JUKI DDL-9000 Engineer's Manual page 44

Points of adjusting sewing
When using the plastic race hook for DS and DF, if the balance of adjustment of the thread take-up spring and the
tension spring is not proper, thread breakage when sewing at high speed, thread breakage when performing
reverse feed stitching, hangnail of thread, or thread breakage when performing concealed seam under stitching
is likely to occur.
(Cautions when performing adjustment)
* When filament thread is used, if the indented part of the needle is tilted to this side, the loop of thread becomes
unstable. As a result, thread breakage or hangnail of thread is likely to occur. For the thread with which such
phenomenon is likely to occur, it is effective to slightly tilt the indented part to the operator's side.
Direction of
inserting thread
* Comparing with the existing lubricating hook, the plastic race hook makes better loops, and is likely to be
affected by the adjustment of the thread take-up spring.
When defective stitches are apt to occur, adjust the thread take-up spring so that the stroke is longer and the
tension is lower than those of the sewing machine with the lubricating hook (level to such an extent that the
spring works up to the end when pulling out thread).
It is effective to increase the stroke of the thread take-up spring to stabilize the loop, however, the spring does
not show its effect enough if the adjustment is performed as shown in the illustrations below.
Adjust the tension of the thread take-up spring to the lower than the specified value so that the thread take-up
spring works up to the last when the thread is pulled out in the direction of the arrow.
When thread take-up
spring moves on the way,
since the tension is high,
thread is fed out from A.
* To make the size of loop small, hook adjusting timing of DF and DS types is 1.8 mm. It is less by 0.2 mm than
the standard value of 2 mm. (Part No. of needle bar : 22886907)
* When even the aforementioned adjustments cannot solve sewing conditions, change the needle bar thread
guide to B1418227T00. It gives resistance to needle thread, stabilizes loop and prevents thread from thread
breakage.
Direction of
indented part
Direction of
needle eyele
B
A
Thread take-up spring
− 41
Operator's side
works up to the end.
−
X