Abstract: A magnetic force control device includes a first pole piece having an interaction surface, made of a ferromagnetic material, and configured to be in contact with an N pole of a permanent magnet, a second pole piece having an interaction surface, made of a ferromagnetic material, and configured to be in contact with an S pole of the permanent magnet or another permanent magnet different from the permanent magnet, rotary permanent magnet configured to be rotatable to define a first arrangement state in which an N pole thereof is magnetically connected to the second pole piece and an S pole thereof is magnetically connected to the first pole piece and a second arrangement state in which the N pole is magnetically connected to the first pole piece and the S pole is magnetically connected to the second pole piece.

Abstract: In one embodiment, a mobile robot energizes its state-variable anchor into a released state while contacting a payload, and then de-energizes it to put it into an anchored state, attaching it to the payload. The mobile robot may then move the payload to a mounting location while the state-variable anchor is de-energized and attached to the payload. As such, the mobile robot may then energize a state-variable anchor of the payload to put it into a released state while at and contacting the mounting location, and then de-energizes it to put it into an anchored state to attach the payload to the mounting location. To then detach the state-variable anchor of the mobile robot and the mobile robot from the payload after the payload is attached to the mounting location, the mobile robot may then energize the state-variable anchor of the mobile robot to put it into a released state.

Abstract: A system for retaining a vehicular component for painting includes a magnetic fixturing element configured to detachably attach at the vehicular component that is to be painted. The magnetic fixturing element comprises a magnetic element. A fixture includes metallic structure that is configured to engage the magnetic fixturing element. With the fixture engaged with the magnetic fixturing element, the component is magnetically retained at the fixture for painting. With the fixture engaged with the magnetic fixturing element, the component is painted by a painting device of the system. After the component that is magnetically retained at the fixture is painted, the magnetic fixturing element is removable from the component and reusable on other components to be magnetically retained at the fixture and painted.

Abstract: A magnetic flux control device according to the exemplary embodiment includes: a pole piece assembly which is provided with an N pole piece and an S pole piece which are formed with first surfaces and second surfaces and made of a ferromagnetic material, and a permanent magnet which is disposed such that an N-pole is in contact with the N pole piece and an S-pole is in contact with the S pole piece; a first outer pole piece, a second outer pole piece, and a base pole piece which are formed with first surfaces and second surfaces and made of a ferromagnetic material; a coil which is wound around at least one of the N pole piece, the S pole piece, the first outer pole piece, the second outer pole piece, and the base pole piece; and a control unit which controls electric current to be applied to the coil.

Abstract: A combination oven and cutting board has a front opening door and a metal upper surface with features that cooperate with the cutting board. The oven may have an internal heating cavity and a front opening door that incorporates a magnet that is used to pull a rack out of the oven.

Abstract: The invention relates to a magnet, which comprises a first permanent magnet for creating a magnetic field, and a shell and a centre, which are arranged to guide a magnetic flux to an object to be gripped. The magnet further comprises a slide, which is arranged to be movable in relation to the shell and the centre, which slide comprises said first permanent magnet, and an electric magnet for moving the slide. The invention also relates to an attaching device, and attaching arrangement and a method for attaching to an object.

Abstract: A clamp assembly comprises a first clamp including a plurality of magnet devices. Each magnet device includes a permanent magnet and a coil surrounding the permanent magnet. The clamp assembly further comprises a controller for pulsing the coils to selectively magnetize and demagnetize the permanent magnets.

Abstract: A method of manufacturing a magnet assembly that includes surrounding a bonded magnet with a sleeve, heating the magnet, and compressing the magnet in an axial direction such that the magnet and sleeve expand in a radial direction.

Abstract: An apparatus including a harness board and a clamp removably connected to the harness board with a magnetic field. The magnetic field permits the clamp to be removed from the harness board. Also, a post is removably connected to the harness board using a magnetic field, and the magnetic field permits the post to be removed from the harness board.

Abstract: The present invention provides a new and useful magnetic device for removeably attaching objects to metallic surfaces and method of use. It comprises a magnet enclosed in an external casing and is believed to be useful by offering a device with multiple attachment points, including a cleat and loop, and is removeably attached to metallic surfaces thereby allowing the user to securely fasten objects in a non-destructive manner, without marring or damaging the target surface. The device contemplated by this invention is also reusable, can be made in a variety of shapes, sizes and of different magnetic strengths. Finally, this device is resilient and useable in outdoor or high moisture environments, including underwater.

