Abstract: An exercise biased weight includes a weight body defining a center of mass and a through offset bore formed at the weight body at a position offset to the center of mass thereof, wherein a diameter of the offset bore is slightly larger than a diameter of a weight bar member for enabling the weight bar member to slidably pass through the offset bore so as to retain the weight body at the weight bar member. Therefore, the weight body is lifted to generate a downward weight force to against an unwanted shaking movement of the weight body.

Abstract: A device and the method for influencing the position of the knot (31) between the upper thread (23) and the lower thread (17) when sewing with a sewing machine (1) using a computer (37), which calculates for every sewing stitch to be formed a control value for an actuator (39), by which a braking force of the thread tension regulator (23) is controlled.

Abstract: A wire reel is detachably provided in a housing chamber of a binding machine body which binds a reinforcing bar. The wire reel includes a cylindrical hub portion which winds a wire, and a pair of parallel flanges overhanging outward from both external peripheral ends of the hub portions. A side wall inside the hub portion is formed of light-transmitting portions which allow the light from a transmissive photosensor provided in the binding machine body to be transmitted therethrough.

Abstract: There is provided a sewing-machine bobbin thread tension controller capable of elaborately, accurately controlling bobbin thread tension without depending on frictional force. A bobbin thread tension controller includes an outer shuttle, a middle shuttle presser, a middle shuttle, a bobbin thread tension control mechanism, a shuttle actuation unit, and a bobbin. The middle shuttle has a magnet. A magnet is disposed, in close proximity to the magnet, on an arm attached to a rotary shaft of a shuttle actuation motor provided in the shuttle actuation unit. The middle shuttle is rotated by rotating the magnet by means of the motor. Further, a rotary disc is provided, in close proximity to the middle shuttle, on a rotary shaft of a bobbin thread tension control motor of the bobbin thread tension control mechanism and is provided with a magnet. A magnet is disposed on a part of the bobbin facing the rotary disc.

Abstract: The present invention provides a bobbin thread feeder of sewing machine of simple structure in which a lower thread can be reliably fed at an appropriate tension. A lower thread bobbin 21 can be removably contained through an opening for containing a lower thread bobbin 17 in a rotary hook 20 of a horizontal rotary hook 30 provided in a sewing machine frame. A thread tension plate and a thread tension spring are attached while overlapping along the inner circumference of the rotary hook 20, and function as a tension generating portion 22 for imparting resistance to pulling out a lower thread being guided through the gap between the thread tension plate and the thread tension spring. A needle plate 16 with an opening for taking the lower thread bobbin 21 in and out is provided above the rotary hook 20. The needle plate 16 comprises a guiding slit 27 that guides the lower thread formed thereon.

Abstract: A sewing machine includes a rotating hook, a lower shaft rotating the rotating hook in synchronization with vertical movement of the needlebar, a lower shaft gear including a helical gear and slidably mounted on the lower shaft, a hook gear including a helical gear capable of mesh engagement with the lower shaft gear and mounted on the rotating hook, a drive force transmission mechanism supporting the lower shaft gear so that the lower shaft gear is axially moveable and transmits rotation of the lower shaft to the lower shaft gear, a cam mechanism axially moving the lower shaft gear to adjust at least one of a left encounter timing for seizure of the needle thread loop by the hook beak when the needle occupies a left needle location and a right encounter timing for seizure of the needle thread loop by the hook beak when the needle occupies a right needle location.

Abstract: An apparatus for adjusting a timing of a needle and a looptaker of a sewing machine provided at a zigzag sewing machine having an upper shaft for driving a needle bar, a lower shaft for driving a looptaker, a machine frame, and a timing belt for connecting and synchronizing the shafts includes a cam member including a first cam surface and a second cam surface, a first arm member and a second arm member supported by the machine frame and a first pulley and a second pulley mounted to the first arm member and the second arm member respectively and always contacting the timing belt, the first pulley following the first cam surface and the second pulley following the second cam surface.

Abstract: A sewing machine with a hook (8) that is drivable in rotation about a vertical axis comprises a bobbin case (21) with a lifter cam (31). A case lifter (33) is provided, having a sensing lever (40) and a lifter lever (32) that bears against a lifter cam (28). The sensing lever rests on a cam face (42) of an axial cam disk (39) which is mounted on the transmission shaft that actuates a hook-driving shaft (10).

