Juki LH-3128 / LH-3168 WB — parts catalog
- Page 1 (cover): This is the cover page for the JUKI LH-3128, LH-3128-7-WB, LH-3168, and LH-3168-7-WB Engineer's Manual, dated 1993.12.
- Page 2 (text): This page contains a preface and caution notes for an engineer's manual, along with instructions for before operating the machine.
- Page 5 (text): This page contains specifications for LH model sewing machines, detailing model designations, stitch types, sewing speeds, stitch lengths, needle gauges, and presser foot lifts for models with and without thread trimmers, presented in two tables.
- Page 6 (parts_list): This page contains two parts lists for LH-3128 sewing machine models, S type and A type, detailing various components like needle gauges, throat plates, feed dogs, needle clamps, presser feet, and slide plates with their respective part numbers.
- Page 7 (parts_list): This page contains parts lists for the LH-3128, G type and LH-3128, F type sewing machines, detailing needle gauge, throat plate, feed dog, needle clamp, presser foot, and slide plates.
- Page 8 (parts_list): This page contains two parts lists, Table 7 for the LH-3128-7, S type, and Table 8 for the LH-3128-7, A type, detailing various machine components with their corresponding part numbers.
- Page 9 (parts_list): Table 9 lists parts for the LH-3128-7, G type sewing machine, including needle gauge, throat plate, feed dog, needle clamp, presser foot, slide plate, and wiper.
- Page 10 (parts_list): This page contains parts lists for the LH-3168, S type and LH-3168, A type sewing machines, detailing needle gauge, throat plate, feed dog, needle clamp, presser foot, and slide plate assemblies with corresponding part numbers.
- Page 11 (parts_list): This page contains Table 12, which lists parts for the LH-3168, G type sewing machine, including needle gauge, throat plate, feed dog, needle clamp (left and right), presser foot, and slide plate assemblies, along with their corresponding part numbers and codes.
- Page 12 (parts_list): This page contains parts lists for the LH-3168-7, S type and LH-3168-7, A type sewing machines, detailing needle gauge, throat plate, feed dog, needle clamp, presser foot, slide plate, and wiper for various codes.
- Page 13 (parts_list): This page contains Table 15, which lists parts for the LH-3168-7, G type sewing machine, including needle gauge, throat plate, feed dog, needle clamp, presser foot, slide plate, and wiper, along with their corresponding part numbers and dimensions.
- Page 14 (parts_list): This page lists major components and expendable parts for sewing machines, including motors, pulleys, V-belts, needles, bobbins, hooks, and thread pressers, with their respective part numbers and descriptions.
- Page 15 (parts_list): This page lists renewal parts for sewing machines, categorized by whether they are for models with or without a thread trimmer, and includes part numbers and names.
- Page 16 (text): This page contains special notes for safe operation of JUKI sewing machines, including instructions on thread trimmers, belt tension, oiling, and lubrication after extended periods of disuse, accompanied by diagrams illustrating various machine components.
- Page 17 (text): This page contains descriptions and diagrams of different types of hooks for sewing machines, including LH-3128 and LH-3168 models, and instructions on how to use the thread guide arm for synthetic threads.
- Page 18 (text): This page details standard adjustments for the needle bar and feed dog, including initial positioning and height adjustments, with accompanying diagrams and measurements.
- Page 19 (text): This page provides instructions on how to adjust the feed dog on an industrial sewing machine, including steps for setting the stitch dial, adjusting the feed dog position, and checking the height of the feed dog. It also details the results of improper adjustment.
- Page 20 (diagram): This page contains diagrams and a table related to standard adjustment of the needle bar height for various sewing machine models including LH-3128 and LH-3168 series.
- Page 21 (text): This page provides instructions on how to adjust the needle bar height for various sewing machine models, including LH-3128S, LH-3128A, LH-3128G, LH-3128-7S, LH-3128-7A, and LH-3128-7G. It details the steps for adjustment, referencing figures and specific components like the needle clamp and spring shoe, and includes a caution regarding potential changes to the needle entry point.
- Page 22 (diagram): This page contains diagrams illustrating standard adjustments for needle entry, including figures 18, 19, 20, and 21, with associated part numbers and descriptions.
- Page 23 (text): This page provides instructions on how to adjust the needle bar and feed dog for models LH-3128 and LH-3168, along with potential results of improper adjustment.
- Page 24 (diagram): This page details standard adjustments for needle-to-hook relation, including lift of the needle bar and clearance between the needle and the hook, with accompanying diagrams and a table of values.
- Page 25 (text): This page provides instructions on how to adjust the hook and needle clearance, and how to change the position of the needle and blade point of the hook, along with a diagram illustrating these components.
- Page 26 (diagram): This page contains diagrams and instructions for standard adjustments, specifically focusing on the position of the connecting link and rocking arm plate, and the initial position of the bobbin case opening lever for models LH-3128-7 and LH-3168-7.
- Page 27 (text): This page provides instructions on how to adjust the sewing machine, including steps for loosening screws, adjusting the connecting link and rocking arm, and turning the handwheel. It also details the results of improper adjustment, such as towel-like stitches or bobbin case breakage.
- Page 28 (diagram): This page details standard adjustments for sewing machines, including clearance between the throat plate and bobbin case stopper, illustrated with diagrams and a table of parts with their engraved marks and thicknesses.
- Page 29 (text): This page provides instructions on how to adjust the hook driving shaft of a sewing machine, including potential results of improper adjustment and a caution regarding a lubricating felt.
- Page 30 (diagram): This page contains diagrams illustrating standard adjustments for feed timing and the relation between the main shaft and the hook driving shaft, with figures 32, 34, and 35.
- Page 31 (text): This page provides instructions on how to adjust the feed timing of a sewing machine, including a diagram illustrating the results of proper adjustment and detailed steps for the adjustment process.
- Page 32 (diagram): This page illustrates the standard adjustment for lubrication, specifically the amount of oil in the face plate, with diagrams showing the process and components involved.
- Page 33 (text): This page provides instructions on how to adjust the oil level in the sewing machine, along with the results of improper adjustment.
- Page 34 (text): This page details standard adjustments for sewing machines, including the amount of oil in the hook and stitch length adjustment for normal and reverse feed stitching, with accompanying diagrams and conditions for each adjustment.
- Page 35 (text): This page provides instructions on how to adjust the oil amount in the hook and the stitch length for reverse feed stitching, along with potential results of improper adjustment and a diagram illustrating the oil amount adjusting screw.
- Page 36 (diagram): This page contains diagrams illustrating the synchronizer installation, needle-up stop position, and needle-down stop position of the sewing machine, with reference numbers and figures labeled.
- Page 37 (text): This page provides instructions on how to adjust the synchronizer and needle-up stop position of a sewing machine, along with potential results of improper adjustment and troubleshooting tips.
- Page 38 (diagram): This page shows diagrams and conditions for the initial position of the conversion lever for LH-3168 and LH-3168-7 sewing machines.
- Page 39 (text): This page provides instructions on how to adjust the sewing machine, along with a section on the results of improper adjustment. It details steps for turning the handwheel, pressing the conversion fixing lever, and aligning sections of the conversion lever and thread tension plate. It also includes a caution against loosening specific screws and describes potential issues if there is play at the clamping screw.
- Page 40 (text): This page details standard adjustments for sewing machine attachments, including the thread trimmer, counter knife and thread presser, and clamp pressure, with accompanying diagrams and conditions for each adjustment.
- Page 41 (text): This page provides instructions on how to adjust the thread trimmer, including steps for counter knife adjustment and results of improper adjustment.
- Page 42 (diagram): This page shows diagrams and conditions for the initial position of the moving knife, including figures 55, 56, and 57, with detailed conditions for proper alignment and spacing.
- Page 43 (text): This page provides instructions on how to adjust the moving knife and counter knife, along with the results of improper adjustment, including troubleshooting for thread trimming and bobbin thread failures. It also includes a diagram illustrating failed stitches.
- Page 44 (diagram): This page illustrates the standard adjustment for positioning the thread trimming cam and thread trimming timing, with detailed diagrams for Figures 59, 60, and 61.
- Page 45 (text): This page provides instructions on how to adjust the thread trimming mechanism of a sewing machine, including steps for proper adjustment and troubleshooting common issues like excessively advanced or retarded timing.
- Page 46 (diagram): This page contains diagrams and adjustment instructions for the thread trimming magnet and the rising amount of the tension disk when releasing the thread tension.
- Page 47 (text): This page provides instructions on how to adjust the thread trimming mechanism of a sewing machine, including troubleshooting common issues like thread trimming failure or the needle thread slipping off.
- Page 48 (diagram): This page shows the standard adjustment for the follower guide, including a diagram illustrating the correct clearance and a diagram of the sewing machine.
- Page 49 (text): This page provides instructions on how to adjust the follower guide plate and cam follower, along with the results of proper adjustment. It details the steps for setting the clearance and confirms the correct positioning. The page also outlines potential issues if the adjustment is incorrect, such as the thread trimmer not actuating or components breaking.
- Page 50 (diagram): This page contains a diagram illustrating standard adjustment for installing the joint rod (asm.) with numbered parts and conditions for adjustment.
- Page 51 (text): This page contains instructions on how to adjust a sewing machine, along with the results of improper adjustments. It details steps for connecting rods, shafts, and arms, and lists potential issues like thread failures and machine locking if adjustments are incorrect.
- Page 52 (diagram): This page contains diagrams and instructions for standard adjustments, specifically for wiper components and the position of the reverse stitching magnet.
- Page 53 (text): This page provides instructions on how to adjust the wiper mechanism on a sewing machine, along with a table listing different gauge sizes, their corresponding part numbers, and dimensions. It also details the results of proper and improper adjustments.
- Page 54 (diagram): This page details the standard adjustment for the reverse feed control lever on sewing machines, with specific instructions and measurements for machines equipped with and without an automatic reverse feed stitching function, illustrated by Figures 72, 73, and 74.
- Page 55 (text): This page provides instructions on how to adjust the reverse feed stitching function of a sewing machine, including troubleshooting for improper adjustments.
- Page 56 (parts_list): This page lists replacement components for sewing machine specifications, including tension springs, stitch dials, and needles, categorized by type (S, A, G, F).
- Page 57 (diagram): This page contains diagrams labeled Fig. 75 and Fig. 76, illustrating components related to gauge replacing procedures for a sewing machine, with numbered callouts corresponding to the text on the page.
- Page 58 (text): This page contains instructions for adjusting the sewing machine, including needle-to-hook clearance and presser foot attachment, with accompanying diagrams.
- Page 59 (diagram): This page contains a diagram illustrating the components involved in replacing the timing belt of an LH-3128 sewing machine, along with a step-by-step procedure for removing the timing belt.
- Page 60 (text): This page contains instructions on how to install the timing belt, including steps for tightening screws, attaching components, and adjusting the needle bar. It also includes a diagram (Fig. 81) illustrating the side plate attaching plane and a measurement of 33±0.5 mm.
- Page 61 (text): This page contains a troubleshooting chart for common sewing machine issues, detailing phenomena, causes, items to be inspected, and corrective measures.
- Page 62 (text): This page contains a troubleshooting guide for common sewing machine problems like loose stitches and puckering, detailing the causes, items to inspect, and corrective measures.
- Page 63 (text): This page details troubleshooting steps for stitch skipping in industrial sewing machines, outlining phenomena, causes, items to inspect, and corrective measures, along with diagrams illustrating needle and hook positions.
- Page 64 (diagram): This page details troubleshooting steps for needle thread trimming failure and bobbin thread trimming failure, outlining causes, items to inspect, and corrective measures, accompanied by a diagram illustrating thread trimming mechanics.
- Page 65 (text): This page contains a troubleshooting guide for sewing machine issues, detailing phenomena, causes, items to inspect, and corrective measures. It covers problems like bobbin case idling, stitch skipping, and thread trimming issues.
- Page 66 (text): This page details troubleshooting steps for sewing machine issues, including problems with the feed dog and bobbin thread tension, and provides corrective measures.
- Page 67 (text): This page contains a troubleshooting guide for sewing machine thread issues, detailing phenomena, causes, inspection items, and corrective measures. It also includes a specific part number for a felt pad.
- Page 68 (text): This page contains a troubleshooting guide for sewing machine issues, detailing phenomena, their causes, items to inspect, and corrective measures.
