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Adjustment Procedure
3) Thread trimming cam timing
The aim of the thread trimming cam timing is matching the en-
graved line A of the control box with the colorless engraved line on
the hard wheel ❻ and the center of the colorless engraved dot.
[1] For checking of the thread trimming cam timing
1. Tilt the sewing machine head.
2. Turn handwheel ❻ by hand in the normal direction of rotation un-
til the thread take-up lever goes up slightly below the upper dead
point. Press cam follower ❶ with fingers to the left (in direction
of arrow E) and engage the roller ❷ with the groove C of the
thread trimming cam ❸.
3. In this state, turn the handwheel ❻ in the direction which is
opposite to the normal direction of rotation until the handwheel ❻
goes no further. (If the handwheel is turned further, it reaches the
position at which cam follower ❶ starts moving.)
At this moment, match the engraved line A on the control box
with the colorless engraved line on the hard wheel ❻ and the
enter of the colorless engraved dot.
[2] Adjustment of the thread trimming cam timing
1. Tilt the sewing machine head.
2. Loosen the screws No.1 and No. 2 of thread trimming cam set-
screw ❼ in the written order.
3. Match the engraved line A on the control box with the colorless
engraved line on the hard wheel ❻ and the enter of the colorless
engraved dot.
4. Pressing cam follower ❶ to the left (in the direction of arrow E),
engage thread trimming cam ❸ with roller ❷. Then, turn only
thread trimming cam ❸ with fingers in the direction which is
opposite to the normal direction of rotation of feed driving shaft
❹ until it will go no further without turning feed driving shaft ❹. At
this position, tighten the screws No. 1 and No. 2 of thread trim-
ming cam setscrew ❼ in the written order while pressing thread
trimming cam ❸ against roller ❷.
Results of Improper Adjustment
○ In the case of using a high-count
filament thread, thread loop for-
mation may be unstable. If faulty
loop spreading occurs in this state,
correct the thread trimming cam
timing by aligning the marker line
on the pulley cover with the red
marker dot, instead of the green
marker dot, on the handwheel.
○ The alignment point between
thread trimming cam ❸ and roller
❷ is position (F) from which cam
follower ❶ starts moving. It is not
the position (G) at which you feel
that the thread trimming cam ❸
comes in contact with roller ❷ for
the first time.
* Be sure to correct the thread trim-
ming cam timing carefully since it
largely affects the loop spreading
timing.
– 48 –
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