JUKI DDL-555-4 - Troubleshooting Sewing Issues; Thread Breakage Causes and Solutions; Stitch Skipping Diagnosis

VII. TROUBLES AND CORRECTIVE MEASURE
Troubles
Causes
Corrective measures
Page
1. Thread 1) Thread quality is poor.
o Use the thread of better
breakage
quality.
17
2) Thread is too thick for the
o Correct the combination of
needle size.
thread and needle.
3) Thread is broken by the
o Prevent the needle from
heat of the needle.
over-heating (synthetic
thread).
4) Thread tension is too high.
o Reduce the thread tension.
16
5) Thread path on the sewing
o Remove such scratches or
hook, throat plate, tension
burrs from the thread path
discs, thread take-up or other
by using an oilstone or buff.
components has scratches or
or replace the defective
burrs.
parts.
6) Stitches are skipping.
o Provide the sewing hook
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blade with a proper clearance
from the needle and a correct
timing.
Hn.sure the needle bar height.
7) Bobbin thread tension is too
o Adjust the thread tension
17
low. between the needle and
bobbin threads.
8) The needle recess does not
o Insert the needle in the cor
17
face to the correct direction.
rect way.
2. Stitch
1) Distance from the .sewing
o Correct the clearance and
23
skipping
hook blade from the needle
timing of the .sewing hook
is not correct. related to the needle.
2) Needle bar height is not
o Align the engraved line of the
23
correct.
needle bar with the bottom
end of the needle bar lower
bushing.
3) Needle is bent.
o Replace the needle.
4) Needle hole in the throat
o Bring down the needle bar
plate is too great. and increa.sc the sewing hook
stroke (it occurs in light
weight materials).
5) Needle slot in the presser
n Bring down the needle bar and
foot is too great.
increase the .sewing hook
stroke.
6) Thread clings to the heated
o Prevent the needle from over
needle.
heating.
7) Thread tension No. 1 is too
o Reduce the thread ten.sion by
16
high.
turning counter-clockwi.se the
tension nut No. 1.
8) Presser foot does not give a
o Increase the presser bar
18
sufficient pressure to the pressure.
works.
9) Bobbin thread tension is too
o Increa.se the bobbin thread
17
low. tension.
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From the library of: Superior Sewing Machine & Supply LLC