Abstract: A method for assembling a cylindrical magnet assembly, which includes at least one coil mounted on a former, to a bore tube is provided. The method involves providing a cavity in the former at selected locations. At each of the selected locations, the material of the bore tube is deformed to form a radially-directed protrusion. Each protrusion is brought to bear against a periphery of each corresponding cavity.

Abstract: A method for producing a switchable core element-based permanent magnet apparatus, used for holding and lifting a target, comprised of two or more carrier platters containing core elements. The core elements are magnetically matched soft steel pole conduits attached to the north and south magnetic poles of one or more permanent magnets, inset into carrier platters. The pole conduits contain and redirect the permanent magnets' magnetic field to the upper and lower faces of the carrier platters. By containing and redirecting the magnetic field within the pole conduits, like poles have a simultaneous level of attraction and repulsion. Aligning upper core elements “in-phase,” with the lower core elements, activates the apparatus by redirecting the magnetic fields of both pole conduits into the target. Anti-aligning upper core elements “out-of-phase,” with the lower core elements, deactivates the apparatus resulting in pole conduits containing opposing fields.

Abstract: Magnetic clips for use with a substrate holder for holding a substrate in a processing chamber of a plasma treatment system. The clip includes first and second body members each having a clamping surface and a magnet. The first body member is configured to be mechanically connected with the substrate holder. The second body member is pivotally connected by a hinge with the first body member for movement relative to the first body member between closed and opened positions. In the closed position, an edge region of the substrate is positioned between the clamping surfaces. In the opened position, the edge region is released. The magnet on the second body member magnetically attracts the magnet on the first body member, when the second body member is in the closed position, to apply a force that restrains movement of the edge region of the substrate relative to the clamping surfaces.

Abstract: Preferred embodiments of the present magnetic locking system can be used for releasably locking a first component to a second component. In one embodiment, the locking system includes a ferro-magnetic member associated with the first component, where the ferro-magnetic member is made of a ferro-magnetic material, and a housing attached to the second component and positioned adjacent to the ferro-magnetic member. Preferably, the housing includes first and second blocks that sandwich an intermediate block. Further, the first and second blocks are each preferably made of a ferro-magnetic material and the intermediate block is made of a non-ferro-magnetic material. Additionally, there is also an aperture formed within the housing, with a permanent magnet rotatably seated within the aperture.

Abstract: A method and device for a switchable core element-based permanent magnet apparatus, for holding and lifting a target, comprised of two or more carrier platters containing core elements. The core elements are magnetically matched soft steel pole conduits attached to the north and south magnetic poles of one or more permanent magnets, inset into carrier platters. The pole conduits contain and redirect the permanent magnets' magnetic field to the upper and lower faces of the carrier platters. By containing and redirecting the magnetic field within the pole conduits, like poles have a simultaneous level of attraction and repulsion. Aligning upper core elements “in-phase,” that is, north-north/south-south with the lower core elements, activates the apparatus by redirecting the combined magnetic fields of the pole conduits into the target.

Abstract: The magnetic fixing device comprises a clamping plate having a fixing surface to which a clamping object is fixed and plural magnetic force generation mechanisms. The magnetic force generation mechanisms each comprise a magnetic material member facing the fixing surface, plural permanent magnets arranged around the outer periphery of the magnetic material member, a first Alnico magnet placed on the back of the magnetic material member, and a first coil for switching the polarity of the first Alnico magnet, and can be switched between the absorption state in which the clamping object is adsorbed and the non-absorption state in which the clamping object is not adsorbed. An operation state indication mechanism capable of presenting an indicator indicating that the plural magnetic force generation mechanisms are in the absorption state or in the non-absorption state is provided on the fixing surface or outer periphery of the clamping plate.

Abstract: Disclosed is technology for holding a substrate and, specifically, an object holding apparatus including a chuck for holding an object, a holding unit for holding the chuck, a generating unit provided in the holding unit, for generating a field related to an attraction force, a member provided in the chuck and attracted by the generating unit in accordance with the field, and a supporting unit for supporting one of the generating unit and the member, for movement at least in a direction nearing the other and in a direction away from the other.

