Troble-Shooting And Maintanance - SunStar KM-818 User Manual

Troble-shooting and maintanance

6 6
Problem
1.@Thread cutting
2. Jumping of stitch
3. Inadequacy of the
Thread Tension
20
Cause
① There are rough holes on the path of
the thread, the needle end or the slot
of the inner hook of the needle plate.
② Upper thread tension is strong.
③ The space of inside the middle hook
guide is big.
④ The needle touches the end of the
hook blade.
⑤ The oil of the inside the hook is
insufficient.
⑥ The upper thread tension is weak.
⑦ The thread take-up spring is weak or
its movement rate is low.
⑧ The timing of the needle and hook is
either too fast or too slow.
① The timing of the needle and hook is
either too fast or too slow.
② The pressing pressure is too weak.
③ The gap between the upper part of
the needle hole and the end of the
hook blade is irregular.
④ The support of the hook needle is
malfunctioning.
⑤ The selection of the needle is
incorrect.
① There is no lower thread inside the
tension spring of the bobbin case.
② The path of the thread has uneven
spots.
③ The bobbin is not moving smoothly.
④ The space inside the middle hook
guide is too big.
⑤ The lower thread tension is too weak.
⑥ The lower thread is wound too
tightly.
Solution
○ Polish the needle with sand paper and the
inner hook with a buff.
○ Decrease the upper thread tension.
○ Make the space smaller, referring to "20.
Adjustment of the middle hook guide."
○ Refer to "17. Relations between the
needle and the hook."
○ Lubricate the lace of the hook, referring
to "5. Lubrication."
○ Strengthen the upper thread tension.
○ Strengthen the spring and increase its
movement rate.
○ Refer to "17. Relations between the
needle and the hook."
○ Refer to "17. Relations between the
needle and the hook."
○ Fasten the thumb screw.
○ Refer to "17. Relations between the
needle and the hook."
○ Refer to "18. Adjustment of the hook
needle support."
○ Replace the needle with one of the next
higher rank.
○ Refer to "7. Lower threading."
○ Polish it with sand paper or buff it.
○ Replace the bobbin or the hook.
○ Refer to "20. Adjustment of the middle
hook guide."
○ Strengthen the lower thread tension.
○ Loosen the lower thread.