Abstract: A vertical axis hook (10) for a lockstitch sewing machine comprises a hook body (11) with a hook point and a peripheral needle guard plate (12) mounted on the hook body, the plate comprising a fastening and positioning portion and an adjustable portion integral with each other. It further comprises a plate adjustment means to adjust the radial position of the adjustable portion with respect to the hook point. The plate adjustment and positioning means (16) acts in a position of the adjustable portion of the plate which is near the fastening portion thereof.

Abstract: A sewing machine includes a hook having a distal end formed with a thread hooking portion, and a thread hooking device mounted on the thread hooking portion of the hook. Thus, the thread hooking device includes a plurality of thread guide portions provided on the bottom of the thread hooking portion to draw a plurality of sewing threads of different patterns and colors, thereby enhancing the diversity of the sewing threads so as to satisfy the user's different requirements. In addition, the sewing threads can be introduced into the thread hooking portion rapidly and conveniently, thereby facilitating operation and replacement of the sewing threads.

Abstract: A vertical axis hook (10) for a lockstitch sewing machine comprises a hook body (11) with a hook point and a peripheral needle guard plate (12) mounted on the hook body, the plate comprising a fastening and positioning portion and an adjustable portion integral with each other. It further comprises a plate adjustment means to adjust the radial position of the adjustable portion with respect to the hook point. The plate adjustment and positioning means (16) acts in a position of the adjustable portion of the plate which is near the fastening portion thereof.

Abstract: In a chain stitch sewing machine which performs a required chain stitch sewing with respect to a cloth to be processed, by cooperation of a needle reciprocable up and down and a looper arranged under a needle plate, the chain stitch sewing machine comprises: (1) a large diameter drive gear rotatably provided in a base, (2) a looper support supported by the base so that it can slide in a lateral direction, (3) two or more loopers arranged on the looper support at intervals of a predetermined pitch along the lateral direction and freely rotatable on their own axes, (4) small diameter driven gears respectively provided in the two or more loopers and each engageable with the drive gear, and (5) a lock mechanism for non-rotatably locking the two or more loopers at a required timing.

Abstract: A sewing machine having a projection formed on an inner shuttle of a shuttle-inner shuttle assembly to prevent the inner shuttle from being rotated in the same direction in which the shuttle is rotated, thereby providing a gap through which the needle thread passes.

Abstract: A horizontal rotating hook for a sewing machine which has a structure so that an opener mechanism, which is adapted to wear and provide noise, is not required. The opener structure is avoided by using a needle thread fastener that is located adjacent to a rotating hook bobbin case holder position bracket in a rotating hook bobbin case holder for fastening needle thread temporarily. Thus, when the loop of the needle thread captured by the hook point of a rotating hook goes through into the rotating hook bobbin case holder, the rotating hook bobbin case holder is moved in a direction opposite to the rotation direction of the rotating hook (reversed) by the tension of the thread.

Abstract: A looper is rotated under a throat plate, a stitching needle moves up and down through a needle hole formed in the throat plate and thus a cloth on the throat plate is stitched. After the cloth has been stitched, the thread between the needle hole and the looper is brought to a thread holding means disposed aside by thread drawing pieces and is maintained at its position by the thread holding means. Accordingly, even when the thread at this position is cut over the thread holding means, the thread can remain extending from the looper.

Abstract: A bobbin-thread supply device for a sewing machine. The operator inserts the bobbin into the bobbin holder, draws bobbin thread from the bobbin, and passes the tip of the bobbin thread through the slit in the cover above the bobbin holder. Since the slit in the cover extends above where the tension bracket is joined onto the tension spring, the bobbin thread is guided between the tension bracket and the tension spring through the tension regulating portion. The bobbin thread can thus easily be set with appropriately tension applied thereon. At the same time, the length of the bobbin thread can be adjusted for proper sewing operation.

Abstract: The feed dog (17) for the fabric in a sewing machine is provided with a spring-wire (21) bent and passing through a hole of a support (23). When the feed dog (17) is in its upper position, the support (23) abuts the plate (18), which lowers the end (24) of the wire (21) so as to exert a tension on the lower thread (8) of the seam. When the feed dog is lowered, the wire (21) resumes its normal position, namely its end (24) is displaced upwardly with respect to the dog (17) and the thread (8) is thus relaxed.

