[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.
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.
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.
[Fig.4-20]
[Fig.4-22]
Hook point
0.1~0.3mm
[Fig.4-21]
Top point of hook
circumference
Top edge of
needle eye
Needle tip
a
Top edge of
needle eye
Hook
allowance
(gap)
Hook point
Lower dead
stop of the
needle
Hook point
a. At lower dead stop of the needle bar
2.3~3.7 mm
1.8~2.2 mm
0.5~1.5 mm
The figures may change according
to needle specification/number.
b. At needle-hook timing
c. At needle-hook timing