JUKI DLN-6390 Engineer's Manual page 27

Adjustment Procedures
1) Assembling the needle feed shaft
1 Position the lateral position of needle feed shaft 1 with thrust collars 3 so that
the end plane of needle feed shaft arm (rear) 2 aligns with the chamfering of
needle feed shaft 1.
2 Assemble needle feed shaft 1 with two thrust collars 3 so that the shaft smoothly
moves without thrust play.
3 When tightening needle feed shaft arm (rear) 2, tighten it at the position where
the setscrews in thrust collars 3 of needle feed shaft 1 are not located on the
window plate side.
2) Adjusting the lateral position of the needle bar
1 Adjust the lateral position of needle bar 7 by moving needle bar rocking base
bushing 6 in the direction C as shown in the figure.
2 Check that setscrew !4 in the needle bar rocking base bushing and clamp
screw !3 in the needle feed arm, front are loosened, lightly hit section D of
needle bar rocking base 4 with the plastic hammer or brass bar, and move
bushing 6 until needle !5 comes to the center of needle hole ! 6 .
3 Perform this adjustment before 4) Assembling the needle bar rocking base
guide below.
3) Assembling the needle bar rocking base and the roller guide base
1 Put needle bar rocking base shaft bushing 6 between needle bar rocking base
4 and roller guide base 5, and temporarily tighten roller guide base 5 so that
needle bar rocking base 4 smoothly moves without play in the direction A as
shown in the figure.
* Securely perform the thrust removing since if there is a thrust play at needle bar
rocking base 4, stitch skipping may occur.
2 The roller guide base 5 is assembled not directly by normal tightening with a
screw but by gripping at first around with a base holder not to let it make rotary
move in the direction B as indicated in the figure.
Otherwise, direct tightening with a screw makes it unable to fix right positioning
of the needle.
Thereafter, the accurate needle bar 7 positioning is acquired by fastening a
screw @ 0 for roller guide base 5 with keeping pushing the needle bar frame 4
by hand in the direction B shown in the figure.
In tightening the screw @0 be sure to check no ratting nor shaking exists with
the needle bar 7 by moving it up and down.
When the center of needle bar 7 is not obtained, seizure of the
(Caution)
needle bar may occur. Securely perform the centering of needle
bar 7. Especially, be careful that jar is apt to occur near the
highest position of the needle bar.
4) Assembling the needle bar rocking base guide
1 Assemble needle bar rocking base guide !2 with setscrew !9 at the position
where there is no torque in the direction of rotation of needle bar rocking base
4.
* When the position of needle bar rocking base guide !2 is not obtained, the horn
section of needle bar rocking base 4 is worn up and the lateral play at the
needle bar may occur. Be sure to check the torque of needle bar rocking base
4 after securely tightening setscrew ! 9 of needle bar rocking base guide !2 .
5) Adjusting the initial position of the needle bar
1 For the initial position of the needle bar, tighten needle feed shaft arm (front) 9
at the position where the interval between needle bar 7 and presser bar 8 is 9
mm when the scale of needle feed dial is "0" and the needle bar is in its lower
dead point.
* For the interval between needle bar 7 and presser bar 8, there is a section of
9 mm on gauge !0 supplied as accessories. Use it at the time of adjustment.
* Adjust the interval between needle bar 7 and presser bar 8 at the bottom end
section of needle bar lower bushing !1 .
Results of Improper Adjustment
™ Torque turns heavy if needle bar
7 is operated without fightening
the needle clamp screw !7 .
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