool in direct contact with any of a plurality of guidance features for firearm lower receiver manufacturing. It is straightforward to use, resists wear and produces accurate and repeatable results in the hands of both skilled and unskilled users.
The foregoing has been a detailed description of illustrative embodiments of the invention. Various modifications and additions can be made without departing from the spirit and scope if this invention. Each of the various embodiments described above may be combined with other described embodiments in order to provide multiple features. As used herein the directional terms, such as, but not limited to, “up” and “down”, “upward” and “downward”, “rear”, “rearward” and “forward”, “top” and “bottom”, “inside” and “outer”, “front” and “back”, “inner” and “outer”, “interior” and “exterior”, “downward” and “upward”, “horizontal” and “vertical” should be taken as relative conventions only, rather than absolute indications of orientation or direction with respect to a direction of the force of gravity. Furthermore, while the foregoing describes a number of separate embodiments of the apparatus and method of the present invention, what has been described herein is merely illustrative of the application of the principles of the present invention. For example, the foregoing jig can be adapted to machining and finishing other parts for a firearm, such as portions of an upper receiver that is being repaired, modified or fabricated. Moreover, the jig can be sold as part of a kit with additional right and left carriages and guide pins that are adapted for machining other firearms (for example, polishing the internal surfaces or repairing a restored firearm). This jig can be adapted for firearms of various sizes and shapes by interchanging the carriages, thereby providing a jig that can be useful to a person finishing a firearm, and repairing and/or restoring a firearm. Also, it is expressly contemplated that the size and shape of the plates of the jig can vary. In general, they are sized in an embodiment proportionally to the depiction herein relative to the size of the lower receiver. Accordingly, this description is meant to be taken only by way of example, and not to otherwise limit the scope of this invention.
This application is a continuation of U.S. application Ser. No. 16/931,165, filed Jul. 16, 2020, entitled JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER, which application is a continuation of U.S. application Ser. No. 16/206,878, filed Nov. 30, 2018, entitled IMPROVED JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER, which application is a continuation of U.S. application Ser. No. 15/979,322, filed May 14, 2018, entitled IMPROVED JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER, which application is a continuation of U.S. application Ser. No. 15/726,351, filed Oct. 5, 2017, entitled IMPROVED JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER, which application claims the benefit of U.S. Provisional Application Ser. No. 62/404,710, filed Oct. 5, 2016, entitled IMPROVED JIG FOR MANUFACTURING OF FIREARM LOWER RECEIVER, the entire disclosures of each of which applications are hereby incorporated by reference.
Number | Date | Country | |
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20240133647 A1 | Apr 2024 | US |
Number | Date | Country | |
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62404710 | Oct 2016 | US |
Number | Date | Country | |
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Parent | 16931165 | Jul 2020 | US |
Child | 17814201 | US | |
Parent | 16206878 | Nov 2018 | US |
Child | 16931165 | US | |
Parent | 15979322 | May 2018 | US |
Child | 16206878 | US | |
Parent | 15726351 | Oct 2017 | US |
Child | 15979322 | US |