JUKI LK-1900B series, Engineer'S Manual

Page: 67 / 174

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Adjustment procedures Results of Improper adjustment
1. Needle thread clamp notch R adjustment
1) Loosen the two setscrews ❶ .
2) Push the needle thread clamp link (asm.) ❷
in Direction A so that the distance between
the needle thread clamp ❹ and the needle
thread clamp base ❺ becomes 17.5 mm
(common to S and H type) (LK-1900BB,
1903BB, 1900BNB, 1903BNB : 15 mm).
Move the needle thread clamp notch RH
in Direction D, lightly press it toward the nee-
dle thread clamp cam plate ❾ and tighten
the two setscrews ❶ .
2. Needle thread clamp notch F adjustment
1) Loosen the two setscrews ❼ .
2) Push the needle thread clamp link (asm.) ❷
in Direction C so that the distance between
the needle thread clamp ❹ and the needle
thread clamp base ❺ becomes 22 mm (com-
mon to S and H type) (LK-1900BB, 1903BB,
1900BNB, 1903BNB : 20 mm).
Move the needle thread clamp notch FH
in Direction E, lightly press it toward the nee-
dle thread clamp cam plate ❾ , and tighten
the two setscrews ❼ .
o
If the distance is too long between the needle
thread clamp ❹ and the needle thread clamp base
❺ , the needle thread release timing becomes
earlier and this can be a cause of unthreading at
the beginning of sewing.
o
If the distance is too short between the needle
thread clamp ❹ and the needle thread clamp base
❺ , the needle thread release timing is delayed
and this can be a cause of needle thread end re-
maining on the rear side of the material.
When the needle thread clamp notch is adjusted
improperly
o
The notch position cannot stay in the standard
range even after the adjustment of the needle
thread clamp sensor according to “(36) Adjustment
of the needle thread clamp reference position”.
[LK-1900BB/BNB]
o
If the distance is too long between the needle
thread clamp ❸ and the needle thread clamp base
❺ , needle thread can not be held during sewing.
As a result, needle thread trimming failure at the
beginning of sewing will occur. If the distance is
too short, needle thread which has been cut is
held by the needle thread clamp after sewing. As a
result, needle thread may be rolled in next seam.
[LK-1903BBS/BNBS]
o
A distance between the needle thread clamp ❸
and the needle thread clamp base ❺ is not in the
range of standard position adjustment, needle
thread which has been cut can not be sucked. As
a result, needle thread may be rolled in next seam.
o
If the distance is too long between the needle
thread clamp ❹ and the needle thread clamp base
❺ , the needle thread release timing becomes
earlier and this can be a cause of needle thread
end remaining on the rear side of the material or
jamming of needle thread into the needle thread
clamp ❹ .
o
If the distance is too short between the needle
thread clamp ❹ and the needle thread clamp base
❺ , the needle thread clamp timing is delayed
and this can be a cause of failure in needle thread
clamping.
When the needle thread clamp notch is adjusted
improperly
o
The notch position cannot stay in the standard
range even after the adjustment of the needle
thread clamp sensor according to “3.-(36) Adjust-
ment of the needle thread clamp reference posi-
tion”.