A kit for adding or replacing an automated upper walking foot stepping height adjustment to a sewing machine, the kit includes a mounting assembly including an actuator bracket, an actuator coupled to the actuator bracket, a drive assembly, and a needle drive assembly. The actuator includes an actuator shaft that extends and retracts. The drive assembly includes a drive shaft, a drive arm coupled to the drive shaft and the actuator shaft, and a guide coupled to the drive shaft. The needle drive assembly includes a variable drive crank coupled to the guide and configured to couple to a needle drive shaft of a sewing machine. Selectively extending and retracting the actuator shaft selectively adjusts a stepping height of an upper walking foot.

A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

A sewing machine includes: a needle vertical movement mechanism which moves a sewing needle; a moving mechanism which holds a workpiece by a holding frame; an inner presser-foot device which moves an inner presser foot on an upper side of the workpiece held by the holding frame; a control device which controls the moving mechanism based on sewing data in which stitch positions are defined in order in a series of sewing; and a height detector which detects a height of the inner presser foot. The control device lowers the inner presser foot to an upper surface of the workpiece held by the holding frame, detects the height of the inner presser foot by the height detector, and determines suitability of a thickness of the workpiece, at one or plural stitch positions defined in the sewing data before starting the sewing in accordance with the sewing data.

A pressure adjustment mechanism of the sewing machine presser foot comprises a motor, a screw actuated by the motor, a spiral spring and a pressing plate for pressing against an upper end of the presser foot. A nut is screwed and connected on the screw, and the nut is lifted or lowered by the screw. The pressing plate is underneath the nut. The circumferential direction of the nut is unfixed. The spiral spring is located between the nut and the pressing plate, an upper end of the spiral spring is pressed against the nut, and a lower end of the spiral spring is pressed against the pressing plate. The spiral spring is being compressed under the effects of the nut and the pressing plate.

A pressure adjustment mechanism of the sewing machine presser foot comprises a motor, a screw actuated by the motor, a spiral spring and a pressing plate for pressing against an upper end of the presser foot. A nut is screwed and connected on the screw, and the nut is lifted or lowered by the screw. The pressing plate is underneath the nut. The circumferential direction of the nut is unfixed. The spiral spring is located between the nut and the pressing plate, an upper end of the spiral spring is pressed against the nut, and a lower end of the spiral spring is pressed against the pressing plate. The spiral spring is being compressed under the effects of the nut and the pressing plate.

A sewing machine includes a drive shaft rotated by a motor, a cam member fixed to the drive shaft and including a first cam and a second cam, a forked member including a main body member and an auxiliary member, an urging device, and a presser mechanism. At least one of a first cam surface of the first cam and a second cam surface of the second cam is inclined with respect to the drive shaft. The main body member and the auxiliary member are disposed to face each other such that the cam member is clamped between them. The urging device urges the main body member and the auxiliary member in a direction to clamp the cam member. The presser mechanism drives a presser member to hold a cloth, by swinging of the forked member caused by the rotation of the cam member.

A sewing machine includes a drive shaft rotated by a motor, a cam member fixed to the drive shaft and including a first cam and a second cam, a forked member including a main body member and an auxiliary member, an urging device, and a presser mechanism. At least one of a first cam surface of the first cam and a second cam surface of the second cam is inclined with respect to the drive shaft. The main body member and the auxiliary member are disposed to face each other such that the cam member is clamped between them. The urging device urges the main body member and the auxiliary member in a direction to clamp the cam member. The presser mechanism drives a presser member to hold a cloth, by swinging of the forked member caused by the rotation of the cam member.

A sewing machine external unit includes: a holder holding fabric; a driver being detachable from a bed of a sewing machine and driving the holder along an upper surface of the bed; a pressing member moving in an up-down direction according to movement of a sewing needle in the up-down direction, pressing the fabric while the sewing needle is stuck in the fabric, and rising together with the sewing needle in response to the sewing needle coming out of the fabric and rising; a position detector detecting a position of the pressing member in the up-down direction; a signal output part outputting a signal to the sewing machine; and a controller outputting a needle drive signal for driving the sewing needle from the signal output part to the sewing machine, and controlling driving of the holder and/or the sewing needle based on a detection result of the position detector.

A sewing machine external unit includes: a holder holding fabric; a driver being detachable from a bed of a sewing machine and driving the holder along an upper surface of the bed; a pressing member moving in an up-down direction according to movement of a sewing needle in the up-down direction, pressing the fabric while the sewing needle is stuck in the fabric, and rising together with the sewing needle in response to the sewing needle coming out of the fabric and rising; a position detector detecting a position of the pressing member in the up-down direction; a signal output part outputting a signal to the sewing machine; and a controller outputting a needle drive signal for driving the sewing needle from the signal output part to the sewing machine, and controlling driving of the holder and/or the sewing needle based on a detection result of the position detector.

A sewing machine that suppresses sewing defects is provided. The sewing machine includes: a sewing needing, held by a needle bar and moving back and forth while holding an upper thread: a shuttle, configured to hold a bobbin which is housed in a bobbin case and around which a lower thread is wound, and cooperating with the sewing needle to form a seam; a presser foot member, configured to press a to-be-sewn article at a sewing position directly below the sewing needle: a pressure adjustment portion, adjusting pressure applied to the to-be-sewn article by the presser foot member; a feeding mechanism, where endless feeding belts for feeding the to-be-sewn article from the sewing position to a first direction are disposed on two sides of a second direction orthogonal to a first direction with respect to the sewing position, the feeding mechanism is provided with a belt drive portion, and the belt drive portion independently drives the feeding belts on one side of the second direction with respect to the sewing position and the feeding belts on another side of the second direction with respect to the sewing position; and a control portion, configured to control the pressure adjustment portion to make a pressure of the presser foot member be corresponding to a difference between a feeding amount of the feeding belts on one side of the second direction with respect to the sewing position and a feeding amount of the feeding belts on another side of the second direction with respect to the sewing position.