Patent Publication Number: US-2023150152-A1

Title: Lockable tool with sliding scale release

Description:
CROSS REFERENCE To RELATED APPLICATIONS 
     This application claims priority to Ser. No. 17/572,711, filed Jan. 11, 2022, which itself claims priority to Ser. No. 16/689,620, filed Nov. 20, 2019, which itself claims priority to Ser. No. 15/792,204, filed Oct. 24, 2017, and to provisional application Ser. No. 62/436,570, filed Dec. 20, 2016. The entire contents of these applications are incorporated herein by reference. 
    
    
     BACKGROUND 
     The invention relates generally to lockable tools, such as knives, which can be opened with the activation of a release. 
     Lockable knives and other tools, e.g., with spring biased blades, have a variety of configurations and release button designs. For example, some knives have a reciprocating (sliding) button and are referred to as having Flylock mechanisms. Existing Flylock sliding buttons generally move along the long longitudinal length axis of the knife, within an opening in a distal portion of the handle. As used herein, for purposes of reference only, an open knife will be referred to as oriented with the free tip of the blade at the distal end and its blade edge facing upwards, to define a front left side of the handle and a rear right side of the handle. When closed, the tip will point in the proximal direction with the blade edge facing downwards and protected, with a front left handle side and a right rear handle side. 
     The side of the handle portion of a Flylock design knife is typically only a cover plate (“scale”), and not part of the frame or opening mechanism. Flylock mechanisms typically have a complex multiplicity of parts, including pins, springs, levers, cams and screws that are factory assembled into a permanent unit. Typically, they are not internally user serviceable, and are not readily reconfigurable for both left-hand and right-hand activation.  FIG.  5   a    shows a Flylock style knife  501  with a scale  510  installed and a sliding button  511  for releasing the Flylock mechanism showing through an opening  512  in scale  510 .  FIG.  5   b    shows Flylock style knife  501  with scale  510  removed. Sliding button  511  in the direction of arrow  521  lifts a square tip sear  520  out of a square cut recess cavity  521  in a blade  522  (not shown), and a resilient member (not shown) causes the knife to automatically swing from a closed to the open position shown in  FIGS.  5   a  and  5   b   . Knife  501  is closed manually. 
       FIG.  5   c    illustrates a conventional knife  550  activated by the pivoting or rocking motion in the direction of an arrow  551  of an external handle scale  552  on knife  550 .  FIG.  5   d    depicts knife  550  of  FIG.  5   c   , with scale  552  removed, showing an internal spring plate and a sear bellcrank/toggle. The parts of these conventional knives require multiple fasteners and are commonly factory finished. This makes them inconvenient for users to service or reconfigure. Many conventional scale release knives have square cut sears and sear holes. These interacting parts, by nature of a factory manufacturing method, require tolerance clearance to fit together. The resulting tolerance fit leave micro-gaps in the machinery that have a cumulative effect resulting in potential blade wiggle in either open or closed positions. This is observable in surviving Flylock style knives manufactured in the early 1900&#39;s, and also in modern knives, as part surfaces wear with age, increasing the loose play in an “locked” blade. 
     In addition to the complexity of conventional mechanisms, the appearance of these mechanisms can be undesirable. For example, buttons and levers can be unsightly. They can also be difficult to manipulate under certain circumstances. 
     These and other shortcomings in the prior art are addressed by the present invention. 
     SUMMARY OF THE INVENTION 
     An easy opening lockable tool, with a sliding scale north-south (front-rear) release along the longitudinal axis of the tool, is provided by the present disclosure. The tool, such as a knife, can be configured for both right-hand and left-hand use. It can have fewer parts and can be easily serviced or reconfigured by a user. Tools in accordance with the invention can have a sliding scale that can be moved in the distal-proximal/north-south/forward-rearward direction along the longitudinal axis of the tool to activate the release to permit automatic or manual opening and/or closing of the tool. The tool can include a frame with two opposing side walls and a gap therebetween to receive the tool. The tool can swing out the top of the cavity, between open and closed configurations. It can be spring biased or swung with a flip of the wrist. Alternatively, the tool can have an out-the-front opening mechanism, with closed top and bottom edges and a front (distal) opening through which the tool can extend and retract. Each side wall can be the mirror image of the other, for reconfiguration for use by the opposite hand. By slidably mounting the scales on the frame and coupling the scale to the release mechanism, the unlocking mechanism can be activated by reciprocating the scale along the longitudinal axis. 
     In one embodiment of the invention, one and preferably both of the walls can have an opening, such as a keyhole shaped opening having a round portion near the distal end of the wall and a slot proximal to the round portion. The opening can be shaped to receive a circular cam that can be joined to a resilient member, such as a coil kick spring that biases the cam to rotate. Without the spring, it can be opened with a flip of the wrist. The cam can be joined to the tool, to automatically swing the tool open when the cam is released. If present, the slot of the keyhole can have a shelf at its proximal end. 
     A sear can be provided to releasably lock the cam in place, with the tool in the open or closed position. The sear can be biased in camming engagement with the cam, preferably in the distal direction. The sear can have a head for engaging the cam and a shaft extending proximally from the head. The proximal end of the sear shaft can be placed on the shelf. The head portion at the distal end can be a projection (or receptacle) for engaging a corresponding projection (or receptacle) on the cam. For example, the sear head can be wedge shaped and nest into one of a pair of V-shaped grooves in the cam or grooves on the sear head can receive projections on the camming surface. The grooves or projections are preferably symmetric and on opposite sides of the cam, one to lock the cam and the tool open and one to lock the tool closed. In another embodiment of the invention, the wedge or grooves can be formed on a base of the tool, which rotates around a shaft or axle. The tool can be biased into the open position by a spring. In another embodiment of the invention, the scale can be biased into the direction of the groove (or wedge) and the sear can be coupled to the scale. In this embodiment, the sear is indirectly biased into the locking engagement. In still another embodiment of the invention, the tool opens out-the-front by a conventional mechanism that is activated by sliding the scale along the longitudinal axis. Reciprocating the scale, which is coupled to the activation mechanism, along the longitudinal axis, unlocks the tool so that it will automatically open or close. 
     In one embodiment of the invention, one side of the tool can include a sliding cover (scale) coupled to the sear. In one embodiment of the invention, the cam or tool can be biased into the open position. If the tool is locked in the closed position, sliding the scale proximally along the longitudinal axis can unlock the cam or other mechanism and permit the resilient member to rotate the cam (or tool), which in turn, kicks open the tool. Releasing the handle can permit the sear to advance into the cam and eventually the groove in the cam and lock the tool in an open position. To close the tool, the handle is again slid proximally to release the cam from the sear, and the tool can be closed by hand. The scale/cover is released and the sear is resiliently urged in the distal direction and engages a groove on the cam to lock the tool back in the closed position. 
     The sear can have a chisel or wedge shape tip head at its distal end or a matching groove. The circular cam can include V-shaped notches that match a V-shaped sear head or a wedge shaped projection to engage a notch in the tip of the sear. The head can act a cam follower and wedge into the V-notches in the open and the closed positions. This wedging action produces an open blade that locks more stiffly in place, with less movement or play than many other configurations. 
     In one embodiment of the invention, the tool can be fit together similarly to a mechanical puzzle and requires only two fasteners, such as screws or pins—one to connect the scale to the sear and one to connect the cam to the tool. All the other parts can be configured and arranged to fit together into place like a three dimensional jigsaw puzzle. 
     The major components of a tool in accordance with the invention can comprise the tool assembly (a blade or other tool), which is coupled to a cam, which can be coupled to a resilient member such as a coil kick spring; a handle assembly (a frame and one or two sliding covers); and the release assembly (the sear coupled to a cover and resiliently biased into and interacting with the cam). These elements can be puzzle fit and hold themselves in place. The screws or pins fasten together the moving sub-assemblies. The screws or pins are internal and need not be seen when the tool is assembled. This provides a clean outward appearance, without visible pins or screws. 
     The scale release front (left side) scale button is preferably flush and can match the rear (right side) scale cover plate, which only functions to cover the internal mechanism and need not perform a mechanical function other than sealing. Alternatively, both scales can function to activate separate releases for separate tools. Thus, when the tool is a knife, it can appear to be a trick knife with no visible release or activator. 
     Tools in accordance with the invention can be made to be user serviceable, and require no special tools to disassemble and reconfigure between left hand or right hand operation. Thus, this tool design, referred to as a scale release/hidden button design, can include parts, assemblies, features and qualities that constitute, e.g., a knife with a folding blade that may be spring operated that locks open and locks closed. 