Abstract: An amount of a lower thread to be supplied from a bobbin in each stitch forming operation is first determined on a theoretical basis in accordance with the stitch control data stored in a pattern memory. The sewing machine is provided with a bobbin rotation detector which detects every rotation of the bobbin to estimate a lower thread amount which has actually been supplied from the bobbin. A control unit compares the theoretical amount and the practical amount to lead out a correction coefficient which will be applied to the theoretical amount for the next stitch forming operation.

Abstract: An automatic bobbin thread guiding apparatus in combination with a sewing machine has a work supporting bed, a throat plate, a shuttle race slide and a horizontally rotating shuttle. A bobbin thread holding assembly is provided between the shuttle race slide and the rotating shuttle, for clamping and carrying the bobbin thread end, and is operatively connected with the slide. A bobbin thread engagement guiding mechanism is provided for guiding the bobbin thread catching portion of the assembly so as to make the bobbin thread engage automatically with the bobbin thread tension adjusting mechanism in the rotating shuttle when the assembly is driven backward, and then to hold the catching portion at a given position for making the bobbin thread intersect with the needle thread loop when the assembly reached its rear end position.

Abstract: A device for guiding a lower thread in a zigzag stitching sewing machine is provided with a lower thread guiding unit that determines two lower thread drawing positions in accordance with a selected pattern. The lower thread guiding unit includes a lower thread guiding part which, at one of the two positions, acts on the lower thread to guide a lower thread drawing position to a center of a needle amplitude. A lower thread releasing element, at the other of the two positions, cooperates with the lower thread guiding unit to release the lower thread engaged with the lower thread guiding part.

Abstract: A two-needle lockstitch sewing machine apparatus providing a hooking arrangement such that each thread loop is positioned in the same direction in relation to the needle position. The hooking arrangement is effective to stitch each left and right stitch line with a needle thread having almost the same degree of twist. Thus, uniform stitch lines are obtained and the "edge effect" which is often experienced when the needle thread passes through the needle eye during stitching is eliminated.

Abstract: A relatively long needle (22) is supported at the lower end of a needle bar (28). The needle bar (28) and needle (22) are moved up and down and forwardly and rearwardly. The needle bar (28) and needle (22) are moved forwardly while they are in materials (M) which are being sewed together, to in that manner advance the materials (M) stitch by stitch. The materials (M) are supported on a bed (10) which includes a slot (20) which is elongated in the direction of the stitch path. The needle (22) is received in the slot (22). A side boundary of the slot (20) provides a side guide surface (84) which is contiguous a first side of the needle (22). An upper thread (76) extends downwardly from a thread guide (110) into a side groove (86) in the first side of the needle (22), to and through a needle eye (80). A recess (82) is formed in the second side of the needle (22) above the needle eye (80). Following downward movement of the needle (22) through the materials (M), the needle (22) is moved upwardly.

Abstract: A rotary looptaker includes a looptaker body rotatable about a vertical axis and a bobbin case restrained from rotary motion with the looptaker body. A plurality of annular protrusions are provided on a flange of the bobbin case so as to extend in a circumferential direction of the bobbin case and are in engagement with a flat surface formed on a raceway of the looptaker body. When the looptaker body is rotated, the bobbin case slides relative to the looptaker body through a very small contact area between the annular protrusions and the flat surface, thus reducing sliding friction between the looptaker body and the bobbin case. Accordingly, noise and vibration are decreased when a rotation restraining projection of the bobbin case contacts a restraint element secured to a machine frame.

Abstract: A composite rotary loop taker which includes a loop seizing point mounted on a substantially annular frame, for use in a lock-stitch sewing machine. The loop seizing point forms a smoothly curved junction with the leading edge of a crosswise member between the opposite sides of a rotatably mounted substantially annular frame, said smoothly curved junction adapted to receive a thread loop and expand the loop over a stationary bobbin basket to form a lock stitch. Preferably, the loop seizing point, downwardly extending lug toward the smoothly curved junction and an inwardly extending foot therefrom are metal, together with a crosswise reinforcing member and a partially circumferential supporting wall on the opposite side of the annular frame.

Abstract: A sewing machine having a vertically reciprocating needle carrying an upper thread, a needle plate secured to a sewing machine housing and provided with a needle penetrating hole, a loop-taker arranged below the needle plate and operated in synchronism with reciprocation of the needle for interlocking a lower thread carried thereby with the upper thread, and a feed dog for feeding a fabric placed on the needle plate in a predetermined direction on which a stitch composed of the interlocked upper and lower threads has been formed. A swingable arm is operated to interfere with the normal travelling path of the lower thread between the loop-taker and the needle hole to draw a predetermined amount of the lower thread out of the loop-taker, while the fabric is not being fed.

