JUKI DDL-9000 Engineer's Manual page 36

[Adjusting the needle and feed timing]
When performing adjustment of feed driving cam timing, or inclination and height of the feed dog, the needle and
feed timing will change. As a result, defective sewing or needle breakage may result.
In this case, adjust the timing in the following procedure.
1) Checking the timing of lowering of the feed dog
Turn the handwheel by hand and check the top end of needle eyelet in the state that the top end of the feed
dog is aligned with the top surface of the throat plate at the end of feed.
In this state, when the top end of the needle eyelet has been already lowered from the top surface of the throat
plate, the needle pierces the material in the state that the material is being fed when sewing the thick section,
and needle breakage due to needle bend may result.
On the contrary, when the top end of the needle eyelet is excessively positioned above the top surface of the
throat plate, stitch tightness is deteriorated.
Perform adjustment in the following procedure so that the feed dog is lowered at the top end of the needle
eyelet except when intentionally changing the adjustment.
2) Adjusting the timing
☆ Adjusting places are three, lower sprocket, thread trimmer cam and hook.
① Tilt the machine head, and loosen two setscrews (A) in the lower sprocket.
② Fix the feed driving cam at the feed dog lowering timing (position where the top end of the feed dog is
aligned with the top surface of the throat plate), turn the handwheel gradually to the position where the top
end of the needle eyelet is aligned with the top surface of the throat plate. In this state, tighten the two
setscrews in the lower sprocket.
(Reference value for tightening torque : 4.5N•m)
③ Loosen two setscrews in the thread trimmer cam, and adjust the cam timing to the position of the red
marker dot (green marker dot when the length of remaining needle thread is short). (Refer to the item 3-5.)
④ Adjust the hook timing by aligning the marker line on the needle bar with the bottom end of needle bar lower
bushing.
* After the aforementioned adjustment is completed, operate the sewing machine and check whether noise
occurs or thread trimmer normally works.
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(A)
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