Page 1 — ENGINEER'S MANUAL
2-Needle, Needle-feed, Lockstitch Machine
LH-3128
2-Needle, Needle-feed, Lockstitch Machine with
an Automatic Thread Trimmer
LH-3128-7-WB
2-Needle, Needle-feed, Lockstitch Machine with an
Organized Split Needle Bar
LH-3168
2-Needle, Needle-feed, Lockstitch Machine with an
Organized Split Needle Bar and an Automatic Thread Trimmer
LH-3168-7-WB
ENGINEER'S MANUAL
JUKI
NO. VI-15
1993. 12
jintex.in
Page 2
PREFACE
This Engineer's Manual is written for the technical personnel who are responsible for the service and maintenance of the
machines.
The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel factory contains
information which are not covered by the Instruction Manual.
Separately refer to the Instruction Manual and Engineer's Manual for the SC-1 for the explanation of the motor components of
the sewing machine with a thread trimmer. Refer to the "Instruction Manual for the CP-30 series" and the "Installation Manual
for the Control Panel" for the explanation of the control panel.
It is advisable to use the pertinent Instruction Manual and Parts List together with this Engineer's Manual when carrying out the
maintenance of these machines.
CAUTION
1. Keep your hands away from the needle when you
turn the power switch ON or while the machine is
operating.
2. Do not put your fingers into the thread take-up
cover while the machine is operating.
Do not operate your machine with thread take up
cover removed.
3. Be sure to turn the power switch OFF before tilting
the machine head or removing the V belt.
4. During operation, be careful not to allow your or
any other person's head or hands to come close to
the handwheel, V belt, bobbin winder or motor.
Also, do not place anything close to them. Doing so
may be dangerous.
5. If your machine is provided with a belt cover, finger
guard or any other protectors, do not operate you
machine with any of them removed.
6. For the machine that is not equipped with a thread trimmer and uses a clutch motor, never depress
the foot pedal unless the main switch has turned ON.
BEFORE OPERATION
1. Don't run the machine before filling the oil reservoir with the prescribed lubricating oil.
2. After setting up your machine, make sure that it runs in the correct direction; lower the needle by turning
the handwheel and watch the handwheel's revolution by momentarily switching the power "on" (correct
rotational direction of the handwheel: counterclockwise when viewed from the handwheel's end.)
3. Run the newly installed machine at a speed of 2,500 s.p.m. or lower for the first 4 weeks.
4. Confirm the ratings of your power source by the machine plate stuck on the motor (power voltage, phase
etc.)
jintex.in
Page 5
1. SPECIFICATIONS
(1) Model designation (LH model without thread trimmer)
LH-31
O: Without automatic reverse feed
B: With automatic reverse feed
Needle gauge
A: Light-weight materials
F: Foundations (LH-3128)
G: Jeans
S: Medium-weight materials
28: Small hook
68: Small hook
for corner
stitching
Table 1
Model
LH-3128
LH-3168
Stitch type
A
G
S
F
A
S
G
Max. sewing speed
3000 s.p.m
Max. stitch length (forward and reverse stitching)
5 x 5 mm
Needle (standard)
DP x 5
(#9~#14)
DP x 5
(#18~#22)
DP x 5
(#11~#18)
134 SES SERV 7
(Nm 65~80)
DP x 5
(#9~#14)
DP x 5
(#11~#18)
DP x 5
(#18~#22)
Presser foot lift
Hand lifter
5.5 mm
Knee lifter
12 mm
Organized split needle bar mechanism
Not provided with
Provided with
*1: 134SES SERV7 Nm65
(2) Model designation (LH model with thread trimmer)
LH-31
-7
00: Without wiper, without automatic reverse feed
OB: Without wiper, with automatic reverse feed
WO: With wiper, without automatic reverse feed
WB: With wiper, with automatic reverse feed
Needle gauge
A: Light-weight materials
S: Medium-weight materials
G: Jeans
28: Small hook
68: Small hook for corner stitching
Table 2
Model
LH-3128-7
LH-3168-7
Stitch type
A
S
G
A
S
G
Max. sewing speed
3000 s.p.m
Max. stitch length (forward and reverse stitching)
5 x 5 mm
Needle (standard)
DP x 5
(#9~#14)
DP x 5
(#11~#18)
DP x 5
(#18~#22)
DP x 5
(#9~#14)
DP x 5
(#11~#18)
DP x 5
(#18~#22)
Presser foot lift
Hand lifter
5.5 mm
Knee lifter
12 mm (with wiper: 9 mm)
Organized split needle bar mechanism
Not provided with
Provided with
-1-
Jinte.x.in
Page 6 — LIST OF GAUGE COMPONENTS
2. LIST OF GAUGE COMPONENTS
(1) LH-3128, S type
Table 3
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
$ 1.9
2.0
C
5/32
4.0
226 25206
226 30206
101 47759
101 52650
D
3/16
4.8
226 25305
226 30305
101 47858
101 52759
E
7/32
5.6
226 25404
226 30503
101 47957
101 52858
226 01058
226 00555
F
1/4
6.4
226 25503
226 30602
101 48054
101 52957
G
9/32
7.1
226 25602
226 30800
101 48153
101 53054
H
5/16
7.9
226 25701
226 30909
101 48252
101 53153
K
3/8
9.5
226 25800
226 31006
101 48351
101 53252
W
7/16
11.1
226 25909
226 31105
101 48450
101 53351
L
1/2
12.7
226 26006
226 31303
101 48559
101 53450
M
5/8
15.9
226 26105
226 31402
101 48658
101 53559
226 01157
226 00654
N
3/4
19.1
226 26204
226 31501
101 48757
101 53658
P
7/8
22.2
226 26303
226 31709
101 48856
101 53757
Q
1
25.4
226 26402
226 31808
101 48955
101 53856
226 01256
226 00753
R
1-1/8
28.6
226 26501
226 31907
101 49052
101 53955
S
1-1/4
31.8
226 26600
226 32004
101 49151
101 54052
T
1-3/8
34.9
226 26709
226 32103
101 49250
101 54151
226 01355
226 00852
U
1-1/2
38.1
226 26808
226 32202
101 49359
101 54250
(2) LH-3128, A type
Table 4
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
$ 1.4
1.6
A
3/32
2.4
226 25008
226 35007
101 47551
226 37557
B
1/8
3.2
226 25107
226 30107
101 47650
226 37656
C
5/32
4.0
226 25206
226 35104
101 47759
226 37555
D
3/16
4.8
226 25305
226 35205
101 47858
226 37854
E
7/32
5.6
226 25404
226 35403
101 47957
226 37953
226 01058
226 00555
F
1/4
6.4
226 25503
226 35502
101 48054
226 38050
G
9/32
7.1
226 25602
226 35700
101 48153
226 38258
H
5/16
7.9
226 25701
226 35809
101 48252
226 38357
K
3/8
9.5
226 25800
226 35908
101 48351
226 38456
W
7/16
11.1
226 25909
226 36005
101 48450
226 38555
L
1/2
12.7
226 26006
226 36203
101 48559
226 38753
226 01157
226 00654
M
5/8
15.9
226 26105
226 36302
101 48658
226 38852
N
3/4
19.1
226 26204
226 36401
101 48757
226 38951
P
7/8
22.2
226 26303
226 36609
101 48856
226 39157
Q
1
25.4
226 26402
226 36708
101 48955
226 39256
226 01256
226 00753
R
1-1/8
28.6
226 26501
226 36807
101 49052
226 39355
S
1-1/4
31.8
226 26600
226 36906
101 49151
226 39454
T
1-3/8
34.9
226 26709
226 37003
101 49250
226 39553
226 01355
226 00852
U
1-1/2
38.1
226 26808
226 37102
101 49359
226 39652
-2-
jintex.in
Page 7
(3) LH-3128, G type
Table 5
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
2.2
2.0
D
3/16
4.8
226 25305
B1613 512 DOH
101 27358
226 40353
E
7/32
5.6
226 25404
B1613 512 EOH
101 27957
226 40452
F
1/4
6.4
226 25503
B1613 512 FOH
101 48054
226 40551
G
9/32
7.1
226 25602
B1613 512 GOH
101 48153
226 40759
H
5/16
7.9
226 25701
B1613 512 HOH
101 48252
226 40858
K
3/8
9.5
226 25800
B1613 512 KOH
101 48351
226 40957
226 01058
226 00555
L
1/2
12.7
226 26006
B1613 512 LOH
101 48559
226 41252
M
5/8
15.9
226 26105
B1613 512 MOH
101 48658
226 41351
N
3/4
19.1
226 26204
B1613 512 NOH
101 48757
226 41450
P
7/8
22.2
226 26303
B1613 512 POH
101 48856
226 41658
226 01157
226 00654
Q
1
25.4
226 26402
B1613 512 QOH
101 48955
226 41757
R
1-1/8
28.6
226 26501
B1613 512 ROH
101 49052
226 41856
S
1-1/4
31.8
226 26600
B1613 512 SOH
101 49151
226 41955
T
1-3/8
34.9
226 26709
B1613 512 TOH
101 49250
226 42052
226 01256
226 00753
U
1-1/2
38.1
226 26808
B1613 512 UOH
101 49359
226 42151
226 01355
226 00852
(4) LH-3128, F type
Table 6
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
1.4
1.4
B
1/8
3.2
226 25107
226 28002
226 30107
101 47650
101 85957
D
3/16
4.8
226 25305
226 28200
226 35304
101 47858
101 86054
F
1/4
6.4
226 25503
226 28408
226 35502
101 48054
101 86757
226 01058
226 00555
G
9/32
7.1
226 25602
226 28507
226 35700
101 48153
101 86153
H
5/16
7.9
226 25701
226 28701
226 35809
101 48252
101 86856
Asterisk (*) shows throat plate Part No. for tape attaching.
