Versatile caliper mounting and measurement accessory

Several caliper accessories are provided that make a conventional caliper suitable for more sophisticated applications traditionally reserved for more expensive measurement devices. One of these accessories, a magnetic caliper mounting device, has a shallow scale-bar-mounting channel for receiving the scale bar of the caliper, a retainer adapted to releasably secure the scale bar of the caliper within the channel of the caliper mount, and a magnet associated with the caliper mount to secure the apparatus to a planar metal surface. Another accessory, a caliper jaw extender, is either incorporated into a magnetic caliper mounting device or provided as a spring pack accessory to a magnetic caliper mounting device. The caliper jaw extender has a spring-biased retractor that hooks onto a caliper's movable frame and biases the frame toward an extended position. Kits are also provided comprising various combinations of a conventional caliper and accessories.

FIELD OF THE INVENTION

This invention relates generally to calipers, and more specifically, to mounting devices for calipers.

BACKGROUND OF THE INVENTION

Sliding calipers are handheld tools used to very precisely measure the distance between two symmetrically opposing sides. They are frequently used in checking or inspecting dimensions of parts and/or assemblies in metal, plastic, and woodworking fields. Conventional handheld sliding calipers are relatively inexpensive, but they are not suitable for many applications, such as the positioning of a sawtable fence, a milling machine travel table or spindle, or a metal lathe carriage, top slide, or tailstock. Stated another way, conventional handheld sliding calipers are generally not suitable as a generic machine positioning device.

Typically, precise movements of machining tools such as sawtable fences, milling machine tables, and metal lathe carriages are made by recording the relative positions noted by crude markings adjacent to a hand wheel or hand crank on the machine. Alternatively, precise single-application devices, designed specifically for a sawtable, milling machine, or metal lathe and typically costing hundreds of dollars, can be obtained and installed on these machines (or in some cases are purchased with the machine).

There is a need for an inexpensive, multiple-application accessory that can adapt a conventional handheld sliding caliper for use in making precise measurements on a wide variety of wood, metal, and plastic-working machines. There is also a need for an accessory for spring-biasing the movable frame of a conventional sliding caliper for two-way positioning detection.

SUMMARY OF THE INVENTION

A simple and inexpensive accessory for a standard caliper is provided to transform a standard caliper from a parts precision measuring tool into a generic machine positioning device.

To meet the need for an accessory that makes a conventional caliper suitable for more sophisticated applications traditionally reserved for more expensive measurement devices, a magnetic caliper mounting device is provided having a shallow scale-bar-mounting channel for receiving the scale bar of the caliper, a retainer adapted to releasably secure the scale bar of the caliper within the channel of the caliper mount, and a magnet associated with the caliper mount and having a flat exposed surface operable to secure the apparatus to a planar metal surface.

The magnetic caliper mounting device mounts, via force of magnetic attraction alone, onto a flat metal surface, such as table saw top, a metal lathe carriage, or a milling machine table, and enables a conventional caliper to be used to precisely position wood-working, plastic-working, and metal-working pieces, such as the fence of a table saw fence, the table and spindle of a milling machine, and the carriage, top slide, and tailstock of a metal lathe. The magnetic caliper mounting device, when mounted on a vertical metal surface, also adapts a conventional caliper into a precise height gage.

The materials and tooling needed to manufacture the magnetic caliper mounting device are relatively inexpensive, and the magnetic caliper mounting device can be inexpensively incorporated into a kit that includes a conventional caliper.

The present invention also encompasses numerous enhancements to the basic embodiment described above. For example, some versions of the caliper mounting device include a tapered jaw mounting channel for receiving the movable jaw of a sliding caliper.

Another version of the caliper mounting device includes two orthogonally-oriented scale-bar mounting channels for facilitating measurements, using two conventional calipers, in two dimensions. Yet other versions include one or more pivotable caliper holders to orient a caliper at a desired angle around the caliper holder's axis of rotation. Yet further versions include a universal joint operable to position the caliper at any angle with respect to the planar metal surface to which the device is mounted. Some versions include a permanent disc magnet, and other, more elegant versions of the caliper mounting devices include one or more switchable magnets to facilitate removal.

