– 153 –
Trouble
Cause (1)
Cause (2)
Check and corrective measures
10. Irregular stitch
Thread knots appear on either
side of material at random.
10-1) The matters related to the
hook are inappropriate.
1-A) Hook oil is too large or too small
in amount.
Adjust the oil volume to the appropriate level.
1-B) The hook is defective. (Thread
catch, defective thread path,
etc.)
Replace the hook or modify the thread path.
10-2) The bobbin or bobbin case is
defective.
2-A) The bobbin thread cannot be
pulled out smoothly due to poor
fit between the bobbin and bob
-
bin case.
Replace the bobbin or bobbin case.
2-B) Defective thread winding around
the bobbin winder causes the
bobbin thread to be caught.
Correct the bobbin thread winding tension or
the position of the bobbin winding tensioner.
2-C) The tension adjusting spring of
the bobbin case is defective.
Replace the bobbin case.
2-D) The bobbin thread idles in the
bobbin case.
Adjust the tension of the idling prevention
spring with reference to "3.-(4)."
2-E) The bobbin is inserted into the
bobbin case in the wrong direc-
tion.
Refer to "3.-(4)." Irregular stitches are correct-
ed by rotating the bobbin in the reverse direc-
tion.
10-3) The needle or bobbin thread
tension is too low.
Increase the tension of the needle or bobbin
thread.
10-4) The thread take-up spring is
inappropriately adjusted.
4-A) The stroke of the thread take-up
spring is too long or too short.
Adjust the stroke of the thread take-up spring.
4-B) The tension of the thread take-
up spring is too high or too low.
Adjust the tension of the thread take-up spring.
10-5) The thread path is defective.
5-A) The thread path is not smooth.
Finish the thread path appropriately.
To the next page
To the next page