-3-
jintex.in
Page 8
(5) LH-3128-7, S type
Table 7
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
$
2.0
2.0
C
5/32
4.0
226 60302
102 37907
101 47759
101 52650
D
3/16
4.8
226 60401
102 38004
101 47858
101 52759
226 50857
226 50352
102 09230
E
7/32
5.6
226 60500
102 38103
101 47957
101 52858
F
1/4
6.4
226 60609
102 38202
101 48054
101 52957
G
9/32
7.1
226 60708
102 38301
101 48153
101 53054
H
5/16
7.9
226 60807
102 38400
101 48252
101 53153
K
3/8
9.5
226 60906
102 38509
101 48351
101 53252
W
7/16
11.1
226 61003
101 68300
101 48450
101 53351
226 50956
226 50451
102 09500
L
1/2
12.7
226 61102
102 38707
101 48559
101 53450
M
5/8
15.9
226 61201
102 38806
101 48658
101 53559
N
3/4
19.1
226 61300
102 38905
101 48757
101 53658
P
7/8
22.2
226 61409
101 68706
101 48856
101 53757
Q
1
25.4
226 61508
102 39002
101 48955
101 53856
226 51053
226 50550
102 09807
R
1-1/8
28.6
226 61607
101 68904
101 49052
101 53955
S
1-1/4
31.8
226 61706
101 69001
101 49151
101 54052
226 51152
226 50659
102 09906
(6) LH-3128-7, A type
Table 8
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
$ 1.4
1.6
A
3/32
2.4
226 60104
226 65004
101 47551
226 37557
B
1/8
3.2
226 60203
226 65103
101 47650
226 37656
C
5/32
4.0
226 60302
226 65202
101 47759
226 37755
D
3/16
4.8
226 60401
226 65301
101 47858
226 37854
226 50857
226 50352
102 09230
E
7/32
5.6
226 60500
226 65400
101 47957
226 37953
F
1/4
6.4
226 60609
226 65509
101 48054
226 38050
G
9/32
7.1
226 60708
226 65707
101 48153
226 38258
H
5/16
7.9
226 60807
226 65806
101 48252
226 38357
K
3/8
9.5
226 60906
226 65905
101 48351
226 38456
W
7/16
11.1
226 61003
226 66002
101 48450
226 38555
226 50956
226 50451
102 09500
L
1/2
12.7
226 61102
226 66200
101 48559
226 38753
M
5/8
15.9
226 61201
226 66309
101 48658
226 38852
N
3/4
19.1
226 61300
226 66408
101 48757
226 38951
226 51053
226 50550
102 09807
P
7/8
22.2
226 61409
226 66705
101 48856
226 39157
Q
1
25.4
226 61508
226 66804
101 48955
226 39256
R
1-1/8
28.6
226 61607
226 66903
101 49052
226 39355
226 51152
226 50659
102 09906
S
1-1/4
31.8
226 61706
101 49151
226 39454
-4-
jintex.in
Page 9 — (7) LH-3128-7, G type
(7) LH-3128-7, G type
Table 9
Needle gauge
Throat plate
Feed dog
Needle clamp
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
2
2.0
D
3/16
4.8
226 60401
102 39101
101 47858
226 40353
226 50857
226 50352
102 09230
E
7/32
5.6
226 60500
102 39200
101 47957
226 40452
F
1/4
6.4
226 60609
102 39309
101 48054
226 40551
G
9/32
7.1
226 60708
102 39408
101 48153
226 40759
H
5/16
7.9
226 60807
102 39507
101 48252
226 40858
K
3/8
9.5
226 60906
102 39606
101 48351
226 40957
W
7/16
11.1
226 61003
101 70801
101 48450
226 41054
L
1/2
12.7
226 61102
102 39804
101 48559
226 41252
226 50956
226 50451
102 09500
M
5/8
15.9
226 61201
102 39903
101 48658
226 41351
N
3/4
19.1
226 61300
101 71106
101 48757
226 41450
P
7/8
22.2
226 61409
101 71205
101 43856
226 41658
102 09807
Q
1
25.4
226 61508
101 71304
101 48955
226 41757
226 51053
226 50550
R
1-1/8
28.6
226 61607
101 71403
101 49052
226 41856
S
1-1/4
31.8
226 61706
101 71502
101 49151
226 41955
226 51152
226 50659
102 09906
-5-
jintex.in
Page 10 — Table 10
Table 11
(8) LH-3168, S type
Table 10
Needle gauge
Throat plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
$ 2.0
2.0
C
5/32
4.0
226 25206
226 30206
B1402-528-CAO-A
101 52650
D
3/16
4.8
226 25305
226 30404
B1402-528-DALA
B1402-528-DARA
101 52579
E
7/32
5.6
226 25404
226 30503
B1402-528-EAL
B1402-528-EAR
101 52858
226 01058
226 00555
F
1/4
6.4
226 25503
226 30602
B1402-528-FALA
B1402-528-FARA
101 52957
G
9/32
7.1
226 25602
226 30800
B1402-528-GAL
B1402-528-GAR
101 53054
H
5/16
7.9
226 25701
226 30909
B1402-528-HALA
B1402-528-HARA
101 53153
K
3/8
9.5
226 25800
226 31006
B1402-528-KALA
B1402-528-KARA
101 53252
L
1/2
12.7
226 26006
226 31303
B1402-528-LAL
B1402-528-LAR
101 53450
M
5/8
15.9
226 26105
226 31402
B1402-528-MAL
B1402-528-MAR
101 53559
226 01157
226 00654
N
3/4
19.1
226 26204
226 31501
B1402-528-NAL
B1402-528-NAR
101 53658
Q
1
25.4
226 26402
226 31808
B1402-528-QAL
B1402-528-QAR
101 53856
226 01256
226 00753
(9) LH-3168, A type
Table 11
Needle gauge
Throat plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
$ 1.4
1.6
B
1/8
3.2
226 25107
226 30107
B1402-528-BA0-A
226 37656
C
5/32
4.0
226 25206
226 35205
B1402-528-CAO-A
226 37755
D
3/16
4.8
226 25305
226 35304
B1402-528-DALA
B1402-528-DARA
226 37854
E
7/32
5.6
226 25404
226 35403
B1402-528-EAL
B1402-528-EAR
226 37953
226 01058
226 00555
F
1/4
6.4
226 25503
226 35502
B1402-528-FALA
B1402-528-FARA
226 38050
G
9/32
7.1
226 25602
226 35700
B1402-528-GAL
B1402-528-GAR
226 38258
H
5/16
7.9
226 25701
226 35809
B1402-528-HALA
B1402-528-HARA
226 38357
K
3/8
9.5
226 25800
226 35908
B1402-528-KALA
B1402-528-KARA
226 38456
L
1/2
12.7
226 26006
226 36203
B1402-528-LAL
B1402-528-LAR
226 38753
M
5/8
15.9
226 26105
226 36302
B1402-528-MAL
B1402-528-MAR
226 38852
226 01157
226 00654
N
3/4
19.1
226 26204
226 36401
B1402-528-NAL
B1402-528-NAR
226 38951
Q
1
25.4
226 26402
226 36708
B1402-528-QAL
B1402-528-QAR
226 39256
226 01256
226 00753
-6-
jintex.in
Page 11 — (10) LH-3168, G type
(10) LH-3168, G type
Table 12
Needle gauge
Throat plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Code
Inch
mm
$ 2.2
2.0
D
3/16
4.8
226 25305
B1613 512 DOH
B1402-528-DALA
B1402-528-DAR A
226 40353
226 01058
226 00555
E
7/32
5.6
226 25404
B1613 512 EOH
B1402-528-EAL
B1402-528-EAR
226 40452
F
1/4
6.4
226 25503
B1613 512 FOH
B1402-528-FALA
B1402-528-FARA
226 40551
G
5/16
7.1
226 25602
B1613 512 GOH
B1402-528-GAL
B1402-528-GAR
226 40759
H
5/16
7.9
226 25701
B1613 512 HOH
B1402-528-HALA
B1402-528-HARA
226 40858
K
3/8
9.5
226 25800
B1613 512 KOH
B1402-528-KALA
B1402-528-KARA
226 40957
L
1/2
12.7
226 26006
B1613 512 LOH
B1402-528-LAL
B1402-528-LAR
226 41252
M
5/8
15.9
226 26105
B1613 512 MOH
B1402-528-MAL
B1402-528-MAR
226 41351
226 01157
226 00654
N
3/4
19.1
226 26204
B1613 512 NOH
B1402-528-NAL
B1402-528-NAR
226 41450
0
1
25.4
226 26402
B1613 512 QOH
B1402-528-QAL
B1402-528-QAR
226 41757
226 01256
226 00753
-7-
jintex.in
Page 12
(11) LH-3168-7, S type
Table 13
Needle gauge
Throat
plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser
foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
$
2.0
$
2.0
C
5/32
4.0
226 60302
102 37907
B1402-528-CAO-A
101 52650
D
3/16
4.8
226 60401
102 38004
B1402-528-DALA
B1402-528-DARA
101 52579
226 50857
226 50352
102 09230
E
7/32
5.6
226 60500
102 38103
B1402-528-EAL
B1402-528-EAR
101 52858
F
1/4
6.4
226 60609
102 38202
B1402-528-FALA
B1402-528-FARA
101 52957
G
9/32
7.1
226 60708
102 38301
B1402-528-GAL
B1402-528-GAR
101 52054
H
5/16
7.9
226 60807
102 38400
B1402-528-HALA
B1402-528-HARA
101 52153
K
3/8
9.5
226 60906
102 38509
B1402-528-KALA
B1402-528-KARA
101 52252
L
1/2
12.7
226 61102
102 38707
B1402-528-LAL
B1402-528-LAR
101 52450
102 09500
M
5/8
15.9
226 61201
102 38806
B1402-528-MAL
B1402-528-MAR
101 52559
226 50956
226 50451
N
3/4
19.1
226 61300
102 38905
B1402-528-NAL
B1402-528-NAR
101 52658
102 09807
Q
1
25.4
226 61508
102 39002
B1402-528-QAL
B1402-528-QAR
101 52856
226 51053
226 50550
102 09906
(12) LH-3168-7, A type
Table 14
Needle gauge
Throat
plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser
foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
$
1.4
$
1.6
B
1/8
3.2
226 60203
226 65103
B1402-528-BA0-A
226 37656
C
5/32
4.0
226 60302
226 65202
B1402-528-CAO-A
226 37755
D
3/16
4.8
226 60401
226 65301
B1402-528-DALA
B1402-528-DARA
226 37854
226 50857
226 50352
102 09230
E
7/32
5.6
226 60500
226 65400
B1402-528-EAL
B1402-528-EAR
226 37953
F
1/4
6.4
226 60609
226 65509
B1402-528-FALA
B1402-528-FARA
226 38050
G
9/32
7.1
226 60708
226 65707
B1402-528-GAL
B1402-528-GAR
226 38258
H
5/16
7.9
226 60807
226 65806
B1402-528-HALA
B1402-528-HARA
226 38357
K
3/8
9.5
226 60906
226 65905
B1402-528-KALA
B1402-528-KARA
226 38456
L
1/2
12.7
226 61102
226 66200
B1402-528-LAL
B1402-528-LAR
226 38753
M
5/8
15.9
226 61201
226 66309
B1402-528-MAL
B1402-528-MAR
226 38852
226 50956
226 50451
N
3/4
19.1
226 61300
226 66408
B1402-528-NAL
B1402-528-NAR
226 38951
102 09500
Q
1
25.4
226 61508
226 66705
B1402-528-QAL
B1402-528-QAR
226 39256
226 51053
226 50550
102 09807
102 09906
-8-
jintex.in
Page 13 — Table 15
(13) LH-3168-7, G type
Table 15
Needle gauge
Throat
plate
Feed dog
Needle clamp
(left)
Needle clamp
(right)
Presser
foot
Slide plate
(left) asm.
Slide plate
(right) asm.
Wiper
Code
Inch
mm
3
2
2.0
D
3/16
4.8
226 60401
102 39101
B1402-528-DALA
B1402-528-DARA
226 40353
226 50857
102 09230
E
7/32
5.6
226 60500
102 39200
B1402-528-EAL
B1402-528-EAR
226 40452
226 50352
F
1/4
6.4
226 60609
102 39309
B1402-528-FALA
B1402-528-FARA
226 40551
G
9/32
7.1
226 60708
102 39408
B1402-528-GAL
B1402-528-GAR
226 40759
H
5/16
7.9
226 60807
102 39507
B1402-528-HALA
B1402-528-HARA
226 40858
K
3/8
9.5
226 60906
102 39606
B1402-528-KALA
B1402-528-KARA
22640957
L
1/2
12.7
226 61102
102 39804
B1402-528-LAL
B1402-528-LAR
226 41252
102 09500
M
5/8
15.9
226 61201
102 39903
B1402-528-MAL
B1402-528-MAR
226 41351
226 50956
226 50451
N
3/4
19.1
226 61300
101 71106
B1402-528-NAL
B1402-528-NAR
226 41450
102 09807
Q
1
25.4
226 61508
101 71304
B1402-528-QAL
B1402-528-QAR
226 41757
226 51053
226 50550
102 09906
-9-
JIN텍.in
Page 14 — 3. LIST OF THE MAJOR COMPONENTS
(1) List of motor, motor pulley and V-belt
3. LIST OF THE MAJOR COMPONENTS
(1) List of motor, motor pulley and V-belt
Table 16
Without thread trimmer
With thread trimmer
Model
LH-3128, LH-3168
LH-3128-7, LH-3168-7
Frequency
50 Hz
60 Hz
Common to 50 Hz and 60 Hz
Motor
Clutch motor
MTL2200040S
SC-1
AC servo motor 200V
M0001351AA0
M6101351AA0
Motor pulley
070
MTKP0070000
060
MTKP0060000
080
MTSP00800B0
V-belt
42"
MTJVH004200A
41"
MTJVH004100A
40"
MTJVH004000A
(2) List of expendable parts
Table 17
Without thread trimmer
With thread trimmer
Part No.
Part name
Part No.
Part name
B9117051000
Bobbin
10210805
Bobbin
22612055
Latch hook (asm.)
22653158
Latch hook (asm.) with thread trimmer
22612758
Cap hook (asm.)
22653059
Cap hook asm. with thread trimmer
22688253
Hook (asm.) for an organized
split needle bar
22693857
Hook (asm.) for an organized split
needle bar and a thread trimmer.
22603708
Felt
10211605
Moving knife
10210805
Bobbin (F type)
22655302
Counter knife
22655401
Thread presser
22603708
Felt
-10-
jintex.in
Page 15
(3) Other renewal parts
Table 18
Without thread trimmer
With thread trimmer
LH-3128, LH-3168
LH-3128-7, LH-3168-7
Part No.
Part name
Part No.
Part name
22601504
Slide plate window
22601504
Slide plate window
22604300
Timing belt
22604300
Timing belt
B3128051000
Thread take-up spring (A)
B3128051000
Thread take-up spring (A)
B3128527000
Thread take-up spring (B)
B3128527000
Thread take-up spring (B)
22628903
Idling prevention sheet (0.3)
10111508
Idling prevention spring
22653802
Idling prevention sheet
- 11 -
jintex.in
Page 16 — 4. SPECIAL NOTES FOR SAFE OPERATION
4. SPECIAL NOTES FOR SAFE OPERATION
(1) For the LH-3128 and -3168 models of sewing machine without a thread trimmer, the throat plate, feed dog and presser foot
developed for the LH-512 or -515 are applicable. Furthermore, commercially available thread trimmer, throat plate, feed dog
and presser foot can also be used with them.