To meet the need for an accessory for spring-biasing the movable frame of a conventional sliding caliper, a caliper mounting device—which may or may not be magnetically mounted—is provided having a shallow scale-bar-mounting channel for receiving the scale bar of the caliper, a retainer adapted to releasably secure the scale bar of the caliper within the channel of the caliper mount, and a caliper jaw extender. The caliper jaw extender has a spring-loaded retractor, a refractor connector adapted for connection to the movable frame of the caliper, and a spring with sufficient tension to pull the caliper's movable frame, if unobstructed and connected to the retractor, toward an extended position.

Another embodiment of the invention separates the caliper jaw extender from the caliper mounting device as a spring pack accessory. This accessory can be mounted on a basic caliper mounting device to bias a conventional caliper's movable frame toward the extended position.

Other accessories are also provided, including a caliper mounting device for the T-slot of a milling machine, a caliper mounting device for the carriage guide of a metal lathe, and a magnetically-mounted depth probe stop accessory to adapt the caliper mounting device for measuring movements of the table of a milling machine.

It is the inventor's intent that the scope of any of the claims be defined by the language of the claims, and not narrowed by reference to the embodiments described in this summary, the detailed description of the invention, or to any particular need, object, or suggested solution described in this specification. As such, the invention will be understood to encompass embodiments that meet only one of the needs, or have only one of the advantages, described above, as well as embodiments that meet various combinations of the needs and have various combinations of the advantages described above.

DETAILED DESCRIPTION

In describing preferred and alternate embodiments of the technology described herein, as illustrated inFIGS. 1A-39B, specific terminology is employed for the sake of clarity. The technology described herein, however, is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish similar functions.

FIGS. 1A and 1Bdisplay a conventional sliding caliper10mounted in one embodiment of a magnetic caliper mounting apparatus20. The caliper10comprises a scale bar12, a movable frame13, depth probe14, a fixed outside jaw15, a movable outside jaw16, a fixed inside jaw17, and a movable inside jaw18. Movable outside jaw16and movable inside jaw18are rigidly connected to the movable frame13. Depth probe14is also coupled to and moves synchronously with the movable frame13. The particular caliper10depicted in the drawings also comprises a zero-resettable digital readout19, in which a user can place the movable frame13in a desired “zero” position and press a “zero set” button8on the digital readout19, so that the digital readout will indicate the precise distance the movable frame13is later moved from that “zero” position. A typical digital readout19has a resolution and accuracy of approximately 1 thousandth of an inch (˜25 micrometers) or better. Other conventional calipers include dial calipers vernier calipers that incorporate a dial or vernier scale rather than (or in addition to) the digital readout19. Most conventional calipers also have a retainer or clamping screw251(FIG. 25) to enable a user to block the movable part and easily transfer a measurement.

Most conventional sliding calipers10share some common dimensions. The scale bar12typically has a width of about five-eighths of an inch, and a thickness of about ⅛ of an inch. The outside jaw16has a straight inside edge and a tapered outside edge that tapers at an angle of about 15 degrees from the straight inside edge for most of the jaw length. The depth probe14is recessed within a bottom-side slot of the scale bar12and telescopes between retracted and extended positions.

FIGS. 2A-2Cand3depict a basic embodiment of a magnetic caliper mounting apparatus20configured to mount a conventional sliding caliper10near and its longitudinal axis9parallel to a metal surface. The mounting apparatus20comprises a permanent disc magnet22, a caliper mount24, and a retainer30adapted to releasably secure a caliper's scale bar within a channel of the caliper mount24. The magnet22has a flat exposed surface38for securing the apparatus20to a metal surface without a clamp or screw. A bolt or rivet39secures the caliper mount24to the magnet22.

InFIGS. 2A-2Cand3, the caliper mount24takes the form of a molded cylindrical plastic housing having a height less than 1 inch and a diameter of about 1½ to 2½ inches, or more preferably about 1¾ inches. Other, significantly different, caliper mount embodiments are depicted in further drawings.

Caliper mount24includes a shallow primary channel25for receiving the scale bar12of a sliding caliper10. The scale bar mounting channel25has a width26of approximately five-eighths of an inch, that is, slightly wider than the standard width of the scale bar12of a conventional sliding caliper10. The scale bar mounting channel25has a depth27of approximately 0.110 inches, that is, slightly less than the standard thickness of the scale bar12of a conventional sliding caliper10. The scale bar mounting channel25extends transversely between opposing channel walls28and29and longitudinally between opposite edges31and32of the caliper mount24.FIG. 1Bdepicts a caliper10mounted within the scale bar mounting channel25.

