The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.

The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.

Disclosed herein are a lower-thread supply device of sewing machine and a sewing method. The device includes a bobbin case (300) having an outlet (330) from which lower thread is drawn out, and a needle through-hole (340) through which a needle (600) moving downwards with upper thread (a) being fitted passes, and a hook body (200) in which the bobbin case (300) is mounted, the hook body being installed to be rotatable by a power device of a sewing machine, guiding upper thread (a2) on a sewn fabric side to a front area of the bobbin case (300) while catching and dragging the upper thread (a) via a hook (210), and guiding upper thread (a1) on a spool side to a rear area of the bobbin case (300). The bobbin case (300) is installed not to be rotated when the hook body (200) rotates.

Disclosed herein are a lower-thread supply device of sewing machine and a sewing method. The device includes a bobbin case (300) having an outlet (330) from which lower thread is drawn out, and a needle through-hole (340) through which a needle (600) moving downwards with upper thread (a) being fitted passes, and a hook body (200) in which the bobbin case (300) is mounted, the hook body being installed to be rotatable by a power device of a sewing machine, guiding upper thread (a2) on a sewn fabric side to a front area of the bobbin case (300) while catching and dragging the upper thread (a) via a hook (210), and guiding upper thread (a1) on a spool side to a rear area of the bobbin case (300). The bobbin case (300) is installed not to be rotated when the hook body (200) rotates.

The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.

The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.

Disclosed herein are a lower-thread supply device of sewing machine and a sewing method. The device includes a bobbin case (300) having an outlet (330) from which lower thread is drawn out, and a needle through-hole (340) through which a needle (600) moving downwards with upper thread (a) being fitted passes, and a hook body (200) in which the bobbin case (300) is mounted, the hook body being installed to be rotatable by a power device of a sewing machine, guiding upper thread (a2) on a sewn fabric side to a front area of the bobbin case (300) while catching and dragging the upper thread (a) via a hook (210), and guiding upper thread (a1) on a spool side to a rear area of the bobbin case (300). The bobbin case (300) is installed not to be rotated when the hook body (200) rotates.

Disclosed herein are a lower-thread supply device of sewing machine and a sewing method. The device includes a bobbin case (300) having an outlet (330) from which lower thread is drawn out, and a needle through-hole (340) through which a needle (600) moving downwards with upper thread (a) being fitted passes, and a hook body (200) in which the bobbin case (300) is mounted, the hook body being installed to be rotatable by a power device of a sewing machine, guiding upper thread (a2) on a sewn fabric side to a front area of the bobbin case (300) while catching and dragging the upper thread (a) via a hook (210), and guiding upper thread (a1) on a spool side to a rear area of the bobbin case (300). The bobbin case (300) is installed not to be rotated when the hook body (200) rotates.

The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.

The length of a sewing machine stitch is adjustable by varying the effective length of a first bar of a multi-bar linkage operably secured to a feed dog of the sewing machine. The effective length of the first bar is defined between an anchor point and a pivot point, with the pivot point being secured to a slider configured for movement along the length of the first bar. The slider comprises a pinion gear configured to engage a gear rack of the first bar, such that rotation of the pinion gear causes movement of the slider and the pivot point relative to the anchor point. Moreover, to accommodate the adjustable stitch length, the sewing machine additionally comprises an adjustable looper thread eyelet configured to adjust the length of the looper thread path to accommodate increased tension or slack in the looper thread due to the changed stitch length.