With Regard To Sewing - JUKI DLN-6390 Engineer's Manual

(2) With regard to sewing

Troubles
1. Stitch skipping 1-1) Needle components
1-2) Hook components
1-3) Defective feed
1-4) Thread tension components
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Cause (1)
1)-A Needle is bent.
1)-B Installation of needle is
1)-C Blunt of needle tip
1)-D Needle is too thin for
1)-E K i n d o f n e e d l e i s
2)-A Blunt or worn-out of
2)-B Defective hook timing
2)-C Height of needle bar is
2)-D Clearance at blade point
2)-E No needle guard
3)-A Stitch skipping due to
4)-A Needle thread tension is
4)-B Tension of thread take-
4)-C Stroke of thread take-up
4)-D Stroke of thread take-up
4)-E Tension of thread tension
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Cause (2)
Replace the needle.
Install the needle again.
wrong. (Orientation or
insufficient insertion)
Replace the needle.
Replace the needle with a proper needle
thread used or cloth. (thick needle if possible).
Replace the needle with a proper one.
improper. SCHMETZ UY180GVS is recommended.
Correct the blade point of hook or replace
blade point of hook the hook.
Adjust the timing according to 4-(2).
Perform the adjustment described in the
Instruction Manual as the aim and in
accordance with the conditions of cloth and
thread, perform fine adjustment according
to 4-(21).
Adjust the height of needle bar according
improper. to 4-(1).
Making as the base the adjustment
procedure described in the Instruction
Manual, in accordance with the conditions
of cloth and thread, perform fine
adjustment according to 4-(21).
• When setting the needle bar rather in a
• When setting the needle bar rather in a
Make small the clearance between needle
of hook is improper. and the blade point (Make it near to "0".)
Especially, in case of thick materials, use
the designated hook with needle guard.
Refer to the item "Stitch gathering at
stitch gathering overlapped section".
Decrease the tension.
too high. (excessively
tightened)
Correct to the proper tension. (0.2N is
up spring is too high. recommended.)
Correct to the proper stroke. (8 mm is
spring is too large recommended.)
Correct to the proper stroke at the position
lever is small. of arm thread guide A. (Position of marker
line is standard, and when moving
counterclockwise, stroke of thread take-up
lever is increased.)
Adjust the tension to such an extent that
No. 1 is too low. thread does not move roughly between
thread tensions No. 1 and No. 2.
(However, when the tension of thread
tension No. 1 is excessively high, thread
trimming performance is affected. Do not
excessively increase the tension.)
Corrective measures
lower position, be careful of the needle
thread lock between needle and inner
hook needle guard at the lower dead
point of the needle bar.
higher position, be careful of the contact
between the blade point of hook and the
belly section of needle.