     The handle body frame can be a one-piece item with a “C” or “U” shaped channel cross section, having two opposing walls and creating a blade well cavity for receiving the blade (or other feature) in a closed position. An out-the-front embodiment can have no open sides or top/bottom edges, and has an open front. The handle body can include dovetail groove tracks cut along the long axis of one or both sides of the exterior of the handle body and the scale can ride in those tracks. Thus, some, but not all the frame is covered. Alternatively, the dovetail groove can be on the inside of the scale and a rib on the frame can ride in the groove and the scale can cover all of the side of the frame. The case can have edges that wrap around the sides of the frame and cover the frame from top to bottom. The handle body can include a thru hole to act as a blade pivot bushing inside diameter, through one or both of the frame walls and cavities made to conceal internal components, such as the sear and allow access for internal assembly. 
     In another embodiment of the invention, the tool has an out-the-front opening mechanism. For example, the tool can have the mechanism described and depicted in U.S. Pat. No. 7,562,455, the entire contents of which are incorporated herein by reference. This mechanism can be activated by coupling the release to the scale and then activating the release mechanism by sliding the scale along the longitudinal axis. 
     The handle features and following internal parts combine to produce an external appearance of a preferred operating mechanism that is sleek and without visible fasteners. The blade locking device can include a chisel point (wedge shaped) sear that by nature of its physical shape as a wedge, can force the blade to come to battery or precisely stop in position with low wiggle or play. The chisel point sear can interact with a matching V-notched cam surface on a shaft (or vice versa), such as a step-shaft part in a fashion that normal metal fatigue or abrasive wear is not detrimental to the location fit of said parts. Alternatively, the V-notches can be formed into the base of the blade, without the need for a separate shaft. Alternatively, the spring forcing the sear forward can be attached to the scale and the scale can be attached to the sear. Subsequent use will not adversely affect blade alignment, but rather, could cause the contact surface to sharpen and improve the wedge fit. 
     The V-notch cam surface profile can be on a multifunctional step shaft, which when fastened to the tool blade, can index the blade to both open and closed positions, locate and retain the blade within the handle so that it will not fall out, act as a pivot shaft bushing and bearing for the blade rotation, and act as a fastening point for the resilient member, such as a coil kick spring. Alternatively, the cam shaft can be incorporated into the base of the tool. 
     A knife or other tool in accordance with the invention can include insert cover plates referred to as scales, that can slide and move inside or over a dovetail groove track, cut along the long axis of both outer sides of the handle body or inside of the scale. The scale multifunctions as both a cover plate and a release mechanism. The scale release can be flush and match the nonfunctional rear scale cover plate in such a way that it appears to be trick knife with a hidden release. 
     A chisel point sear can be attached to the underside (inner surface) of one of the scales to constitute the operating mechanism sub-assembly or release of the automatic blade. The sear can be attached to the scale with a fastener inserted through openings in the handle body in a manner that the fasteners and sear resilient member, such as a compression spring are hidden from view upon final assembly. 
     A multifunction step shaft and coil kick spring in accordance with the invention can be manufactured with a thin profile, so as to be easily concealed under the exterior scale cover plates. Using multifunction parts can reduce the total number of parts, which can include 1 blade, 1 sear, 1 sear shaft, 2 handle covers, 1 frame, 2 springs, and  2  screws. The parts can be easily disassembled and reassembled by the user, as opposed to a factory permanent pinned assembly. 
     The internal parts, handle and blade in accordance with the invention can all be made to be ambidextrous, such that either the front (left) or rear (right) scale activates the release, so that reassembly can be for either right handed or left handed users. 
     The internal parts can be configured such that the same parts can be used in any blade (or other tool) size and or external profile appearance and provide an easy interchangeability of parts. 
     The internal chisel point sear and the step shaft device can work with a coil kick spring and also with conventional leaf kick springs inside the blade as well. 
     The external sliding scale can be surface cut into a trademark design appearance shape or pattern profile without adversely affecting the internal components, in such a way that the trademark shape applied to the folding tool can also be applied to an Out-the-Front (OTF) knife or telescoping blade knife, so as to produce a matching set. 
     The external sliding scale is interchangeable on existing stockpiles of knives, and can be produced with a variety of grip patterns, semi-precious material inserts, or can be engraved or printed as a billboard with any company Logo. 
     In another embodiment of the invention, the lockable tool is made with a frame having a rear proximal position, a front distal position, a forward direction along a longitudinal axis from the rear position to the front position. The frame has a first plate extending along the longitudinal axis from the rear to front position. A middle plate is parallel to and aligned with the first plate. A second plate is parallel to and aligned with the middle plate, with a gap between the first plate and the middle plate. 
     A base of the tool has a first engagement portion or notch and second engagement portion or notch in the tool base and is pivotably coupled to a forward position or slidingly coupled to the frame. The tool is displaceable between a closed, retracted configuration wherein the tool is enclosed within the frame and an open extended configuration outside the frame, wherein the tip points towards the forward direction. 
     The frame and tool are configured to form a selectively releasable activation mechanism for opening and/or closing the tool. The mechanism has at least one projection selectively and releasably received in the first notch of the tool to lock the tool in the retracted configuration, and to unlock the tool by releasing the projection from the first notch. The second plate is slidably mounted with respect to the middle plate and coupled to the locking mechanism, wherein sliding the second plate along the longitudinal axis with respect to the middle plate moves the projection out of the first notch to unlock the tool, allowing the biasing mechanism to bias the tool into the extended configuration. 
     The tool can be a knife blade, screw driver, comb, corkscrew or file. The lockable tool can be pivotably coupled to the middle plate with a shaft and can be biased into the open extended configuration with a resilient member coupled to the tool and the frame, to urge the tool to pivot from the retracted to the extended configuration. The tool can include a second notch or other engagement portion to lock the tool in the open configuration. The locking mechanism can be adapted and configured such that a projection extends into the second engagement portion when the blade is in the extended configuration to releasably lock the tool in the extended configuration. 
     The locking mechanism can be configured and adapted such that sliding the second plate (scale) along the longitudinal axis moves the projection in the horizontal direction out of the first notch. The projection of the locking mechanism can be biased in a horizontal direction and can include an inclined end. An inner surface of the second plate can include an inclined surface, and sliding the second plate along the longitudinal axis can cause the inclined surface of the plate to contact the inclined end of the projection and displace the projection in the opposite horizontal direction to unlock the tool. 
     The locking mechanism projection base can be of substantially the same shape as the notch. The notch can have a circular shape with a diameter larger than a smallest diameter of the projection base, and the notch has an open portion of the circular shape. The open portion of the notch can have an angle of 80° to 10° of the circular shape. A rod can extend from the projection base in the horizontal direction. The end of the rod can be curved or inclined to interact with an inner surface of the plate, such that moving the plate pushes the rod and thereby, the projection out of the notch. 
