The reason why the thick thread sewing machine can sew canvas or leather with thickened fabrics is that the large rotary shuttle and hook thread are used to form a lock stitch. This kind of sewing stitch is mainly divided into three basic links:

1) Lead the top thread through the seam material to form the top thread loop. In this link, the machine needle moves downward to pierce the sewing material and pass the upper thread through the sewing material. When it reaches the lowest point, it starts to rise up. Due to the resistance between the thread and the needle and the sewing material, the thread is blocked, so that the top thread accumulates at the bottom of the needle hole of the machine and gradually forms a thread loop. The purpose of forming a thread loop is to enable the rotary hook tip to smoothly thread the bottom thread.

2) The top thread passes around the bobbin sleeve to form interweaving with the bottom thread. After the upper thread loop is formed, the shuttle tip of the rotary shuttle shell hooks the thread loop. During the movement of the rotary shuttle, the thread passes around the bobbin sleeve storing the bobbin thread. At this time, the thread take-up lever rises to pull the thread loop out of the shuttle tip, and the upper thread loop around the bobbin thread is released from the rotary shuttle.

3) Tighten the bottom and top thread and hide the thread knot in the seam material. The upper thread loop and the lower thread form a combination of interlaced threads, continue to shrink, and retract in the seam material. At the same time, the thread threading hole of the thread take-up rod rises, and the top thread is pulled out from the thread threading device to supplement the consumption of the top thread.

If there is a problem that the thick material sewing machine eats thick jumpers or the presser foot is low during the sewing process, adjust the presser foot or increase the rotary hook.