JUKI MF-7900 Series Engineer's Manual page 21

Adjustment procedures
1. Length of the rocking thread take-up
(1) Loosen screws ❶ and move rocking thread take-up ❷ to the
right or left to adjust the length.
2. Position of the rocking thread take-up
(1) Loosen screw ❺ and move rocking thread take-up ❷ up or
down to adjust the position.
(Caution) When adjusting the position of rocking thread take-
up ❷ , adjust the rocking thread take-up to the same
plane of the edge of rocking thread take-up shaft
❸ and fix it so that spreader thread take-up ❻ and
spreader thread guide ❼ do not come in contact with
each other.
To adjust the timing of the rocking thread take-up ❷ , remove
3.
the top cover, loosen setscrew ❾ in the rocking thread take-up
ball arm and move the position of rocking thread take-up ball
arm ❽ to and fro.
(1) Standard adjustment figure is the position where the rear end
(anti operator's side) of rocking thread take-up ball arm ❽
aligns with engraved marker line  on rocking thread take-up
shaft ❸ . (As the standard at this time, note that the clearance
provided between the rear end of rocking thread take-up ball
arm ❽ and thrust collar  is 8 mm.)
1. When loosening setscrew ❾ in rocking thread
(Caution)
take-up ball arm, there is a case where rocking
thread take-up ❷ rotates by its weight. After the
adjustment, be sure to check the rocking po-
sition (flush at the lowest position) of rocking
thread take-up ❷ .
2. When moving rocking thread take-up ball arm
❽ to the operator's side, adjust rocking thread
take-up ball arm ❽ within the range where it
does not come in contact with rocking thread
take-up bushing  (operator's side).
4. Relation between timing of rocking thread take-up and needle
thread loop
Delay timing
(Move to operator's side.)
Loop becomes small.
Adjusting procedure is the same as step 3. Loosen setscrew
❾ in rocking thread take-up ball arm and adjust the position of
rocking thread take-up ball arm ❽ .
(Caution) Adjust the timing of rocking thread take-up ❷ each
time in accordance with thread used or conditions.
Advance timing
(Move to anti-operator's side.)
Loop becomes large.
– 7 –
Results of Improper adjustment
◦ When length of rocking thread
take-up ❷ is lengthened, needle
thread is tightened.
(Caution) When lengthening
rocking thread take-
up ❷ , check whether
it comes in contact
with the thread take-up
cover.
◦ When length of rocking thread
take-up ❷ is shortened, needle
thread is loosened.
◦ When installing position of rock-
ing thread take-up ❷ is raised,
needle thread is loosened.