     Other objects, advantages and embodiments of the invention will be apparent from the specification and the drawings and the scope of the invention will be indicated in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more readily apparent from the specific description accompanied by the following drawings, in which: 
         FIG.  1    is an exploded perspective view of a lockable tool, in the form of a knife, with a north-south sliding scale release, according to an embodiment of the present disclosure; 
         FIG.  2    an exploded perspective view of the sear and step shaft cam of the tool with sliding scale release of  FIG.  1   ; 
         FIGS.  3   a  and  3   b    are partially assembled exploded perspective views of the tool with sliding scale release aligned with the longitudinal axis of the tool of  FIG.  1   ; 
         FIG.  4    is a side view of variations on a lockable tool with north/south sliding scale release according to different embodiments of the present disclosure; 
         FIGS.  5   a - 5   d    are side views of prior art knives 
         FIG.  6    is a partial exploded perspective view of a tool in accordance with the invention having wedge receiving notches for receiving the wedge shaped tip of a sear, formed into the base of the tool; 
         FIG.  7    is an exploded perspective view of a tool in accordance with the invention in which a sliding scale is biased forward and the sear is coupled to the scale; 
         FIG.  8    is an exploded perspective view in accordance with the invention of a sear having a wedge receiving notch at its tip and a camming shaft having wedge projections for engaging the notch on the sear; 
         FIG.  9    is an exploded perspective view of a tool having a sear with a wedge receiving notch at its tip and a knife blade having wedge shaped projections extending from the blade base, for engaging the tip of the sear in accordance with the invention; 
         FIG.  10    is a perspective view of a tool in accordance with an embodiment of the invention, in which the tool opens out-the-front, in the closed, retracted configuration; 
         FIG.  11    is a perspective view of the tool of  FIG.  10    in an open, extended configuration; 
         FIG.  12    is a cross-sectional end view of a tool in accordance with an embodiment of the disclosure; 
         FIG.  13    is a cross-sectional end view of a tool in accordance with another embodiment of the disclosure; 
         FIG.  14    is a cross-sectional end view of a tool in accordance with another embodiment of the disclosure; 
         FIG.  15    is a cross-sectional end view of a tool in accordance with another embodiment of the disclosure; 
         FIG.  16    is an exploded perspective view of a lockable tool in accordance with an embodiment of the disclosure; 
         FIG.  17    is an exploded perspective view of a lockable tool, in the form of a knife, with a north-south sliding scale release, according to an embodiment of the present disclosure; 
         FIG.  18    is an exploded perspective view of a lockable tool, in the form of a knife, with a north-south sliding scale release, in accordance with another embodiment of the disclosure; 
         FIG.  19    is a partial bottom view of the tool of  FIG.  18   , in a retracted and locked condition; 
         FIG.  20    is a partial side view of the tool of  FIG.  18   , in a partially extended condition, taken along line XX of  FIG.  19   ; 
         FIG.  21    is a partial bottom view of the tool of  FIG.  18    in a partially extended condition; 
         FIG.  22    is a partial side view of the tool of  FIG.  18    in a partially extended condition, taken along line XXII of  FIG.  21   ; 
         FIG.  23    is a partial bottom view of the tool of  FIG.  18   , in a locked, extended condition; 
         FIG.  24    is a partial side view of the tool of  FIG.  23   , in a locked, extended condition, taken along line XXIV of  FIG.  23   ; 
         FIG.  25    is a perspective view of a lockable tool, in the form of an out-the-front knife with a north-south sliding scale release in accordance with an embodiment of the invention; 
         FIG.  26    is a partially exploded perspective view of the knife of  FIG.  25   ; and 
         FIG.  27    is a more fully exploded perspective view of the knife of  FIG.  25   . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present disclosure may be understood more readily by reference to the following detailed description of the disclosure taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this disclosure is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the claimed disclosure. 
     Also, as used in the specification and including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It is also understood that all spatial references, such as, for example, horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of the disclosure. 
     Tools in accordance with preferred embodiments of the invention can include a tool mounted on a frame having a length, height and width. The tools are advantageously opened (unlocked) by sliding a scale (side cover) in the north/south direction along the longitudinal lengthwise axis. The scale can have substantially the same height as the frame or be slightly taller or shorter. The scale can ride in a groove on the frame side defined by ridges at the top and bottom of the frame. This can leave the ridges exposed or the scale can wrap around the ridges to substantially cover the side of the frame from the horizontal perspective. The side of the frame can have a rib, and the top and bottom of the scale can wrap around the top and bottom edges of the rib. In both situations, the scale is coupled to the unlocking mechanism. 
     In another embodiment of the invention, the scale can be secured to the frame with a device extending into the frame. With a security device coupled directly to the frame, a flat engagement of the scale to the frame, that does not involve a mating between the scale and frame, is acceptable. Thus, longitudinal sliding of the scale can unlock and open the tool or unlock an open tool which can close automatically or manually. 
     An exploded perspective view of a tool, in accordance with a preferred embodiment of the invention, is shown generally in  FIG.  1    in the form of a knife  200 . Knife  200  includes a frame  2 , having a U-shaped cross section and a front-side dovetail groove  12  on the front (left-hand) side and a rear-side dovetail groove  13  on the rear (right-hand) side. Knife  200  is assembled for right-handed use, wherein it is activated by moving a left side front cover (scale)  1  in the longitudinal north/south direction of an arrow  201 . Note that frame  2  is symmetrical and knife  200  can be re-assembled as a mirror image for left hand use. 
     Handle frame  2  can be formed from a metal block, milled so that all features are symmetrical, front and back. Frame  2  can be constructed in other manners, including stamping and welding and other ways as will be apparent to those of skill in the field. Handle frame  2  is formed with two opposing walls, a front wall  2   a , which faces a rear wall  2   b , with a blade well cavity  11  therebetween. A front left side scale receiving groove  12  is located on the outside of front wall  2   a  and a rear right side scale receiving groove  13  is located on the outside of rear wall  2   b . Grooves  12  and  13  are optionally formed in a dovetail fashion to help retain the covers (scales) to frame  2 . Additional configurations for slidingly retaining scales  1  and  3  to frame  2  are depicted in  FIGS.  12 - 14   . Other configurations will be apparent to those of skill in the art. 
     Blade well cavity  11  is formed as a narrow gap between walls  2   a  and  2   b , and is slightly wider than a blade  8 . Dove tail grooves  12  and  13  extend along the north/south longitudinal axis of frame  2 . Front scale  1  (left side looking down on knife  200  with the distal end facing forward and the open blade facing down) rides in groove  12 . Rear scale  3  rides in groove  13 . Front scale  1  and rear scale  3  are cut with dovetail edges, to slide into grooves  12  and  13  to retain scales  1  and  3  to frame  2 . 
     Frame  2  is also formed with a pivot hole  14 , which has the form of a circular thru hole, completely through frame  2 . In other embodiments of the invention, the hole can be through only one of the walls or can be in the form of a recess, not a thru hole. Pivot hole  14  is sized to fit the major diameter of a step shaft  7 , preferably with a precise fit. Frame  2  also has a keyseat slot  15 , extending proximally from pivot hole  14 . Keyseat slot  15  has two sections. The distal section of slot  15 , closest to pivot hole  14 , is a thru hole extension from pivot hole  14 . The proximal section of slot  15  is a true keyseat and has a floor that does not extend all the way through the wall of groove  12 . Thus, the proximal end of keyseat slot  15  acts as an internal shelf, and the distal end of slot  15 , near pivot hole  14 , is a thru hole allowing access to the far side internals for parts assembly. The wall of frame  2  having groove  13  is preferably symmetrical to that of groove  12  and should have a mirror image keyseat slot with a shelf at its proximal end for reconfiguration for left hand use. 
     Grooves  12  and  13  in frame  2  are identical in size. Front scale  1  has a size allowing a running and sliding fit into dovetail groove  12 , so that scale  1  may move along the longitudinal axis with finger or thumb pressure in a strictly reciprocating fashion, as a release activator, as discussed below (see arrow  201  indicator markings on scale  1 ). The dovetail edges of rear scale  3  are cut slightly wider as a location fit or press fit, so that scale  3  can be removably tapped or pressed into place into frame groove  13 , as a cover plate. Scale  3  should fit tightly enough, so as not to move with finger pressure during activation of scale  1 . Thus, the dovetail edges of scales  1  and  3  should be cut differently, so that when a user&#39;s hand causes scale  1  to move proximally, the user&#39;s hand will urge scale  3  in a distal direction, which will wedge scale  3  more firmly in place in groove  13 . If reconfigured for left hand use, scale  1  and scale  3  are switched to fit into grooves  13  and  12 , respectively, and scale  1  will act as the release and slide in groove  13 , with scale  3  motionless in groove  12 . 
       FIG.  2    depicts a sear  4 , with a wedge shaped chisel point head  19  at its distal end. Chisel point  19  is preferably formed with two flat sides extending proximally from the point tip. Chisel point  19  is preferably symmetrical. Chisel point  19  of sear  4  also includes a flat side  17  having a connection structure in the form of a screw hole  18  formed all the way or partially through sear  4 , proximal from point  19 . In alternate embodiments of the invention, hole  18  need not be threaded or fully through sear  4  and can have other attachment structures or a smooth bore. A guide post shaft  16  ( FIG.  2   ) extends proximally from chisel point head  19  of sear  4 . A sear spring  5 , which is a compression spring, fits over guide post shaft  16  and acts as a resilient member to urge sear  4  in the distal direction. 
     Sear  4  and sear spring  5  are inserted into keyseat slot  15  of groove  12 . Shaft  16 , with spring  5  thereon rests on the shelf of keyseat slot  15 . Chisel point head  19  extends in the distal direction, into pivot hole  14 . As shown in  FIGS.  1  and  3     b , screw  6  is then inserted into the thru hole portion of slot  15  of groove  13 , then the thru hole portion of slot  15  of groove  12 , then into a hole in the underside of handle scale  1  (not shown). Thus, scale  1  is connected to sear  4  by screw  6  and they can act as a unit, whereby reciprocating scale  1  along the longitudinal axis can displace sear  4  back and forth along the same axis. Compression spring  5  will keep sear  4  and scale  1  biased in the distal position. Hand pressure can compress spring  5  and move scale  1  and therefore also sear  4  in the proximal direction. 
