With Regard To Thread Trimming - JUKI LU-1510N-7 Engineer's Manual

(2) With regard to thread trimming

Troubles
One or several stitches
1
skip at the start of sewing.
Causes
Thread remaining at the
needle top after thread
trimming is short.
Bobbin thread is not
clamped.
Needle is too thick.
Needle hole in the feed
dog is too large.
Pressure of the presser
foot is too low.
Stitches are too small.
Checking
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 moving knife and
the hook.
Presser foot drops from
cloth at the time of
thread trimming.
Position of the clamp
spring.
Pressure of the clamp
spring is too low.
There are scratches
on the clamp spring.
Needle thread removes
bobbin thread.
– 71 –
Corrective measures
Thread the needle thread correctly.
Adjust so that abnormal needle
thread tension is not applied.
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 "(22)-6) Threader cam
timing".
Polish with buff or replace the
part.
Perform thread trimming on cloth.
Refer to "(22)-1) Position of the
counter knife and the clamp
spring".
Refer to "(22)-1) Position of the
counter knife and the clamp
spring".
Replace the clamp spring with a
new one.
Increase or decrease the tension
of the tension controller No.1.
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.
Do not pass thread through the
thread presser section of the
thread guide on the needle bar.