If the thread is too dense, just loosen the adjusting screw on the stitch length adjusting device downward and adjust one or two grids. Due to the different sewing materials or purposes, the stitches must be adjusted: 1. Just look at the length of the stitch length and the number on the adjusting screw washer on the stitch length adjusting device. The larger the number, the longer the stitch length, and the smaller the number, the shorter the stitch length. 2. When choosing a long stitch length, just loosen the adjusting screw on the stitch length adjusting device and move it down and tighten it. 3. When selecting a short stitch length, just loosen the adjusting screw on the stitch length adjusting device and move it upward and tighten it. In short: users can adjust as needed.
Generally, do not replace the bobbin case for this type of failure. Do not change the needle easily. It needs to be checked. If it is loose or misplaced, correct it.
1. Check whether the direction of the needle is reversed, especially for round-handle needles, the operator needs to decide by himself.
2. Check whether the needle bar moves up due to the loose screw。
3. Check whether the crank screw of the lower shaft is loose, causing the lower shaft to be misaligned left and right or circumferentially shifted.
4. Check whether the pendulum shuttle spring is broken.
5. Check whether the screws of the shuttle bed cover are loose, causing the cover to shift to the left.
6. Check whether the gear hook at the lower end of the needle bar is loose or not.
There are two main possibilities for this situation: First, the needle is installed incorrectly. Read the manual of the sewing machine carefully. No matter which brand has a detailed description and illustration, if there is no error, then see if it is the step of threading the upper thread. Wrong; the second is the threading error of the bobbin and the bobbin case. The correct method can also be found in the manual. The tip of the hook is not at the right time. When the needle rises 2 to 3 mm, the tip of the hook turns to a place 1 mm above the eye of the needle. When passing the needle, the needle cannot be hit or not. There are gaps.