InFIGS. 2A-2Cand3, a shallow nested groove35extends longitudinally along and down the middle of scale bar mounting channel25, and facilitates unhindered movement of the telescoping depth probe14of a sliding caliper10mounted on the caliper mount24. The groove35preferably has a width of approximately one-quarter inch. InFIGS. 4A-4Band5, a slightly wider curved recess45replaces the nested groove35and serves the same function.

The caliper mount24preferably also includes a tapered jaw mounting channel21for receiving the movable outside jaw16of a sliding caliper10. Tapered jaw mounting channel21extends from the perimeter of the caliper mount24to the scale bar mounting channel25. The width of tapered jaw mounting channel21tapers from a width of approximately seven-sixteenths of an inch at the perimeter of the caliper mount24downward, at an angle of approximately 15 degrees, to the scale bar mounting channel25.FIG. 1Bdepicts a caliper10mounted within the tapered jaw mounting channel21.

The invention contemplates a wide variety of retainers adapted to releasably secure the scale bar12of the caliper10within the scale bar mounting channel25of the caliper mount24. InFIGS. 2A-2Cand3, the retainer comprises a thumb screw30that is mounted vertically with respect to the scale bar mounting channel25of the caliper mount24. The thumb screw30comprises a twist cap33that presses onto a socket head cap screw34. A plastic washer36is mounted on a shaft34of the thumb screw30(i.e., on the socket head cap screw34) and is adapted to press against the top surface of the scale bar12of the caliper10. The threads of the socket head cap screw34are received by a nut37that is mounted on the inside of the caliper mount24, above the magnet22. InFIGS. 2A-2C, the retainer30is adapted to also releasably secure the movable outside jaw16of a sliding caliper10within the tapered jaw mounting channel21of the caliper mount24.

FIGS. 5 and 6depict an alternative magnetic caliper mounting apparatus50with another embodiment of a retainer. The retainer comprises a thumb screw60that is mounted horizontally with respect to the scale bar mounting channel55of the caliper mount54. As withFIG. 3, the thumb screw50comprises a twist cap63that presses onto a socket head cap screw64. The threads of the socket head cap screw64are received by an internally threaded insert or bushing66. The thumb screw60, when turned to the engaging position, presses against a flexible wall52of the scale bar mounting channel55, causing the flexible wall52to press against a side of the scale bar12of the caliper10. When turned to a disengaging position, the thumb screw60backs off the flexible wall52, thereby releasing the caliper10from the mounting channel55's grip.

FIGS. 7A and 7Bdepict another alternative magnetic caliper mounting apparatus70with yet another embodiment of a retainer. As withFIGS. 5 and 6, the retainer comprises a thumb screw72that is mounted horizontally with respect to the scale bar mounting channel75of the caliper mount74. As withFIGS. 5 and 6, the thumb screw72comprises a twist cap73that presses onto a socket head cap screw71, whose threads are received by an internally threaded insert or bushing76. But in this embodiment, the thumb screw72has a plastic or polymer tip78that, when turned to the engaging position, protrudes through wall79of the scale bar mounting channel75, and presses against a side of the scale bar12of the caliper10. When turned to a disengaging position, the tip78of the thumb screw72backs away from the side of the scale bar12of the caliper10, releasing the caliper10from the mounting channel75's grip.

FIGS. 8A and 8Bprovide perspective and exploded views of another alternative magnetic caliper mounting device80with yet another embodiment of a retainer. The retainer comprises a cam82that is mounted to a side of the channel85of the caliper mount84and is operable to rotate about a vertical axis between a caliper release position and a caliper retaining position. Cam82comprises a handle83that is secured by a pin86to the end of a vertically-mounted cam shaft81. When the cam handle83is turned from a release position to a retaining position, the projecting cam portion87of the cam shaft81presses against a flexible wall89of the channel85, causing the flexible wall89to press against a side of the scale bar12of the caliper10. The handle83also has a projecting cam portion88that, when turned to the engaging position, overlies and additionally clamps the caliper scale bar12in place.

