The present invention relates generally to a method and apparatus to true archery arrows and more specifically to a method and apparatus to true either an arrow insert or the arrow end for subsequent mounting of an arrow tip in line with the longitudinal axis of the arrow.
A modern arrow comprises several components, some of which are designed to be assembled and/or replaced by an archer with the intent of facilitating interchangeability or repair in a simple home workshop environment or, if need arise, in the field. One group of such components are 1) the arrow tip, 2) the arrow shaft and 3) the threaded insert that connects the arrow tip to the arrow shaft.
To achieve true flight, the longitudinal axis of the tip should be collinear with the longitudinal axis of the arrow shaft. Any deviation of the tip away from the longitudinal axis of the shaft must be minimized to prevent inadvertent arrow flight. An arrow is generally constructed having a hollow cylindrical inner diameter. A threaded insert is placed within the hollow center of the arrow shaft such that a face of the threaded insert is perpendicularly aligned to the longitudinal axis of the arrow shaft. The arrow tip is normally threaded onto or into the threaded insert and abuts the face of the threaded insert. A drawback of the conventional method of installing the threaded insert to the arrow shaft is that assembly is often done by the archer and includes an adhesive to join the threaded insert to the arrow shaft. The following situations are known to cause alignment problems: 1) the face of the threaded insert not being perpendicularly aligned to the centerline of the insert, 2) the combined misalignment of the threaded insert and arrow shaft joint, 3) the build-up of excessive amounts of adhesive between the threaded insert and the arrow shaft forcing the threaded insert face out of perpendicular alignment with the longitudinal axis of the arrow shaft. When any of these situations occur, the tip when threaded into or onto the threaded insert will abut the misaligned insert face forcing the tip out of collinear alignment with the longitudinal axis of the arrow shaft.
The adhesive used to join the threaded insert to the arrow shaft is normally an epoxy or a hot-melt glue. When applying the adhesive, an archer who is performing this operation will not have the necessary tools to ensure that the runout between the threaded insert and the arrow shaft is minimized when the threaded insert is assembled. A small error in runout (i.e., misalignment) on the mounting surface is greatly magnified at the arrow tip. The minimum magnification ratio of this error is normally about 10:1. An exemplary 0.025 mm (0.001 inch) error in runout will therefore magnify to a 0.25 mm (0.01 inch) misalignment of the arrow tip from the desired longitudinal axis of the arrow shaft.
A further drawback exists if the alignment of the machined or squared end of the arrow shaft is not perpendicular with the longitudinal axis of the arrow shaft. An archer when joining the threaded insert to the arrow shaft normally has no means of truing the end of the arrow shaft before insertion of the threaded insert. This error is further magnified when the threaded insert is joined with the arrow shaft. Most arrow shafts are now constructed of aluminum or a carbon fiber composite material. At the present time, there is a need for an effective means to machine, clean, or de-burr the end of an arrow shaft, and, when the shaft material is a carbon fiber composite, an effective means that minimizes splintering of the arrow shaft.
According to one aspect of the present invention, an apparatus is provided to perpendicularly align an end face on an arrow shaft with the arrow longitudinal axis. In this regard, the present invention may be utilized at the forward (tip) end of the arrow shaft with or without an arrow insert or the rear (nock) end of the arrow shaft. Furthermore, the present invention may be used in the first instance to assemble a new arrow during maintenance of an arrow or to re-square an arrow. The apparatus comprises a frame having at least one longitudinal channel. The channel is in parallel alignment with the frame's longitudinal axis. A cutting surface is mounted on the frame perpendicularly aligned to the frame longitudinal axis. An assembly which includes an insert and an arrow shaft is rotatably supported by the channel. The insert end of the assembly is placed adjacent to the cutting surface. The assembly is rotated within the channel and a face of the insert end is cut against the cutting surface to perpendicularly align a face of the insert end with the arrow longitudinal axis.
In a further aspect of the present invention, a hand tool for machining true an arrow insert is provided. This hand tool comprises a tool frame having a head portion and a base portion. The first channel is provided in the head portion. A second channel is provided in the base portion, wherein the second channel is collinearly aligned with the first channel. A cutting tool is supported from the head portion by a tool support channel. A cutting face of the cutting tool is perpendicularly aligned with both the channels. An arrow shaft which has an insert end is longitudinally aligned within both the channels and the insert end is rotated against the cutting face to perpendicularly true the insert end to the arrow shaft.
In a further aspect of the invention, a hand tool for machining true an arrow insert is provided. The hand tool comprises a tool frame having a head portion, a base portion, and a longitudinal axis. A V-shaped first channel is provided in the head portion. The first channel is parallel to the longitudinal axis. A V-shaped second channel is provided in the base portion. The second channel is also parallel to the longitudinal axis and collinearly aligned with the first channel. A cutting tool is supported from the head portion, the cutting tool adjacent to the first channel. A cutting face of the cutting tool is perpendicularly aligned with both the first and the second channels. An arrow shaft having an insert is longitudinally rotatably aligned along an arrow shaft longitudinal axis within both the first and the second channels. The insert is positioned adjacent to the cutting face, and the insert is perpendicularly trued by the cutting face to the arrow shaft longitudinal axis by rotating the arrow shaft within the first and second channels.
