Adjustment of Buttonhole sewing machine cutter

The needle thread of the Buttonhole sewing machine is cut by a cutter and then broken off, which is mainly caused by the failure of left and right, front and back, height, and opening time of cutter. It is recommended to check and adjust according to the following methods.

1. Adjustment of front and back movement of top thread cutting

(1) The front and back movement of the upper thread scissors is 4 ~ 5mm.

(2) Adjustment method: loosen the fixing screw of the roller shaft at the front end of the presser foot lever, move it to the right to increase the front and rear movement of the scissors, and decrease it to the left.

2. Adjustment of left and right positions of side thread cutter of Buttonhole sewing machine

(1) When the top line scissors move to the top, it should be consistent with the center of the needle, and the front end of the top line scissors should exceed 5mm to the right than the falling center of the cutter (Fig. 1).

(2) When the top thread scissors are closed, ensure that there is no overlap of 0.3 ~ 0.5mm between the moving blade and the fixed blade. When the top thread scissors cut the top thread, they should also clamp the thread head left on the machine needle, and ensure that the suture will not fall off from the top thread scissors when sewing again.

(3) Adjustment of left and right positions of top thread scissors: Step on the left pedal, when the upper thread cutter moves to the top, loosen the fastening screw of the swing frame of the face line scissors, and adjust the front, rear, left and right positions of the upper thread scissors by moving the swing frame back, left and right.

(4) Adjustment of the closing amount of moving cutter and fixed cutter of upper thread scissors (Fig. 2):

 Loosen the fastening screw ② of the closing shear control board and move the closing shear control board ③ back and forth. When the closing shear control board ③ moves towards the operator, the closing time is delayed due to the reduction of the closing amount.

3. Height adjustment of upper thread cutter of Buttonhole sewing machine

Adjust the height of the thread cutter after the presser foot is lifted. The fixed cutter is required not to touch the presser foot. During movement, it is not allowed to touch the needle clamp, and try to lower the thread scissors. As shown in Figure 2, loosen the set screw ① of the face line scissors and move the face line scissors up and down for adjustment.

4. Adjustment of the opening time of thread cutter

(1) Under the condition of not affecting the horizontal stitch, it is better to keep clamping the top thread for a long time. When starting sewing, the thread head clamped by the top thread scissors is not allowed to come out. After about 3 ~ 5 stitches, open it slowly.

(2) Adjustment method: loosen the screw ② in Figure 2 and move the shear opening control board ④ back and forth for adjustment. When moving towards the operator, the scissors are opened in advance. Note: do not cause the fixed shear closing control board ③ out of position.