What's the matter with needle skipping on computer sewing machines?

We all know that computerized lockstitch machine jumping needle is a very ordinary fault, no matter what brand, what model more or less will have jumping needle phenomenon, repair information can also be found everywhere, but there are still many friends have confusion about the solution to such problems. For this reason, I deliberately explain the adjustment techniques in the form of graphics in the simplest way.

First. Sewing machine needle and shuttle fit (standard fit)

In the case of a sewing machine with a graduated needle bar, when the needle bar is at its lowest point, you should first make sure that the upper engraved line of the sewing machine needle bar is in line with the lower end of the needle bar sleeve.

Secondly, the bobbin tip of the rotary shuttle should be aligned with the center of the machine needle when the needle bar rises from the lowest point until the lower engraved line of the needle bar is aligned with the lower plane of the needle bar sleeve.

Second, the three factors of needle skipping caused by bad thread loop of sewing machine needle

When the sewing machine needle rises from the lowest point, the friction between the fabric and the sewing thread is greater than the friction between the sewing thread and the machine needle, so the size and shape of the thread ring thread throw are formed.

1. Small loop, small rise, bad stitching: too much elasticity of the stitching thread, the fabric is raised, the fabric is not fixed properly, and too much resistance of the stabbing fabric.

2. Fabric resistance is too little: fabric is too loose and the thin material needle is too thick.

3. The resistance of the fabric is too large (the stitching line is stretched) and the resistance of the thick material piercing is too large.

Third, the three factors caused by the collapse of the thread ring jump needle

1. Bad stitch: easy to collapse (excessive twist)

2. The shape of the thread loop moves due to the twist of the thread loop.

3. The chemical fiber thread tends to sag downward so that the thread loop becomes larger.

Four, Adjustment techniques

As well as the size of the thread ring, because the needle plate is usually difficult to observe in the maintenance process, we can not open the sewing table like overlock machines can see the formation of the thread ring process, I give you a suggestion; use a standard needle plate to process it into the shape of the following figure, you can easily observe and judge the whole process of the thread ring, which is conducive to our judgment of the next step in the correct adjustment, the correct solution to the problem promptly. Especially for the inexperienced friends more a good helper.

In conclusion, from the above we can see that the main reason for jumping the needle is the size of the thread loop caused the main reason for the impact of the size of the thread loop is due to; the twist of the sewing thread, the fabric is the too loose extremely thin material needle is too thick, the fabric is too elastic, the fabric is fixed poorly, too thick, the needle and the rotation of the needle with improperly caused by the unstable thread loop jumping needle. As long as we find the cause, then the next step can be adjusted for different reasons to correspond on.