In still a further version of the invention, a method for truing an arrow insert is provided. The method comprises the steps of providing a tool frame having a head portion, a base portion, and a longitudinal axis; disposing a V-shaped first channel in the head portion, the first channel parallel to the longitudinal axis; disposing a V-shaped second channel in the base portion, the second channel parallel to the longitudinal axis; supporting a cutting tool from the head portion, the cutting tool adjacent to the first channel; perpendicularly aligning a cutting face of the cutting tool with both the first and second channel; rotatably aligning an arrow shaft within both the first and second channels; positioning the insert end of the arrow shaft and insert assembly adjacent to the cutting face; and rotating the arrow shaft within the first and second channels to remove material from a face of the insert and perpendicularly true the insert face to the arrow shaft longitudinal axis.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
Referring to
First V-channel 18, second V-channel 20 and tool support channel 24 are shown in the arrangement of
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Arrow shaft 46 normally comprises aluminum or carbon fiber composite materials. Most modern arrow shafts are provided in aluminum material. End face 50 of arrow shaft 46 is normally provided perpendicular to the longitudinal axis of arrow shaft 46 such that an insert face 54 of the insert 40 inserted into the arrow shaft 46 is perpendicular to the longitudinal axis of the arrow shaft 46.
Referring now to
To cut or true the insert face 54 of the insert 40, the arrow shaft 46 is rotated in direction of arrow C as shown and simultaneously translated in direction D. A combination of rotation and translation of the arrow shaft 46 presses the insert face against the cutting face 38 to cut or true the insert face 54. It is necessary that a minimum of 50% of the surface area of insert face 54 contact the cutting face 38 of cutting tool 32. This ensures that perpendicularity of the insert face is maintained when the insert face 54 is trued.
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Cutting tool 32 can be affixed to tool frame 10 in a permanent or semi-permanent installation. Means (not shown) of attaching cutting tool 32 to tool frame 10 can be by a strap (not shown) or other mechanical devices. It is necessary to retain the cutting tool 32 against the tool support channel 24 such that the cutting tool 32 is not allowed to rotate as the arrow shaft 46 rotates against the cutting face 38 of the cutting tool 32. A semi-permanent means of affixing the cutting tool 32 is preferred as it permits replacement of the cutting tool 32. The end face 50 of the arrow shaft 46 may also be trued, de-burred, or cleaned using the cutting tool 32 of the present invention. If the arrow shaft 46 material is aluminum, the invention can readily be used to true the end of the arrow shaft 46. If the arrow shaft 46 is a carbon fiber composite material, however, the material of the arrow shaft may splinter against the cutting face 38 of cutting tool 32. The truing of the face of an arrow shaft of carbon fiber composite material must therefore be performed with greater care. When truing, de-burring, or cleaning the end face 50 of an arrow shaft of carbon fiber composite material, the preferable material for the cutting face 38 of the cutting tool 32 would be an abrasive such as a diamond impregnated adhesive, aluminum oxide or carborundum in place of carbide.
In one version of the invention the V-shaped channels 18 and 20, as well as the tool support channel 24 are anodized with a hard plastic coating impregnated in the face of each V-channel. Providing this anodized face reduces the friction when the arrow shaft rotates within the V-shaped channels. In another version of the invention, the V-shaped channels are not anodized with a plastic coating because the material of tool frame 10 comprises a metallic material such that the V-shaped channels are hardened to a Rockwell hardness in the range of about C60 to about C70 Rockwell hardness. This degree of hardness promotes minimum sliding friction between the V-shaped channel and the outside body of the arrow shaft. In yet another version of the invention, the use of dynamic locating devices (e.g. knife-edge rollers, ball or roller bearings, etc.), in place of V-channels, would promote minimum friction in the rotation of the arrow shaft.
Modern arrow shafts vary in diameter up to about 0.89 centimeters (0.35 inches). The use of V-shaped channels or an alternate to the V-shaped channel identified herein assures that the longitudinal axis of the arrow shaft is parallel to the longitudinal axis F of the tool frame 10 regardless of its diameter.
The preferable material for the cutting face 38 of the cutting tool 32 is a high strength steel or carbide material. Other materials can be substituted for the cutting face 38 including Carborundum, aluminum oxide, diamond impregnated, or similar abrasives in place of carbide. A smooth finish is desired for the insert face 54 after truing by the present invention. The material for tool frame 10 is preferentially aluminum. Plastic materials can also be used for tool frame 10 provided that the material chosen provides sufficient stiffness to maintain collinear alignment of the V-shaped channels (including the tool support channel). Collinear alignment of the V-shaped channels is critical to permit truing of the insert face 54 perpendicular to the longitudinal axis of the arrow shaft.
The geometry of the V-shaped channels can be varied from that shown by the figures provided herein without departing from the spirit and scope of the present invention. A V-shaped channel is preferred in order to accommodate a wide range of arrow shaft diameters with the present invention. While V-shaped channels 18, 20 and 24 as shown have an included angle of 90°, a greater or less than 90° separation between walls of the channels can be used without departing from the spirit or scope of the invention. Likewise, other geometric shapes or dynamic locating devices can also be provided as long as the requirement for a minimum of 50% engagement between insert face 54 of insert 40 and the cutting face 38 of cutting tool 32 is provided.
It is desirable to cut or true the insert face of the insert to within about 0.008 mm (0.003 inches) perpendicularity to the longitudinal axis of the arrow shaft. In use it is also desirable to identify when the insert face has been trued over its entire face. This can be accomplished by first marking the insert face, prior to engaging the insert face with the cutting tool, with a material such as a bluing agent, a chalk material, or an ink, i.e. from a permanent ink marker. Visual indication of complete cutting of the insert face will therefore be provided by removal of the marking material from the insert face by the cutting tool.
The present invention provides several advantages. A user in the field can improve the collinear alignment of an arrow tip to the longitudinal axis of the arrow shaft, thus improving arrow flight accuracy. The cutting tool is provided on a tool frame which is relatively small to be easily transported and used in the field. The cutting tool is replaceable and the overall tool frame can be supported on any flat surface.
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 60/358,227, filed on Feb. 20, 2002. The disclosure of the above application is incorporated herein by reference.
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Number | Date | Country | |
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60358227 | Feb 2002 | US |