JUKI lbh-1790 series Engineer's Manual page 9

Adjustment Procedures
1. Enter timing gauge [1] 1 supplied with the machine as
accessories between the throat plate and the lower end of the
needle bar as shown in the figure, fit the needle bar to timing
gauge [1] 1, loosen the setscrew 2 in the needle bar
connection, and adjust the height of the needle bar.
(Caution) Adjust the height of the needle bar when the needle
is positioned in the center of the needle hole in the
throat plate.
2. Table of timing gauge
Timing gauge
Sub-class type
[1]
S (standard) 12.0 mm
K (knits) 11.3 mm
Part No. of timing gauge : 13943402 (S : standard)
Adjustment Procedures
1. Turn the hand pulley in the normal direction of rotation, and make a
state that the needle is in the center of hole in the throat plate and the
needle bar starts going up from the lowest dead point. Then enter
timing gauge [2] 1 between the throat plate and the lower end of the
needle bar as shown in the figure and loosen setscrew 2 in the
hook shaft joint to adjust the timing.
2. Loosen setscrew 2 in the hook shaft joint and adjust so that
the clearance between the needle and the blade point of the
hook is 0.01 to 0.04 mm when the needle is rocked to the
extreme right of the hole in the throat plate.
3. Adjust with setscrew 5 so that the engagement of the top end of
bobbin case positioning stopper 3 and inner hook 4 is 0 to 0.2 mm.
4. Bend the needle guard and adjust so that the clearance between the
needle and the needle guard is 0 to 0.02 mm.
(Caution)
1. When adjusting the needle guard, adjust so that there is no
clearance between the inner hook presser and the rear plate.
2. When moving the needle guard to the needle side, put a
screwdriver from the direction of the arrow mark, while
pressing the loop guide, and perform the adjustment.
Engraved mark
[2]
14.5 mm 79NS1
14.3 mm 791K
13782107 (K : knits)
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Results of Improper Adjustment
™ For the floppy fabrics, it is
effective when the needle bar is
s l i g h t l y l o w e r e d t h a n t h e
standard value.
Results of Improper Adjustment
™ For the floppy fabrics, it is
effective when the hook timing
is slightly retarded than the
standard value.
(Clrarance provided between the
upper end of the needle eyelet
and the blade point of the hook
is desired to be approximately
1.0 mm.)
™ For the purl stitching, if the hook
timing is advanced, crest of
seam is likely to be improved.
On the contrary, if the hook
timing is retarded, stitch skipping
is improved, but crest of seam
i s l i k e l y t o b e s l i g h t l y
deteriorated.
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