(2) When putting a V-belt on the handwheel of the sewing machine head and the motor pulley, adjust the position of the motor so
that the V belt is tensed to the extent where it slackens by approximately 10 mm when the center of the belt is pressed by hand.
(3) Fill the oil pan with sewing machine oil (New Defrix Oil No. 2) until the H mark is reached.
(4) When you operate your machine for the first time after the set-up or after an extended period of disuse, apply a few drops of
oil to the portions indicated by the arrow in Fig. 1.
1) Main unit of the machine arm
(Pour oil from the plug hole.)
2) Face plate
3) Hook driving shaft saddle
4) Hook race surface (left and right)
Fig. 1
- 12 -
jintex.in
Page 17
(5) Hook differs with the type of sewing machine, i.e., the sewing machine with/without a thread trimmer. Be sure to use a hook that is exclusively designed for the sewing machine head. For the LH-3128 and -3168 models of sewing machine without a thread trimmer, commercially available hooks can be used.
(6) How to pass the bobbin thread (The bobbin thread winding direction is indicated by the arrow.)
1) LH-3128 Latch hook
LH-3128-7 Latch hook with a thread trimmer
Fig. 2
3) LH-3168 Hook for an organized split needle bar
LH-3168-7 Hook with a thread trimmer and
an organized split needle bar
Fig. 4
2) LH-3128 Cap hook
LH-3128-7 Cap hook with a thread trimmer
Fig. 3
(7) When synthetic threads are used, use the thread guide arm (asm.) for the thread stand if the thread flaps during sewing.
Thread guide arm (asm.)
Fig. 5
Thread stand (asm.)
-13-
jintex.in
Page 18 — STANDARD ADJUSTMENT
5. STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(1) Needle bar and feed dog
1) Initial position of the needle bar
Conditions
• The needle bar is in the lowest dead point.
• Feed amount (stitch length): 0
• LH-3128, LH-3128-7
3
13.5±0.1
Top surface of the throat plate
Fig. 6
• LH-3168, LH-3168-7
14.2±0.1
Top surface of the throat
Fig. 7
2) Position and height of the feed dog
Conditions
• Feed amount (stitch length): 0
• When the feed dog is in the highest position of its stroke, it should rise 0.9 to 1.1 mm from the top surface of the throat
plate.
Fig. 9
Clearance
Top surface of the throat plate
0.9 to 1.1 mm
Fig. 10
Feed bar
Feed bar
Feed rock shaft
Fig. 11
Gear of the hook
driving shaft
Fig. 12
Hook driving shaft saddle
-14-
jintex.in
Page 19
HOW TO ADJUST
1. Set the stitch dial at "0" on the scale.
2. Turn the handwheel to bring needle bar to the lowest dead point.
3. Loosen screw ④ shown in Fig. 8.
4. Adjust the inner dimension provided between needle bar ① and
presser bar ② to the specified dimension. Then, tighten screw ④.
Feed rock shaft crank
Feed rock shaft
Fig. 8
(Caution) 1. Distance from needle bar ① to presser bar ②
should be the distance provided between the bot-
tom end of the presser bar and the bottom end of
presser bar lower bushing ③.
2. After the adjustment, the needle entry point in the
needle slot in the feed dog may change.
RESULTS OF
IMPROPER ADJUSTMENT
When the stitch length is maximized, the feed
dog will come in contact with the feed dog.
Stitch skipping or needle breakage will be
caused.
Thread trimming failure will be caused.
Position of the feed dog
1. Attach feed dog ① to the bed using screws ④. Attach throat
plate ② to the bed using screws ③.
2. Loosen clamping screw ⑤ in the feed rocker in Fig. 11. Move
feed rocker ⑥ in the axial direction to adjust so that respective
feed dogs ① teeth are equidistantly spaced in feed dog slots ② in
the throat plate as illustrated in Fig. 9. After the adjustment,
tighten screw ⑤.
3. If the position of the feed dog is not properly adjusted by the
procedure described above, suppose that feed dog ① has been
attached with inclined. So, loosen screws ④, and adjust the
inclination angle of the feed dog ① to "0." Then, tighten screws
④ and perform the aforementioned step 2).
Height of the feed dog
1. Set the stitch dial at "0" on the scale.
2. Turn the handwheel to bring feed dog ① to the position where it
rises the most above throat plate ②.
3. Loosen screw ⑦ in Fig. 12, and move feed bar lifting fork up or
down to adjust so that feed dog ① rises 0.9 to 1.1 mm above the top
surface of throat plate ②. Then, tighten screw ⑦.
(Caution) 1. After the adjustment, the needle entry point in the
needle slot in the feed dog may change.
When the feed dog is positioned too high:
The feed dog will come in contact with the
throat plate.
The stitch length will be larger than the
value indicated by the scale on the stitch
dial.
Thread trimming failure will occur.
When the feed dog is positioned too low:
The stitch length will be smaller than the
value indicated by the scale on the stitch
dial.
The moving knife will come in contact
with the feed dog at the time of thread
trimming resulting thread trimming fail-
ure.
-15-
jintex.in
Page 20 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
3) Needle bar height
Conditions
Needle bar should be in its lowest dead point.
Feed amount (stitch length): 0
LH-3128, S, A and G type
LH-3128-7, S, A and G type
Meets with the upper
engraved marker line
Marker lines engraved
on the needle bar
Fig. 13
LH-3128, F type
(43±0.1)
Top surface of the throat plate
12.4±0.1
Fig. 14
LH-3168, S, A and G type
LH-3168-7, S, A and G type
Table 19
LH-3168
LH-3168-7
a
12.6±0.15
11.5±0.15
Top surface of the throat
Fig. 15
-16-
jintex.in
Page 21
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
Change in height of the needle bar may result
in stic skipping or thread breakage.
o LH-3128S, -3128A, -3128G
LH-3128-7S, -3128-7A, -3128-7G
Needle bar
connection
1. Set the stitch dial at "0."
2. Turn the handwheel to bring
needle bar 1 to the lowest
dead point.
3. Loosen clamping screw 7.
4. Align the upper marker line
engraved on needle bar 1 with
the lower surface of needle bar
frame 2. Then, tighten
clamping screw 7.
Fig. 16
o LH-3128F
1. Set the stitch dial at "0."
2. Turn the handwheel to bring needle bar 1 to the lowest dead point.
3. Loosen clamping screw 7.
4. Adjust so that bottom end of needle clamp 3 is spaced 12.4 ±0.1
mm from the top surface of the throat plate. Then, tighten clamping
screw 7.
* The two marker lines engraved on the needle bar are ineffective.
o LH-3168S, -3168A, -3168G
LH-3168-7S, -3168-7A, -3168-7G
The needle bar height is determined by the height of the needle clamp.
Needle clamp 6 goes up or comes
down by 0.6 mm in one revolution.
Remove screw 5 and move
needle clamp 6 up or down.
Spring shoe 8 goes up or comes
down by 0.3 mm in one revolution.
Remove screws 4 and 5, draw
out needle clamp 6 from needle
bar 1, and turn spring shoe 8.
1. Set the stitch dial at "0."
2. Turn the handwheel to bring
needle bar 1 to the lowest dead
point.
3. Turn needle clamp 6 and/or
spring shoe 8 to adjust the
clearance provided between the
bottom of the needle bar and the
top surface of the throat plate to
dimension a shown in Table 19.
Then tighten screws 4 and 5.
(Caution) 1. After the adjustment, the needle entry point in the
needle slot in the feed dog may change.
Fig. 17
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Page 22 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
4) Needle entry
Conditions
Needle bar should be in the lowest dead point.
Feed amount (stitch length): 0
The needle should enter the center of the needle slot in the feed dog.
1
Needle slot in the feed dog
Fig. 18
Feed dog
Feed bar
Feed rock shaft
Fig. 20
LH-3168
LH-3168-7
Fig. 19
LH-3128
LH-3128-7
Needle bar connection
Fig. 21
-18-
jintex.in
Page 23
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
• LH-3128, -3128-7
1. Attach needle ① to needle clamp ②.
2. Set the stitch dial to "0."
3. Turn the handwheel to bring needle bar ③ to the lowest dead point.
4. Loosen clamping screw ④.
5. Turn needle bar ③ to adjust so that needle ① enters the center of
the needle slot in feed dog ⑤. After the adjustment, tighten screw
④.
6. If needle ① is longitudinally dislocated in the needle slot in the
feed dog, loosen clamping screw ⑥ in feed rocker ⑦ and adjust
the longitudinal position of the needle by turning feed rocker ⑦.
After the adjustment, tighten screw ⑥.
(Caution) 1. Do not change the needle bar height.
2. Do not loosen needle clamp ②.
• LH-3168, -3168-7
1. Attach needle ① to needle clamp ②.
2. Set the stitch dial to "0."
3. Turn the handwheel to bring needle bar ③ to the lowest dead point.
4. Loosen clamping screws ⑧ and ⑨.
5. Turn needle clamp ② to adjust so that needle ① enters the center
of the needle slot in feed dog ⑤. After the adjustment, tighten
screws ⑧ and ⑨.
6. If needle ① deflects in the longitudinally direction of the needle
slot in the feed dog, loosen screw ⑥ and properly adjust the
longitudinal position of the needle in the needle slot by turning
feed rocker ⑦. After the adjustment, tighten screw ⑥.
(Caution) 1. Needle clamp ② can be turned in the clearance
provided between screw ⑧ and the rightmost and
leftmost edges of the slot in the needle bar.
• Stitch skipping and thread breakage will be
caused.
• Poorly tensed seam will result.
• When the feed dog has elongated needle
slots (2 mm x 3 mm), the needle thread will
be loosened if the needles enter the far end
of the respective elongated slots, as viewed
from the operator.
• When the feed dog has elongated needle
slots, thread trimming failure will result if
the needles enter the near end of the re-
spective elongated slots, as viewed from the
operator, at the time of thread trimming.
-19-
jintex.in
Page 24
STANDARD ADJUSTMENT
(2) Needle-to-hook relation
Conditions
• The needle bar ascends from the lowest dead point of its stroke.
• Feed amount (stitch length): 2.5 (For G type, it should be set at 3.5.)
1) Lift of the needle bar
LH-3128
LH-3128-7
Lift of the needle bar when the lower marker line on the needle
bar meets the bottom end of the needle bar frame: a=2.2mm
Fig. 22
3) Position of the needle and the blade point of the hook
Center of the needle aligns
with the blade point of the hook.
Fig. 24
2) Clearance between the needle
and the blade point of the hook
0~0.05 mm
Fig. 23
Table 20
a mm
b mm
S. A. G
2.2
1.2
F
3.2
0.9
0.5 mm
Fig. 25
- 20 -
jintex.in
Page 25
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
To adjust the clearance between the needle and the blade point of the
hook and the needle gauge
1. For the sewing machine with a thread trimmer, loosen hinge screw 16
in the connecting link in Fig. 27 on page 22.
2. Loosen screws 1 and 2 in the hook driving shaft saddle and two
screws 6 in the hook driving gear. At this time, do not remove the
screw No. 1 (retained in the flat section of hook driving shaft 7).
Loosen the screw to such an extent that the screw
No. 1 does not come hook driving shaft when turning hook driv-
ing shaft 7 by hand.
3. For the sewing machine of which sewing specification is S, A or F,
set the stitch dial at 2.5 on the scale.
For the sewing machine of which sewing specification is G, set the
stitch dial at 3.5 on the scale.
4. Raise needle bar 9 from the lowest dead point of its stroke by di-
rection a. At this time, align the lower marker line engaged on
needle bar 9 with the bottom end face of needle bar frame 10, and
the lift of the needle bar will be 2.2 mm.
5. Move hook driving shaft saddle 3 to the right or left to adjust so
that the specified clearance is provided between the needle and the
blade point of the hook and the needle guard provides the specified
effective amount. Then, tighten screws 1 and 2 to secure hook
driving shaft saddle.
6. Adjust so that an approximately 0.5 mm clearance is provided be-
tween hook driving shaft screw gear 5 and hook driving shaft
saddle 3. Then fix hook driving shaft screw gear 5 by tighten
screws 6.
7. Attach connecting link (asm.) 2 in position using hinge screw 16
as illustrated in Fig. 27 on page 22.
To change the position of the needle and the blade point of the hook
1. Loosen three screws 12 in hook driving shaft gear 11 in Fig. 26.
2. Align the blade point of the hook with the center of the needle, and
tighten screws 12.
Fig. 26
(Caution) 1. Confirm that hook driving shaft gear 5 does not
come in contact with hook driving shaft saddle 3
and hook driving shaft gear guide 4.
