Regarding the broken needle or thread of the multi-needle machine, the author believes that the problem of the gap between each needle should be dealt with. Below, the author takes Morimoto 1412 multi-needle machine as an example to introduce the most common technical failures in use-needle and thread breakage. Due to the large number of needles in multi-needle sewing machines, the gap between each needle should be carefully adjusted during debugging.
　　 First of all, we should choose high-quality needles, such as organ needles. After all the needles are installed, we should check whether all the needles are in the center of the needle plate hole after entering the needle plate hole, and then check whether the needle is in the center of the presser foot hole. When the needle descends to the bottom dead center, the looper retracts to the end, and the distance between the tip of the looper and the center of the needle is 3 mm. At this time, the needle starts to rise. When the curved needle tip reaches the center of the needle, it should be 2 mm above the needle hole, and the lateral gap between the curved needle tip and the needle is 0, and the gap between the guard needle and the needle is 0.5 mm.
　　 Then, we can check whether the distance between the head of the looper and the needle is 0.5 mm when the looper needle is moved to be flush with the needle. We can adjust the position of the line finger back and forth. It should be noted that the plane of the line finger is facing upwards, and the distance between the bottom and the head of the looper is 0.5 mm. This position is very important. We should carefully adjust the first thread-drawing finger, the machine needle and the looper needle. If the stitches skip continuously during the sewing process, it is mostly related to this position.
　　 Again, the amount of looper thread hitting is generally adjusted to between 6 mm and 7 mm. Without affecting the stitch, the looper should be relaxed as much as possible. After debugging, the thread should be threaded correctly. Press a piece of cloth under the presser foot, and we must carefully check the formation of the thread loop: if the needle thread loop is small, when the thread take-up lever is at the bottom dead center position, the upper thread hook should be flush with the thread take-up lever hole. Hang on the thread hook; if the thread loop is large, do not hang it on the thread hook.
　　 Finally, we must carefully check whether the spool finger can separate the looper thread correctly, and the test can be started after the inspection is completed.

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