Abstract: An extension for use with a socket wrench is provided. A drive socket is at a first end of the extension. A hexagonal drive surrounds the drive socket and extends from the first end of the extension towards a second end of the extension. A flange with a knurled edge is at a second end of the hexagonal drive. A tool gripping flange is between the flange with the knurled edge and the second end of the extension. A male drive is at the second end of the extension.

Abstract: A tool bit holder that accommodates and secures specific ranges of hexagonal wrench sizes in different physical orientations therein, for four purposes: speed rotation of the tool for fast bolt extraction, support of the hexagonal wrench's shaft for an increased torque application, mechanically strengthening of a hexagonal wrench, and for the application of torque centered about the longitudinal axis of the working arm of the hexagonal tool bit so as to prevent the stripping out of the hexagonal socket in the mechanical fastener.

Abstract: A wrench assembly for attachment and removal of a tip to a handpiece of a surgical system includes a core and a shell including a central portion that defines a central bore. In various embodiments, the core includes an outer portion fixedly coupled to the shell and an inner portion configured for insertion into the central bore. The inner portion is removably coupled to the outer portion by a separation mechanism configured to facilitate separation of the inner portion from the outer portion at a predetermined torque.

Abstract: A selectively flexible extension tool includes a line assembly; and a plurality of sequentially arranged links, the line assembly operable with the plurality of sequentially arranged links to move the plurality of sequentially arranged links between a slacked position and a tensioned position, the plurality of sequentially arranged links spaced from one another when in the slacked position to allow the plurality of sequentially arranged links to pivotably move relative to one another, the plurality of sequentially arranged links pressed against one another when in the tensioned position to rigidly fix the plurality of sequentially arranged links to one another.

Abstract: A reaming guide is provided that includes a peripheral member configured to mate with a peripheral guide feature; a rigid body extending from the peripheral member to adjacent to a reaming head of a reamer, where the rigid body is configured to be mounted to the reamer proximal of the reaming head; and a depth stop coupled with the rigid body, the depth stop having a distal portion configured to contact a first reamed glenoid surface when the reaming head has fully reamed a second reamed surface to a planned depth, the second reamed surface being angled to the first reamed surface.

Abstract: A screw bit body which allows for efficient torque force application onto a socket fastener. The screw bit body includes a plurality of laterally-bracing sidewalls, a first base, and a second base. The laterally-bracing sidewalls are radially distributed about a rotation axis of the screw bit body with each further including a first lateral edge, a second lateral edge, a bracing surface, and an engagement cavity. The engagement cavity creates an additional gripping point to prevent slippage in between the screw bit body and the socket fastener. The engagement cavity traverses normal and into the bracing surface. Additionally, the engagement cavity traverses into the screw bit body from the first base to the second base. The engagement cavity is specifically positioned offset from the first lateral edge by a first distance.

Abstract: A hex headed bit and socket for enhanced non-slip application of torque force having a hex head with contoured fastener engagement surfaces. The contoured fastener engagement surface extends transversely in angular longitudinal inclination. Defined multiple engagement edges correspondingly embed themselves during rotational engagement within the so engaged fastener pulling the hex head bit into the engaged fastener imparting enhanced translateral points of tool engagement for extraction. Recessed areas on flat hexagonal free end tool portion defining alternate spaced pairs of parallel engagement edges.

Abstract: A storable and labor-saving screwdriver and screwdriver heads thereof are provided, relating to the field of screwdriver technology, which includes a grip handle in a cylinder shape and a handle head labor-saving assembly, wherein a rear end of the grip handle is provided with the handle head labor-saving assembly, the handle head labor-saving assembly is retractable, a plurality of inner hexagonal storage chambers are uniformly distributed on the grip handle along a longitudinal direction. The screwdriver can be used to tighten and replace screws of different specifications and models. It has advantages in simple operation, compact structure, and smaller volume, which is easy to carry, and easier for a screwdriver to tighten screws and save labor.

Abstract: A tool bit includes a drive portion configured to be selectively coupled to a tool and composed of a first material, a shank coupled to the drive portion ad being composed of the first material, and a working end portion configured to engage a fastener. The working end portion includes a first segment and a second segment. The first segment is coupled to the shank and composed of the first material. The second segment is fixed to the first segment at a connection interface and composed of a second material different than the first material. The second segment includes a first portion and a second portion. Solely the second portion engages the fastener when the tool bit drives the fastener.