Stitch skipping or thread breakage will re-
sult.
-21-
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Page 26 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
4) Position of the connecting link (asm.) and rocking arm plate
LH-3128-7, LH-3168-7
Fig. 27
Conditions
• Rocking arms (left) and (right) should come in contact with the respective rocking arm stopper screws.
• The cam roller shaft should come in contact with the follower stopper.
(3) Initial position of the bobbin case opening lever
Conditions
• The bobbin case opening lever should be moved backward until it will go no further.
• Press the bobbin case stopper against the throat plate ribs.
Press the bobbin case stopper
against the throat plate ribs.
Backward
travel end
0.1 to 0.3 mm
Fig. 28
- 22 -
jintex.in
Page 27
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Loosen two screws 1 in connecting link (asm.) 2 and screw 3
in rocking arm plate 4 in prior to the adjustments 1), 2) and 3) of
(2) on page 20.
2. After you have finished the adjustments 1), 2) and 3) of (2) on page
20, adjust the length of connecting link (asm.) 2 so that rocking
arm (left) 9 and rocking arm (right) 10 come in contact with stop-
per screw 11 in the rocking arm. Then tighten screw 3.
3. To adjust rocking arm plate 4, turn cam follower (asm.) 13 and
joint rod 12 in direction C or D so that cam roller shaft 14 comes in
contact with follower stopper plate 15. Then tighten screw 3.
(Caution) 1. Do not leave screws 1, 3 loosened. Doing so
will cause the sewing machine lock at the time of
thread trimming.
If the connecting link (asm.) and the rocker
arm are not properly positioned, thread trim-
ming failure will result.
1. Turn the handwheel to move bobbin case opening lever 2 back-
ward until it will go further.
2. Turn bobbin case 3 in the direction opposite to the direction of rota-
tion of the hook until bobbin case stopper 4 comes in contact with
throat 5.
3. Loosen screw 1 in the bobbin case opening lever and adjust so that
a 0.1 to 0.3 mm clearance is provided between bobbin case 3 and
bobbin case opening lever 2. Then tighten screw 1.
If the clearance between the bobbin case
and the bobbin case opening lever is larger
than the specified value:
O Towel-like stitches, loosened stitches or
thread breakage will result.
If the clearance is smaller than the specified
value:
O The bobbin case may break.
-23-
jintex.in
Page 28 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(4) Clearance between the throat plate and the bobbin case stopper
• A clearance of 0.8 to 1.0 mm should be provided between the top surface of the groove on stopper of the throat plate
and the top surface of the stopper of the bobbin case.
Throat plate
Bobbin case stopper
0.8 to 1.0 mm
Hook driving shaft upper bushing thrust plate
Hook driving shaft upper bushing spacer
Fig. 29
Fig. 30
Table 21
Part No.
Name of part
Engraved mark
Thickness
Sewing machine with a thread trimmer
10109700
Hook driving shaft upper bushing thrust plate
A
0
1
10110906
"
C
1
1.1
10111003
"
D
2
1.2
10111102
"
E
3
1.3
10111201
"
F
4
1.4
10109809
"
B
5
1.5
10112506
"
G
6
1.6
10112605
"
H
7
1.7
10112704
"
K
8
1.8
Sewing machine without a thread trimmer
10112506
Hook driving shaft upper bushing thrust plate
G
6
1.6
10112605
"
H
7
1.7
10112704
"
K
8
1.8
22614002
Hook driving shaft upper bushing spacer
A
A
1.9
22614101
"
B
B
2.0
22614200
"
C
C
2.1
22614309
"
D
D
2.2
22614408
"
E
E
2.3
22614507
"
F
F
2.4
- 24 -
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Page 29 — Fig. 31
HOW TO ADJUST
1. Remove the throat plate bobbin case opening lever, feed dog and
needle.
2. Loosen three screws which are used to secure the hook driving shaft
gear.
3. For the sewing machine equipped with a thread trimmer, also remove
the moving knife and counter knife.
4. Draw out the hook.
5. Replace the thrust plate and spacer of the hook driving shaft upper
bushing with appropriate ones.
* Thrust plates and spacers of the hook driving shaft upper bushing are
prepared respectively for the sewing machine with/without a thread
trimmer.
Hook driving shaft
Felt
Fig. 31
(Caution) 1. A lubricating felt is placed on the bottom of the hook
driving shaft of this sewing machine. So, do not
tighten the screw with the hook raised.
Doing so will cause an axial play, resulting in thread
trimming failure, stitching troubles or breakage of
the hook point.
RESULTS OF
IMPROPER ADJUSTMENT
If the clearance provided between the throat
plate and the bobbin case stopper is larger
than the specified value:
The bobbin case may come off the throat
plate.
If the clearance provided between the throat
plate and the bobbin case stopper is smaller
than the specified value:
Isolated idling loops will result.
Moving knife will come in contact with the
hook at the time of thread trimming.
- 25 -
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Page 30 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(5) Feed timing
Condition
• The marker dot engraved on the hook driving
shaft should be aligned with the marker dot
engraved on the feed rock cam.
Bed
(As viewed from the rear of the bed)
Fig. 32
Marker dot on the hook driving shaft
Feed rock cam
Marker dot on the feed rock cam
Feed rock rod
Hook driving shaft
Feed rock cam
Marker dot on the hook driving shaft
Marker dot on the feed rock cam
Aligned
(6) Relation between the main shaft and the hook driving shaft
Marker dot on the
machine arm
Blue marker dot on the handwheel
(40°)
Screw No. 1
04mm hole
Fig. 34
Fig. 35
- 26 -
jintex.in
Page 31
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Loosen screws 1 and 2 in the feed rock cam.
2. Align the marker dot engraved on the feed rock cam with the marker dot
engraved on the machine arm.
(Caution) The adjustment result of the feed timing will be affect-
ed by the position from which you observe the marker
dots. So, be sure to adjust the feed timing while
observing the marker dots from the correct position.
If the feed timing shifts in the axial direction while
adjusting the feed timing, an extra load will be applied
to the cam. So, be careful.
Late
Fig. 33
Early
O If the feed timing is changed, the needle
entry in the slot in the feed dog will also
change. In this case, properly adjust the
needle entry with respect to the feed dog.
1. Remove the timing belt from lower sprocket 2 of the hook driving
shaft.
2. Turn handwheel 1 until the blue marker dot engraved on the handwheel
is aligned with the marker dot engraved on the machine arm.
3. Turn hook driving shaft 3 until the screw No. 1 is aligned with the 4
mm hole in the bed.
4. Put the timing belt on lower sprocket 2 while securely keeping the
main shaft and hook driving shaft held in the correct position.
(Caution) 1. Confirm that the screw No. 1, that is aligned with the
4 mm hole in the bed, rests on the flat section of the
hook driving shaft.
If the relation between the main shaft and the
hook driving
shaft is not correct:
O Thread trimming timing, needle entry in
the feed dog slot and feed timing will
change, causing the sewing machine to be
locked. So, carefully adjust the relation
between the aforementioned shafts.
-- 27 --
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Page 32 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(7) Lubrication
1) Amount of oil in the face plate
A sheet
of paper
Fig. 37
Fig. 36
Adequate amount of oil
One minute
Conditions
Oil splashes are made on a sheet of paper while
making the sewing machine run for one minute
after having made it run idle for one minute.
Detailed figure of portion A
0 to 3 mm
Fig. 38
Face plate oil amount
adjusting felt
Face plate oil pipe (asm.)
- 28 -
jintex.in
Page 33
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Loosen locknut 1 of the face plate oil amount adjusting screw.
2. Move face plate oil amount adjusting screw 2 up or down. Tight-
ening the screw will decrease the amount of oil in the face plate.
Loosening the screw will increase it.
3. After the amount of oil is properly adjusted, tighten locknut 1.
(Caution) 1. Adjust the height of face plate oil amount adjusting
screw 2 within the range of 0 to 3 mm taking the
height of the top face of locknut 1 for reference.
Then, fix the screw.
2. Do not leave locknut 1 in the loosened state.
o If the amount of oil is insufficient, the
needle bar crank or the needle bar crank rod
will be seized.
o If the amount of oil is excessive, oil leak-
age will result.
- 29 -
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Page 34 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
2) Amount of oil in the hook
Adequate
amount of oil
Fig. 39
Conditions
Oil splashes are made on a sheet of paper
while making the sewing machine run for
five seconds after having made it run idle for
two minutes.
A sheet of paper
Oil amount
adjusting screw
Oil amount
decreases
+
Oil amount
increases
Hook
(8) Stitch length in the normal feed stitching and reverse feed stitching
Conditions
When the stitch dial is set at "3," the difference in the stitch length between the normal feed stitching and reverse feed
stitching should be 0.2 mm or less.
Feed regulator base
Screw
Reverse feed control lever
shaft
E ring
Large
Spring
Small
Marker dot
Feed regulating rod
Fig. 41
- 30 -
jintex.in
Page 35
HOW TO ADJUST
1. Adjust the amount of oil in the hook using oil amount adjusting screw
mounted on the hook driving shaft saddle.
Tightening the screw will decrease the amount of oil in the hook.
Tightening the screw will increase it.
(Caution) Adjust the position of the oil amount adjusting screw
referring to Fig. 40.
Approx. 30 mm
Fig. 40
1. Set the stitch dial at "3."
2. Loosen two screws 1 in the feed regulator base.
3. Move feed regulator base pin 2 in the direction of the arrow to
adjust so that a difference in stitch length between the normal feed
stitching and the reverse feed stitching to 0.2 mm or less.
RESULTS OF
IMPROPER ADJUSTMENT
o If the amount of oil in the hook is insuffi-
cient, poorly-tensed seam will result.
Furthermore, the hook will become hot
causing seizure.
o If the amount of oil in the hook is exces-
sive, the thread will be stained with oil. The
material will also be stained with oil.
o The stitch length for the reverse feed stitch-
ing will be different from that for the nor-
mal feed stitching.
-31-
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Page 36 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(9) Synchronizer
1) Installing the synchronizer
Fig. 42
Fig. 43
1±0.2 mm
Fig. 44
2) Needle-up stop position of the sewing machine
Marker dot on
the machine arm
Fig. 45
Fig. 46
3) Needle-down stop position of the sewing machine
Fig. 48
- 32 -
jintex.in
Page 37
HOW TO ADJUST
How to replace the synchronizer
1. Remove the bolt cover. Loosen screws 1 in the handwheel and
remove handwheel 3.
2. Remove the screw in the cable metal fittings and remove two screws
2 in stator of the generator. Then, remove stator 4.
3. Fix a new stator using screws 2.
4. Place the cable in the cable metal fittings and tighten the screw.
5. Assemble the handwheel 3, making sure that the screw No. 1
comes in contact with the flat section of the main shaft. Also adjust the
lateral position of the handwheel so that a 1±0.2 mm clearance is
obtained between stator 4 and handwheel 3.
6. Route the cable properly and put the V belt on the handwheel.
7. Install the belt cover.
8. Adjust the needle-up stop position of the sewing machine using screw
5 in the magnet mounting base of the handwheel.
(How to adjust)
Stop the needles. Loosen screw 1 and adjust the needle-up stop
position of the sewing machine within the range of the slot.
• To advance the needle-up stop timing of the sewing machine → Move
the screw in direction A.
• To retard the needle-up stop timing of the sewing machine → Move
the screw in direction B.
(Caution) 1. Do not run the sewing machine with screw 1
loosened, while and after making the adjustment.
Only loosen screw 1 and never remove it.
(How to adjust)
Loosen screw 1, and move the screw in direction A until it will go no
further. Then, tighten screw 1.
(Caution) 1. Do not run the sewing machine with screw 1
loosened, while and after making the adjustment.
Only loosen screw 1 and never remove it.
RESULTS OF
IMPROPER ADJUSTMENT
• The stator is made of plastic. So, tighten
the screw with an approximately 15 kg.cm
torque.
• Confirm that the handwheel does not inter-
fere with the stator.
• Confirm that the V belt does not come in
contact with the cable.
• Attach the belt cover to the sewing ma-
chine. Making the sewing machine run at
low speed, check that there is not any rub-
bing noise.
Early
Fig. 47
Late
• If the needle-up stop position of the sew-
ing machine is not properly adjusted,
thread trimming failure will result. The
cam roller will not come off the thread
trimming cam at the time of thread trim-
ming, but will come off from the cam at the
start of next sewing with a noise.