     Referring again to  FIG.  2   , sear  4  acts as a cam follower to a step shaft  7 . Step shaft  7  has a major diameter  20  and a minor diameter  24 . In other embodiments of the invention, it can have a single diameter or multiple diameters. In still other embodiments (see, e.g.  FIGS.  6  and  9   ), the camming surface can be built into the base of the tool. As shown in  FIGS.  3   a  and  3   b   , major diameter  20  nests in pivot hole  14  and is held in place by scale  1  on the front side of groove  12  and by scale  3  on the rear side of groove  13 . Before inserting step shaft  7 , the proximal portion of a blade  8  is placed in the distal end of frame  2 , with the edge of blade  8  facing in the same direction as cavity  11 . Minor diameter  24  is inserted through a thru hole  80  in the proximal end of blade  8 . Blade  8  is then joined to step shaft  7  by inserting a screw  10  through a screw hole  23  (or smooth hole) in step shaft  7  and into a screw hole  100  in the proximal end of blade  8 . Blade  8  and shaft  7  now pivot as a unit about pivot hole  14 . 
     An external end  90  of a coiled kick spring  9  is inserted into a saw cut  25  at the bottom of minor diameter  24 . External end  90  of kick spring  9  presses against frame  2 . In this manner, kick spring  9  is constructed and arranged to impart a rotational bias against step shaft  7 , which in turn imparts rotational bias to blade  8 . 
     With blade  8  in the open position, chisel point  19  of sear  4  will nest in a V-notch  21  ( FIG.  2   ) of major diameter  20 . To release blade  8 , scale  1  is slid proximally along the longitudinal axis, to detach point  19  from notch  21 . The user can then fold blade  8  closed by hand, against the bias of spring  9 . Sear  4  acts as a cam follower until blade  8  is in the closed position and a closed position V-notch  22  faces point  19 . Scale  1  can then be released and sear  4  (and therefore scale  1 ) will then move distally and sear  4  will lock into closed position notch  22 . To open blade  8 , scale  1  is moved proximally along the longitudinal axis; sear  4  disengages from closed position notch  22 ; spring  9  urges shaft  7  to rotate and cause blade  8  to swing open. Sear  4  follows major diameter  20 , until it locks into open position notch  21 , to lock blade  8  in the open position. Scale  1 , sear  4 , spring  5 , shaft  7 , spring  9  and blade  8  are thereby adapted to cause blade  8  to swing into in the open position when scale  1  is moved in the longitudinal proximal direction to disengage sear  4  from shaft  7 . 
     The parts shown are made such that knife  200  can be disassembled and reassembled into a left-hand or right-hand knife by switching scale  1  and scale  3 , moving sear  4  and shaft  7  to slot  15  in groove  13  and reversing sear  4  and screw  6 . 
     Note that compression spring  5 , on shaft  16  of sear  4 , is coupled to front scale  1  by sear retaining screw  6 . That combination constitutes a moving sub-assembly of parts within the whole of knife  200 . Also, step shaft  7 , with kick spring  9  inserted in cut  25  is coupled to blade  8  by screw  10 . It therefore constitutes a separate moving sub-assembly of parts within the whole of knife  200 . 
     Step shaft  7  has multiple purposes and functions. Major diameter  20  of step shaft  7  functions as a main pivot bearing for folding knife blade  8 . It also acts as a structural/puzzle retaining piece which will be explained below with reference to  FIGS.  3   a  and  3   b   . Major diameter  20  has two symmetrical V-Notches  21  and  22 , which are  180  degrees apart, and are sized to match chisel point  19  of sear  4 . Screw hole  23  is positioned  90  degrees from the alignment of V-notches  21  and  22 . Hole  23  can be a smooth bore for a location pin, but is preferably drilled, threaded and countersunk to be suitable for a flathead screw, to fasten step shaft  7  to knife blade  8 . 
     Minor diameter  24  of step shaft  7  fits into hole  80  in the proximal end of knife blade  8 . Minor diameter  24  requires a length sufficient to protrude thru the thickness of knife blade  8 . Minor diameter  24  has bottom saw cut  25 , on which coil kick spring  9  will act, to impart rotational bias to shaft  7  and thereby, blade  8 . 
       FIGS.  3   a  and  3   b    depict other parts of the assembly, and also illustrate the simplicity of the design, and that the manner of assembly is a mechanical puzzle. Because of the way the parts fit together, only two fasteners, such as screws, are required. 
       FIG.  3   a    shows the first steps of the preferred assembly of knife  200 . First, the proximal end of blade  8  is placed into the distal end of cavity  11  of frame  2 . Next, step shaft  7  is inserted thru pivot hole  14  and through hole  80  in the proximal end of blade  8 . The jigsaw puzzle fit prevents blade  8  from falling away from frame  2 , and allows blade  8  to swing back into cavity  11  into a closed condition and out, into an open condition, typical of a folding pocket knife. Then, step shaft  7  is rotated so that hole  23  aligns with a screw hole  100  of blade  8 . Fastener screw  10  is then screwed into hole  100 , thus aligning V-Notches  21  and  22  at the correct index point. 
     Continuing with groove  12  facing up, sear  4  and spring  5  are combined and placed into handle keyseat slot  15 . Scale  1  is then inserted into front handle dovetail groove  12 , in a sliding, free moving fashion. Scale  1  prevents sear  4  from falling out of key seat slot  15 . No additional fasteners are needed. 
       FIG.  3   b    shows the further steps of the assembly of knife  200 . Accessing through pivot hole  14  and the open portion of keyseat slot  15  in frame  2 , from the side of groove  13  ( FIG.  3   b   ), scale  1  is slid until its fastener hole (not shown) is aligned with hole  18  of sear  4 . Fastener screw  6  is inserted through the opening in slot  15 , and into the hole inside scale  1  to attach sear  4  to the underside of scale  1 . Then the inner end of coil kick spring  9  is pressed onto sawcut  25  of the end of minor diameter  24  of step shaft  7 . Finally, rear scale  3  is slid into dovetail groove  13  and releasably or permanently wedged (press fit) into place. Rear scale  3  can also be glued into position or left releasable. 
       FIG.  4    depicts how the blades and covers of a tool in accordance with the invention can be replaced for enhanced production and marketability to amateur knife-makers. One of the benefits of tool designs in accordance with the invention, is that the internal working parts can be standardized and operate with a variety of alternative exterior tool variations. For example, the knife body itself can exhibit changes in the outward appearance and dimensions, without affecting the standard sear, step shaft, springs and screws, which can be stockpiled. 
     It should be understood that although the present disclosure is described as relating to knife blades, that blade element can be replaced by other tools. For example, the knife blade can be replaced by a saw, a ruler, a file, a screwdriver, a fish scaler, a comb, a cork screw, a bottle opener, a can opener, an ice pick, etc. Other replacement blades are contemplated. 
     Furthermore, the ease of disassembly and reassembly can make for kits that include a basic handle component with multiple blades and other tool components. Referring to  FIG.  4   , reference numeral  26  refers to that group of parts (blade pivot shaft, resilient member for the shaft, sear, resilient member for the sear, and two connectors), which are all the internal parts. The automatically opening mechanisms for tools in accordance with the invention can consist essentially of these parts and any other parts can be excluded. These parts can be identical throughout any knife variant. Likewise, a stockpile of handle scales  1  and  3  can be made. The scales should have the male dovetail edges, are square cut, and can run oversize, to be trimmed later. 
     Scale  1  shows as a reference, the chisel point sear fastened to the underside, which converts a normal cover plate scale, into a sliding release. The basic handle frame  2 , can have a rectangular profile. Frame  2  has a large thru bore on one side, which also has a machined key seat stepped slot. Female dovetail tracks run between distal and proximal ends along the length axis. All of this machining enhances the mechanical puzzle effect of the assembly. All of this machining can be confined to the center or one end of the tool body, allowing subsequent modification to the periphery of the handle at a later time. It can be made oversize, to be trimmed later. Other shapes are contemplated. 
     The second row of parts depicted in  FIG.  4   , blade  8 , a handle body  2 ′, a scale or cover plate  1 ′, can be construed as a basic utility knife, with a minimum of machining to be functional. 
     Another benefit of a design in accordance with the invention is the user serviceability of the assembly. Rather than a factory fixed assembly, a variety of blades ( 27 ,  28  and  29 ) can be swapped out by a user with relatively low mechanical skill. Even more Swiss army style saws, files and other devices can be produced, including a disposable razor blade holder, requiring only the two-hole pattern in the base of the folding blade. The existing stockpiles of internal parts simply “plug-and-play” with these options. 
     Another benefit of this design is ease of modification of the handle shape. A handle body  30  that has its profile milled for a tapered hand grip, or another variant profile  32  can be attached. Within specific limits, the handle body can be altered after the fact by a kit buyer to craft his own custom designs. 
