– 45 –
4) Adjusting the knife pressure
1. Loosen setscrews in the moving knife.
2. Adjust the installing position of the moving knife so that the position
where moving knife and counter Knife start coming in contact
with each other starts at the position of 6 to 7 mm from the top end
of the moving knife. At this time, if moving knife comes in contact
with the clamp spring, the knife pressure is increased by the clamp
pressure. So, adjust the knife pressure in the state that the clamp
pressure is not applied to the knife.
3. Tighten setscrews in the moving knife.
(Caution) Operate the sewing machine with the knife pressure
minimized to such an extent that both needle and bob-
bin threads can be trimmed.
1. Loosen setscrew in the rocking arm.
2. Adjust so that the distance between the top end of the counter knife
and the top end of the moving knife is 2±0.2 mm when moving
knife travels to its back end.
3. Tighten setscrew in the rocking arm so that there is no thrust
play at the moving knife shaft.
4. In case of 2-needle, both the left and right are the same adjustment
value.
(Check) At this time, check that rocking arm comes in close
contact with thread trimmer stopper plate .
1. Loosen setscrews in the thread trimmer shaft connecting plate.
2. Adjust the clearance between thread trimmer driving plate and
cam roller A to 0.1 to 0.2 mm.
3. Make the edge of thread trimmer cam come in close contact with
cam roller B , and temporarily tighten setscrews in the thread
trimmer cam.
4. Make safety clutch disk come in close contact with thread trim-
mer cam , and securely tighten setscrew in the safety clutch
disk.
5. Tighten setscrews in the thread trimmer shaft connecting plate.
(For connecting procedure, refer to “7) Connecting the rocking arm
and the thread trimmer roller arm”.
(Caution) Install the thread trimmer cam in the state that thread
trimmer driving plate comes in close contact with
the follower installing base.
When the knife pressure is high
o Blade sections of the counter knife
and the moving knife may be dam-
aged.
oTorque at the time of thread trim-
ming is increased resulting in mo-
tor-stop.
o Defective thread trimming opera-
tion will result.
When the knife pressure is low
o Defective thread trimming will re-
sult.
When there is no clearance between
the cam roller and the driving plate
o Thread trimmer cam interferes with
the cam roller resulting in break-
age or machine lock.
When the clearance between the
cam roller and the driving plate is
large
o Cam roller enters during operation
resulting in machine rock.
Adjustment Procedures Results of Improper Adjustment
Adjustment Procedures Results of Improper Adjustment
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