The timing to detect the needle-down stop
position of the sewing machine should be
advanced the most. If the timing is retarded,
troubles will result such that the thread
trimmer fails to cut the thread, reverse-feed
stitches may not to be sewn accurately on the
normal-feed stitches at the time of automatic
reverse stitching or the needle thread will be
insufficiently tensed at the corner of a mate-
rial at the time of sewing the corner.
-33-
jintex.in
Page 38 — STANDARD ADJUSTMENT
(10) Initial position of the conversion lever
LH-3168, LH-3168-7
STANDARD ADJUSTMENT
(10) Initial position of the conversion lever
LH-3168, LH-3168-7
Conditions
Section A of the conversion lever is set at the
"0" position of the thread tension plate, the
leftmost end face of the needle bar frame is
almost aligned with the standard line of the
slider.
Fig. 49
Conversion plate Standard line
Slider escape spring
Fig. 50
Fig. 51
- 34 -
jintex.in
Page 39
HOW TO ADJUST
1. Turn the handwheel to bring the needle bar to the lowest dead point.
2. Press conversion fixing lever ① to release conversion lever ②.
3. At this time, confirm that section A of conversion lever ② is aligned
with the "0" position of thread tension plate ③.
4. If they are not aligned with each other, loosen conversion shaft
clamping screw ⑤ as illustrated in Fig. 51, and align section A of
conversion lever ② with the "0" position of thread tension plate ③.
Then, firmly tighten conversion arm clamping screw ⑥.
(Caution) 1. Do not loosen two screws ⑥ in the conversion
lever.
2. When tightening conversion arm clamping screw
⑤, using conversion lever ② and conversion
arm ④.
If there is a play at the clamping screw, conver-
sion lever ② will be pushed against conversion
plate ⑦. In this case, the function to stop either
needle bar separately will not work normally, the
separately-stopped needle will not be released
from the stop state or needle bar breakage will
occur.
RESULTS OF
IMPROPER ADJUSTMENT
If the initial position of the conversion lever
is not correct, the function to separately drive
the needle bars will not work properly.
-35-
jintex.in
Page 40 — STANDARD ADJUSTMENT OF THE ATTACHMENTS
6. STANDARD ADJUSTMENT OF THE ATTACHMENTS
STANDARD ADJUSTMENT
(1) Thread trimmer
1) Vertical position of the moving knife
Conditions
• The moving knife should come in contact with the
moving knife rest and should not be pushed against
the moving knife rest when the knife oscillates.
Align
Fig. 52
2) Initial position of the counter knife and thread presser
Align
Conditions
• Only loosen the screw in the counter knife and never remove it.
Fig. 53
3) Clamp pressure
Increases
Decreases
Fig. 54
Moving knife
Thread
presser
If the moving knife comes in single-sided contact with the thread
presser, the thread will come off the needle thread clamp.
The figure shown above illustrates the state of contact between the
perser, the thread will come off the needle thread clamp.
underside of moving knife and the thread pressure.
- 36 -
jintex.in
Page 41
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Remove the counter knife, thread presser and rocker arms (left and
right) from hook driving shaft saddle 6.
2. Loosen two screws 1 in moving knife shaft thrust collar.
3. Move moving knife shaft joint 3 up or down to adjust the height
of thrust collar 2 so that moving knife 4 comes in contact with
moving knife rest 5 and moving knife 4 is not pushed against
moving knife rest 5 when rocker moving knife 4. After the
adjustment, fix thrust collar 2.
1. Loosen screw 1 in the counter knife.
Do not remove the screw from the knife.
2. Align the rear end of counter knife 2 with section L of thread pres-
ser 3. Then, simultaneously move the counter knife and thread
presser back in direction A until they will go no further.
3. Keeping thread presser 3 held in the backward travel end, move
counter knife 2 forward in direction B by 1 mm.
4. Tighten screw 1 in the counter knife.
(Caution) 1. Be sure to correctly adjust the initial position of the
counter knife and thread presser. The initial posi-
tion of the moving knife is determined by the posi-
tion of the counter knife.
1. The underside of the moving knife comes in contact with the thread
presser when the thread presser, moving knife and counter knife are
installed on the sewing machine.
2. In the aforementioned state, make the thread presser adjusting metal
fitting with the thread presser.
Loosen screw 2, and perform the adjustment by turning screw
1. After the adjustment, tighten screw 2.
If the thread is not properly clamped by the thread presser even when the
aforementioned two adjustment steps have been properly performed:
* Loosen screw 2, and turn screw 1 in the direction of the arrow
to adjust the clamping pressure of the thread presser.
After the adjustment, tighten screw 2. For reference of the ade-
quate pressure of the thread presser, tighten screw 1 by 90° from
the position at which the thread presser adjusting metal fitting comes
in contact with the thread presser.
If the pressure of the thread presser is insuf-
ficient:
O Stitch skipping will occur when changing
the thread from a thick one to a thin one.
If the presser of the thread presser is exces-
sive:
O Several stitches will skip at the start of
sewing.
If the shape of the thread presser is defective:
As viewed from this side
O Bobbin thread clamp failure will
be caused.
O Needle thread clamp failure will
occur.
O Normal
--37--
jintex.in
Page 42 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
4) Initial position of the moving knife
Fig. 55
Hook driving
shaft saddle (left)
Fig. 56
Moving knife rest
Hook
driving
shaft
saddle
No clearance
34
Fig. 57
Align
Align
8
7
Conditions
Top end of the counter knife should be spaced 0.8±0.4 mm away from the top end of the moving knife.
Rocker arms (left and right) should be aligned with the stopper screw.
No clearance should be provided between the rocker arms (left and right) and the hook driving shaft saddle and be-
tween the moving knife shaft thrust collar and the saddle.
- 38 -
jintex.in
Page 43
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Turn moving knife 2 to adjust so that the top end of counter knife
1 is spaced 0.8±0.4 mm from the top end of moving knife 2.
2. Fit rocker arm (left) 3 and rocker arm (right) 4 into moving knife
shaft joint 5 and make them come in contact with respective stop-
per screws 7.
3. Adjust the thrust section using thrust collar 6, rocker arm (left)
3 and rocker arm (right) 4. Then tighten screws 8 and 9.
(Caution) 1. Confirm that the top end of counter knife 1 is
0.8±0.4 mm away from the top end of moving knife
2 when rocker arm (left) 3 and rocker arm
(right) 4 are pressed against respective stopper
screws 7.
If the distance between the top end of the
moving knife and that of the counter knife is
larger than the specified value:
Thread trimming failure will result.
Bobbin thread clamp failure will occur.
If the distance between the top end of the
moving knife and that of the counter knife is
smaller than the specified value:
Bobbin thread clamp failure will occur.
The bobbin thread and needle thread will
fail to interlace with each other at the start
of sewing.
(Failed stitches at the start
of sewing)
Fig. 58
* If a bobbin thread clamp failure occurs
after replacing the feed dog, particularly
when the feed dog with a round needle hole
is replaced by one with a slot, lower the
moving knife (i.e., decrease the distance
(0.8±0.4mm) from the moving knife to the
counter knife).
- 39 -
jintex.in
Page 44 — 5) Position of the thread trimming cam and the thread trimming timing
STANDARD ADJUSTMENT
5) Position of the thread trimming cam and the thread trimming timing
Fig. 59
Minimize the clearance while
preventing a contact.
Fig. 60
Marker dot (red) on the handwheel
Marker dot on
the machine arm
(reference)
Press
End of lobe
Cam roller
The cam
roller
reaches the
R (round)
portion
located this
side of the
end of lobe.
Cam groove
Fig. 61
--40--
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Page 45
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Move thread trimming cam ④ in the lateral direction in terms of
hook driving shaft ⑧ to minimize the clearance provided between
cam roller ③ and plane A of thread trimming cam as long as they are
not pushed against each other when cam roller shaft ② comes in
contact with the follower stopper plate ①. Then, temporarily tighten
screw ⑤ in the thread trimming cam.
2. Pressing hook driving shaft thrust collar ⑥ against the rightmost
end face of thread trimming cam ④, securely tighten two screws
⑦.
3. Loosen screws ⑤.
4. Turn handwheel ⑨ until the marker dot engraved on the machine
arm is aligned with red marker dot engraved on the handwheel.
5. Fit cam roller ③ of cam follower (asm.) ⑩ in the groove on
thread trimming cam ④. (Press cam follower (asm.) ⑩ in the
axial direction of cam follower shaft ⑪.)
6. Tighten two screws ⑤ to fix thread trimming cam ④ when cam
roller ③ is aligned with R (round) portion located this side of the
end of lobe of thread trimming cam ④ and also comes in contact
with plane A of the cam groove on thread trimming cam ④.
(Caution) Checking the thread trimming timing
1. Pressing cam follower (asm.) ⑩ in direction B,
gradually turn handwheel ⑨ in the reverse direc-
tion (away from the operator).
2. Handwheel ⑨ will be hitched when cam roller ③
of cam follower (asm.) ⑩ reaches the R (round)
portion of the cam groove on thread trimming cam
④. Now, confirm the red marker dot engraved
on the handwheel is aligned with the marker dot
engraved on the machine arm.
Thread trimming
timing is excessively
advanced.
Fig. 62
Thread trimming
timing is excessively
retarded.
If the thread trimming timing is excessively
advanced:
Needle thread will come of the needle
eyelet.
Thread trimmer will fail to operate nor-
mally, which will result in thread trim-
ming failure.
Needle thread clamp failure will occur at
the time of thread trimming.
If the thread trimming timing is excessively
retarded:
The needle will interfere with the wiper.
Thread trimming failure will occur.
-41-
jintex.in
Page 46 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
6) Position of the thread trimming magnet
Conditions
When the thread trimming solenoid is in the OFF state, a clearance of 0.8 to 1.2 mm should be provided between the
leftmost end face of the thread trimming cam and the end face of the presser plate driving screw.
It is recommended not
to disassemble the
components unless
disassembling them
is really necessary.
Cam follower (asm.)
0.8 to 1.2 mm
Fig. 63
Thread trimming magnet
Hook driving shaft
7) Rising amount of the tension disk when releasing the thread tension
Conditions
A clearance of 1 mm should be provided between the tension disks when the thread tension release arm is locked by the
thread tension release plate after the arm has rocked the most.
Large
Small
Cam roller shaft
1 mm
Fig. 64
- 42 -
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Page 47
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Loosen two screws 1 in follower presser plate (asm.) 2.
2. Move follower presser plate (asm.) 2 to adjust so that a 0.8 to 1.2
mm clearance is provided between the leftmost end face of thread
trimming cam 3 and presser driving screw 4. Then tighten
screws 1.
If the clearance between the thread trimming
cam and the presser plate driving screw is too
large:
O Thread trimming failure will be caused.
(Caution) 1. Determine the position of follower presser plate
(asm.) 2 so that follower presser plate 5 is in
parallel to the leftmost end face of thread trimming
cam 3.
2. When replacing a component contained in follower
presser plate (asm.) 2, attach a new part in posi-
tion while preventing the part from being pressed
against the related components by moving the
plunger of the presser plate shaft and plunger in the
axial direction at any desired position (in terms of
360°).
If the clearance between the thread trimming
cam and the presser plate driving screw is too
small:
O Thread trimmer will actuate repeatedly,
causing the thread trimmer to break.
1. Pressing presser plat shaft 6 in the direction of the arrow as shown
in Fig. 65, turn the handwheel in the normal direction of rotation to
make the thread trimmer actuate.
2. When thread tension release arm 1 rocks and thread tension release
wire 2 is drawn the most, thread tension release plate 3 and
thread tension release cam 4 will be locked.
3. Loosen nut 4 and adjust thread tension release wire 2 so that a
clearance of 1 mm is provided between the tension disks. After the
adjustment, tighten nut 4.
If the clearance provided between the tension
disks is too large:
O Related components will break.
If the clearance provided between the tension
disks is too small:
O The remaining length of the needle thread
will be decreased.
O The needle thread will slip off the needle
eyelet.
Press
Follower presser plate (asm.)
Thread trimming cam
Fig. 65
-43-
Jinttex.in
Page 48 — 8) Position of the follower guide
STANDARD ADJUSTMENT
8) Position of the follower guide
Conditions
When the cam roller shaft comes in contact with the follower stopper plate (Figs. 59 and 60 on page 40), a clearance
of 0.2 to 0.3 mm should be provided between the follower guide plate and the cam follower (asm.).