     In another embodiment of the invention, a scale  31  is a potential billboard for engraving or printing is available. Buyers can purchase replacements with various semi-precious inlaid materials, or pre-printed sports logos and so forth. 
     A scale  33 , modified to fit a custom profile, the ends can be changed, but the long sides should remain the dovetail shape to fit the sliding track in the handle body. An assembled fancy profile knife  34 , with no visible fasteners can be assembled. A sliding button scale coverplate  35 , which has a surface texture grip pattern milled into its top surface can also be provided. 
     Another benefit of this design is a concern for factory manufacturing. The same setup for a short knife can be used for a longer knife. All of the machining for the release components are on one end of the handle body. Unlike other knives that require custom back spine springs tailored to a specific length, this design permits use of the same basic group  26  for any length knife. 
     A standard rectangular profile handle body  36 , similar to body  2 , except longer, a longer blade  37 , a custom contour profile  38 , an assembly of a long stiletto design  39  with a traction grip pattern sliding scale release button, can all be provided. 
     Not shown is yet another version possible for collectors, a folding boar knife/trench knife, a folding knife with a long blade that is fitted to a short handle body. When closed, the blade end protrudes like a short sheath knife, only to spring open (by a hidden release sliding scale button) into a full length fighting knife. 
     The wedge shape of chisel point  19  of sear  4 , by nature of its wedging action to lock (open or closed) blade  8 , can produce a product that is more solid and robust in both the open and closed positions than previously marketed folding boar knives. All of this is possible by the mix and match/plug and play components, that can be marketed separately or in multi-part kit form. 
     The scale can be removable and interchangeable to swap out advertising company logos engraved or printed as a billboard, or to swap different grip materials. Matched sets of both a folding design of the disclosure and an out-the-front (OTF) knife with similar outward appearance and the north/south slidable scale release of the invention can be achieved. 
     The components of the automatic opening tool with north/south sliding scale release described herein can also be provided as a kit to an end user. The tool can be provided to a user disassembled and the user can assemble the components as desired. 
       FIG.  6    depicts a portion of a lockable tool  600 , in accordance with another embodiment of the invention, in which the wedge receiving notch features of the step shaft of tool  200  are combined with a base  650  of a blade  608 . Thus,  FIG.  6    depicts a blade  608  with an open position V-shaped notch  621  and a closed position V-shaped notch  622  formed into base  650  of blade  608 . 
     An axle  620  replaces stepped shaft  20  of tool  200  and is provided to permit blade  608  to pivot, such as from force provided by a kick spring  609 . Axle  620  rides in a frame (not shown) of tool  600 . The frame of tool  600  can be otherwise similar to frame  2  of tool  200 . An end of kick spring  609  can fit into a cut  625  in base  650  of blade  608 . Spring  609  is otherwise held in the frame of tool  600 . Notches  621  and  622  are sized to receive a wedge shaped head  619  of a sear  604 , urged forward by a spring  605  of the frame of tool  600 , which is modified accordingly. 
       FIG.  7    depicts an exploded view of an automatically opening tool  700 , in accordance with another embodiment of the invention, which is similar to tool  200 . Rather than spring  5  directly urging sear  4  of tool  200  in the distal direction, a spring  705  is positioned in a groove  715  of a frame  702 . An end of spring  705  is coupled to a post on an inside portion of a front scale  701 . Spring  705  urges scale  701  in the distal direction. Scale  701  is coupled to a sear  704 . Sear  704  engages symmetrically oriented V-shaped notches  721  and  722  on a step shaft  720 . A kick spring  709  is coupled to and urges a blade  708  into an open configuration. Step shaft  720  is likewise coupled to blade  708  and operates similarly to tool  200 . 
       FIG.  8    depicts a step shaft  820  and a sear  804  of a tool  800  in accordance with another embodiment of the invention. Sear  804  receives a projection from the step shaft  820 , which is the opposite of the arrangement of tool  200 . Otherwise, the configuration can be similar to tool  200 . Sear  804  is urged in the distal direction, towards step shaft  820  with a compression spring  805 , similar to the construction of tool  200 . Rather than having a chisel point, sear  804  has a V-shaped notch  819 . Step shaft  820  is similar to step shaft  20 , but rather than having a pair of V-shaped notches  21  and  22 , step shaft  820  includes a pair of wedge shaped projections  821  and  822 . Thus, this embodiment of the invention functions similarly to tool  200 , except that the relative positions of the chisel point wedge shaped tip and the V-shaped notches are switched. 
     In accordance with yet another embodiment of the invention,  FIG.  9    depicts a tool  900  having a north/south sliding scale activation in the form of a blade  908 , which functions similarly to blade  608  and has an overall construction similar to tool  600 . However, rather than including notches  621  and  622 , blade  908  includes a pair of projections  921  and  922  formed into a base  950  of tool  908 , to engage with a V-shaped notch  919  of a sear  904 . Sear  904  is urged in the distal direction by a coil spring  905 . Blade  908  pivots about an axle  920 , which is similar to axle  620 . Blade  908  includes a cut  925 , which can engage an end of a kick spring (not shown). As with tool  200  or  600 , to open or close blade  908  moving the scale of tool  900  along the longitudinal axis causes sear  904  to move longitudinally in the proximal direction to disengage either projection  921  or  922  from notch  919 . If blade  908  is closed, the kick spring will urge blade  908  into the open configuration or it can be swung open manually. If blade  908  is open, it can be closed manually. 
     As discussed above,  FIGS.  5   a  through  5   d    depicts conventional automatically opening tools.  FIG.  5   a    depicts knife  501  that is opened by activating button  511 . In another embodiment of the invention, a knife similar to knife  501  can be constructed, without opening  512  and with activation button  511  attached to an inside surface of scale cover  510 . By constructing knife  501  so that scale cover  510  can slide along the longitudinal axis, the knife can be opened and closed with a north/south sliding scale configuration. Similarly, those of ordinary skill in the art will understand how the activation mechanism of knife  550  can be converted to one activated by sliding the scale along the longitudinal axis. 
     Activation mechanisms in accordance with the invention can also be used with out-the-front opening tools.  FIG.  10    depicts an automatically opening out-the-front knife  1000 . Knife  1000  includes a blade  1008  within a frame  1002 . A pair of scales  1001  and  1003  of the same height as frame  1002  are mounted on the sides of frame  1002 . Scales  1001  and  1003  cover frame  1002  from the horizontal perspective. Front cover  1001  can slide along the longitudinal axis in the direction of an arrow  1201 . Front cover  1001  includes a peg  1100  which is coupled to activate the conventional out-the-front opening mechanism, modified to be activated by sliding scale  1001 . Knife  1008  includes any of various known out-the-front opening mechanisms (not shown) on frame  1002 , in which an activation switch is reciprocated along the north/south longitudinal axis. Out-the-front knives typically have an internal extension mechanism to bias the tool both from a closed configuration to an open, extended configuration. They typically also have a retraction mechanism to bias the tool from an open, extended configuration to a closed, retracted configuration. Such extension and retraction mechanisms are well known in the art. Thus, unlocking a closed tool can automatically extend it to the open configuration and unlocking an open tool can automatically retract it to a closed configuration. Both can be accomplished with sliding scale activation in accordance with the invention. 
     U.S. Pat. No. 7,562,455, the contents of which are incorporated herein by reference, in their entirety, depicts and out-the-front opening knife. The knife is activated by reciprocating a button exposed on the outside of the front cover to automatically extend the blade. Activating an extended knife will automatically retract the blade. The activation mechanism of knife  1000  is activated by sliding scale  1001  along the longitudinal axis to cause peg  1100  (or a different type of structure apparent to those skilled in the art) to either cause blade  1008  to extend into the open configuration of  FIG.  11    or to cause knife  1000  to retract to the closed configuration of  FIG.  10   . 
       FIG.  12    depicts the frame and scale covers of an automatically opening tool  1200 , in accordance with an embodiment of the invention, similar to knife  200 . Knife  1200  includes a frame  1202  with a left side front scale receiving groove  1202   a  and a right side rear scale receiving groove  1202   b . A left scale  1201  is slidingly engaged in left groove  1202   a  and a right scale  1203  is removably fixed in right groove  1202   b . Left and right scales  1201  and  1203  cover most, but not all of the respective left and right sides of frame  1202 . 
     Grooves  1202   a  and  1202   b  act as female receptacles for scales  1201  and  1203 . Thus, they cover most of the left and right sides of frame  1202 , but do not cover the entire left and right sides. Scales  1201  and  1203  have a trapezoidal cross section, with a wider inside base portion facing frame  1202  and a cavity therein and a more narrow outside surface facing outward from the central cavity. The outer edges of groove  1202   a  and  1202   b  are angled inward, to retain scales  1201  and  1203  to frame  1202 . 