Abstract: The present invention relates to a movable pole extension (4) for a magnetic clamping apparatus (1) for holding a ferromagnetic workpiece (P), comprising a fixed pole member (5) extending in a predetermined longitudinal direction (X-X) and at least two pole members (6, 7) attached to said fixed pole member (5), said at least two pole members (6, 7) being movable relative to said fixed pole member (5). The movable pole extension is characterized in that it has holder means (8) operably coupled to said fixed pole member (5), wherein said holder means (8) are movable in said predetermined longitudinal direction (X-X) between a first operating position (P1) and a second operating position (P2) and operate on said at least two movable pole members (6, 7) to hold them in coupled contact with said fixed pole member (5).

Abstract: Provided is a magnetically coupled device, a method of assembling the magnetically coupled system, and a method whereby positioning a first arrangement and a second arrangement prevents a magnetic field generated from within a first plurality of magnets and a second plurality of magnets from affecting a magnetically sensitive component.

Abstract: A magnet assembly is provided including a housing having a first end and a second end. A magnet is placed within a recess formed in the first end of the housing and a spring is positioned in at least a portion of the second end of the housing. A method of mounting a magnet assembly in a tool is provided. The method includes providing a magnet assembly including a housing having a recess formed in a first end of the housing and a spring positioned in a second end of the housing. The method further includes placing the magnet assembly into an opening defined in a tool and placing a magnet into the recess, and pressing the magnet against the spring to position the magnet within the tool.

Abstract: A coupling ring (13), which on its underside has a plurality of permanent magnets (16) that are preferably disposed concentrically and with angular offset, and which is disposed laterally on that part of the transport device which is moved in the Z direction, serves to temporarily couple an instrument (10) or tool onto a transport mechanism. The coupling ring cooperates with a coupling plate (17), which is disposed on the upper side of the respective instrument to be coupled-on, and which has permanent magnets (19) of correspondingly opposite polarity disposed with the same distribution.

Abstract: A method of of fabricating an electromagnet is provided in which a core having a flux return backplate on one end and a cover plate on the other end of the core is provided. For example, the flux return backplate may be fixed to one end of the core and the cover plate may be fixed to the other end of the core. A plurality of layers of wire may then be wound about the core between the flux return backplate and the cover plate, prior to fixing a flux return ring to the cover plate to at least partially enclose the wire.

Abstract: A switch type ON/OFF structure for hoisting magnetic disks has a handle turnable towards one side to demagnetize and towards another side to generate a magnetic force to attract and move a work piece. The handle is hinged on one end surface of a hoisting magnetic disk which also has a first detent member and a second detent member. The first and second detent members can stop the turning of the handle. The handle further has an extensible latch member at one side spaced from the handle at a selected interval. The latch member has a distal end slidable over the second detent member and extendable downwards to allow the second detent member to be wedged in the interval and anchored. Thereby the hoisting magnetic disk can provide the magnetic attracting force and hoist and move the work piece safer.

Abstract: An apparatus for magnetizing a wellbore tubular includes a plurality of co-axial magnetizing coils deployed on a frame. The coils are typically deployed about a track on which the tubular may be traversed. Exemplary embodiments may further include a magnetic field sensor disposed to measure the imparted magnetic field along the length of the tubular as it is removed from the track after magnetization. Exemplary embodiments of this invention provide for semi-automated control of tubular magnetization and thereby enable a repeatable magnetic pattern to be imparted to each of a large number of wellbore tubulars.

Abstract: An apparatus for sensing relative positions of mechanically coupled devices. The apparatus includes a magnetically actuated switch connected to a set of flux conductors to form a switch assembly. A permanent magnet is affixed to a set of flux conductors to form a magnet assembly. The flux conductors are positioned adjacently to conduct flux from the permanent magnet to the magnetically actuated switch. Movement of either assembly results in the reduction of flux conduction between the magnet and the magnetically actuated switch. The apparatus can be integrated into a helmet mount for night vision goggles to sense the relative position of the helmet mount for controlling the operation of the night vision goggle.

Abstract: An object holding apparatus including a chuck for holding an object, a holder configured to hold the chuck, a generator provided in the holder and configured to generate a field related to an attraction force, a member provided in the chuck and configured to be attracted by the generator in accordance with the field, and a support configured to support one of the generator and the member. The support is configured to allow the one to move toward the other and away from the other, and the support includes a leaf spring.

