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19. LIST OF TROUBLE USUALLY ENCOUNTED AND THEIR POSSIBLE
CAUSES
(1) Breaking of needle :-
a. The needle used being unsuitable for the material or / and the thread.
b. The shuttle back not being well replaced after cleaning of the shuttle race.
c. After changing of needle, the needle being improperly set into the needle clamp or
not being inserted into the uppermost end of the needle clamp. Screw in the
needle clamp not being well tightened.
d. Needle being bent.
e. Presser foot being improperly fastened screw of the adjustable foot press not well
tightened.
f. Moving of the fabric by force while sewing.
(2) Breaking of needle thread (upper thread) :-
a. Wrong process of threading.
b. Needle thread too tense, or poor quality of the thread used.
c. The balance wheel being turned in the wrong direction.
d. The reel of threads being over-fully wound, so that part of the thread being wound
upon the spool pin.
e. Unsuitable needle used for a certain type of material or / and thread.
f. The needle not well inserted or the needle being bent.
g. The shuttle body being damaged by knocking so that the place where the thread
passes is rough.
(3) Breaking of bobbin thread (under thread) :-
a. The hole of the needle plate being rough after the breaking of needle.
b. Thread on the bobbin being loosely wound or over-full.
c. The shuttle race back being damaged by knocking so that the place where the
thread passes is rough.
d. Tension of the bobbin thread being too strong.
(4) Hitting of thread in the shuttle race :-
a. The balance wheel being turned in the wrong direction.
b. The upper and lower thread not being pressed tight under the presser foot.
c. The end of the under thread not yet being picked up or being caught in the latch of
the bobbin case.
(5) Skipping of stitches :-
a. Unsuitable needle used for a certain type of material or / and thread.
b. Needle being bent or its point too blunt.
c. The flat side of the needle facing the wrong direction after being inserted or the
needle not well inserted.
d. The shuttle race back not being well replaced after cleaning of the shuttle race.
e. The presser foot being improperly fastened.
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