Abstract: The present invention provides a handling tool (60, 160) for a dental component (20, 40) having a distal end (69, 169), a proximal end (68, 168) and a longitudinal axis L. Further, the handling tool (60, 160) comprises a grip (63, 163) at the proximal end, a shaft (65, 165) located distally of the grip (63, 163) with an engagement section (61, 161) for engaging an engagement feature (32, 132) of a fastening element (30, 130) and a retaining section (62, 162) for retaining the dental component (20, 40) to be fastened by the fastening element (30, 130). The retaining section of the handling tool is configured to allow for a rotation relative to the dental component.

Abstract: Methods and apparatus for a fastener head having a dual zone socket area and a mating driver bit according to aspects of the present technology include a fastener configured with driving surfaces adapted to provide enhanced engagement between each other during use. The fastener includes a recessed socket area with a sidewall that has an upper inwardly tapering section and a lower vertical section that extends to the bottom of the recessed socket area. The upper inwardly tapering section of the sidewall may also include an offset relative to the lower vertical section to create asymmetrical driving and removal surfaces. The technology also includes a corresponding mating driver bit configured with mating surfaces to the fastener to provide enhanced engagement between the fastener and mating driver bit. The technology also allows either the fastener or the driving bit to be used with preexisting fasteners and driver bits.

Abstract: A tool bit for driving a fastener includes a shank including a tool coupling portion configured to be coupled to a tool, a head portion configured to engage the fastener, and a nickel coating on the head portion. The head portion is composed of powdered metal (PM) steel having carbide particles distributed uniformly throughout the head portion.

Abstract: A tool adapted for use with a bone plate assembly includes a driver with an engagement portion configured to engage a locking element, and a tubular holder. The driver may be configured to extend with the engagement portion through the tubular holder, and may be axially movable and rotatable within the holder. The holder may have a radial slot adapted for insertion of the locking element. The holder may include a portion with an internal thread for cooperation with an external thread of the locking element. The locking element may be used with a polyaxial bone anchor.

Abstract: A fastener including a first recess and a second recess adjacent the first recess. The first recess includes a side surface defining a shape of the first recess and a stability surface oriented at an angle of greater than 1° and less than or equal to 89° relative to a major axis of the fastener.

Abstract: A multipurpose drive tool having a handle to secure an extension driver between an extended position and a retracted position. The extension driver has a proximal end with a ¼ inch socket extending outwardly for use with a plurality of driver bits, and a distal end socket having a 5/16 inch socket. The drive tool further has a ? inch and 7/16 inch socket secured to the handle, having a base member housing with biasing springs for frictionally engaging the driver bits. The extension driver has grooves that interact with a ball bearings positional placement thereof, and a pin for securing the extension driver in an extended or retracted position.

Abstract: The present disclosure relates to a powered screwdriver. The powered screwdriver includes a housing, a motor housed in the housing and a tool holder driven by the motor. The tool holder selectively holds both a screwdriver bit and a hex key. The hex key includes a bend such that legs of the hex key are transverse to one another.

Abstract: A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure.

Abstract: A hex headed bit and socket for enhanced non-slip application of torque force having a hex head with contoured fastener engagement surface channel within the respective first and secondary alternating flat tool engagement sides. The contoured channels are tapered transversely and extend in angular inclination across hex head bit flat side. The defined primary channel lateral edges correspondingly embed themselves during rotational engagement within the so engaged fastener pulling the hex head bit into the engaged fastener imparting enhanced translateral points of tool engagement.

Abstract: A hand tool includes a first jaw, a first handle fixed to the first jaw, a second jaw, and a second handle pivotally coupled to the second jaw, a link member, and an adjustment member. The adjustment member is operable to axially move a first end of the link member to vary a distance between the first and second jaws. The adjustment member includes an engagement surface engageable with the first end of the link member, a shank in threaded engagement with a bore in the first handle, and a flange extending from the shank opposite the engagement portion. The flange includes a first side, a second side opposite the first side, and an elongate opening extending through the first and second sides.

