Union Special XF500 Industrial Sewing Machine Maintenance Guide

3.7 Bending needle avoidance

When the curved needle moves from left to right and the needle shaft descends, the needle tip should only contact the lower third of the back of the curved needle. Loosen the two screws (A in Figure 13) and rotate the eccentric screw B: increase the clearance counterclockwise and decrease clockwise. After adjustment, the bending needle setting needs to be rechecked.

3.8 Rear protection needle

When the needle guard is in the forward position, the maximum gap between the horizontal direction and the needle should be 0.002 inches, as low as possible, so that its vertical plane is about 3/64 inches (1.2mm) away from the needle tip, until the bent needle tip moves to the left and is flush with the right side of the needle. Adjust screws D and E. Changing the needle size may require adjusting the needle guard, but changing the stitch length is not necessary.

3.9 Setting of fabric feeding teeth

The feeding teeth should be at the center of the needle board, with equal gaps on both sides and ends. At the highest point, the tooth tip should protrude approximately 3/64 inches (1.2mm) from the needle plate. Left and right adjustment: Loosen the three screws supporting the needle plate and the positioning sleeve screw, and tighten the positioning sleeve first after adjustment. Front and rear adjustment: Loosen the two screws (A in Figure 16) of the feeding tooth holder and move it back and forth. Leveling adjustment: Remove the needle plate, loosen the relevant screws, rotate the feeding teeth tilt cam (A in Figure 18) to make the feeding teeth horizontal, and then lock them. The feeding lifting amount can be adjusted by turning the knob (B in Figure 19): increasing the lifting towards the operator and decreasing it in the opposite direction. After adjustment, manually rotate the handwheel to confirm that the feeding teeth do not touch the needle plate or bend the needle.

3.10 Line trace length adjustment

XF511B100MF: Adjust by using the screw (A in Figure 21) in the slot of the right needle plate to extend the trace backward and shorten it forward.

Other models: Press and turn the adjustment knob (A in Figure 20) to shorten clockwise and lengthen counterclockwise. The limit screw C can prevent the knob from exceeding the maximum line trace.

3.11 Low inertia presser foot (single needle model)

When the needle bar is at the bottom dead center and the presser foot falls on the needle plate, the gap between the top of the screw in the presser foot and the top of the groove is 1/32 inch (0.8mm); When the foot lifting rod is released, there is a gap of 1/16 inch (1.6mm) between the bottom of the foot lifting link (A in Figure 22) and the bottom of the foot pressing rod guide plate (B). Adjust nut C and screw D, presser foot guide plate screw E, and lift foot arm screw F.

3.12 Feeding presser foot (XF511H100MAW)

When the presser foot lands on the needle plate, the distance from the top of the spring to the top of the yoke is 5/8 inch (15.9mm), and the bottom mark of the presser foot is aligned with the needle. When lifting the foot, press the sole slightly backwards (maximum 1/64 inch). Adjust nut C, spring adjustment nut, stop screw D, etc. to match the feeding amount of the upper and lower layers of fabric.

3.13 Pressure Foot Rod and Pressure Foot (Double Needle/Three Needle)

When the dead center of the needle bar and the presser foot are on the needle plate, the gap between the bottom of the screw (A in Figure 24) and the groove bottom of the presser foot bar guide plate (B) should be at least 1/64 inch, and the gap between the bottom of the presser foot bar guide plate and the top of the lower bushing should be at least 1/32 inch. The gap between the bottom of the lifting link (C) and the guide plate (D) is 1/16 inch. Adjustment steps: loosen the screw E of the presser foot bar guide plate, loosen the nut F, unscrew the screw A to make the gap between the guide plate and the guide plate at least 5/64 inch, align the presser foot and the needle, tighten the screw E after pressing, and then adjust the spring pressure.

3.14 Wire loosening device

The needle and thread tension plate (A in Figure 25) should start releasing when the presser foot is lifted to 1/8 inch from the endpoint, and fully release when the presser foot is at its highest point. Loosen screw C and adjust the tension component by moving it up and down.

3.15 Bending Needle Thread Picking Rod and Stripping Board

The wire rod (A in Figure 27) should be centered on the left and right sides of the release plate (B). When the needle rod descends, the thread picking rod should detach when the needle tip is flush with the bottom of the bent needle. Adjust by using the two screws on the wire rod. The adjustable wire hole (C) is located 1/2 inch below the center of the mounting screw. Distance board height: The lowest point of the wire picking cam is flush with the upper surface of the distance board, adjust screw K.

3.16 Needle and thread control settings (single needle)

The needle rod eye (A in Figure 28) cooperates with the needle thread cam (B) to ensure that the needle thread just touches the cam at the top and bottom dead points of the needle rod. The eye position is adjustable, and the cam can move forward and backward. When the loose wire (B in Figure 29) is 0.5mm away from the top cover surface, the needle rod is at the bottom dead center, and the adjustable thread hole (C) of the wire control component is in the "T" position, adjust the needle and thread tension to form a tight thread trace; Turning to the "L" position will loosen the trace.