JUKI AC-172N-1790AN Instruction Manual page 38

(3) Threading the bobbin case
Bobbin
Rotating direction of bobbin and threading
1) Fit the bobbin so that it rotates in the direction of the arrow.
Pass the thread through thread slit ❶ , then through under the tension spring ❷ , again through thread
2)
slit ❸ , and pull the thread from ❹ .
Threading at ❹ for purl stitching is different from that for whip stitching. So, be careful.
3)
(4) Adjusting the bobbin thread tension
Adjust the bobbin thread tension as given below when the bobbin thread is pulled up at the position where
thread slit ❶ of bobbin case comes up.
Purl stitch
Whip stitch
Turning tension adjust screw ❷ clockwise will increase bobbin thread tension, and turning it
counterclockwise will decrease the tension.
Adjust the bobbin thread tension to lower for synthetic filament thread, and to higher for spun thread.
The thread tension is higher by approximately 0.05N when the bobbin case is set to the hook since idle-
prevention spring is provided.
When bobbin thread tension is adjusted, make sure of the needle thread tension setting of the
memory switch. (Refer to
Purl stitch
❶
Bobbin case
0.05 to 0.15N
0.15 to 0.3N
"II-2-9. Changing needle thread tension"
❷
❸
❹
❷
❶
To such an extent that bobbin case quietly comes down
when holding thread end coming from bobbin case and
shaking it quietly up and down.
To such an extent that bobbin case barely comes down
when holding thread end coming from bobbin case and
shaking it somewhat strongly.
– 34 –
Whip stitch
p.91.)
❹