T-8421C, 8422C, 8452C, 8722C, 8752C
13. STANDARD ADJUSTMENT
67
13-4. Clearance between rotary hook and needle plate
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.
Model Distance (A)
Without thread trimming
T-8421C
0.9 – 1.2 mm
With thread trimming
T-8422C
T-8722C
T-8452C
T-8752C
1.4 – 1.7 mm
• Check clearance (A) each time parts such as the rotary
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.
Part code Thickness
SA4444-001 0.8 mm
SA4038-001 1.0 mm
S09260-001 1.2 mm
• 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
hook (1) when tightening the set screws (5) so that the
rotary hook (1) does not lift up.
If the clearance is too large
• The inner rotary hook may come out from the needle
plate (2).
If the clearance is too small
• Poor thread tightening may occur.
• Lower thread trimming errors may occur (models with
thread trimmer).
• The right upper thread may be cut too short (models
with thread trimmer).
* These problems may occur particularly if the stitch
length is large or when carrying out thread trimming
during chaining-off.
3054M
3055M
3056M
Touching gently
To Next Page
Loading...
Need help?
General
