Lower Thread Tension (Basic Settings); Upper Thread Tension (Basic Settings) - Bernina 330 Service And Maintenance Manual

5.10.3 Lower thread tension (Basic settings)

Check:
•
Use a cotton thread DMC 50 BLANC
gauging thread.
•
Use gauge 001 538.70.00 to adjust lower thread
tension.
•
The bobbin case is inserted into the weight gauge in
exactly the same way as into the hook.
•
Hold free end of thread firmly and let bobbin case
and gauge (without additional weight) hang free.
•
The bobbin case must not move downwards.
•
After attaching an additional weight (5g, art. no.398
117 030) the thread should unwind fast.
•
(unwinding speed 1m in 2–4 seconds)
Correction:
•
Use a small screwdriver to adjust the lower thread tension by
turning the bobbin case screw accordingly.
•
Turn screw counterclockwise to slacken.
•
Turn screw clockwise to tighten.

5.10.4 Upper thread tension (Basic settings)

Check:
•
Refit rear cover.
•
Turn adjusting wheel until red bar mark is in line with mark on housing.
•
Thread machine as far as and including thread take-up lever using cotton
gauging thread DMC 50 BLANC 652010.20.++.
•
Set take-up lever to top dead centre (TDC).
•
Lower presser foot and unwind approx. 30cm thread from
the spool.
•
Attach upper-thread tension adjusting gauge 008709.72.00
to thread end.
•
With 85g attached, the upper-thread tension gauge should
stay in place.
•
Attach 8g (5g + 3g) additional weight.
•
Now the thread should unwind very slowly.
Correction:
•
Turn adjusting wheel as appropriate.
•
Hold clamp lever 1 down (adjusting wheel is now unlocked).
•
Turn adjusting wheel until red bar mark is in line with mark
on housing.
•
Engage clamp lever 1 as appropriate.
BERNINA International AG · Seestrasse 161 · CH-8266 Steckborn · Switzerland
for
652010.20.++
9
1
3gr + 5gr.
44