Abstract: The electromagnetic clamp and method includes an electromagnet and a clamping piece located on opposite sides of a structure to clamp the structure. The electromagnet attracts the clamping piece through the structure when the electromagnet is energized, such that the electromagnet and clamping piece exert force on the structure, and an operation, such as drilling and/or fastener installation, may be performed on the structure. The configuration of the electromagnet creates the force necessary to securely clamp the structure. The electromagnet includes a coil and a core, and the core of the electromagnet is located within a longitudinal aperture that extends through the coil. The smallest lateral dimension of the core is chosen to maximize the flux density between the core and the clamping piece. As such, the smallest lateral dimension of the electromagnet may be greater than the distance between the clamping piece and the electromagnet.

Abstract: A component carrier for holding at least one component (12), in particular for surface coating by electrodeposition, having at least one holding magnet (31), the magnetic field lines of which run through the component (12) in a region close to a contact surface (36), having a diaphragm (16), which accommodates the at least one component (12) in a holding position (38) with respect to the at least one holding magnet (31) on at least one contact surface (36) of an electrically conductive housing (14), the pole axis of the at least one holding magnet (31) being positioned transversely with respect to the contact surface (36), in which component carrier a resulting magnetic holding force which acts on the at least one component (12) in the holding position (38) can be reduced by displacement of the at least one holding magnet (36) out of the holding position (38) or by displacement of the at least one component (12) out of the holding position (38) or by a relative movement of the at least one component (12) and

Abstract: A method and apparatus for fabricating a rotor for an electric traction motor including forming cavities in the rotor, injecting magnetic material in a portion of the cavities, configuring an electrical winding in a portion of the cavities, and post-magnetizing the magnetic material.

Abstract: A magnetic holding device for storing and organizing tools that are intrinsically or have been made magnetically conductive is disclosed that includes a first plate having a width, a thickness and at least one opening and a magnet having a first and a second magnetic region attached to the first plate, wherein the magnetic regions of the magnet are located on opposite sides of the at least one opening in the first plate.

Abstract: A module (1, 16, 19, 28, 50, 52, 54, 100) for the creation of assemblies comprising at one active magnetic element of attraction (2, 3, 17, 23, 33, 34, 42, 47, 48) and a least one ferromagnetic element (6, 21, 22, 30, 40, 44) suitable for defining areas (13, 14, 35, 36, 88, 90, 80, 82, 110, 10, 250, 260, 92, 94) for connection to other modules, with it is possible to create an assembly of modules (1, 16, 19, 28, 50, 52, 54, 100, 37, 15) which provides a magnetic circuit which closes totally or at least partially via the ferromagnetic elements present (6, 21 22, 30, 40, 44, 55, 104, 37, 15).

Abstract: A device for holding components made of a ferromagnetic material that are arranged consecutively in a row and are held in place with one contact surface resting against at least two adjacent magnetic poles of opposite polarity, with the magnetic lines of force between the magnetic poles being concentrated in a region close to the contact surface of the components without magnetically influencing the working surfaces opposite the contact surfaces, in which the component holding capacity of the device is considerably increased, without impairing the residual magnetic field in the edge areas, by arranging multiple rows of the components parallel to each other and assigning to the outer rows of the components additional magnetic circuits that divert or compensate for the residual magnetic field of the working surfaces of the components.

Abstract: A magnetic doorstop including a first section consisting of a magnet secured with a retaining shim mounted on an elongated adjustment screw and a second section consisting of a magnet secured with a retaining shim mounted on an attachment screw. The first section is attached to an interior wall of a dwelling and the second section is attached to the interior door. When the door is opened, the first and second sections contact magnetically securing the door in an open position.

Abstract: A multi-cathode electron beam plasma etcher is disclosed. The multi-cathode electron beam plasma etcher is comprised of: a vacuum chamber; several cathodes which are installed in the upper end of the upper part of the chamber and generates an electron beam in order to generate plasma in a large area; an acceleration electrode and a deceleration electrode which, form an acceleration and a deceleration tube structure in order to withdraw much of the electron beam, are arranged sequentially from the front of the cathode, and form an electrostatic lens when the differential voltage is applied respectively; first vacuum evacuation device to made the upper part of the chamber vacuum; an etching gas injection device which is installed in the side wall around the upper end of the lower part of the chamber; second vacuum evacuation device which is installed in the lower part of the chamber; and a holder of the etched body which is installed in the lower part of the chamber.