FIGS. 9A and 9Bprovide perspective and exploded views of another embodiment of a magnetic caliper mounting device90with a different type of cam92for securing the scale bar12of a caliper10. Like cam82, cam92is mounted to a side of the channel95of the caliper mount94and is operable to rotate about a vertical axis between a caliper release position and a caliper retaining position. Cam92comprises a cam handle93that is mounted on a cooperating cam piece99and secured by a pin96to a shaft91that anchors the cam92to the housing of the caliper mount94. When the cam handle93is turned from an open position to a closed position, the projecting cam portion97of the cam piece99overlies and clamps the caliper scale bar12in place.

FIGS. 10A and 10Bprovide perspective and exploded views of another embodiment of a magnetic caliper mounting device100with a different type of cam102for securing the scale bar12of a caliper10. Like cams82and92, cam102is mounted to a side of the channel105of the caliper mount104and is operable to rotate about a vertical axis between a caliper release position and a caliper retaining position. Cam102comprises a cam handle103that is secured by a horizontal pin106to a shaft101that anchors the cam102to the housing of the caliper mount104. A washer107mounted on the shaft101beneath the handle103facilitates movement of the cam102. The cam102works by pushing down on the cam handle103(which rotates about horizontal pin106) to lock the caliper10in place or pulling up on the cam handle103to release the caliper10.

FIG. 11Aillustrates a magnetic caliper mounting device110using a spring finger112to secure the scale bar of a caliper. A spring finger112is embedded in one of the walls113of the scale bar mounting channel115of the caliper mount114. Other embodiments may include an opposing pair or two opposing pairs of spring fingers112mounted in both walls113of the scale bar mounting channel115.FIG. 11Bis a perspective view of another embodiment of a magnetic caliper mounting device116using both a thumb screw117and a spring finger112to bias the scale bar of a caliper to the opposite wall (and optionally under a lip, not shown, of the opposite wall) of the channel115.

FIG. 12illustrates the use of the magnetic caliper mounting device20as a height gage for precise true size comparisons of a widget125. The magnetic caliper mounting device20is attached to the vertical face124of a metal piece123sitting on top of a flat table122. A digital readout caliper10is mounted in the magnetic caliper mounting device20so that the scale bar12is vertically positioned. The movable frame13is moved to its lowest position, with the depth probe14contacting the surface of the table122. The “zero set” button8of the digital readout19is set. Next, the movable frame13is lifted, a widget125inserted beneath the depth probe14, and the movable frame13again lowered, this time so that the depth probe14contacts the top of the widget125. Then, the widget's width is read from the digital readout.

FIG. 13illustrates the use of the magnetic caliper mounting device20mounted on a table saw130for precise positioning of the table saw fence135. The magnetic caliper mounting device20is attached to the upper surface of the table saw130. A digital readout caliper10is mounted in the magnetic caliper mounting device20so that the scale bar12is positioned horizontally and perpendicular to the saw fence135. When a very precise cut is needed for a groove or board width, the following procedure may be utilized. First, adjust the fence135in close proximity to the desired location of the cut. Second, make a sample cut. Third, use a caliper10to measure any needed adjustment to the cut. Fourth, mount the caliper10in magnetic caliper mounting device20, position the caliper's movable frame13so that the depth probe14touches the fence135, and press the “zero set” button8. Fifth, move the fence135, while watching the caliper's digital readout19, until it reflects the needed adjustment measured in step3.

FIGS. 14A and 14Billustrate an embodiment of a magnetic caliper mounting device140having two orthogonally-oriented scale-bar mounting channels142and146operable to mount a caliper10in two different orientations or two calipers10simultaneously. A first scale-bar mounting channel142is oriented to hold the caliper parallel to a planar metal surface to which the caliper mounting device140is mounted. The channel142is preferably also oriented at an angle of between 15 and 45 degrees, more preferably about 30 degrees, to tilt a mounted caliper10in a direction that makes measurement reading easier. A second scale-bar mounting channel146is oriented to hold the longitudinal axis9of another caliper10perpendicular to the planar metal surface to which the caliper mounting device140is mounted. A retainer144or148positioned to the side of each channel142and146is operable to secure a caliper within its corresponding channel142or146. Because channels142and146are oriented at right-angles to one another, the device140is operable to simultaneously mount two calipers10in orientations perpendicular to one another.

