47
19. Adjustment of bobbin thread tension
Requirement:
The force required for pulling cotton thread 50/2 or synthetic fiber thread 100/3 off the bobbin must be
approximately 25 - 30 g.
Check:
• When a threaded bobbin case hangs on its thread, it must not slide downwards by its own weight.
• With a sharp upward movement of the hand, the thread must run off gradually (fig. 44).
• There must not be any thread waste under the tension spring.
• The tension spring must rest evenly and parallel on the bobbin case.
Adjustment:
• Loosen the knurled screw a little and turn it in again until a resistance is felt when the thread is pulled
off.
Check:
• Carry out as described under „Check“
Note:
• Once the bobbin thread tension has been set correctly, tension adjustments must be made only to
the needle thread tension.
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