       FIG.  13    depicts the scales and frame of an automatically opening tool in the form of a knife  1300  in accordance with another embodiment of the invention. Knife  1300  includes a frame  1302  having a left wall  1302   a  and a right wall  1302   b  defining a blade well cavity  1311  therebetween. A left scale  1301  is slidingly mounted on left wall  1302   a . A right scale  1303  is releasably fixedly mounted on right wall  1302   b . Left and right walls  1302   a  and  1302   b  each include a projecting retention rib  1350 . Left and right scales  1301  and  1303  each include a retention groove  1360 . Retention ribs  1350  are received in retention grooves  1360 , to hold scales  1301  and  1303  to frame  1302 . Retention ribs  1350  have flared edges, which extend outward (up and down) from walls  1302   a  and  1302   b . Retention grooves  1360  are defined by the edges of scales  1301  and  1303 , which are flared inwardly. Thus, scales  1301  and  1303  can substantially cover the entire sides of frame  1302 . 
       FIG.  14    depicts the scales and frame of an automatically opening tool in the form of a knife  1400  in accordance with another embodiment of the invention. A frame  1402  of knife  1400  is similar in structure to frame  1302  and includes a left wall  1402   a  and a right wall  1402   b , defining a blade well cavity  1411  therebetween. A left scale  1401  is slidingly mounted on left wall  1402   a . A right scale  1403  is releasably fixedly mounted on right wall  1402   b . Left and right walls  1402   a  and  1402   b  each include a projecting retaining rib  1450 . Left and right scales  1401  and  1403  each include a retention groove  1460 . Retaining ribs  1450  are received in retention grooves  1460 , to hold scales  1401  and  1403  to frame  1402 . Retaining ribs  1450  have flared edges, which extend outward and upward down from walls  1402   a  and  1402   b . Retention grooves  1460  are defined by edges  1461 , which extend inward towards each other. 
     The edges of scales  1301  and  1303  are angled, to match the angled flare of retaining ribs  1350 . This provides a close tolerance, but can be difficult to machine. Edges  1461  of scales  1401  and  1403  can be squared off. This can be easier to machine, but provides a looser fit. However, it can provide more sliding friction. 
     An automatically opening tool  1500 , in accordance with another embodiment of the invention, is shown in  FIGS.  15  and  16   . Tool  1500  is similar to tool  700 , shown in  FIG.  7   . However, the scales are not retained to the frame in a nesting engagement, as with tool  700 . Automatically opening tool  1500  includes a frame  1502 , with a first scale  1501  and a second scale  1503 , mounted on opposite sides thereof. Scales  1501  and  1503  enclose the outward facing sides of frame  1502 . A pair of top and bottom edges  1521  of first scale  1501  and a pair of top and bottom edges  1523  of second scale  1503  are not entrapped by, nor do they entrap any portions of frame  1502 . Rather, the top and bottom outside edges of frame  1502  are notched; top and bottom edges  1521  and  1523  of scales  1501  and  1503  are at right angles to the sides of scales  1501  and  1503 ; and top and bottom edges  1521  and  1523  merely ride against frame  1502 . There is no interaction between frame  1502  and edges  1521  and  1523  to retain scales  1501  and  1503  to frame  1502 . Scales  1501  and  1503  ride over the sides of frame  1502  as a free cap or cover. 
     Automatically opening tool  1500  includes knife  708 , spring  709  and notched shaft  720 , as in tool  700 . However, the nature and arrangement of sear  704  and spring  705  are modified, as are the slots in which they are positioned. Scale  1501  includes a rear attachment member  1551 , which can be a post, hook, wire, or otherwise. Rear attachment member  1551  extends through a slot  1515  in frame  1502  and can attach to a spring, which urges scale  1501  in the distal, forward direction or to a corresponding member to secure scale  1501  in sliding engagement against frame  1502 . A forward attachment member  1552  extends through a forward slot  1516  in frame  1502  and can attach to a sear  704 ′, which can be similar to sear  704 . Alternatively, sear  704 ′ can be coupled to a spring, similar to sear  4  of  FIG.  1   . Because rear slot  1515  and forward slot  1516  are narrow, the attachment of scale  1501  through these slots retains scale  1501  in sliding engagement to frame  1502 . Members  1553  and  1554  can be used to secure scale  1503  to frame  1502 . As will be apparent to those familiar with the art, other arrangements with a cap-like scale that covers substantially all the sides of the frame and exposes substantially none of the frame sides is also acceptable. 
       FIG.  17    depicts a selectively lockable tool  1700 , in accordance with still another embodiment of the invention. Tool  1700  is similar to tools  600  and  900 , in that a base  1750  of a blade  1708  comprises a portion of the locking and release mechanism. Tool  1700  includes a U-shaped frame  1702 , with a pair of sidewalls  1703 , that can be similar to the frames of the other embodiments of the invention. Frame  1702  can be unitary or assembled from multiple pieces. Sidewalls  1703  form a tool receiving slot  1704  therebetween. 
     In a retracted configuration, blade  1708  is received within slot  1704  and pivotably coupled to frame  1702  with a shaft  1720 . Base  1750  includes a shaft receiving through hole  1751 . A complementary shaft receiving hole  1752  is formed through one or both sidewalls  1703 . In one embodiment of the invention, shaft  1720  is formed as a two-piece shaft  1720   a  and  1720   b . Portion  1720   a  is preferably a keyed pivot barrel, with portion  1720   b  as a complementary pivot screw. Together, they act to pivotably secure blade  1708  to frame  1702 . 
     Base  1750  includes a groove  1760  formed therethrough. A stop pin  1770  is positioned through groove  1760  and is located between walls  1703  of frame  1702 . Groove  1760  is partially circular, and concentric with hole  1751  through base  1750 . Thus, as blade  1708  extends and retracts between the open and closed positions, stop pin  1770  rides in groove  1760 . The ends of groove  1760  act to stop blade  1708  from further rotation and help properly position blade  1708  in the retracted or extended configurations. 
     Tool  1700  includes an optional and removable coil spring  1709 , which can be located around shaft  1720 . Coil spring  1709  includes a first end  1709   a , which is received in a corresponding hole in frame  1702 , to secure spring  1709  to frame  1702 . A second end  1709   b  is received in a hole  1725  through base  1750 . Spring  1709  can be enclosed in a pair of cap/bushings  1709   c . The second half of the pair may be placed on the other side of blade  1708  (not enclosing spring  1709 ), in order to ensure centered alignment of blade  1708  in channel  1704 . In another embodiment of the invention, spring  1709  is removed and tool  1700  is opened manually, such as with a flick of the wrist. In another embodiment of the invention, spring  1709  is removed or replaced, as desired, to switch tool  1700  between an automatically opening tool, and a manually opening tool. One or more washers (not shown) can be used to take the position of spring  1709  if said spring is not included. 
     At least one of the walls  1703  of frame  1702  includes a spring receiving slot  1706 . A compression spring  1705  resides in slot  1706 . A pin  1707 , which can be in the form of a torx screw secured to an inside surface of scale  1701 , rides in slot  1706 . An inward end of pin  1707  extends into slot  1706  and is biased in the forward position by spring  1705 . In this manner, because pin  1707  is secured to scale  1701 , spring  1705  biases scale  1701  to the forward position. However, scale  1701  can be manually slid rearwards along the longitudinal axis against the force of spring  1705  to unlock tool  1700 . 
     With blade  1708  in the locked, extended configuration, a release pin  1780  interfaces with the flat tang catch surface as part of a notch  1721 , thus preventing blade  1708  from rotating into the closed configuration. Release pin  1780  is secured to the inner surface of scale  1701 . For example, pin  1780  can be in the form of a shaft extending from a base  1790 . Base  1790  can fit into a recess formed in the inner surface of scale  1701  and can be secured with a torx screw  1791 . To close tool  1700 , scale  1701  is retracted rearwards along the longitudinal axis, which moves release pin  1780  rearwards, out of a position in notch  1721 , where it had locked blade  1708  in the open configuration, and blade  1708  can be rotated closed by hand. Release pin  1780  can slide forward into camming engagement against base  1750 . As blade  1708  rotates further, pin  1780  will slide into a second groove/notch  1722  in base  1750 , to lock blade  1708  in a closed configuration. 