Abstract: A dual-diameter arrow shaft is disclosed. An arrow shaft is disclosed with a proximal diameter and a distal diameter, wherein the proximal diameter is smaller than the distal diameter, wherein the distal diameter is approximately equal to the diameter of a standard shaft hunting arrow, while the proximal diameter is approximately equal to that of a micro-diameter shaft hunting arrow. The arrow may have more weight front of center, and the distal diameter of the arrow may be suited for installing standard-sized inserts and additions to the arrow, while the proximal diameter is smaller than the distal diameter for better flight. The distal diameter is large enough for a sleeve with extra weight to fit snugly over the arrow shaft.

Abstract: A surgical instrument comprises a first member extending between a proximal end and a distal end configured for fixation with tissue. A second member defines a longitudinal passageway and is connected with a navigation component such that the distal end is disposable with the passageway at a selected distance from the navigation component. The navigation component is positioned relative to a sensor to communicate a signal representative of an orientation of the first member. A third member extends between a proximal end and a distal end. The third member is mountable with the first member along the orientation such that the distal end of the third member is engageable with the tissue. Systems, spinal implants, constructs and methods are disclosed.

Abstract: A method for connecting a screw and a rotary tool in a rotationally fixed manner, wherein the drive surfaces of the driving profiles have a constant inclination relative to their profile axis, which is the same for all drive surfaces of both components. In the component with the outer driving profile, the drive surfaces are all concave or all convex, and in the component with the inner driving profile, the drive surfaces are curved complementary to the drive surfaces of the outer driving profile, in such a way that, in the plugged-together state, the drive surfaces of the two components, viewed in the circumferential direction, come into surface contact/engagement with one another on both sides of the apex of the concave/convex curvature. The driving profiles are designed in such a way that they do not come into contact with each other in the transition regions located between the drive surfaces.

Abstract: A drain connector (10) is configured to be installed with a sanitary appliance (100) from bottom-up. The drain connector (10) includes a main body (12) connectable at a first end to an inlet end of a waste pipe system or trap. A hollow stalk member (14) is received at least partially within the main body (12). The hollow stalk member (14) is arranged to extend and retract relative to the main body (12) via a second end of the main body (12). The drain connector (10) includes at least one sealing element (24) defining an interference and active sealing fit between the main body (12) and the hollow stalk member (14).

Abstract: The present disclosure provides medical instruments and medical instrument components having targeted torsional failure. Such targeted torsional failure helps prevent a surgeon from applying excessive torque that may damage an implant or bone, and also helps avoid the problems and complications that arise when medical instruments break within patients during surgical procedures. To provide such targeted torsional failure, the disclosed medical instrument components include a breakaway section designed so that the component breaks at a desired amount of torque, at a desired location, and in a desired way. The provided medical instrument components may also include a sleeve to increase side-loading strength that may otherwise be reduced due to the breakaway section. The increased side-loading strength may help prevent accidental bending-type failures. The presently disclosed medical instrument component therefore provides targeted torsional failure without sacrificing side-loading strength.

Abstract: A modular uniplanar pedicle screw assembly for use with a polyaxial bone fastener. The modular assembly comprises a uniplanar tulip assembly adapted to be coupled to a head of the polyaxial bone fastener, wherein the uniplanar tulip assembly includes a longitudinal slot. The modular assembly further includes an adapter having a lower portion and an upper portion. The lower portion is sized and shaped to be received in a recess of the bone fastener head. The upper portion extends from the lower portion and is adapted to slide along the longitudinal slot of the uniplanar tulip assembly to allow movement of the uniplanar tulip assembly in a first plane along a direction that is parallel to a longitudinal axis of the longitudinal slot, the longitudinal slot preventing movement of the uniplanar tulip assembly in a second plane lateral to the first plane relative to the bone fastener.

Abstract: A screw bit body allows for efficient torque force application onto a socket fastener. The screw bit body includes a plurality of laterally-bracing sidewalls, a first base, and a second base. The laterally-bracing sidewalls are radially distributed about a rotation axis of the screw bit body with each further including a first lateral edge, a second lateral edge, a bracing surface, and an engagement cavity. The engagement cavity creates an additional gripping point to prevent slippage in between the screw bit body and the socket fastener. The engagement cavity traverses normal and into the bracing surface. Additionally, the engagement cavity traverses into the screw bit body from the first base to the second base. The engagement cavity is specifically positioned offset from the first lateral edge by a first distance.

