SunStar SWF/B Series User Manual page 41

5) Relationship between the Take-up Lever and the Hook
Hook point timing is directly related to thread tension and thread breaks. The following pictures show the location
of hook when the take-up lever starts to move up from the lower dead stop (main shaft rotation angle: 295°).
Fast Hook Timing
too
small
Slow Hook Timing
too
large
[ CAUTION ] In normal hook timing, the hook should fall in the C range in the picture below.
(A) The hook timing falls in the A range. The hook
point will take up the thread when the loop is too
small. Stitching will be faster than the take-up
movement. As a result, the thread will be too
loose and skipped stitches will occur.
[Fig. 5-32]
(B) The hook timing falls in the B range. The hook
point will take up the thread when the loop is too
large, so there may not be skipped stitches.
However, the take-up movement will be faster
than the stitching movement and thread breaks
will occur.
[Fig. 5-33]
(B)
(C)
(A)
[Fig. 5-34]