Abstract: A rotary switch adapted to be integrated into a push-to-start electrical control for a clothes dryer or the like employs a rotatable and axially translatable operator having an outwardly extending arm supporting a downward finger which travels across a pivotally mounted and downwardly arcuate lever to open and close contacts mounted on one end of the lever with rotation of the operator. Stops on rotation ensure that the finger is positioned on the lever so as to provide positive biasing of the operator to its end positions. The armature of a relay is actuated by a second arm from the operator contacting the armature within a triangle formed by the electromagnet coil and pivot supports preventing de-stabilization of the armature by the operator. Assembly of the relay to a base of the switch is provided by integrally molded hooks receiving tabs which cover holes necessary for the hook's manufacture.

Abstract: A magnetic socket holder includes a molded plastic tray with a center bar having laminated keeper plates and bar magnets positioned therein to define pole pieces which permit the forming of magnetic circuits that when closed enhance the holding action of sockets in the tray, as well as holding action of the tray on a magnetizable surface. An integrally molded handle is provided for carrying the tray and sockets.

Abstract: A magnetic socket holder includes a molded plastic tray with a center bar having laminated keeper plates and bar magnets positioned therein to define pole pieces which permit the forming of magnetic circuits that when closed enhance the holding action of sockets in the tray, as well as holding action of the tray on a magnetizable surface. An integrally molded handle is provided for carrying the tray and sockets.

Abstract: In the magnetic chuck disclosed herein, a pair of elongate pole members are arranged to provide magnetic contact with a workpiece along parallel lines and thus are somewhat in the nature of rails. Preferably, the ends of the poles are segmented and provide for height adjustment to accommodate workpieces which are not entirely flat. The pole members extend along the sides of an elongate base plate with a space therebetween. Interposed between each pole member and the base member is a relatively thin layer of permanent magnetic material which resists de-magnetation. A switchable permeable magnet is provided between the pole members above the base plate and this latter permanent magnet is surrounded by a coil which allows the polarity of its magnetism to be switched so that it either aids or opposes the thin magnetic layer in polarizing the pole ends.

Abstract: A magnetic chuck assembly comprises top and bottom plates separated by a layer of non-magnetizable material, each plate having magnetizable sections separated by strips of non-magnetic material. A rotor mounted between the top and bottom plates carries a plurality of permanent magnets substantially symmetrically disposed therein. The magnets in each half of the rotor are of the same polarity but those in one half are of opposite polarity to those in the other. When the rotor is turned to a position in which all the magnets of like polarity in one half thereof lie between the magnetizable sections of the plates on the same side of the non-magnetizable strips, the sections become magnetized and hold a magnetizable workpiece in place on the edges of the plate. Switching the rotor to a position in which equal numbers of magnets of opposite polarity lie between the magnetizable sections serves to de-energize the latter and release the workpiece.

Abstract: A holding device for immobilizing a cable includes a generally cylindrical electromagnet with a central passageway extending therethrough and a holding assembly comprised of a ferromagnetic body joined to a tubular stem. The ferromagnetic body and stem have a passageway therethrough and are disposed so that the stem passes through the central passageway of the electromagnet. A cable which passes through the passageway of the stem and affixed thereto is immobilized when the electromagnet is activated.

Abstract: An apparatus for producing a uniform magnetic field in a test sample having an angled end during a magnetic particle test procedure, includes a conductive, angled fixture having a contact surface and an overall shape corresponding to that of the angled end of the test sample, so that when a pulsed current is passed through the blade, the resulting uniform magnetic field permits detection of defect indications in the angled end.

Abstract: A magnetic attachment mechanism adapted for interfacing with the manipulator arm (11) of a remote manipulator system and comprising a pair of permanent magnets (31,32) of rare earth material which are arranged in a stator-rotor relationship. The rotor magnet (32), is journalled for rotation about its longitudinal axis between pole plates (35,36) of the stator magnet (31), each of which includes an adhering surface (35a,36a). In a first rotary position corresponding to the "ON" condition, each of the poles of the rotor magnet (32) is closely adjacent a stator magnet pole plate of like polarity whereby the respective magnet fields are additive for producing a strong magnetic field emanating from the adhering surfaces (35a,36a) for attracting a ferrous magnetic plate 20, or the like, affixed to the payload (20 or 50).

