JUKI LK-980 Series Quick start guide

No. IV-8-1
1983.8
lIUKI
LK-980
Series
High Speed 1-Needle, Cylinder Bed, Lockstitch
Bar Tacking Industrial Sewing Machine
ENGINEER'S MANUAL
TOKYO JOKI INOOSTRIAL CO., LTD
FOREIGN TRADE BUSINESS DIV.
From the library of: Superior Sewing Machine & Supply LLC

INTRODUCTION
This booklet consists mainly of 3parts, the first part is for the "Standard Adjust
ments" covering the basic adjustments and their directions, the second part is for
elimination of mechanical troubles and the third part is for the subclass models of the
LK-980 series.
We hope all service engineers will read and study carefully the first part "Standard
Adjustment."
The "Standard Adjustment" explained in simple terms with illustrations will
facilitate quick access to the practical services for service engineers in the field. The
columns "Possible problems or phenomena caused by improper adjustments" and
"Corrections" are added for inexperienced service engineers.
To make optimum use of this booklet, we advise you to refer to "PARTS BOOK
for the LK-980 series."
If the brief descriptions given in "Standard Adjustment" are not enough, refer to
the relative item for further details.
From the library of: Superior Sewing Machine & Supply LLC

CONTENTS
I. STANDARD ADJUSTMENTS 1
II. MEASURES TO ELIMINATE STITCHING FAILURES 12
(1) Thread escape 12
(2) Thread breakage 14
(3) Thread trimming failure 17
(4) Needle breakage 18
(5) Precautions when sewingsynthetic materials 19
(6) Loose stitching 19
III. THINGS TO BE NOTED WHEN DISASSEMBLING AND ASSEMBLING THE MACHINE 20
(1) How to remove the shuttle driver shaft 20
(2) How to remove the main shaft 20
IV. ELIMINATION OF EXCESSIVE PLAY 20
(1) Excessiveplay in the main shaft 20
(2) Excessive play of the feed cam driving worm against the feed cam driving worm wheel 21
(3) Excessive play
of the feed cam roller 21
(4) Excessiveplay in the shuttle driver shaft 21
(5) Cork linings
ia the clutch components 21
V. DETAILS OF ADJUSTMENT 22
(1) Adjustment for starting and stopping 22
(2) Adjustment of the pedal pressure decreasing unit 27
(3) Adjustment of the thread trimmer components 29
(4) Feed cam components 30
(5) Adjustment
of the shuttle race 31
(6) Height
of the work clamp foot 32
(7) Height
of the wiper 32
(8) Checking the safety device 32
(9) Adjustment of the bobbin winder 33
(10) Tension
of the V-belt 33
(11) Silicone oil lubricator 33
(12) Application of "lock-tight" paint 33
(13) Greasing 34
(14) Replacement parts 36
VI. HINTS ON SUBCLASS MODEL MODIFICATIONS 38
VII. UTILIZATION OF SPECIAL COMPONENTS 41
From the library of: Superior Sewing Machine & Supply LLC

I. STANDARD ADJUSTMENTS
Standard adjustments
(1) Needle and sewing hook
1) Height of the needle bar
When the needle bar has reached Its lowest position, the upper
engraved line on the needle bar must align with the bottom
end of the needle bar bushing (lower).
2) Shuttle
With the above needle bar position, the pointed end of the
shuttle must align with the needle center.
3) Clearance between the needle surface and the shuttle must be
0.05 to 0.1 mm.
4) There must be no clearance between the needle and the shuttle
driver. The top end of the shuttle driver prevents the needle
from bending as shown In Fig. 1-b.
5) Clearance between the top end of the shuttle driver and the
shuttle must be 0.3 to 0.5 mm (about 1/64").
When the needle has
reached its lowest
position.
When the needle thread
is taken up by the
shuttle.
Upper engarved
line
Lower engraved
line
Fig. 1-a
Fig. 1-b
0.05—0. Inim
Fig. 1-c
Onim
Shuttle driver
Fig. 1-d
Note:
Adjustments of "Height of the needle bar" and "shuttle" may vary
In some subclass models
(2) Feed cam
Adjust the cam so that the cloth feed motion Is completed when
the needle point has come down 7 to 10 mm (9/32" to 25/64")
above the throat plate surface.
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7—lOram
t
Fig. 2
From the library of: Superior Sewing Machine & Supply LLC

Possibletroubles and phenomena caused by
Improper adjustments
(1) When sewing materials whichtend to flutter while
being stitched, set the needle bar slightly lower
than the standard height.
When sewing a heavy-weight material, providing
it isnot of a type that tends to flutter, set the
needle bar slightly higher than the standard
height.
(2) When using a synthetic or soft and thin thread
(for example, cotton thread #80), in order to
prevent it from falling down and snagging, do not
allow it to form a large loop.
(3) If the shuttle comes closer to the needle than
0.05 mm, they may touch and scratch each other.
The scratcheson their surfaceswill damage a thin
or synthetic thread.
If the clearance is greater than 0.1 mm stitch-
skipping will result.
(4) If
the shuttle driver dosen't come into close
contact with the needle, the needle will bend
backwards. The bent needle will hit the blade
point of the shuttle scratching them both. If this
happens the thread is likely to be broken or torn
by these scratched surfaces.
If the needle isonly slightlybent, stitching will not be
affected. If, however, it isbent too much, it may
cause stitch-skipping.
(5) If the clearance between the shuttle driver and
the shuttle isgreater than 0.3 to 0.5 mm (about
1/64"), a noisewill result during operation. If it
is too small, a thick thread may fail to be drawn
out resulting in formation of a loose stitch.
If the needle point height is set closer to 7 mm
(9/32"), the stitch will be tightly formed. Whenthe
needle point height is set closer to 10 mm (25/64"),
it prevents synthetic needle thread from coming out
on the surface of the material and forming an idle
loop on the first stitch. (No special care is needed for
sewing heavy-weight material)
Corrections
See "3. Needle Bar Components" in the Parts Book.
Remove
the face plate and adjust the needle bar
height by loosening screw (SS-6090670-TP) of needle
bar connection.
See "5. Shuttle Driver Shaft Components" in the
Parts Book.
Loosen screw (SS-6121212-TP) and adjust the shuttle
driver.
See "5. Shuttle Driver Shaft Components" in the
Parts Book.
Loosen screw (SS-6151220-SP) to set free shuttle
race and adjust the shuttle race position in the axial
direction by turning shuttle raceadjustingshaft
(B1819-280-000)
Loosen screw (SS-6121212-TP) and adjust shuttle
driver in the axial direction by taking care not to turn
the shuttle driver in the direction of rotation. If you
mistakenly allow the shuttle driver to rotate, readjust
the shuttle according to 2).
Although eachend of the shuttledriverishardened,
you can bend it at the middle point when adjusting
the clearance at the shuttle. Remove the shuttle from
the shaft for bending, otherwise the shuttle mayshake
on the shaft when rotating. Alsotake care to keep
point (3) at an equal distancefrom each lipof the
shuttle, in order to let the thread passthrough
smoothly. It is advisable to tap the shuttle at the
point © .
Fig. 1-e
See "6. Feed Cam Components" in the Parts Book.
Loosen nut (NS-6360621-SN) and also loosen feed
cam position stud (B2207-280-000). Now the feed
cam can be freely adjusted in the normal direction
of rotation.
(Note) (Once you have adjusted the feed cam position,
you should not change it afterwards. If changed,
you must readjust the thread tension release
components and the stop-motion regulating
cam (Refer to the relevant paragraphs in this
Manual.)
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From the library of: Superior Sewing Machine & Supply LLC