Adjusting The Thread Trimming Timing - Brother S-7200B Service Manual

6-11. Adjusting the thread trimming timing

Lowest position of needle bar
Reference
line (a)
Direction of
cam rotation
Raised 5 mm
<
1. Turn the machine pulley to raise the needle bar 5 mm
Reference
line (b)
1204B
2. At the above position, push the plunger (1) of the thread
3. Check that the clearance between the edge of the thread
1205B
<Movable knife and fixed knife position adjustment >
1206B
1. Turn the machine pulley, and then push the plunger (1) of
2. In this condition, turn the machine pulley until the roller
1207B
3. Install the feed dog, needle plate and presser foot.
Mating mark
1208B
S-7200B
Remove the presser foot, needle plate and feed dog.
Thread trimming cam position adjustment >
from its lowest position (reference line (a) position) so
that reference line (b) is aligned with the bottom edge of
the needle bar bush.
trimming solenoid with your finger in the direction of the
arrow.
Adjust the position of the thread trimmer cam (2) at this
time so that the roller shaft (4) of the thread trimmer cam
lever assembly (3) touches the hollow (c) of the thread
trimmer cam (2) and so that the clearance between the
edge of the thread trimmer cam (2) and the roller shaft (4)
is 0.6 to 0.8 mm, and then tighten the set screws (5). (Fig.
[A])
trimmer cam (2) and the roller shaft (4) is 0.5 mm when
the roller shaft (4) returns to the right. (Fig. [B])
* Tighten the two set screws (5) to approximately 4 N.m.
the thread trimming solenoid with your finger.
shaft (4) of the thread trimmer cam lever assembly (3) is
sitting on top of the thread trimmer cam (2), then move
the thread trimmer lever (7) to adjust its position so that
the tip of the fixed knife (5) and the blade of the movable
knife (6) are meshed by 1 mm, and then tighten the screw
(8).
* Adjust so that the meshing amount is 1 mm at this time,
by using the position where the mating marks on the
thread trimmer holder and the bushing are aligned as a
guide.
* Tighten the screw (8) so that there is no play in the
forked shaft (9).
* The lower thread finger (10) must be underneath the
movable knife (6).
6. ADJUSTMENTS
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