JUKI MF-7800D Series, Engineer'S Manual

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1. Adjustment of needle thread trimmer
(1) Adjusting the engagement of knives
1) Adjust so that the engagement of fixed knife with moving
knife is 0.5 mm.
2) When adjusting the engagement, loosen setscrews and move
knife holder up or down to adjust.
(2) Adjusting the pressure of clamp spring
1) Top covering thread is held with clamp spring after thread
trimming.
2) Holding pressure can be adjusted by loosening nut and
turning screw .
3) Holding pressure is increased when tightening screw and it
is decreased when loosening screw .
4) After the adjustment, tighten nut .
5) Make the holding pressure as low as possible within the range
of holding the top covering thread.
(3) Adjusting the position of the blade point of moving knife
1) Bring the needle bar to its highest position.
2) When hinge screw is lowered, moving knife lowers
together.
3) Adjust the moving knife to position where the hook section of
moving knife enters the concave of the bottom surface of
spreader and catches the top covering thread in the state
that moving knife is fully lowered. After the adjustment, tighten
screws and .
4) Screws are for adjusting vertical position of the knife, screws
for adjusting lateral position of the knife, and screws for
adjusting angle of the knife.
(Caution) Make sure that the moving knife does not interfere with
other components such as presser, needle, spreader
, etc. within the working range of moving knife .
2. Adjusting the speed of moving knife
Stroke of air cylinder is 20 mm.
Speed of the moving knife can be changed with speed controllers
and .
(1) When you desire to change the protruding speed of moving knife
, loosen the nut of speed controller and turn the adjustment
screw.
When you desire to change the returning speed of moving knife ,
loosen the nut of speed controller and turn the adjustment screw.
(2) After the adjustment, tighten the nuts of speed controllers and
.
o When the protruding speed of
moving knife is slow, thread
trimming failure will be caused.
o When the returning speed of
moving knife is fast, needle
thread clamp failure will be
caused.
Adjustment Procedure
Results of Improper Adjustment
UT25