Adjusting The Sensitivity Of Sensors; Wiper; Thread Hauler - JUKI LK-1942ZA5050 Instruction Manual And Parts List

6. Adjusting the sensitivity of sensors

Configuration
Stitch skipping detection sensor amplifier
No bobbin-thread
detection sensor amplifier
Output indicator lamp
Current amount
SET button
of light received/
set value

7. Wiper

Standard adjustment

8. Thread hauler

Standard adjustment
Adjustment procedures
Adjust the sensitivity of the sensors
with the sensor amplifiers mounted
inside the heat cutter control box.
1. Place thread to be used in front of
the reflective plate. Press the SET
button shortly.
For the no bobbin-thread detection
sensor, press the SET button with
the reflective plate of the bobbin
removed.
2. Press the SET button again with the
thread removed. For the no bob-
bin-thread detection sensor, press
the SET button with the reflective
plate of the bobbin illuminated by
the optical axis.
When the respective optical axes
of the sensors illuminate the corre-
sponding reflective plates, the output
indicator lamp of the corresponding
amplifier lights up as long as the
sensor sensitivity is adjusted correct-
ly. The adjustment is completed by
checking the above.
Adjustment procedures
1. Loosen the wiper
mounting screw. Adjust
so that the left end face
of wiper is spaced 13 to
15 mm away from the
center of needle.
2. The center of the R
section (concave sec-
13 mm - 15 mm
tion) at the top end of
wiper has to pass the
needle tip.
3. The wiper must not in-
terfere with the needle.
Adjustment procedures
1. The standby position of the thread
hauler has to be adjusted so that it
does not interfere with the thread
Thrust collar
which is passed between the thread
controllers Nos. 1 and 2 when the
cylinder is extruded the most.
2. Adjust the position of thrust collar
of stopper to adjust the thread
hauling amount. (Initial value: 32
mm)
32mm
– 15 –
Results of improper adjustment
• Faulty detection of bob-
bin thread can occur.
• Faulty detection of stitch
skipping can occur.
Results of improper adjustment
• If the wiper is excessively spaced
from the needle, the remaining
length of needle thread will be
longer, and if it is excessively
close to the needle, the remain-
ing length of needle thread will be
shorter causing slip-off of thread
from needle eyelet.
• If the center of the concave
section of the wiper is not aligned
with the needle tip, faulty thread
trimming can occur.
• If the wiper comes in contact with
the needle, the needle can break.
Results of improper adjustment
• If the thread hauling
amount is too large,
the thread will slack-
en resulting in faulty
thread trimming.
• If the thread hauling
amount is too small,
the length of thread re-
maining at the needle
will be shorter resulting
in slip-off of the thread
from needle eyelet.