Adjusting The Bobbin Thread Tension; Installation Of Bobbin Case - JUKI LBH-1790A Series Instruction Manual

5. 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 0.05 to 0.15N
Whip stitch 0.15 to 0.3N
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, check the needle thread tension setting of the
memory switch. (Refer to "V-22. Memory switch data list" p.52.)

6. Installation of bobbin case

WARNING :
To protect against possible personal injury due to abrupt start of the machine, be sure to start the
following work after turning the power off and ascertaining that the motor is at rest.
❶
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.
1) Lift up and hold bobbin case latch lever between
two fingers.
2) Push the bobbin case into the hook so that it is
supported by the hook shaft ❶ and then snap in
the latch lever.
Press the bobbin case until the predetermined
position is reached, and it will click.
1. If the bobbin case is out of the
predetermined position, it can jump
out from the hook to cause the
needle thread to tangle on the hook
shaft. Check to be sure that the
bobbin case is properly installed in
the correct position.
2. There is a difference in the shape of
bobbin case between the standard
hook and the dry one. They have
nothing in common with each other.
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