Adjusting The Longitudinal Position Of The Blade Point Of Lower Knife; Adjusting The Thread Trimmer Sensor; Adjusting The Speed Of Looper Thread Trimmer - JUKI MF-7500 Series Instruction Manual

Blade point of lower knife is in the
center of thickness of looper.





9. Adjusting the longitudinal
1) Advance the needle bar by 15º from its upper dead
point.
Adjust so that the blade point of lower knife ❹ is
2)
❹
placed at the center of thickness of the looper 
when the lower knife  is projected until its top
end is aligned with the end face of the looper  .
Loosen nut  , move lower knife holder ❺ to and
3)
fro, and adjust the position of the blade point of
lower knife ❹ .
After the adjustment, tighten nut  .
4)
❺

10. Adjusting the thread trimmer
The safety switch is installed so that the sewing ma-
chine does not start unless the looper thread trimmer
device returns to its home position.
Loosen setscrews  .
1)
Adjust switch plate  so that LED of thread trim-
2)
mer sensor  lights up in the state that the thread
trimmer device is fully returned to its home position.
Tighten setscrews  .
3)
11. Adjusting the speed of
Speed of the looper thread trimmer device can be changed
with speed controllers  and  of air cylinder ❸ .
1) When you desire to change the protruding speed
of lower knife, loosen the nut of speed controller  ,
and turn the adjustment screw.
When you desire to change the returning speed of
lower knife, loosen the nut of speed controller  ,
and turn the adjustment screw.
❸ 
2) After the adjustment, tighten the nuts of speed con-
trollers  and  .
– 13 –
position of the blade point of
lower knife
Perform the work with the needle bar at the
highest position when actuating the thread
trimmer mechanism by hand.
sensor
Perform the work with the needle bar at the
highest position when actuating the thread
trimmer mechanism by hand.
looper thread trimmer
• When the protruding speed of lower knife is
slow, thread trimming failure will be caused.
• When the returning speed of lower knife is
fast, lower thread clamp failure or uneven
needle thread remaining length will be
caused.