You can install the knife first. When installing the upper cutter, lower the lever of the upper cutter until it leans against the lower cutter. Then, install the upper knife, which should be close to the two blades and flat. When finally tightening the fixing screw, tilt the upper cutter to one side.
Extended data:
Four-thread sewing machines, also known as sewing machines, yard sewing machines and bone sewing machines, are generally divided into three, four and five threads. The main function is generally to prevent pilling in the seams of clothing. Four-thread wrapping needle is a double-thread and four-thread needle, which adds one more needle and thread than three-thread wrapping needle, which increases the strength. It is used to sew the pieces of high-grade clothes with high tension and strong friction, such as shoulders and sleeves, especially for sewing coats.
Four-thread sewing machine structure: including sewing machine body, one side of sewing machine body is connected with a workbench, a support seat is arranged below the workbench, and a rotating shaft is rotatably connected above the support seat. The upper end of the rotating shaft is rotatably connected with a turntable, which is fixedly connected with the shell, and a clamping block is movably connected in the shell, and the bottom end of the clamping block is connected with the shell through a return spring.
When the cloth needs to be hemmed, the electromagnet attracts the metal support rod, and the metal support rod presses the return spring, and the small wheel presses on the fed cloth, so that the cloth will not wrinkle when it is fed. When the feeding direction of the cloth needs to be changed in the sewing process, the user only needs to gently rotate the turntable by hand to prevent the cloth from wrinkling due to manual feeding and sewing the edge.
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