Lower Thread Tension - Bernina KL. 940 Service Manual

LOWER THREAD TENSION
For testing use thread No. 60,3-ply, white, left-twist. This thread is contained in the
bobbin case of every new machine.
The lower thread tension is checked with the setting weight No. 398 140 0 4 (1 4 gr.).
The bobbin case is placed in the weight gauge just as in the hook.
Check:
Hold the free end of the thread and
suspend the bobbin case with setting
weight. (Bobbin must be 3/4 full). Place
the setting screw 1 13 on the bobbin case
in such a way that thread may only slowly
move downwards after attaching the
additional tolerance weight No.
398 141 03 (3 gr.).
Note:All test weights for upper and lower
thread tension are intended only to
determine the basic tension value. During
sewing the thread tension can be regulated
according to need.
The upper thread tension must be adapted to the lower thread tension.