Follower mounting base
Contact
0.2 to 0.3 mm
Press
Fig. 66
JUKE
Fig. 67
- 44 -
jintex.in
Page 49
HOW TO ADJUST
1. Move follower guide plate 2 to adjust so that a 0.2 to 0.3 mm clear-
ance is obtained between follower guide plate 2 and cam follower
(asm.) 1 when the cam roller shaft comes in contact with the fol-
lower stopper plate (Figures 59 and 60 on page 40). Then, fix the
follower guide plate by tightening screw 3 .
(Caution) 1. Confirm, by pressing cam follower (asm.) 1 in
the direction of the arrow, that the cam roller shaft
comes in contact with the follower stopper plate.
RESULTS OF
IMPROPER ADJUSTMENT
If the clearance provided between the fol-
lower guide plate and the cam follower
(asm.) is larger than the specified value:
• A play at the moving knife in the rocker
direction will be larger.
If the clearance provided between the fol-
lower guide plate and the cam follower
(asm.) is smaller than the specified value:
• The follower will fail to come off the
thread trimmer to actuate at the start of sewing. In
this case, the related components will break
or the sewing machine will be locked.
- 45 -
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Page 50 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
9) Installing the joint rod (asm.)
No clearance
Fig. 68
Conditions
o The rocker arm (right) should come in contact with the rocker arm stopper screw. In addition, the cam roller shaft
should come in contact with the follower stopper plate.
- 46 -
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Page 51
HOW TO ADJUST
RESULTS OF
IMPROPER ADJUSTMENT
1. Connect joint rod (asm.) 2 to cam follower (asm.) 1 and fix it
there.
2. When cam roller shaft 3 comes in contact with follower
stopper plate 4 and rocker arm (right) 5 comes in contact with rocker
arm stopper screw 6, fit rocker arm plate 7 over moving knife
shaft 9. Then fix the rocker arm plate on rocker arm (right) 5
using screw 8.
(Caution) 1. When fixing the rocker arm plate on the rocker arm
(right), be sure to fix it while lifting the joint rod
(asm.) in the direction of arrow A.
If there is a clearance between the follower
stopper plate and the cam roller shaft or
between the rocker arm stopper screw and
the rocker arm (right), the initial position of
the moving knife will be improper. In this
case, following trouble will be caused.
• Bobbin thread clamp failure will occur.
• Thread trimming failure will occur.
• The sewing machine will be locked.
- 47 -
jintex.in
Page 52 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(2) Wiper components
Fig. 69
(3) Position of the reverse stitching magnet
Conditions
• Stitch length (feed amount): Maximum
• A clearance of 0.5 to 1 mm should be provided
between the reverse stitching magnet and the
plunger radial plate when the reverse feed con-
trol lever is pressed down until it will not go
further.
Press down until
it will go no further.
Fig. 71
- 48 -
jintex.in
Page 53
HOW TO ADJUST
1. Loosen screw 2. Move wiper 3 in the direction of the arrow so
that the length of the wiper is set to 43.8 mm. Then, tighten screw
2.
2. Loosen two screws 1, and adjust so that the top end of the wiper is
spaced 20.7 mm from presser bar 4. Then, tighten screws 1.
Table 22
Gauge size
Part No.
Dimension
~3/8"
10209230
16
7/16"~5/8"
10209500
24
3/4"~7/8"
10209807
30
1"~1 1/4"
10209906
37
Fig. 70
1. Set the stitch dial to the max. value on the scale.
2. Loosen two screws 2 in magnet mounting base 1.
3. Press reverse feed control lever 3 down until it will go no further.
Then move magnet mounting base 1 up or down to adjust the clear-
ance provided between plunger radial plate 5 and the underside of
reverse feed magnet 4 to 0.5 to 1 mm. Then, tighten screws 2.
RESULTS OF
IMPROPER ADJUSTMENT
o If the wiper is too long (longer than 43.8
mm), the wiper will interfere with the
needle clamp while the sewing machine
is in operation.
o If the wiper is not correctly positioned
(the clearance between the presser bar
and the wiper is larger than 20.7 mm),
the wiper will interfere with the needle
while the sewing machine is in
operation.
o If the wiper is not correctly positioned
(the clearance between the presser bar
and the wiper is smaller than 20.7 mm),
the wiper will come in contact with the
needle while the wiper is in operation.
(The needle may breaks.)
If the clearance provided between the plunger
radial plate and the reverse stitching magnet
is larger than the specified value;
o The attraction of the magnet will be de-
creased. In this case, the machine fails to
start reverse feed stitching.
If there is no clearance provided between the
plunger radial plate and the reverse stitching
magnet:
o The stitch length for reverse feed stitching
will be decreased.
- 49 -
jintex.in
Page 54 — STANDARD ADJUSTMENT
STANDARD ADJUSTMENT
(4) Initial position of the reverse feed control lever
1) For the sewing machine equipped with an automatic reverse feed stitching function
Lightly press the
reverse feed
control lever.
Align
0.2 to 1 mm
Fig. 72
Press the
lever down
until it will
go no further
(Reference valuo
58.4 mm)
Align
Top surface of the bed
Fig. 73
Conditions
Stitch length (feed amount) should be maxi-
mized.
Lightly press the reverse feed control lever
and the lever is aligned with the reverse feed
link (1), a clearance of 0.2 to 1 mm should be
provided between the reverse feed control
lever and the back lever stopper.
2) For the sewing machine that is not equipped with an automatic reverse feed stitching function
Conditions
Stitch length (feed amount): 0
Height of the top surface of the reverse feed
control lever should be 58.4±2 mm above the
top surface of the bed.
Fig. 74
- 50 -
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Page 55
HOW TO ADJUST
For the sewing machine equipped with an automatic reverse feed
stitching function
1. Set the stitch dial at the maximum value on the scale.
2. Lightly press reverse feed control lever 1 down until it meets re-
verse feed link (1) 2. At this time, a clearance of 0.2 to 1 mm
should be provided between reverse feed control lever 1 and
back lever stopper 3.
3. If the aforementioned clearance is smaller than 0.2 mm or larger
than 1 mm, set the stitch dial at 0 (zero) on the scale.
4. Press reverse feed control lever 1 down until it will go no
further.
5. Loosen the screw in the feed adjusting base and turn reverse feed
link (1) 2 to adjust so that a clearance of 14±0.2 mm is provided
between back lever stopper 3 and reverse feed control lever
1. After the adjustment, tighten the screw in the feed adjust-
ing base.
For the sewing machine that is not equipped with an automatic reverse
feed stitching function
1. Set the stitch dial at 0 on the scale.
2. Loosen the screw in the feed adjusting base. Turn reverse feed
control lever 1 to adjust so that the height of the top surface of re-
verse feed control lever 1 to 58±2 mm above the top surface of
the bed. After the adjustment, tighten the screw in the feed adjust-
ing base.
(Caution) When the screw in the feed adjusting base is loosen-
ed, do not move the feed adjusting base in the axial
direction of reverse feed control lever 1. This will
push the feed adjusting base against the reverse feed
control lever. In this case, stitching troubles such as
reduced stitch length for the reverse feed stitching
will occur.
RESULTS OF
IMPROPER ADJUSTMENT
If the clearance provided between the back
lever stopper and the reverse feed control
lever is 0 (zero):
- The kinky reverse feed control lever will
occur.
- Stitch length will be shortened.
If the clearance provided between the back
lever stopper and the reverse feed control
lever is 1 mm or more:
- Stitch length will be reduced when per-
forming reverse feed stitching.
- 51 -
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Page 56 — 7. SEWING SPECIFICATION CHANGE-OVER PROCEDURE
7. SEWING SPECIFICATION CHANGE-OVER PROCEDURE
(1) If it is necessary to change the gauge, refer to "2. Gauge component table" and "8.
Gauge replacing procedure.
(2) Replaceable component table
Table 23
Name of part
S type
A type
G type
F type
Tension spring
Part No.
B3129012A00
Wire diameter
1.0 mm
Part No.
D3129555D00
Wire diameter
0.9 mm
Part No.
B3114232000
Wire diameter
1.2 mm
Part No.
D3129555D00
Wire diameter
0.9 mm
Tension spring No. 1
Part No.
11045101
Part No.
11045101
Part No.
11093606
Part No.
11045101
Stitch dial
Part No.
11071909
Stitch length 5
Part No.
11071909
Stitch length 5
Part No.
11071909
Stitch length 5
Part No.
11072006
Stitch length 4
(Caution) 1
Needle (standard)
DPX5 #14
MDP500B1400
Without a thread
trimmer
DPX5 #9
MDP500B0900
DPX5 #21
MDP500B2100
134 SES
SERV7 Nm65
MC200520650
(Caution) 2
With a thread trimmer
DPX5 #11
MDP500B1100
(Caution) 1. Stitch dial for the F type of sewing specification is different from that for the other types of sewing
specifications. The stitch dial is changed in the steps of procedure described below.
1) Align the "0" on the scale of stitch dial with the marker dot engraved on the machine arm.
2) Remove the screw from the stitch dial. At this time, take care not to allow the stitch dial to turn.
3) Align the "0" on the scale of stitch dial to be used with the marker dot engraved on the machine
arm. Then, tighten the screw.
4) Set the stitch dial at the max. value on the scale. Check that the max. number (5 or 4) on the scale
is aligned with the marker dot engraved on the machine arm. If they are not aligned with each other,
loosen the screw in the stitch dial and adjust the max. number on the scale to the marker dot on
the machine arm. Then, tighten the screw in the stitch dial.
(Caution) 2. When replacing the needle for changing the sewing specification, adjust the needle referring to "(2)
Needle-to-hook timing" on page 20.
Only for the F type of sewing specification, the needle bar height, needle-to-hook timing and the lift-
ing amount of the needle bar from its lowest dead point are different from those for the other types of
sewing specifications. So, adjust those items referring to "3) Needle bar height" on page 16 and "(2)
Needle-to-hook timing" on page 20.
- 52 -
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Page 57
8. GAUGE REPLACING PROCEDURE
(1) How to remove the gauge
1) Turn OFF the power switch.
2) Remove the slide plate, needle, clamp, presser foot, throat plate and feed dog.
* For the sewing machine with a thread trimmer and a wiper, remove the currently-mounted wiper if the size of gauge to
be used is not acceptable to the wiper.
3) Tilt the sewing machine.
4) Loosen screws 1 and 2 in the hook driving shaft saddle.
* For the sewing machine with a thread trimmer, loosen two screws 3 in connecting link (asm.) 4 and screw 6 in
the rocker arm plate 5. Do not remove the aforementioned screws but only loosen them.
5) Loosen two screws 10 in hook driving shaft gear 9.
* At this time, do not lever the screw (screw No. 1) which is tightened in the flat section of hook driving shaft 7.
Loosen the screw to the extent where the screw No. 1 does not come off the flat section of hook driving shaft 7 when
turning hook driving shaft gear 9 by hand.
(2) How to install the gauge
1) Raise the sewing machine.
2) Attach the feed dog in position.
3) Attach the needle clamp and needle in position.
4) Adjust the height of the needle bar.
5) Remove the throat plate.
6) Tilt the sewing machine.
Refer to "2) Position and height of the feed dog" on page 14.
Refer to "4) Needle entry" on page 18.
Refer to "3) Needle bar height" on page 16.
Fig. 75
Fig. 76
- 53 -
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Page 58
7) Move the hook driving shaft saddle from its home position.
Adjust so that the specified clearance is provided
between the needle and the blade point of the hook.
Then, fix the hook driving shaft.
8) Fix the hook driving shaft gear in position.
9) Raise the sewing machine.
10) Attach the throat plate in position.
11) Attach the presser foot in position.
12) Attach the wiper in position.
Refer to "(2) Needle-to-hook relation" on page 20.
Refer to "(2) Needle-to-hook relation" on page 20.
Refer to "(2) Wiper components" on page 48.
(Caution) 1. When attaching feed dog 1, confirm that it is equidistantly spaced in the feed dog slot in throat
plate 2 with respect to the lateral direction. Also confirm that the needle enters the center of the
needle hole in feed dog 1.
Needle hole in
the feed dog
Needle
1
2
Clearance
Fig. 77
2. For the LH-3128F type of sewing machine, adjust the height of the needle bar, when the stitch
length is set to 0 (zero) and the needle bar rests in the lowest dead point of its stroke, so that the
bottom end of the needle clamp is 12.4±0.1 mm above the top surface of the throat plate.
For the A, G and S types of the sewing machines, use the marker line engraved on the needle bar
for the adjustment of the needle bar height.
3. Adjust the clearance provided between the needle and the blade point of the hook to the specified
dimension.
Position hook driving shaft gear 9 so that a clearance of approximately 0.5 mm is provid-
ed between the screw gear and the hook driving shaft saddle.