Abstract: A zigzag sewing machine includes a needle hole member having a round needle hole of a diameter slightly larger than that of a stitching needle. The needle hole member engages a laterally elongated hole in a needle plate and is swingable along the latter. A base member is mounted coaxially with a loop taker and is rotatable relative to the loop taker. The needle hole member is pivoted to the base member for relative vertically swinging movement. A lever swingably mounted on the machine housing engages with the needle hole member, and a cam rotated in synchronism with the vertical reciprocation of the needle is in engagement with the swinging lever. A stepping motor is operatively connected to the needle to reciprocate the needle laterally in the elongated needle plate hole, and the motor is also operatively connected to the base member to reciprocate the base member.

Abstract: A lower thread tension adjusting device for a sewing machine comprising first and second tension arrangements mounted on a bobbin carrier of the sewing machine for tensioning a lower thread with a predetermined tension and a predetermined additional tension, respectively. A positioning device is mounted on the bobbin carrier and movable between first and second set positions in which the positioning devices moves the second tension arrangement to operative and inoperative positions wherein the second arrangement provides and does not provide the predetermined additional tension of the lower thread. A guide assembly guides the lower thread to positions adjacent to one end and a center of a laterally elongated needle hole and simultaneously guides the positioning device to the first and second positions thereof. A control unit moves the guide assembly between first and second guide positions thereof in accordance with selected patterns of straight and zigzag stitches, respectively.

Abstract: A thread checking device is installed in combination with a sewing machine in order to exert a proper tension on the thread loop formed at the eye of the needle when the thread loop passes through betweeen the bobbin case and the rotation stopping member for restraining rotation of the bobbin case. This thread checking device is provided with thread suspending means which comprises a thread suspending part disposed near a specified position where the thread guide of the thread take-up member is located when the needle thread loop passes between the bobbin case and the rotation stopping member. The thread suspending means suspends the needle thread held on the thread guide with the suspending part when the take-up member moves from the maximum thread take-up position to the maximum thread slack position.

Abstract: An opening plate which closes a lower thread bobbin is provided with a drawing of a bobbin on its surface. A bobbin drawing is exactly overlapped with the bobbin when the plate is completely closed. Also a drawing of a thread tension adjusting device in a required position and a drawing of a lower thread normal path are provided on the opening plate. The drawings indicate to a machine operator the position of lower thread holding bobbin correctly inserted in a horizontal full rotation loop taker device and the path of drawing of the lower thread therefrom so as to enable the operator to insert the lower thread holding bobbin in the horizontal full rotation loop taker device correctly in place, and pass the lower thread wound on the bobbin through the thread tension adjusting device correctly.

Abstract: A needle looper assembly for a lockstitch sewing machine wherein the upper thread is retrieved by a sewing needle extending through a work material, which sewing needle has an extensible hook portion for catching an upper thread and drawing the same down through the work material to a looptaker in the bed of the sewing machine. The needle looper assembly is supported on the end of a lever pivotally carried in the sewing machine bed to extend transversely thereof. The lever has the needle looper assembly attached to one end thereof, and may be actuated by a cam so as to drive the needle looper assembly to an elevated thread catching position or to a retracted thread releasing position. Retaining means are provided associated with the needle looper to permit an upper thread to be caught and held during passage through a work material and to be released when in a retracted position adjacent the looptaker.

Abstract: A bed slide for a sewing machine having a frame fabricated of a synthetic resin material, the bed slide extending beyond the throat plate on both sides thereof, and thereby beyond the cavity accommodating the looptaker, and two embodiments of devices attachable to the synthetic resin material spaced from the cavity for slidably retaining the bed slide therein. The first embodiment, a headed stud having a transverse slot therein for receiving a turned back edge of the bed slide is retained in an aperture molded in the synthetic resin material, with a resilient member exerting a pull on the stud for imparting a drag to the bed slide and retaining the same to the bed. In the second embodiment, a Z-shaped member has its lower bar fastened to the sewing machine bed and its upper bar inserted between the bed slide and a turned back end thereof. A portion of the upper bar is bent downwardly to provide for a drag resisting free motion of the bed slide.