Abstract: An electrically isolated adapter may include a drive body made of first metallic material extending along a common axis, a driven body made of a second metallic material extending along the common axis, and an isolation assembly formed of insulating material disposed between the drive body and the driven body. The drive body may include a drive head configured to interface with a socket or fastener. The insulating material has a resistance to electrical current that is higher than the resistance to electrical current of at least one of the first metallic material and the second metallic material. The driven body may include a drive receiver configured to interface with a protrusion of a driving tool. A portion of one of the drive body or the driven body is received inside a portion of the other of the drive body or the driven body such that the drive body and driven body overlap each other along the common axis.

Abstract: A locking element is configured to be used with a polyaxial bone anchor. The locking element including a central axis, a bottom side, a top side opposite to the bottom side, and a peripheral surface portion that extending completely around the locking element that has an external thread. The bottom side defines a first recess facing toward the bottom side for accommodating and applying a force in a direction toward the bottom side to at least the portion of the head of the polyaxial bone anchor. The top side defines a second recess having a non-circular cross-section in a plane perpendicular to the central axis for torqueable engagement with a driver.

Abstract: A track system includes a track member with an elongate shaft mounted thereto. At least one support mechanism is mounted to the track member. The at least one support mechanism includes a housing. An engagement feature includes first and second engagement members spaced-apart from one another to define a receiving area therebetween. The first and second engagement members are operable between deployed and retracted positions relative to the housing. The elongate shaft is received in the receiving area when the first and second engagement members are in the deployed position.

Abstract: Data account management systems and methods are described. A server is in communication with one or more information source systems, at least one user device associated with at least one user and one or more electronic data accounts associated with the user. The server links the electronic data accounts, monitors data among the information source systems and the linked accounts for any changes in activity associated with the user, predicts a behavioral activity of the user via machine learning based on at least one of the monitored data and historical data associated with the user, identifies at least one notification instruction specific to the user based on the predicted behavioral activity, and generates an interactive graphical user interface (GUI) for display on the user device. The interactive GUI presents one or more of the notification instruction and a user profile of the at least one user among the linked accounts.

Abstract: A hex headed bit and socket for enhanced non-slip application of torque force having a hex head with contoured fastener engagement surface channel at the center of the respective alternating flat tool engagement sides. The contoured channels are tapered both transversely and longitudinally and extend in angular inclination across hex head bit flat side. The defined primary channel lateral edges correspondingly embed themselves during rotational engagement within the so engaged fastener pulling the hex head bit into the engaged fastener imparting enhanced translateral points of tool engagement.

Abstract: An automobile wheel can include an outer rim, a hub, and a plurality of lug accessories. The hub, which is generally at the center of the automobile wheel, can have a plurality of lug holes. The plurality of lug accessories can be partially disposed in some, but not all, of the lug holes while leaving the remaining lug holes open. The open lug holes can receive a threaded stud from an automobile wheel hub assembly when the automobile wheel is mounted to the automobile wheel hub assembly. Each lug accessory can have a lug stud and a lug cap. The lug stud can have a flange and a linear member, with the linear member attached to the flange and extending to a free end. The flange can contact a rear surface of the hub when the linear member is inserted into a lug hole. The lug cap can extend over and couple to an opposite end of the linear member from the flange.

Abstract: A solder processing method according to one or more embodiments may include: sequentially supplying at least two solder pieces into a substantially tubular iron tip that is extended vertically, such that the at least two solder pieces are erected within the iron tip in such a manner that on the solder piece which is first supplied, the solder piece which is subsequently supplied rides; and heating the substantially tubular iron tip in a state where the at least two solder pieces are erected within the iron tip in such a manner that on the solder piece which is first supplied, the solder piece which is subsequently supplied rides, to melt the flux to be flown out from at least one of the at least two solder pieces to a space between an inner wall of the iron tip and the at least two solder pieces.

Abstract: A fastener system includes a fastener and a driver, each of which have three alternating lobes and troughs that define the drive surfaces. Each alternating lobes and troughs is defined by an outer radius portion, a drive side transition, an inner transition radius, and a reverse drive portion. The fastener recess and the driver each also have a side wall defined by the outer transition radius that tapers at a taper angle relative to a rotational axis. The fastener side wall may taper at about 60°. The driver side wall may taper at about 60°. Alternatively, the driver side wall may taper at an angle at least 10° less than the taper angle of the recess side wall, such as 42°. The drive side transition defines a drive angle, which may be between 0° and 5°.

