Clearance Between Rotary Hook And Needle Plate - Brother T-8420C Instruction Manual

10. STANDARD ADJUSTMENT

10-3. Clearance between rotary hook and needle plate

37
The clearance (A) between the rotary hook (1) and the
needle plate (2) is adjusted as follows at the time of shipment
from the factory.
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• Check clearance (A) each time parts such as the rotary
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hook (1) and the needle plate (2) that affect clearance (A)
are replaced.
• To adjust clearance (A), replace the thrust ring (4) that is
in between the rotary hook (1) and the rotary hook base
(3).
• Three types of thrust ring (4) are available. Measure the
thickness of the thrust ring (4) that is currently being used,
and replace it with a thrust ring (4) of the appropriate
width.
• When replacing the rotary hook (1), loosen the three set
screws (5). Be careful not to lose the thrust ring (4) at this
time.
NOTE:
There is a piece of felt (7) for lubrication at the base of the
rotary hook shaft (6). Gently press down on the rotary
Touching gently
hook (1) when tightening the set screws (5) so that the
rotary hook (1) does not lift up.
If the clearance is too large
If the clearance is too small
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T-8420C, 8450C, 8720C, 8750C
Model
T-8420C
T-8450C
T-8720C
T-8750C
Part code
SA4444-001
SA4038-001
S09260-001
• The inner rotary hook may come out from the needle
plate (2).
• Poor thread tightening may occur.
Distance (A)
0.9 – 1.2 mm
Thickness
0.8 mm
1.0 mm
1.2 mm