FIGS. 15A-15Bare perspective views of another embodiment of a magnetic caliper mounting device150with a switchable permanent magnet (not shown) and a pivotable caliper holder152operable for mounting a caliper10at any of a plurality of angular orientations around an axis parallel to the caliper mounting device's mounting surface. The caliper mounting device150comprises a molded plastic main housing156that houses a switchable permanent, non-electric magnet, a knob157for activating and de-activating the magnet, and a pivotable caliper holder152. Pivotable caliper holder152, which may be made of molded plastic, has a caliper scale-bar mounting channel153and a retainer154for securing a caliper10within the channel153. Caliper holder152is joined to the main housing156by a joint or hinge155, which in a simple form takes the form of a screw that can be tightened against a nut158. The switchable permanent magnet is preferably, but not necessarily, of a form described by U.S. Pat. No. 6,707,360, which is incorporated herein by reference.

FIG. 16Aillustrates a caliper10mounted on the caliper mounting device150ofFIGS. 15A-15B.FIG. 16Billustrates a caliper10and spring pack260(FIG. 26) mounted between the retainer154of the caliper mounting device150and the clamping screw251of the movable frame13of the caliper10(FIG. 25). As explained further below, the spring pack260biases the movable frame13together with movable outside jaw16, movable inside jaw18, and depth probe14toward an extended position.

FIG. 17illustrates another embodiment of a magnetic caliper mounting device170with a switchable magnet and a pivotable caliper holder172operable for mounting a caliper10at any of a plurality of angular orientations around an axis perpendicular to the caliper mounting device's mounting surface. The caliper mounting device170comprises a molded plastic main housing176that houses a switchable, non-electric magnet, a knob177for activating and de-activating the magnet, and a pivotable caliper holder172. Pivotable caliper holder172, which may be made of molded plastic, has a caliper scale-bar mounting channel173and a retainer174for securing a caliper10within the channel173. Caliper holder172is joined to the main housing176by a joint or hinge175, which in a simple form takes the form of a screw that can be tightened against a nut178.FIG. 19illustrates a caliper10mounted on the caliper mounting device170ofFIG. 17.

FIG. 18illustrates yet another embodiment of a magnetic caliper mounting device180with two pivotable caliper holders182and186operable for mounting calipers at any of a plurality of angular orientations around first and second axes that are respectively parallel and perpendicular to the caliper mounting device's mounting surface. The caliper mounting device180comprises a molded plastic main housing181that houses a switchable, non-electric magnet, a knob187for activating and de-activating the magnet, a first pivotable caliper holder182, and a second pivotable caliper holder186. The first pivotable caliper holder182is joined to the main housing181in the same manner as FIG.15A's pivotable caliper holder152is joined to the main housing156. The second pivotable caliper holder186is joined to the main housing181in the same manner as FIG.17's pivotable caliper holder172is joined to the main housing176.

FIG. 20Aillustrates yet another embodiment of a magnetic caliper mounting device200with a switchable magnet and a universally jointed caliper holder202operable to mount a caliper10at any angle with respect to a planar metal surface to which the caliper mounting device200is mounted. The caliper holder202is coupled to a switchable magnetic base201through a universal joint203. Universal joint203comprises three links204,206, and208each separated by ball joints205and207placed in series between the caliper holder202and switchable magnetic base201.FIG. 20Billustrates a caliper10mounted in the magnetic caliper mounting device200ofFIG. 20A. Also, a spring pack260(FIG. 26) can be mounted on either the thumb screw209or a projecting dowel211of the caliper holder202, depending on the direction in which the caliper10is mounted relative the caliper holder202.

FIG. 21illustrates yet another magnetic caliper mounting device taking the form of a featherboard210operable to be mounted to a metal surface such as a table saw top222(FIG. 22) through two switchable magnets223and224. The featherboard210comprises a caliper holder225joined to a standard featherboard, such as that marketed by Magswitch Technology, Inc., based in Littleton, Colo., that includes two switchable magnets223and224.