Abstract: A driver tool for insertion and removal of a first part configured for threaded engagement in a corresponding threaded bore in a second part has a driving end portion of polygonal shape with multiple flats configured for engagement in a recess in the first part having a corresponding polygonal shape. Some or all of the flats have a respective grabbing feature or edge designed to grab or grip into the opposing surface of the recess to allow a greater amount of torque to be applied to the first part when the tool is rotated in the unthreading direction than when it is rotated in the opposite threading or insertion direction.

Abstract: An insulated multi-tool comprising a pair of opposing jaws, a pair of opposed handles operatively connected to the jaws relative to a pivot to force the jaws into a clamping position about an object, at least one of the opposed handles having a tool-receiving pocket, at least one tool stored in the tool receiving pocket, the at least one tool pivotally attached relative to the tool receiving pocket for movement between a stored position in which the at least one tool is stored within the tool receiving pocket and an open, use position in which the at least one tool is located relative to at least one of the opposed handles for use, and wherein the a pair of opposed handles are electrically insulated from both the pair of opposing jaws and each at least one tool.

Abstract: A screwdriver system can include a primary driver and a secondary driver. The primary driver can include an attachment feature configured to couple to a driver bit socket. The attachment feature can be mechanically coupled to the driver shaft such that torque applied to the attachment feature is transferred to the shaft. The secondary driver can include a driver bit socket at the end of its shaft. The attachment feature of the primary driver can be structured, configured, and oriented such that the secondary driver can reversibly couple to the attachment feature via the driver bit socket of the secondary driver shaft. The secondary driver, when so-coupled, can be oriented with the primary axis of the secondary driver shaft generally perpendicular to the primary axis of the primary driver. In some examples, the primary driver can be a torque wrench.

Abstract: An insulation system for a tool includes a first element configured to electrically insulate an output unit of the tool from a detachably receivable tool element of the tool that is configured to process a workpiece. The insulation system further includes and a second element configured to electrically insulate the output unit toward the outside. A method includes mounting the insulation system on the tool.

Abstract: A screw bit body which allows for efficient torque force application onto a socket fastener from a variety of angles. The screw bit body includes a plurality of laterally-bracing sidewalls, a first base, and a second base. The laterally-bracing sidewalls are radially distributed about a rotation axis of the screw bit body with each further including a first lateral edge, a second lateral edge, a concave surface, a convex surface, and an engagement cavity. The convex surface is adjacent to the first base and the concave surface is adjacent to the second base to create a ball-like shape. The engagement cavity creates a gripping point to prevent slippage in between the screw bit body and the socket fastener. The engagement cavity traverses normal and into the concave surface and the convex surface. Additionally, the engagement cavity traverses into the screw bit body from the first base to the second base.

Abstract: A shaving apparatus has at least one cutting unit detachably coupled to a drive mechanism via a coupling having first and second coupling members. The second coupling member has a coupling cavity. A coupling head of the first coupling member is in a form-locking engagement in the coupling cavity to transfer a driving force, and is detachable from the coupling cavity by movement in an axial direction parallel to an axis of rotation of the cutting unit. The second coupling member has a plurality of recesses, each recess extending in a radial direction from the coupling cavity and being delimited by two radially extending side wall sections. Each of the two radially extending side wall sections forms an edge with a bottom surface of the second coupling member, and the edges of each recess converge in a radially outward direction in relation to the axis of rotation.

Abstract: The present invention relates to an assembly method for a connector, in particular for a high-voltage connector, having an electrical conductor and an electric contact, which assembly method comprises the following steps: providing a screw having a first drive and a second drive which is formed opposite the first drive; establishing a connection with play between the electrical conductor and the electric contact by means of the screw by the screw being inserted respectively into a passage hole in the electrical conductor and in the electric contact and being turned in a first direction by way of its first drive; tightening the connection between the electrical conductor and the electric contact by the screw being turned in a second direction, which is opposite the first direction, by way of its second drive. The present invention further relates to a connector and also to a screw.

Abstract: A guide-sleeve is couplable to an oral surgical guide at a fixed rotational orientation, height, and angle with respect to oral anatomy. An implant delivery device, couplable to a dental implant, drives the implant into tissue of the subject by rotation of the delivery device about its longitudinal axis until the delivery device lockingly engages the guide-sleeve. When the implant lockingly engages the guide-sleeve, the implant is disposed in the tissue at a fixed rotational orientation, depth, and angle with respect to the oral anatomy, and any further advancement and rotation of the dental implant with respect to the tissue is prevented. Other embodiments are also described.