Abstract: A lower thread drawing-out device for a computerized sewing machine, the device having a cup-shaped loop taker with a surrounding wall. The loop taker is rotatable in a timed relation with a vertical reciprocation of the needle to catch the upper thread to concatenate with the lower thread and thereby form lock stitches. A bobbin is arranged in the loop taker so as to form a space between the bobbin and the loop taker surrounding wall. A lower thread drawing out element having a free end in the space is arranged so that when a lower thread is wrapped around the bobbin and extends to a needle, the free end contacts the lower thread at a location. The lower thread drawing out element is rotatable relative to the loop taker. The lower thread is movable transversely at the contact location relative to the lower thread when extended and in response to a rotation of the element relative to the loop taker, thereby compensating for biasing of the lower thread.

Abstract: A thread loop taker device for a zigzag sewing machine having a needle whose position is controlled by electronically stored data which cooperates with the thread loop taker device to thereby produce zigzag stitches. The thread loop taker device comprises a bobbin carrier, a rotational cylindrical member for supporting the bobbin carrier therein; a loop taker coaxial with and about the cylindrical member for rotation therewith, the loop taker having a beak extending from one end and in the direction of the rotation around a portion of the cylindrical member for catching a thread loop formed by the needle; cams rotating with the cylindrical member and engaging the opposite end of the loop taker for rotating the beak relative to the cylindrical member; and a pulse motor drivable in response to a change in the position of the needle so that, when this driving is transmitted to move the cams, the loop taker is actuated.

Abstract: A thread loop taker device for a zigzag sewing machine having a needle whose position is controlled by electronically stored data which cooperates with the thread loop taker device to thereby produce zigzag stitches. The thread loop taker device comprises a bobbin carrier, a rotational cylindrical member for supporting the bobbin carrier therein; a loop taker coaxial with and about the cylindrical member for rotation therewith, the loop taker having a beak extending from one end and in the direction of the rotation around a portion of the cylindrical member for catching a thread loop formed by the needle; cams rotating with the cylindrical member and engaging the opposite end of the loop taker for rotating the beak relative to the cylindrical member; and a pulse motor movable in two opposite directions in response to a change in the position of the needle so that, when this movement is transmitted to the cams, the loop taker is actuated.

Abstract: A rotary loop taker which includes a replaceable loop seizing point mounted on a substantially annular frame, for use in a lock-stitch sewing machine. The loop seizing point has a supporting lug that extends downwardly from immediately behind the base portion of the tapered forward end of the loop seizing point. The supporting lug forms a smoothly curved junction with the base portion of the tapered forward end of the loop seizing point. The rearwardmost position on the smoothly curved junction to which said needle thread loop is pulled by the rotating loop taker lies a first distance from the nearest point on the crack formed by the supporting lug and the wall of the annular frame against which the lug abuts that is sufficient to produce a second distance measured normal to the taut needle thread loop that will avoid snagging the needle thread in the crack just referred to during operation of the sewing machine.

Abstract: A sewing machine needle is capable of vertically reciprocating between upper and lower dead points and swinging laterally within a predetermined amplitude between two extreme lateral positions to form zigzag stitches on a fabric material in cooperation with a hook of a rotary loop taker. The needle comprises a relatively thick upper base portion by which the needle is attached to a needle bar of the sewing machine and a shank formed integrally with the upper base portion and adapted to reciprocatingly pass through the fabric material.

Abstract: A sewing machine has a bobbin mechanism, a sewing needle mechanism, and a mechanism capturing and severing bobbin thread comprising a stationary blade, a picker having at least one hook for capturing a bobbin thread and wherein the picker is movable towards the blade to sever the bobbin thread. At least one notch is disposed on the picker for capturing at least one needle thread and is cooperative with the blade for severing the needle thread upon movement of the picker towards the blade.

Abstract: Opposing plates of a thread tensioning device for use on a lock stitch sewing machine in a thread handling system wherein needle thread is caused to pass between elongate members of a thread holder which meters thread to the looptaker of the machine are formed with recesses through which the thread can fall without restraint to supply thread to the looptaker during the movement thereof from a loop seizing to a cast-off position.

