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(3) With regard to thread trimming
One or several stitches
skip at the start of sewing.
Thread slips off the needle
eyelet.
Defective thread trimming
Needle thread remaining
at the needle top after
thread trimming is short.
Bobbin thread remaining
after thread trimming is
short.
Needle is too thick.
Needle hole in the feed
dog is too large.
Presure of the presser
foot is too low.
Needle thread slips off
the needle eyelet at the
start of sewing.
Needle thread slips off
the needle eyelet
immediately after thread
trimming.
Thread cannot be trimmed.
Check the routing of
needle thread.
Thread tension given by
the tension controller No.
1 is too high.
Check the rising amount
of the thread tension disk
No. 2 at the time of
thread trimming.
Thread trimming timing is
excessively advanced.
There are scratches on
the hook.
Tension of the bobbin
thread is too high.
Check whether the
needle thread remaining
at the needle top at the
start of sewing is short.
Check whether the
needle thread remaining
at the needle top after
thread trimming is short.
A hard-to-slip thread is
used.
The blades of rotary knife
or fixed knife have worn
out or broken.
Pressure of the knife is
insufficient.
Thread the needle thread
correctly. Adjust so that abnormal
thread tension is not applied to the
needle thread.
Decrease the tension given by the
tension controller No. 1.
Adjust so that the disk is raised
by means of the thread release
solenoid.
Refer to “3. (1)-3) Thread trimmer
cam timing”.
Polish with buff or replace the
part.
Decrease the tension of the
bobbin thread.
Replace the needle with a thinner
one.
Replace the feed dog with an
optional one with small needle
hole.
Increase the pressure of the
presser foot.
Refer to the Cause of the previous
item “Needle thread remaining at
the needle top after thread
trimming is short”.
Decrease the number of
threading of the needle thread.
Replace the rotary knife or the
fixed knife with a new one.
Refer to “3. (1) -4) Rotary knife
and fixed knife”.
Troubles Causes Checking Corrective measures
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