Adjustment Of Bobbin Thread Tension; Adjustment Of Needle Thread Tension - Pfaff expression 2014 Service Manual

17. 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. 46).
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.

18. Adjustment of needle thread tension

Requirement:
Within the adjusting range from 3 to 5, the interlacing of the needle thread and the bobbin thread (cotton
thread 50/2 or synthetic fiber thread 100/3) must take place approximately in the middle of the fabric in
straight and zigzag stitch setting (fig. 47 and fig. 50).
46