Abstract: A driver tool for insertion and removal of a first part configured for threaded engagement in a corresponding threaded bore in a second part has a driving end portion of polygonal shape with multiple flats configured for engagement in a recess in the first part having a corresponding polygonal shape. Some or all of the flats have a respective grabbing feature or edge designed to grab or grip into the opposing surface of the recess to allow a greater amount of torque to be applied to the first part when the tool is rotated in the unthreading direction than when it is rotated in the opposite threading or insertion direction.

Abstract: A solder application stamp embodied to transfer solder paste from a reservoir to a contact location of a circuit board. The solder stamp has a basic body having an end area and a protrusion, which protrudes out of the end area. The solder application to create solder paste dots of diameters as small as 10-300 ?m.

Abstract: A power tool is provided that includes a motor housing, an output head, a pinion, at least one pin, and at least first and second rings. The output head includes a rotatable output spindle and extends from the motor housing which extends longitudinally along a first axis. The pinion is located in the output head, is coupled to a drive force, and rotates about the first axis to rotate the rotatable output shaft. The at least one pin is located in the output head. The first ring is coupled to the pinion and rotatable about the first axis with the pinion. The second ring engages, and is movable longitudinally along the first axis relative to, the at least one pin. The second ring is not rotatable about the first axis. Rather, the second ring is movable toward and away from the first ring along the first axis, and selectively engagable with the first ring.

Abstract: A portable computing device includes at least a base portion of a lightweight material that includes at least a wedge shaped top case having a trough formed at an interfacing edge thereof. The trough includes a raised portion having a first contact surface and a receiving area, and a bottom case coupled to the top case to form a complete housing for at least a portion of the portable computing device for enclosing at least a plurality of operational components and a plurality of structural components. The portable computing device also includes at least a lid portion pivotally connected to the base portion by a hinge assembly. In the described embodiments, the lid portion has a display in communication with one or more of the plurality of components in the base portion by way of or more electrical conductors that electrically connect the base portion to the lid portion.

Abstract: A precision handle for hand tools has a body, an elastic element, a sheath, a pressing element, and a group of balls. The mounting protrusion protrudes axially from a rear end of the body. The elastic element is mounted in the body. The sheath is mounted around the mounting protrusion. The pressing element is mounted through and engages with the sheath. The group of balls includes a first ball and a second ball. The first ball is mounted in the mounting protrusion and abuts the elastic element. The second ball is mounted between the pressing element and the first ball. The first ball abuts against the second ball at one point of contact when the pressing element is pressed, thereby decreasing the friction between the body and the sheath. Accordingly, the precision handle for hand tools can be operated smoothly and efficiently.

Abstract: A drain removal tool with a central opening aligned along a central tool axis, a holding section with a hex head for applying torque to the tool, and an engagement section including elongate sharp ridges or teeth extending in a helical pattern from an external surface of the engagement section from the tool for engagement with the drain to be removed. Each elongate sharp ridge has one flat face and a ramp face. Each flat face is aligned along a radius extending outwardly from the central tool axis. The ridges are spaced such that the distance between each flat face is approximately 6 degrees. Each helical ridge is a left hand helical serration on a 15 degree pitch with respect to the central axis of the central opening. The holding section includes a hex head configuration. The central opening in the holding section has a hex configuration.

Abstract: The present invention refers to a shaft of a dental tool comprising a distal end region, a cylindrical shaft region adjoining the distal end region, and a proximal end region which lies opposite the distal end region and which is provided with a polygonal profile that tapers conically in the direction of the distal end region and adjoins a tool part.

Abstract: The driver bit according to the present invention includes: a tip on which a cross blade is formed; a torque transmitting part having a polygonal outer circumference; and a locking groove which extends in the circumferential direction between the tip and the torque transmitting part and into which locking balls enter, wherein the tip has four blade forming grooves forming the cross blade, the blade forming grooves are continuous with the locking groove, and the blade forming grooves are arranged so that the blade forming grooves have bottom parts, at which they are connected with the locking groove, located inwardly of the outer circumference of the torque transmitting part, and the center lines are displaced from a line connecting the shaft center with vertex positions of the polygonal outer circumference and a line connecting the shaft center with center positions of sides of the polygonal outer circumference.