Pfaff 1540 User Manual
Page 69
67
36. 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 20-25 g.
Check:
z
When a threaded bobbin case hangs on its thread, it must not slide downwards by its own weight.
z
Upon sharp upward movements of the hand, the thread must run off gradually (fig. 73).
z
There must not be any thread waste under the tension spring.
z
The tension spring must rest evenly and parallel on the bobbin case.
Adjustment:
z
Loosen the knurled screw a little and turn it in again until a resistance is felt when the thread is pulled
off.
Cross-check:
z
As described under "Check".
Note:
z
Once the bobbin thread tension has been set correctly, tension adjustments should be made only on
the needle thread tension.