Abstract: A magnetic holding device, comprising magnetically activable holding surface having pole members of different polarities, and at least a first and a second single-pole extension members for said pole members of opposite polarities. Each pole-extension member comprises a base portion fastened to a pole member and a movable portion sliding on said base portion along an inclined surface the sliding surfaces of said first and second pole-extension members are slanted in opposite angular directions in respect to said holding surface of the device.

Abstract: A fixture for locating a workpiece in a precisely established position comprises a lower magnetic base and an upper fixture plate, the workpiece being fixtured on the plate. The base includes a permanent magnet which normally clamps the plate to the base but which is disabled and releases the plate when an electromagnet in the base is energized. Prior to clamping the plate to the base, the plate is located in a precise edgewise position on the base by quickly insertable and removable dowel pins adapted to be received by the plate and the base with a precision fit.

Abstract: The invention provides a magnet roll for separation purposes which is made up of a number of axially disposed substantially cylindrical permanent magnets each of which constitutes a segment of the roll. Adjacent segment ends in the roll are of like polarity with pole pieces being defined between the segments. The pole pieces preferably comprise a laminate of two wafer-like discs of no more than 1.5 mm thickness. The pole pieces preferably have flanges projecting beyond the exposed surfaces of the segments to define peripheral extremities which form ridges of frusto-triangular sections. In the preferred arrangments the wafer-like discs are mounted back-to-back with each disc providing half the frusto-triangular profile of a ridge. Preferably the discs include recesses which snugly accommodate the ends of the permanent magnet segments.

Abstract: The magnetic chuck disclosed herein is of the permanent magnet type in which both a top plate and a shiftable pack comprise alternating major pole pieces and magnets, the pack being shiftable so that its magnets either aid or oppose the magnets in the top plate, thereby to change between holding and release states. Improved holding for thin workpieces is obtained by providing a central region in the top plate in which the major pole pieces are thinner than the magnets and in which a plurality of floating minor pole pieces are positioned in the gaps between the major poles. While less flux is available through the thinner major pole pieces, the floating pole pieces provide an increased number of transitions for flux between top plate and workpiece so the total holding force for thin workpieces is improved.

Abstract: A permanent magnetic chuck in which a workpiece holding plate comprises a plurality of permanent magnets each with a magnetic isolator which are alternatively laminated, said magnetic pole pieces and said magnetic isolator are respectively constructed as layers of a plurality of thin magnetic layers and a plurality of thin non-magnetic layers each of which is disposed alternately with each of said magnetic layers; and a sliding magnet member which comprises a plurality of disk-shaped permanent magnets disposed in round holes provided in said member at the same pitch as the lamination pitch of the workpiece holding plate is disposed. The permanent magnets of the workpiece holding plate are so disposed that the same magnetic poles of the adjacent magnets are opposed to each other. The permanent magnets of the sliding magnet member are so disposed that the magnetic lines of flux pass vertically and that the opposite magnetic poles of the adjacent permanent magnets are opposed to each other.

Abstract: A portable container for food and miscellany capable of protecting and preserving its contents in the rough handling environment of the construction worker. The container comprises an insulated hollow body with a compartmented, covered tray therein and a hinged, insulated lid for closing the body and for holding the tray in place within the body. The body also has a permanent magnet in the bottom thereof for holding the container in place on a magnetically attractable surface.

Abstract: When an electromagnet (2) is employed to lift and turn a slab of steel, there is a risk that the slab is dropped, causing undesirable noise. Also, with a flat contact surface of the electromagnet, there is jerking of the apparatus. Improvement in both respects is achieved by the use of a singly curved convex contact surface (7) of the electromagnet, which provides line contact with the slab at all times, avoiding transitions from line contact to face contact.

Abstract: Rotary magnetic file including a base having a bottom and two sides. A shaft is mounted between said sides and a magnet is rotatably mounted on the shaft. A pair of magnetic members are mounted on said shaft at each side of said magnet. A pair of spacer members are mounted on said shaft on the outside of each magnetic members, the average diameter of the magnetic members being equal and less than the diameter of the spacer members. The edge of the spacer members adjacent to the magnetic members is gradually decreased to the dimension of the magnetic members. Index cards with clips of magnetic material may be mounted on said magnet and or magnetic members, the clips being formed to fit between the spacers in a self-centering manner.