First of all, we start with the needle post and the cloth feed tooth. First adjust the feeding amount (adjusting dial) to zero. When there is no feeding, turn the flywheel to make the needle column at the bottom dead center. Loosen the fastening screw of the horizontal feed rocker arm, and adjust the inner distance between the needle post and the presser foot bar to about 1.5mm. If it is not adjusted properly, it will cause skipped stitches and broken stitches. Note that the needle drop point of the feed tooth hole will change after adjustment, and the feed tooth must be adjusted to match. The feeding time should be adjusted so that the engraved point of the horizontal feeding cam coincides with the engraved point of the lower shaft. Do not misalign the horizontal feed cam, otherwise it will cause heavy rotation! Make the needle enter along the center of the feed perforation (very important, otherwise floating will occur!) Misunderstanding One is that the needle bar will be adjusted for general machine repairs. Cooperate with the feeding tooth hole and the needle drop point is not in the middle of the feeding tooth hole, especially when the hole is long!
Next comes the coordination time of the needle and the hook. The bottom dead center of the needle is adjusted according to the sewing material. When the needle rises 2.2mm from the bottom dead center (or look at the lower end surface of the engraved line and the needle column sleeve), move the hook shaft seat left and right to make the distance between the needle and the hook tip be 0-0.05mm , The distance between the needle and the needle stop is 0-0.07mm, and the center line of the needle is consistent with the tip of the hook. It depends on the actual situation to adjust the hooking time faster or slower. Turn the hand wheel to place the thread return hook in the final position. Rotate the inner hook in the opposite direction to the direction of rotation of the hook, so that the hook stop is in contact with the needle plate groove. Loosen the fixing screw of the thread return hook to make the gap between the inner shuttle triangle baffle and the thread return hook 0.2-0.3mm. The gap is too large, causing the thread sleeve to become loose and the thread to break. The gap is too small, causing damage to the return hook. Don't forget, the gap between the upper surface of the needle plate groove and the upper surface of the shuttle stopper is adjusted to 0.8-1.0mm. Replace the backing plate on the rotary hook shaft to change the height of the rotary hook. The second misunderstanding is that the general machine repair will raise the needle board to adjust its gap.
The last is the coordination time between the upper shaft and the lower shaft, and the synchronous toothed belt is removed from the toothed wheel. Turn the hand wheel so that the engraved line of the hand wheel is aligned with the engraved point on the front of the car. Rotate the lower shaft so that there is a small hole in the base to align with the first screw of the lower shaft gear wheel. Ensure that the upper and lower shafts do not move, and install the synchronous toothed belt. If the time is not right, the needle drop point of the feed tooth, the feed time, the change of the mechanical jam, etc.

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