13
MODEL 520
MECHANICAL ADJUSTMENT
NEEDLE CLEARANCE TO SHUTTLE
The clearance between the needle and the tip of hook should be -0.1 to +0.05 mm.
PREPARATION:
1. Remove the needle plate, bobbin holder, and bed cover, and replace the needle with the test
pin (D).
2. Turn the power switch on, and select pattern " " (simple zigzag). (Maximum zigzag width)
ADJUSTMENT PROCEDURE:
1. Loosen the screws (A), (B), (C), then slightly tighten the hinge screw (C).
2. Turn the handwheel toward you, and adjust the clearance between master needle and the
point of the hook in the left and right needle position to –0.1 to +0.05 mm by moving the hook
in the left and right by moving the hook set plate up or down.
3. Tighten the setscrews (A), (B), (C).
4. Check the backlash of the hook drive, gear and lower shaft gear. If the backlash is too great
or not enough, adjust the backlash in accordance with "to adjust the backlash of hook drive
gear and lower shaft gear".
5. Attach the bed cover, needle plate and bobbin holder, and remove the master needle.
Hinge screw (C)
Setscrew (B)
Hook set plate
Setscrew (A)
Test pin (D)
Point of hook
–0.1 to +0.05 mm