     To unlock blade  1708 , scale  1701  is slidingly retracted against the forward force of spring  1705 , which retracts release pin  1780  out of notch  1722 . In the manual embodiment, blade  1708  can be swung out of slot  1704 , into the open configuration, wherein pin  1780  can be locked into notch  1721 . In the automatic embodiment, spring  1709  biases blade  1708  into the open configuration and pin  1780  can ride against or behind base  1750  until scale  1701  is released and locks pin  1780  into notch  1721 . 
     Still another embodiment of the invention is shown in  FIGS.  18 - 24   , as an automatically opening tool  1800  in the form of an automatically opening knife. Tool  1800  is formed with three parallel plates: a right-side plate  1801 , a middle plate  1802  and a left-side plate  1803 . Optional decorative scales can be used to cover the outside surfaces of plates  1801  and  1803 . As with previously described embodiments, the release mechanism of this embodiment can be used to unlock a blade that pivots into the extended configuration or an out the front knife that extends longitudinally to the extended configuration. The pivoting embodiment is disclosed in  FIGS.  18 - 24   . However, those of ordinary skill in the art will also readily appreciate how the release mechanism can be used to unlock an out the front mechanism. 
     Middle plate  1802  includes a main slot  1815  along a longitudinal front-to-rear (North-South) axis of plate  1802  and tool  1800 . A retention slide  1852  extends from the left-side to the right-side of main slot  1815 . Retention slide  1852  includes a retention head  1853  that is shorter than the length of slot  1815 , so that it can slide forward and rearward in slot  1815 . Retention slide  1852  also includes retention wings  1854 , which are longer than the length of slot  1815  and ride on the left side of middle plate  1802 , outside slot  1815 . Retention head  1853  is secured to front scale  1801 , such as with one or more screws. 
     In this manner, right-side plate  1801  is secured to middle plate  1802  and is displaceable in the forward and rearward directions with respect to middle plate  1802 , as retention slide  1852  is moved forward and rearward in slot  1815 . A spring  1805  is secured to both middle plate  1802  at one end, and right-side plate  1801  at its other end, to bias right-side plate  1801  in the forward direction with respect to middle plate  1802 . However, a user can easily slide right-side plate  1801  rearwards with respect to plate  1802  with even a subtle hand gesture, such as by applying thumb pressure. 
     Middle plate  1802  is secured to left-side plate  1803 . A front spacer  1871  and a rear spacer  1872  are used to provide a gap between middle plate  1802  and left-side plate  1803 . A screw  1872   a  can be used to secure the rear end of middle plate  1802  two left-side plate  1803 . 
     A tool, such as a knife blade  1808  can be pivotably secured within the gap between middle plate  1802  and left-side plate  1803 . A kick spring  1809  can be used to bias knife  1808  into the extended condition. Plate  1803  can be formed with a recess  1803   a  to receive spring  1809 . Recess  1803  a can include a slot  1803 b to receive a foot  1809   b  of spring  1809 , to prevent spring  1809  from rotating with respect to plate  1803 . Blade  1808  includes a hole  1825  to receive an arm  1809   a  of spring  1809 , to impart rotational force to blade  1808 . 
     Plate  1808  is secured in the gap between plates  1802  and  1803  in the following manner. A rotation hole  1851  is provided through the tang of blade  1808 . The female part of a tube nut  1820  extends from right-to-left through a hole  1855  through middle plate  1802 , and then through tang hole  1851 . A male portion tube bolt  1820   b  extends from left-to-right , through plate  1803 , where it is received by tube-nut  1820   a . An assembly of washers and bearings is used to promote smooth movement as blade  1808  is swung between a retracted and an extended configuration. In this manner, spring  1809  biases blade  1808  out of the gap between plates  1802  and  1803 , into the extended configuration. The washers and bearings retain spring  1809  and blade  1808  in place, while promoting smooth movement. 
     A spring-loaded plunger-shaped mechanism  1830  for locking and unlocking blade  1808  in either the extended or retracted configurations is depicted most clearly in  FIGS.  19 - 24   . Referring to first to  FIG.  19   , plunger  1830  includes a base  1831  and a rod  1835  extending from base  1931 . Rod  1835  includes a dome-shaped or otherwise inclined top  1836 . Base  1831  includes an inclined locking portion  1832  having a decreasing diameter as it extends from base  1831 . In the locked, retracted configuration, top  1836  of base  1831  nests in a circular notch  1821  formed through the tank of blade  1808 . To unlock and extend blade  1808 , base  1831  of plunger  1830  is disengaged from notch  1821  of blade  1808 , as described below. 
     A spring  1837  biases plunger  1830  in an extended condition from left-to-right. A wedge-shaped activation button  1840  with an inclined surface  1843  for contacting dome  1836  at the rightmost end of rod  1835  is secured in a recess  1842  in an inside surface of right side plate  1801 . Alternatively, plate  1801  can be formed with a corresponding integral structure having the inclined surface. As right-side plate  1801  is slid rearward with respect to plates  1802  and  1803 , inclined portion  1843  of button  1840  rides on dome  1836 , and urges plunger  1830  towards left-side plate  1803 . This causes locking portion  1832  to recede from notch  1821 , such that plunger  1836  no longer prevents spring  1809  from rotating blade  1808  into the open condition, as shown in  FIG.  21   . 
     Referring now to  FIGS.  23  and  24   , blade  1808  will continue to rotate, until a stop groove  1823  in the tang of blade  1808  meets stop member  1871 . Simultaneously, a security groove  1822  in the tang of blade  1808  permits plunger  1830  to re-extend in the right-side direction, as inclined portion  1832  nests into security groove  1822 . In this condition, blade  1808  is maintained in a locked, extended position. 
     To unlock blade  1808  and return blade  1808  into the retracted condition, first, right-side plate  1801  is slid rearward. This causes ramp  1843  of button  1840  to depress plunger  1830 , and withdraw locking section  1832  from security groove  1822 . A user can then rotate blade  1808  back into the retracted configuration, against the bias of spring  1809 . Once the retracted condition is reached, locking portion  1832  once again extends into notch  1821 , to lock blade  1808  in the closed, retracted configuration. 
     In the retracted condition, locking portion  1852  nests into notch  1821  in the tang of blade  1808 . Notch  1821  is in the shape of a partially open circle. The opening is less than 180°, but more than 0°, which would be a closed circle. Preferred openings are about 160° to 20°, more preferably 150° to 30°. The diameter of the opening should be less than the diameter of plunger base  1831 , but wider than the diameter of dome locking portion  1832 , such that plunger can nest into opening  1821 . 
     In preferred embodiments of the invention, the locking mechanism comprises a base having a projection with an inclined end. This inclined end is configured to nest in a corresponding groove in a base portion of the tool, such as in the tang of a knife blade. The base can be biased into the locking position. A rod can extend from the base. An inclined surface can be moved with respect to the rod, to depress the base in a direction opposite the locking position, to move the projection out of the groove. In the unlocked position, a biasing mechanism can automatically open the tool, or a user can manually close the tool. 
     Those of ordinary skill in the art will readily appreciate that the action of sliding the outer plate or scale of an out the front knife to depress a spring biased plunger, as described above, can activate an out-the-front release mechanism. Therefore, an out-the-front knife can be made with essentially the same release mechanism as described herein with reference to  FIGS.  18 - 24   . 
     Referring now to  FIGS.  25 - 27   , another example of an automatically opening tool with forward-rear (north-south) sliding scale release activation is shown generally as an out-the-front knife  2500 . Knife  2500  includes a blade  2508  mounted within a central frame  2502 . Frame  2502  can be formed with a left half and a right half, held together with screws and the like. Frame  2502  includes a central recess between the left and right halves for receiving blade  2508  when in the retracted configuration. A center slide  2552  is also mounted in frame  2502 , positioned to be at the left-side of blade  2508  when blade  2508  is in the retracted configuration, and engaged at a rear end  2508   r  of the tang of blade  2508 , when blade  2508  is in the extended configuration. Center slide  2552  includes a slot  2553  extending between its front and rear edges, along the longitudinal axis of its right-side surface. 
     A left side sliding scale  2501  is coupled to a left side of center slide  2552 , with a pair of screw bearings  2554 , so that left scale  2501  and slide  2552  move as a unit. Bearing screws  2554  are received in screw receiving holes (not shown) on the right-side surface of left scale  2501 . Screws  2554  extend through respective slots  2555  in center slide  2552 , to permit slight play in moving left scale  2501  forwards or rearwards before the release mechanism is activated. 
