SunStar SWF/B Series User Manual page 35

4) Relationship between Needle and Hook
① Adjusting Timing between Needle and Hook
Default timing of the needle and the hook is set by the main shaft angle of 201° . Refer to the below for
relationship between the needle and the hook.
Top point of hook
circumference
Top edge of
needle eye
a
a.At lower dead stop of the needle bar
b. At needle-hook timing
c. At needle-hook timing
[CAUTION]
The hook can move right and left if there is an
allowance in the lower shaft gear. Eliminate the
allowance (gap) by turning the hook clockwise. Then
adjust the timing.
② Adjusting Gap between Needle and Hook Point
• Gap between the hook point and the scarf of the
needle should be 0.1-0.3 mm minimum.
• Thread skip occurs due to thread looping or
inadequate balance/gap between the needle and the
hook. The closer the hook point is to the needle, the
hook point will be inside the loop and threading
will be more stable.
Hook point
Top edge of the needle eye
c
Needle tip
b
Lower dead stop
of the needle
2.3 ~ 3.7 mm
1.8 ~ 2.2 mm
0.5 ~ 1.5 mm
5-17
Hook point
[Fig.5-28]
The figures may change
according to needle
specification/number.
Allowance (gap)
[Fig.5-29]
Hook point
0.1~0.3mm
[Fig.5-30]