The principle to be followed when adjusting the front and rear needle guards is: the contour line of the front and rear needle guards from the direction of the operator should be consistent with the line of the needle tip. In order to prevent the needle from jittering on the needle guard, the guard needle is close to the side of the needle. It should be chamfered appropriately. The front needle guard (near the operator) not only serves as a needle guard but also prevents the sewing thread from forming a thread loop in front of the needle eye (close to the operator), so that the thread loop behind the needle eye is formed smoothly. The rear needle guard must act as a needle guard but cannot block the smooth formation of the thread loop.
Due to different manufacturers and different machine models, the shape of the front and rear needle guards and the allowable adjustment range are some distance from the ideal state. Maintenance personnel are required to move as close as possible to the principles that need to be followed in the actual situation.
When the needle moves down, the front and rear needle guards should move away from the needle. When the needle rises from the lowest position, the front and rear needle guards should move toward the direction of the needle.
When the needle is lowered to the needle guard position, the needle guard should hide from the starting needle to avoid rubbing against the needle.
When the curved needle tip moves to the left to the right needle position, the front and rear needle guards begin to work. The gap between the front (close to the operator) needle guard and the needle is 0.1-0.3mm. The gap between them is 0-0.1mm.