     A pair of bias springs  2505  are provided in a pair of respective spring slots  2515  in the left half of frame  2502 , to urge left scale  2501  back to center, after left scale  2501  is slid forwards or rearwards. Bias springs  2505  are thicker than the depth of spring slots  2515  and protrude out of slots  2515 . The protruding portions of springs  2505  are received in a pair of scale slots (not shown) on the right-side surface of left scale  2501 . Thus, left scale  2501  and therefore, center slide  2552  are biased in a centered position by the force of bias springs  2505 . A user can slide left scale  2501  (and therefore, center slide  2552 ) forwards or rearwards along the north-south longitudinal axis of knife  2500 , with respect to this centered position by manually overcoming the force of bias springs  2505 . This slides center slide  2552  in the forward or rearward direction along the longitudinal axis of frame  2502 . When left scale  2501  is released, bias springs  2505  will urge left scale  2501  back towards the centered position with respect to frame  2502 . 
     Blade  2508  is coupled to center slide  2552  with a peg  2526 . A right side end  2526 r of peg  2526  engages a hole  2525  in the tang of blade  2508 . A left side end  25261  of peg  2526  engages slot  2553 , and can slide in slot  2553  along the longitudinal axis, on the right side of center slide  2552 , as blade  2508  extends and retracts. The ends of slot  2553  are open, such that peg  2526  can extend past the front or rear ends of center slide  2552 . 
     An activation spring  2509  is provided on the left side of center slide  2552 . Activation spring  2509  includes a pair of L-shaped brackets  2509   f  and  2509   r  at the respective front and rear ends of activation spring  2509 . Brackets  2509   f  and  2509   r  engage the respective front and rear ends of center slide  2552 . With this construction, spring  2509  stretches, and produces spring tension between brackets  2509   f  and  2509   r . Spring  2509  provides the force to extend or retract blade  2508  when the release mechanism is activated. 
     Knife  2500  is depicted in the extended, locked-open configuration, with blade  2508  extending out the front of frame  2502 , along the longitudinal axis of frame  2502 . Frame  2502  includes a pair of front and rear spring loaded projections  2504   f  and  2504   r , respectively. Projections  2505 f and  2505 r are spring loaded towards the center of frame  2502 , i.e., towards blade  2508 . 
     As blade  2508  travels out of frame  2502 , a rear portion  2508   r  of the tang of blade  2508  slides past front projection  2504   f . This permits projection  2504   f  to spring into engagement with tang rear  2508   r . This locks blade  2508  in the extended position, as it cannot retract past front projection  2504   f . Thus, in the extended, locked configuration depicted in  FIGS.  25 - 27   , pivotable front projection  2504   f  engages a rear portion  2508   r  of the tang of blade  2508 . This locks blade  2508  in the extended configuration, until front projection  2504   f  is moved out of engagement with tang rear  2508   r  by sliding left scale  2501  rearwards. 
     In this extended, locked configuration, peg  2526  extends just past the front end of center slide  2552 . Peg  2526  nests against forward bracket  2509   f  of spring  2509  and thereby stretches spring  2509  in the forward direction, by the additional distance peg  2526  extends past the front end of slide  2552 . Therefore, in the locked extended configuration, spring  2509  is exerting rearward force on peg  2526 , and therefore, blade  2508 . Therefore, when knife  2500  is extended, spring  2509  is exerting rearward retracting force on blade  2508 . Thus, when blade  2508  is locked in the extended configuration, it is preloaded with rearward retraction force. 
     To activate the activation mechanism and automatically close knife  2500  into the retracted configuration, all that is needed is a slight manual movement of left scale  2501  rearwards. This rearward movement of left scale  2501 , and therefore center slide  2552 , will provide additional stretch to spring  2509  and assist with the retraction of blade  2508 . 
     Automatically retracting blade  2508  from the extended configuration proceeds as follows. Frame  2502  includes a front recess  2522   f  to receive front pivotable projection  2504   f , as it is moved away from blade  2508 . Frame  2502  also includes a rear recess  2522   r , to receive a rear pivotable projection  2504   r . Rear pivotable projection  2504   r  is spring loaded towards the center of frame  2502 , i.e., towards blade  2508 . 
     Center slide  2552  includes an inclined front activation projection  2540 f and a rear activation projection  2540 r. To activate the release mechanism, unlock knife  2500 , and automatically retract blade  2508  into the retracted configuration, the following occurs. Left scale  2501  is slid rearwards manually. This provides a slight additional stretch to spring  2509 . Moving slide  2552  also causes front activation projection  2540 f to slide past the inside (blade-side) of front pivotable projection  2504   f . This moves front pivotable projection  2504   f  out of engagement with the rear of the tang of blade  2508 , and blade  2508  is now free to slide rearwards. Because spring  2509  has been rearwardly pre-loaded, front bracket  2509   f  urges peg  2526  rearwards. This causes blade  2508  to slide rearwards in frame  2502 , as left end  25261  of peg  2526  travels rearwards along slot  2553 . 
     As peg  2526  impacts rear bracket  2509   r  of spring  2509 , it will stretch bracket  2509   r  rearwards from the rear end of center slide  2552 . This pre-loads spring  2509  with forward force for the extension of blade  2508  from within frame  2502 . 
     Once blade  2508  has fully retracted into frame  2502 , and peg  2526  will have slid past the rear end of center slide  2552 , the tang of blade  2508  will have slid to the retracted configuration. As noted above, spring loaded rear pivotable projection  2504   r  is urged toward blade  2508 . As the tang of blade  2508  slides past projection  2504   r , projection  2504   r  will engage a locking notch  2521  in the tang of blade  2508 . This locks blade  2508  into the retracted configuration. 
     Also, in this position, peg  2526  extends past the rear edge of center slide  2552 . As peg  2526  moves past the end of slide  2552 , it engages rear bracket  2529   r  and moves bracket  2509   r  slightly past the end of slide  2552 . This stretches spring  2509 . Stretched spring  2509  causes rear bracket  2509   r  to urge peg  2526 , and therefore blade  2508 , in the forward direction. However, blade  2508  is locked in the retracted configuration because projection  2504   r  is engaged in notch  2521 . Nevertheless, moving peg  2526  past the rear edge of slide  2552  pre-loads blade  2508  in the extension direction. 
     To automatically extend blade  2508  from the retracted configuration, the following is performed to activate the automatic mechanism. Left scale  2501  is slid forward. This provides additional stretch to spring  2509 . This also causes center slide  2552  to move forward. Rear activation projection  2540 r of slide  2552  moves rear pivotable projection  2504   r  out of notch  2521 . This releases blade  2508 , and the force of stretched spring  2509  causes rear bracket  2509   r  to push peg  2526  (and therefore blade  2508 ) forward. Blade  2508  slides forward, out of frame  2502 , until peg  2526  hits front bracket  2509   f . Front projection  2504   f  engages the rear of the tang of blade  2508 , to lock blade  2508  in the extended configuration, with peg  2526  urging front bracket  2509   f  slightly past the front edge of slide  2552 . Thus, again, blade  2508  will be in the locked, extended configuration, preloaded to retract, when the activation mechanism is activated with a rearward movement of scale  2501 . 
     To once again close knife  2500 , left scale  2501  is slid to the rear. This moves center slide  2552  towards the rear. Moving center slide  2552  rearward causes front activation projection  2540 f to urge front pivotable projection  2504   f  away from engagement with the rear of the tang of blade  2508 . This unlocks blade  2508 . Because blade  2508  had been pre-loaded towards the rear direction, because peg  2526  had extended activation spring  2509  slightly past the edge of center slide  2552 , once front pivotable projection  2504   f  is moved out of the way, activation spring  2509  kicks blade  2508  to the rear, towards the retracted configuration. This rearward force and the rearward movement of scale  2501  is enough to cause peg  2526  too overshoot the rear edge of center slide  2552 , engage rear bracket  2509   r , and partially load spring  2509  with forward force. This forward force is used to extend blade  2508  forward to the extended configuration when the mechanism is once again activated. 
     Accordingly, as described above, an automatically opening tool in accordance with preferred embodiments of the invention can include a selectively operable locking mechanism, whereby small north/south movements of an outside scale of the tool along the tool&#39;s longitudinal axis can activate the mechanism for opening and/or closing the tool. 
     While the above description contains many specifics, these specifics should not be construed as limitations of the invention, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other embodiments within the scope and spirit of the invention as defined by the claims appended hereto. 
     Where this application has listed the steps of a method or procedure in a specific order, it may be possible, or even expedient in certain circumstances, to change the order in which some steps are performed, and it is intended that the particular steps of the method or procedure claim set forth herein below not be construed as being order-specific unless such order specificity is expressly stated in the claim. 
     While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. Modification or combinations of the above-described assemblies, other embodiments, configurations, and methods for carrying out the invention, and variations of aspects of the invention that are obvious to those of skill in the art are intended to be within the scope of the claims.