Stitch skipping occurs in different fabrics, and there are different techniques to deal with it:
A. How to deal with stitch skipping caused by two layers of fabric when sewing silk before sand washing
Before the silk fabric is sand washed, the fabric will be very astringent and hard during sewing. This will cause the needle and suture to fail to produce good loops in the sewing material, resulting in skipped stitches. Check whether the needle bar is worn and has gaps: Check whether the tip of the hook is in good condition and standard, because the tip of the hook is a key component for hooking the thread. There must be no burrs, bald tips and other defects. If found, use a diamond file or whetstone gold in time. Grind with sandpaper to meet the standard, and then adjust the angle; check the needle bar height. The needle bar height standard is: when the needle bar is at the bottom dead center, the needle bar scale line should be on the second line. In this way, when the needle bar rises to the root thread, adjust the angle between the needle and the hook tip. When adjusting the angle, you should first pay attention: if there is a slight gap in the needle bar, use your left hand to push the needle bar slightly to the left before adjusting. The standard for adjusting the angle between the needle and the hook is: when the needle bar rises from the bottom dead center to the scale line, the tip of the hook should be 1.1-1.5cm above the needle hole, and the lateral gap between the tip of the hook and the needle is O. 02-0.05cm; The cloth feeding mechanism is also key. First, check whether the cloth feeding cam is properly marked. Because thin materials are being sewn, the teeth should be lower, and the cloth feeding cam should be adjusted appropriately.
B. How to deal with stitch skipping when sewing down fabrics in particularly thick areas
The down fabric is sewn with vacuum cotton and down to form an extra thick layer of 0.7-1.1 cm. In this state, the needle and suture are not easy to form a good thread loop, resulting in skipped stitches. According to the situation of this extra thick layer, the feeding problem should be solved first and the feed dog should be replaced with a thick material feed dog. The needle hole of the needle plate should be larger, and the feed cam should also be adjusted accordingly. The adjustment standard is: the teeth should be raised to a high place, and the tip of the needle should be in the needle hole of the needle plate: the height of the needle bar should also be adjusted significantly, and the needle bar should be adjusted accordingly. When the height is at the bottom dead center of the needle bar, go down to the third line of the needle bar scale and then go down 0.1 cm. In this way, the principle of increasing the needle bar stroke is used to complete the thread hooking: the needle and thread hooking time also change. , adjust the angle when the needle bar rises from the bottom dead center to the root line of the scale. The angle adjustment value is consistent with the above; increase the pressure of the presser foot: due to the thick material, the needle is prone to friction and heat, which may also make it difficult to form a thread loop. , if necessary, it needs to be solved by adding silicone oil at the line crossing.
C. Stitch skipping caused by poor fabric feeding when sewing leather
When sewing leather, the fabric becomes stiff and causes poor feeding, resulting in skipped stitches. You can repair it according to the above method for extra thick materials, but there are differences in solving the feeding problem. You can use a nylon presser foot to solve the problem of poor feeding, or you can apply silicone oil to the leather sewing area.
D. When sewing sand-washed silk, stitches skip when sewing high and low layers
The sand-washed silk fabric is soft, so it is difficult for the needle and suture to form loops when passing through the sewing material. However, if the fabric and the bottom edge overlap at high and low places, it will even cause gaps under the presser foot at high and low places. , the thread loop cannot be formed normally, resulting in stitch skipping. At this time, you should check whether there is any gap in the needle bar; check whether there are thorns or bald tips on the hook tip; check the height of the needle bar. Because it has high and low layers, it can be classified as medium-thick material type. When repairing, you should think calmly before making appropriate adjustments to the height of the needle bar. According to this type of situation, adjust the needle bar height from the needle bar to the third line of the bottom dead center scale as a benchmark. The specific adjustment method is: The adjustment angle should be adjusted when the third line of the scale rises to the root line: Check whether the needle hole of the needle plate is standard: If the presser foot is used with a medium-speed sewing machine, the back of the presser foot should be rubbed off to form When feeding the fabric, the presser foot and the upper and lower layers of sewing material come down smoothly to press the sewing material.
E. When sewing denim, using thick threads may cause thread breakage, thread rolling, and stitch skipping
Denim is sewn with thick thread, which makes it difficult to form thread loops and prevents the thick thread from coming out of the thread loop from the hook positioning hook, resulting in thread breakage, thread rolling, and skipped stitches. In addition to using the above-mentioned thick material type repair method, there is a difference in this. Because thick threads are mainly used, the hook positioning hook must be processed and ground during maintenance so that the thick thread can come out of the positioning hook easily. . And choose a hook that doesn’t suffer too much wear and tear.
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