Experience in handling needle skipping in overlock sewing machines

During normal sewing, when the equipment starts to stitch, the needle and thread are simultaneously threaded. However, sometimes there may be situations where the outer long needle cannot be threaded during stitching, and sometimes it can go several centimeters without threading. If we talk about the car skipping the needle, as long as the long needle is on the line until the end, everything is normal and there is no skipping phenomenon halfway; If the car does not jump the needle, but the needle does not go online when it starts to start, taking the Feima W500 as an example, let me share my personal experience in repairing this problem. When the needle is intact and the machine position is correct, if the needle does not come online during needle lifting, the problem of the thread should be considered. Sometimes the manufacturer's thread has a relatively large twist, and the formed loop is unstable because the long needle is the farthest needle that hooks the thread in the bent needle, so the formed coil is also the largest one. When the quality of the wire is poor and the coil exceeds a certain range during the formation process, the coil will twist and deform, making it difficult for the bent needle to hook into the coil of the long needle.

1、 Take out the longest needle thread from the small wire clamp on the needle shaft, which can reduce the formation of coils and prevent them from twisting easily.

2、 Place a piece of cloth under the presser foot, open the side cover of the differential adjustment and the movable suction plate on the table, rotate the upper wheel of the machine by hand, and then observe the hooking situation between the machine needle and the bent needle from the differential adjustment side. It will be found that when the bent needle starts to enter the long needle loop, the loop has twisted, making it impossible for the bent needle to hook the thread. According to the twisting situation of the needle and thread, the needle can be tilted slightly so that the needle coil can fit the bent needle into the loop (the needle can only change direction slightly, and too much can cause skipping).

3、 If the above method still cannot solve the problem, you can raise the needle bar by about 0.5mm to make the wire loop of the machine needle smaller. In addition, slightly advance the time for the curved needle to hook the thread, because when the curved needle enters the long needle coil, the bottom of the curved needle is in contact with the thread of the needle hole, and the curved needle moves to the left. The bottom of the curved needle contacts the machine needle thread, and the two rub against each other, causing the coil to deform to the left and twist faster. If the bending needle is advanced a little, after the bending needle enters the coil, when friction occurs between the wire and the bottom of the bending needle, causing deformation of the coil, the bending needle has completely entered the coil and the coil cannot slide out from the bending needle tip. The above is just my personal experience in handling the situation