Union Special XF500 Industrial Sewing Machine Maintenance Guide

3.17 Needle and thread control settings (dual needle/triple needle)

At the bottom dead center of the needle bar, the wire hole of the needle bar eye (A in Figure 30) should be 1/16 inch lower than the wire release plate (B) on the wire picking cam (C). At the dead center of the needle bar, the wire of the thread picking cam should just touch the needle thread. When the auxiliary disconnect piece (F) is at the bottom dead center of the needle bar and the adjustable thread hole of the wire control component is in the "T" position, the needle and thread should contact the disconnect piece.

3.18 Wire Cutting Knife Adjustment ("AIR-KLIPP")

Replace blade: The upper blade (A in Figure 31) is fixed by two screws; The lower blade (C) is held by a roller pin (A in Figure 32) and a tension spring (D in Figure 31). When replacing, lift it up and tilt it to the right to ensure that the spring passes through the side hole of the lower blade and the groove aligns with the roller pin.

Cross adjustment: Turn off the motor, connect the air source, press the pedal to make the pneumatic motor work, and ensure that the lower blade does not touch the blade housing. Loosen screw F and move the slider block (E) left and right to position the lower blade 1/32 inch (0.8mm) in front of the upper blade.

Shear angle adjustment: The shear angle should be 0.003 inches (0.076mm), measure the edge of the lower blade and the edge of the upper blade. Rotate the lower blade adjustment screw counterclockwise (C in Figure 32) slightly and repeatedly test the cutting effect. When the line is not cut and the cutting angle is zero, turn clockwise by 1/4 turn.

3.19 Pneumatic pressure regulation

Adjust the pneumatic control system valve to achieve a pressure of approximately 20-22 psi (1.5 bar) when the pneumatic motor of the wire cutter is working. Adjust the suction pressure to the maximum, but ensure that the fabric is not caught by the cutting knife.

3.20 Puller Timing

The feeder must stop intermittent feeding before the needle is inserted into the fabric. Remove the top cover, loosen the four fastening screws of the sprocket (A in Figure 33), and advance or postpone the sprocket position. Adjust to center the belt and apply a torque of 35 in lbs (40 cm/kg). Belt tension: Press between the sprocket and the puller assembly, with a deflection of 1/8 inch (3.2mm), adjusted by the eccentric wheel (D in Figure 34).

3.21 Replacement of feeder line trace length

By replacing the combination of two sprockets (B and C in Figure 35), 59 different trace lengths can be obtained (refer to the sprocket table on page 28). Loosen the tightening screw, replace the sprocket, ensure that the hub is flush with the shaft end, and the first screw is located on the plane of the shaft. Re tighten the belt.

3.22 Adjustment of pressure roller and idler roller

The material roller should be evenly pressed onto the idler roller (A in Figure 39) to ensure that the fabric is sent out straight. If necessary, add shims under the idler roller bearing block. Puller lifting adjustment: When the presser foot lands on the needle plate, there is a gap of 1/32 inch between the puller lifting link (A in Figure 40) and the lifting pin (B). Adjust the lifting timing by loosening screw C.

3.23 Thread shortening device

The factory setting is half of the recommended trace. Loosen the locking screw (A in Figure 41), turn the stop screw B clockwise to reduce the number of needles per inch, and turn counterclockwise to increase.

Maintenance and parts replacement

Regular maintenance is the key to ensuring machine performance and lifespan. It is recommended to follow the preventive maintenance plan, replace worn parts in a timely manner, and insist on using Union Special original parts. The manual is accompanied by a detailed parts list and illustrations for users to easily locate and place orders. Common vulnerable parts include machine needles (Type 108 GHS, 128 GAS, 128 GBS, multiple sizes), feeding teeth, needle plates, presser feet, wire cutting blades, as well as various sealing rings and springs.