Abstract: A rotary loop taker, for use in a lock-stitch sewing machine, which has a detachable and replaceable hook or loop seizing point. A lug extending downwardly from the main body of the replaceable loop seizing point abuts one end wall of a cut-away portion of the annular frame of the rotary loop taker, and carries a foot that extends inwardly from the annular frame toward the rotatable shaft of the device. The inwardly extending lug foot desirably nests in a notch in the crosswise support member on which the annular frame of the rotary loop taker rests, preferably forming a snug fit with the upper surface of the crosswise support member. The preferable form and dimensions of the loop seizing point and the foot extending inwardly from the downwardly extending lug are disclosed. Ledges formed in the inner wall of the replaceable loop seizing point define the initial portion of the raceway for the bobbin case with which the rotary loop taker is used.

Abstract: A clutch which is engaged to rotate and wind thread on a sewing machine bobbin is provided with clutch parts that include a single bladed paddle, and a member with a pair of crossed paddle receiving through slots, one of which has a chamfered upper edge that substantially widens the mouth of the slot and the other of which is without such chamfered edge.

Abstract: A sewing machine having a underbed hook rotatable in a horizontal plane includes a needle bar tilted at an angle with respect to a vertical line to displace a sewing needle rearward to a retracted position. The retracted needle provides on a bed of the sewing machine a relatively large working surface on which sewing can be effected. The hook is also displaced rearward below the bed for coaction with the needle.

Abstract: A non-rotatable, disc-like bobbin carrier is nested in a cup-shaped, vertical axis, rotary loop taker that slidably supports the bobbin carrier at its periphery on an annularly extending, discontinuous lip constituting a circular race slightly offset eccentrically from the loop taker axis of rotation. As the loop taker rotates, the eccentrically positioned bobbin carrier jogs back and forth in reciprocating fashion against one and then the other of a pair of diametrically opposed fixed stops that cooperate to preclude rotation of the bobbin carrier. The movement of the bobbin carrier away from and against each stop is synchronized with movement of a thread loop about the bobbin carrier to permit free passage of the loop between the fixed stops and the moving bobbin carrier.

Abstract: A sewing machine having a drive shaft rotated by a machine motor to vertically reciprocate a needle carrying an upper thread is provided with a device for adjusting the tension of a lower thread pulled out from a bobbin located in a bobbin carrier of the sewing machine. The device includes a tension lever cooperated with a spring element, and a releasing lever which is in engagement with a cam rotated by the drive shaft. The position of the tension lever relative to the lower thread is effected by a manually operated dial and a cam engageable with the spring element. The releasing lever is adapted to intermittently release the tension lever from the lower thread during the stitching operation.

Abstract: A double-lock-stitch sewing machine has a reciprocating needle forming an upper-thread loop with the aid of a rotary gripper assembly. The loop is carried by and formed by a main hook or point of the assembly around a stationary bobbin to engage a bobbin thread in a double-lock-stitch. A counter hook or counter point on the gripper assembly, which normally serves only to control movement of the loop from the main point, is formed on an underside with an auxiliary hook portion for drawing an extra thread length from the supply during each stitch and thus inhibiting bunching of the workpiece.

Abstract: A variable under thread pull off device in a sewing machine for providing the proper amount of slack in the bobbin thread to effect uniform stitch formation. The device will pull off a varying amount of bobbin thread to correspond to that which is required for each particular bight position of the stitch being set.

Abstract: A bobbin case positioning and retaining structure of one piece unitary construction for maintaining the bobbin case in proper operating position. The bobbin case is held captive without the need for operator manipulatable locking devices.

Abstract: The meshing bevel gears used to drive the vertical axis looptaker of a sewing machine are preloaded with a compressed resilient member which is prevented from deflecting to a position beyond its elastic limit during the running of the gears.

Abstract: A sewing machine bobbin case is provided with a thread tensioning device that includes a pivotally movable arm which is spring biased into a position preventing thread from entering the device during the sewing of materials on the machine, but which is disposable by a finger in a position providing for the introduction of thread into the device in preparation for the performance of a bobbin winding operation.

Abstract: A thread engageable finger for guiding needle thread into a thread receiving slot on the bobbin case of a sewing machine, as a seized loop of the thread is moved about the bobbin case by a looptaker, is provided along a thread engaging edge with a predetermined curved contour effective to delay movement of the thread along said edge until the introduction of thread into the bobbin case slot as required for bobbin winding is assured.

Abstract: A control arm for bobbin winding mechanism in a lockstitch sewing machine is provided with a pawl which serves both to guide needle thread into a thread entering slot for a tensioning device on a bobbin case, and to hold an arm of the tensioning device in a position effective to prevent the thread from being pulled out of the slot.