FIGS. 23,24A and24B provide perspective and exploded views of another embodiment of a magnetic caliper mounting device230with an integrated caliper jaw extender235for biasing the movable frame13of a mounted caliper10into an extended position. Caliper jaw extender235comprises a retractor243such as a string or a cord that is spring-biased to spool around a bobbin or spool241. A connector244, such as a ring or a hook, on the end of the retractor243is provided to connect the retractor to a protuberance such as the clamping screw251—of the movable frame13A spirally-round reel spring240is mounted on its outside end247to the inside cavity wall242of the spool241. The inside end246of the spring240is attached to the center post249of the main housing248. The center post249also receives the rivet39which is used to secure the disc magnet22to the main housing248of the device230. The spring240has sufficient tension to pull an unobstructed movable frame13that is connected to the caliper jaw extender235toward an extended position.

One final minor part depicted inFIG. 24Ais the L-bracket nut245. L-bracket nut245serves the same function as nut37ofFIG. 3; that is, to receive the threads of socket head cap screw34. Here, the “L” of the L-bracket nut is provided to extend around the spool241.

InFIGS. 23 and 24A, the main housing248not only houses both the caliper jaw extender235and the disc magnet22, but also provides the channeled surface that serves as the caliper mount. In another embodiment, the reel spring240of mounting device230is substituted with a constant force spring290as shown and described in connection withFIGS. 28 and 29. The caliper mounting devices70,80,90,100,110,140,150,170,180,200, and210described above may also incorporate similar spring mechanisms.

FIG. 25illustrates a caliper10mounted in the magnetic caliper mounting device230ofFIG. 23. The refractor connector244is hooked on to the clamping screw251of the caliper10, thereby biasing the movable frame13together with the movable outside jaw16, movable inside jaw13, and depth probe14into an extended position. The retractor243preferably has a length sufficient to extend the connector244at least 4 inches, and more preferably, about 5 to 5¾ inches, away from the main housing248. In this manner, the movable frame13of a conventional caliper10can be biased toward an extended position along its entire range of travel (or, if not, a substantial part of that range of travel) upon the scale bar12.

FIGS. 26 and 27illustrate a caliper jaw extender in the form of a spring pack accessory260that is physically independent of the caliper mounting device. Spring pack accessory260connects a wide variety of embodiments of the caliper mounting devices (e.g., devices20,50,70,80,90,100,140,150,170,180,200,210) with the movable frame13of the caliper10to bias the movable frame into an extended position. Spring pack accessory260comprises a housing base278and housing cap279that enclose a spool271around which a retractor273is wound. The retractor273, which inFIGS. 26 and 27takes the form of a cord, is biased into a spooled position by a reel spring270that is embedded in the cavity272of the spool271. A connector274, such as a ring or a hook, is provided to connect the end of the retractor273to the movable frame13of the caliper10. The reel (or spiral torsion) spring270has sufficient tension to pull an unobstructed movable frame13that is connected to the spring pack accessory260toward an extended position. The retractor273preferably has a length sufficient to extend the connector274at least 4 inches, and more preferably, about 5 to 5¾ inches, away from the housing base278.

A base connector275is provided to mount the spring pack accessory260to the magnetic caliper mounting device20. Preferably, the base connector275comprises a molded plastic ring or hook adjoining or formed together with the housing base278, and having an interior diameter slightly larger than the diameter of the twist cap33of the magnetic caliper mounting device20.

FIGS. 28 and 29illustrate an alternative embodiment of a spring pack accessory280that uses a spirally wound constant force spring290instead of a reel spring270. Spring pack accessory280comprises a housing base298and housing cap299that enclose a constant force spring290mounted on a drum291. An interior loop end297of the spring290is mounted to anchor296of drum291before being placed around shaft292of housing base298. Here, the “retractor” comprises a portion of the constant force spring290. A connector294, such as a ring or a hook, is provided to connect the end of the constant force spring290to the movable frame13of the caliper10. The constant force spring290has sufficient tension to pull an unobstructed movable frame13that is connected to the spring pack accessory280toward an extended position. The constant force spring290also preferably has a travel length sufficient to extend the connector294at least 4 inches, and more preferably, about 5 to 5¾ inches, away from the housing base298. A base connector295like base connector275is provided to mount the spring pack accessory280to the magnetic caliper mounting device20.

