SunStar HC Series User Manual page 32

4) 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 200° and varies as below.
Top point of hook
circumference
Top edge of
needle eye
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
Hook point
0.1~0.3mm
Hook point
Needle tip
a
[Fig.4-22]
Top edge of
needle eye
Lower dead
stop of the
needle
2.3~3.7 mm
1.8~2.2 mm
0.5~1.5 mm
·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
The figures may change according
to needle specification/number.
Hook
allowance
(gap)
[Fig.4-21]
[Fig.4-20]