FIG. 30Aillustrates the spring pack accessory280ofFIG. 28positioned above a magnetic caliper mounting device20and caliper10.FIG. 30Billustrates the spring pack accessory280mounted on the magnetic caliper mounting device20by hooking base connector295onto twist cap33. The constant force spring290of spring pack accessory280is connected to the movable frame13of the caliper10by having connector294hooked onto clamping screw251.

The caliper mounting device230or spring accessory pack260or280can be used to precisely measure the linear distance between first and second positions of an adjustable portion of a machining tool. A method could be described as follows: (1) obtaining a digital caliper10having a scale bar12, a movable jaw16, a telescoping depth rod14that moves cooperatively with the movable jaw; and a digital readout19having a zero-set button8; (2) mounting the scale bar12of the digital caliper10to a caliper mount20; (3) mounting the caliper mount20to a motionless portion of the machining tool in an orientation wherein the telescoping depth rod14is parallel with a linear path between the first and second positions, and wherein a measurement end of the telescoping depth rod14, while in a substantially retracted position, butts up against an adjustable portion of the machining tool in its first position; (4) mounting a spring-tensioned retractor243or273between the movable frame13and the caliper mount20in order to bias the depth rod14toward an extended position; (5) resetting the digital readout19of the caliper10to the zero position; (6) moving the adjustable portion of the machine from the first position to the second position, during which the spring-tensioned retractor retracts, causing the telescoping depth rod14to maintain contact with the adjustable portion of the machine; and (7) reading the digital readout19of the caliper10to measure the distance traveled between the first and second positions.

FIG. 31illustrates a rod-mountable non-magnetic caliper mount310. Caliper mount310comprises a scale bar mounting channel315and retainer318for securing the scale bar12of a caliper10. Caliper mount310further comprises a cylindrically-shaped hole312for affixing the device310to a rod (not shown), and a tightener319, such as a bolt or screw, for clamping the device310to the rod. The hole312preferably has a diameter of approximately ¼ or ⅜ of an inch (when tightened), making it suitable for mounting on a standard magnetic base holder such as that marketed by McMaster-Carr based in Robbinsville, N.J.

FIG. 32Aillustrates another non-magnetic caliper mount320configured for mounting on the horizontal mounting bar of a metal lathe. Caliper mount320comprises a scale bar mounting channel325and retainer328for securing the scale bar12of a caliper10. Caliper mount320further comprises a channel322sized and shaped to mount on the horizontal mounting bar of a metal lathe.FIG. 32Billustrates a caliper10mounted on the caliper mount320and a spring pack accessory260hooked on both the caliper mount320and the movable frame13of the caliper10.

FIG. 33is a perspective view the non-magnetic caliper mount320ofFIGS. 32A-32Bmounted on the bed334of a metal lathe330to provide for precise positioning of the lathe saddle or carriage332. A caliper10is mounted in the caliper mount320, and a spring pack accessory260is mounted on the caliper mount320and caliper10to bias the movable part13toward the lathe saddle or carriage332. As hand crank336is turned, causing the saddle or carriage332to move to the right or left, the caliper10provides precise information of the position of the lathe saddle or carriage332. It will be understood that a magnetic caliper mounting device20can be used in place of the non-magnetic caliper mount320.

FIGS. 34A and 34Billustrate another non-magnetic caliper mount340configured for mounting on the X-axis T-slot of a mill. Caliper mount340comprises a scale bar mounting channel345and retainer348for securing the scale bar12of a caliper10. Caliper mount340further comprises a T-slot connector342. T-slot connector342comprises a projection346sized and shaped to fit in the horizontal portion of the mill's X-axis T-slot, and a bolt343whose head349fits in the vertical portion of the mill's X-axis T-slot. A wing nut347is provided to tighten the bolt head349against an inside wall of the T-slot.FIG. 34Cillustrates a caliper10mounted on the caliper mount340and a spring pack accessory260hooked on both the caliper mount340and the movable frame13of the caliper10.

FIGS. 35A-35Care perspective views of a magnetically-mounted, universally positionable caliper depth probe stop accessory350. Depth probe stop accessory350comprises a base member351and two rotatable arms352and354. Base member351has two magnets353and356for securing the depth probe stop accessory350to a flat metal surface. Each of the rotatable arms352and354are pivotally attached to the base member351, and can be rotated about an axis to limit the extent of movement of the depth probe14of a caliper10. The rotatable arms352and354rotate about two perpendicular axes that run parallel to the flat metal surface to which the accessory350is secured.

FIG. 36Ais a perspective view of the non-magnetic caliper mounting device340ofFIGS. 34A-34Band the caliper depth probe stop accessory350ofFIGS. 35A-35Cmounted on a milling machine360to provide for precise positioning of the travel table362. The milling machine360comprises a travel table362mounted on a milling machine table Z-axis support frame364mounted in turn to a base frame363of the milling machine. The milling machine360also comprises an X-axis hand crank365operable to move the travel table362to the right or left relative to the milling machine table Z-axis support frame364, a Y-axis hand crank366operable to move the travel table362toward the front or back of the milling machine table Z-axis support frame364, and a Z-axis hand crank367operable to move the milling machine table Z-axis support frame364up or down relative to the base frame363.

The travel table362includes a T-slot361. The non-magnetic caliper mounting device340is mounted to this T-slot361so that it moves with the travel table362. A caliper10is mounted on the non-magnetic caliper mounting device340. The caliper depth probe stop accessory350is magnetically mounted to the milling machine table Z-axis support frame364, and rotatable arm352is positioned to stop the depth probe14of the caliper10. A spring pack accessory260is mounted on the caliper mounting device340and caliper10to bias the movable part13toward the arm352until the depth probe14comes into contact with the arm. As hand crank365is turned, causing the travel table362to move to the right or left (along the X-axis), the caliper10provides precise information—typically far more precise than the information that can be obtained by examining the mill's own measurement markings—of the position of the travel table362.

FIG. 36Bis a perspective view of the magnetic caliper mounting device20ofFIG. 2and the caliper depth probe stop accessory ofFIGS. 35A-35Cmounted on a milling machine to provide for precise positioning of the travel table362. A metallic X-axis T-slot-connecting platform369is mounted in the T-slot361, and the magnetic caliper mounting device20is mounted on the platform369. In all other respects, the steps described above in connection withFIG. 36Aare carried out, with the same results.

FIGS. 37A & 37Bprovide perspective and exploded views of a caliper kit370comprising a sliding caliper10as shown inFIGS. 1A-1Band a magnetic caliper mounting device20as described inFIGS. 2A-2C. The sliding caliper10has a fixed jaw15attached to a scale bar12and a movable jaw16mounted for sliding along the scale bar12. The caliper mounting device20has a magnet22with a flat exposed surface for securing the sliding caliper10to a planar metal surface without a clamp or screw, a shallow channel25for receiving the scale bar12of the caliper10, and a retainer30adapted to releasably secure the scale bar12within the channel25. Channel25is about five-eighths of an inch wide and extends longitudinally between opposite edges of the caliper mounting device20. The kit370also includes a part bay or mold372for positioning the caliper10and magnetic caliper mounting device20in the container371.

FIGS. 38A & 38Bprovide perspective and exploded views of another caliper kit380comprising a container381, the sliding caliper10ofFIGS. 1A-1B, and a magnetic caliper mounting device230with an integrated spring-loaded caliper jaw extender235as described inFIGS. 23 and 24. The kit380also includes a part bay or mold382for positioning the caliper10and magnetic caliper mounting device20in the container381.

FIGS. 39A-39Bprovide perspective and exploded views of yet another embodiment of a caliper kit390comprising a container390, a caliper10, the magnetic caliper mounting device20ofFIGS. 2A-2C, and the spring pack accessory260ofFIG. 26. The kit390also includes a part bay or mold392for positioning the caliper10and magnetic caliper mounting device20in the container391.

This invention also contemplates caliper kits that include combinations of a caliper10with alternative and additional accessories, such as the caliper mounts310,320, and340ofFIGS. 31,32A, and34A, the depth probe stop accessory350ofFIG. 35A. This invention also contemplates accessory kits that lack a caliper10but include any combination of caliper mounting devices and accessories shown and described in this specification.

Having thus described exemplary embodiments of the present invention, it should be noted that the disclosures contained inFIGS. 1A-39Bare exemplary only, and that various other alternatives, adaptations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the specific embodiments illustrated herein, but is limited only by the following claims.