Then, tighten screw 10. Do not remove hook driving shaft gear guide 8.
Needle
0 to 0.05 mm
Blade point
of the hook
Needle guard
of the hook
0 to 0.15 mm
Fig. 78
0.5 mm
Hook driving shaft saddle
Fig. 79
4. When attaching the presser foot, confirm that the needle does not come in contact with the hook.
- 54 -
jintex.in
Page 59 — 9. REPLACING THE TIMING BELT
9. REPLACING THE TIMING BELT
Fig. 80
* The below-mentioned replacing procedure has been prepared for the LH-3128 as an example.
If you want to replace a timing belt for the other types of 2-needle lockstitch machines, refer to the procedure described below.
(1) How to remove the timing belt
1) Tilt the sewing machine, and remove timing belt 32 from the hook driving shaft sprocket.
2) Remove the side plate and face plate.
3) Remove presser bar component 12 through 15.
4) Remove thread take-up component 12 through 15.
5) Remove filler plate 11 from the jaw section and screws 10.
6) Loosen screw 17 in needle bar rocking rear arm 18 and draw out needle bar frame (asm.) 16.
7) Loosen screws 19 in main shaft thrust collar (asm.) 20. Remove the handwheel. Then shift counterweight (joint) 21 out
of position.
8) Remove feed regulating spring 24 from the feed adjusting base pin 25.
9) Set stitch dial 31 at 0 (zero) and loosen screw 22 in feed adjusting base 23.
10) Loosen screws 26 in thrust collar 27. Draw out reverse feed control lever 28 and reverse feed control lever shaft 29.
11) Draw out timing belt 32 from the side plate of the machine arm.
-55-
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Page 60 — How to install the timing belt
– 56 –
jintex.in
(2) How to install the timing belt
1) Put timing belt 32 in position from the side plate of the machine arm. Then pass counterweight (joint) 21 through the tim-
ing belt.
2) Tighten screws 19 in main shaft thrust collar 20 taking care to remove a play at counterweight (joint) 21.
3) Attach the handwheel. At this time, align the hole for screw No. 1 with the flat portion on the main shaft by turning the
handwheel toward the operator. Confirm, now, that the handwheel is not rubbed against the machine arm.
4) Put timing belt 32 on the main shaft sprocket and hook driving shaft sprocket.
At this time, refer to "(6) Timing between the main shaft and the hook driving shaft" on page 26.
5) Put reverse feed control lever 29 and reverse feed control lever shaft 29 in the machine arm. Then pass thrust collar
27 and feed adjusting base 28 over the reverse feed control lever shaft.
Tighten screws 30 in thrust collar 27 at a position where there is no play.
6) Adjust the position of feed adjusting base 28 with respect to the direction toward the hook driving shaft so that the center
of reverse feed adjusting screw 30 meets the center of the cam surface of feed adjusting base.
Tighten screw 22 referring to "(4) Initial position of the reverse feed control lever" on page 50.
7) Fit needle bar frame (asm.) 16 from the face plate and join it with needle bar rocker rear arm 18.
8) Assemble thread take-up components 9 through 15. At this time, confirm that there is no axial play in the thread
take-up components.
9) Attach filler plate 11 to the jaw section with screws 10.
10) Assemble presser bar components 1 through 9.
11) Turn the handwheel to bring needle bar frame (asm.) 16 to the lowest position.
At this time, the stitch dial should be set at 0 on the scale.
12) Set the needle bar so that specified dimensions described in "(1) Needle bar and feed dog, 1) Initial position of the needle
bar" on page 14. In this state, position needle bar rocker rear arm 18 as illustrated in Fig. 81 and tighten screw 17. At
this time, confirm that there is no axial play in the needle bar.
33±0.5 mm
Side plate attaching plane
Fig. 81
13) Re-confirm that needle entry is correct referring to "4) Needle entry" on page 18.
Page 61
10. TROUBLESHOOTING CHART
Phenomenon
Cause
Item to be inspected
Corrective measure
Groove on the bobbin case
stopper of the throat plate
has scratches.
Grind the groove on the bobbin
case stopper.
The needle thread tension is
too high.
The tension applied to the
needle thread.
Needle-to-hook timing is
not properly adjusted.
The clearance provided
between the hook and the
bobbin case opener.
Adjust the clearance provided
between the hook and the bobbin
case opener to 0.2 mm.
The clearance provided
between the needle and the
blade point of the hook.
Adjust the clearance provided
between the needle and the blade
point of the hook to 0.05 mm.
Amount of oil in the hook
is insufficient.
Amount of oil in the hook.
Properly adjust the amount of oil in
the hook.
Thread breakage
Operating range and
pressure of the thread
take-up spring are
improper.
Operating range and
pressure of the thread
take-up spring.
Properly adjust the thread take-up
spring.
Blade point of the hook
has scratches.
Grind the blade point of the hook.
Periphery of the needle
hole in the feed dog has
scratches.
Grind the periphery of the needle
hole in the feed plate.
The machine head is not
properly threaded.
How the machine head is
threaded.
The needle is not properly
installed.
Orientation of the needle.
Replace the needle with a new one.
The needle is bent or has a
blunt point.
Needle
Install the presser foot while facing
it in the correct direction.
The presser foot is not
properly installed.
The needle thread unwists.
If thread is likely to break especially when using a tetron thread:
1) Minimize the needle thread tension and the thread take-up spring
pressure as long as stitches are neatly finished.
2) Wind the thread round the needles to reduce the frequency of the
trouble.
Idling stitches are
produced.
Use the thread guide equipped with
a felt pad.
A thread loop is not made
with consistency when the
blade point of the hook
clamps the needle thread.
-57-
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Page 62
Phenomenon
Cause
Item to be inspected
Corrective measure
Loose stitches are
produced.
Same as the aforementioned causes given in the "Thread breakage." Other causes are described
below in addition to them.
Bobbin fails to move
smoothly.
Replace the bobbin with a new one.
The clearance provided
between the hook and the
bobbin case opener is too
large.
Check the clearance
provided between the hook
and the bobbin case opener.
Adjust the clearance provided
between the hook and the bobbin
case opener to 0.2 mm.
The feed dog is positioned
too high.
Check the height of the
feed dog.
Adjust the height of the feed dog to
1 mm.
The thread path is poorly
finished.
Buff it up.
The clearance provided
between the bobbin case
and the throat plate is not
properly adjusted.
Check the clearance
provided between the
bobbin case and the throat
plate.
Adjust the clearance provided
between the bobbin case and the
throat plate to 0.9 mm.
Puckering
frequently occurs.
The needle thread tension
is too high.
Needle thread tension.
Minimize the needle thread tension
as long as stitches are neatly
finished.
The bobbin thread tension
is too high.
Bobbin thread tension.
Minimize the bobbin thread tension
as long as stitches are neatly
finished.
The tension of thread
take-up spring is too high.
Tension of the thread
take-up spring.
Minimize the thread take-up spring
tension as long as
stitches are neatly finished.
Operating range of the
thread take-up spring is too
large.
Operating range of the
thread take-up spring.
Minimize the operating range of the
thread take-up spring as long as
stitches are neatly finished.
Presser foot pressure is too
low.
Pressure of the presser foot.
Increase the presser foot pressure.
Sewing speed is too high.
(The number of revolutions
of the motor is too large.)
Reduce the sewing speed.
- 58 -
jintex.in
Page 63
Phenomenon
Cause
Item to be inspected
Corrective measure
Stitch skipping
frequently occurs.
Same as the aforementioned causes of "Needle-to-hook relation" in the "Thread breakage"
Presser foot pressure is too
low.
Blade point of the hook is
blunt.
The needle guard of the
hook fails to work.
The needle is too thick for
the thread used.
A heavy-weight material is
used.
Pressure of the presser
foot.
Check the shape of the
blade point of the hook.
Correct the blade point of
the hook or replace the
hook with a new one.
Adjust the needle guard of the hook
so that it works normally.
Replace the needle with one that is
thinner by one
count.
If stitch skipping is likely to occur particularly when using a
spun thread:
Refer to "(2) Needle-to-hook relation."
Lowest position
of the needle bar
When the needle bar
ascends by H mm
Upper
marker
line
Lower
marker
line
Upper marker
line
Lowest position
of the needle bar
When the needle bar
ascends by H mm
Blade point
of the hook
Center of the
needle
0.8 to 1 mm
(H) mm
Lowest position
Stitch skipping is not likely to occur when H mm is adjusted to 2.4 to 2.6
mm. If H (mm) is excessively increased, loosened stitches will result.
So, be careful.
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jintex.in
Page 64
Phenomenon
Cause
Item to be inspected
Corrective measure
Needle thread
trimming failure
Thread trimming timing is
not properly adjusted.
Top end of the moving
knife has scratches or bent.
Properly adjust the thread trimming
timing.
Replace the moving knife with a
new one.
The clearance provided
between the hook and the
bobbin case opener.
Adjust the clearance provided
between the hook and the bobbin
case opener to 0.2 mm.
The clearance provided
between the needle and the
blade point of the hook.
Adjust the clearance provided
between the needle and the blade
point of the hook to 0.05 mm.
The clearance provided
between the bobbin case
and the throat plate.
Adjust the clearance provided
between the bobbin case and the
throat plate to 0.9 mm.
Needle-to-hook relation is
not properly adjusted.
Lift of the needle bar and
the needle bar height.
Adjust the lifting amount of the
needle bar and the height of the
needle bar properly.
The moving knife is
improperly positioned.
Adjust the longitudinal position of
the moving knife.
Operating range of the
thread take-up spring is
too small.
Adjust the operating range of the
thread take-up spring using the
thread take-up spring stopper.
Bobbin thread
trimming failure
Top end of the moving
knife is positioned too low.
Position of the moving
knife blade.
Replace the moving knife with a
new one.
The hook is positioned too
high.
Height of the hook.
Check the height of the hook.
Top end of the moving
knife has scratches or bent.
Replace the moving knife with a
new one.
Needle hole in the feed
dog (throat plate) is too
large.
Replace the feed dog (throat plate)
with one that has a needle hole of
appropriate size.
The feed dog is positioned
too high.
Check the height of the
feed dog.
Adjust the height of the feed dog to
1 mm.
Blade point of the hook has
worn out.
Replace the hook with a new one.
The clearance provided
between the needle and the
blade point of the hook is
not properly adjusted.
Blade point
Pushes out
the bobbin
thread
(Caution)
If the clearance between the needle and the blade point of
the hook is adjusted when the needle guard works, the
needle may bend.
As a result, the moving knife will be improperly positioned
and push out the bobbin thread, causing a thread trimming
failure.
Needle guard
Bobbin
thread
- 60 -
jintex.in
Page 65
Phenomenon
Cause
Item to be inspected
Corrective measure
Bobbin case idles
at the time of thread
trimming.
Thread is not wound round
the bobbin in the correct
direction.
Amount of thread wound
round the bobbin.
Wind the bobbin with thread until
80% of its capacity is reached.
The bobbin is wound with
thread of which amount
exceeds 80% of its
capacity.
Replace the idling prevention spring
with a new one.
Pressure of the idling
prevention spring is too
low.
Use an idling prevention sheet with
the machine.
A bobbin made of iron is
used.
Type of the bobbin used.
Replace the bobbin with a specified
aluminum bobbin for the sewing
machine with a thread trimmer.
Thread path on the hook is
poorly finished.
Grind the thread path on the hook or
replace the hook with a new one.
The needle-up stop timing
is excessively advanced.
Position of the red marker
dot engraved on the
handwheel and the marker
dot engraved on the
machine arm when the
sewing machine stops with
its needle up.
Properly adjust the needle-up stop
position of the sewing machine.
Stitch skipping at
the start of sewing.
Slip-off of the
thread at the start
of sewing.
Bobbin thread presser
spring fails to clamp the
bobbin thread after thread
trimming.
Check whether the thread
is clamped under the
moving knife after thread
trimming.
Adjust the position of the moving
knife or replace the thread presser
with a new one.
The feed dog is positioned
too high.
Check the height of the
feed dog.
Adjust the height of the feed dog to
1 mm.
Pressure of the thread
take-up spring is too high
or the stroke of the spring
is too large.
Thread take-up spring.
Decrease the pressure of the thread
take-up spring or reduce the stroke
of the spring.
Length of thread remaining
at the needle eyelet is
insufficient.
Adjust the pretensioner to a lower
value so that a longer thread remains
at the needle eyelet after thread
trimming.
The needle used is too
thick.
Use a thinner needle.
To be continued to
the next page
- 61 -
jintex.in
Page 66
Phenomenon
Cause
Item to be inspected
Corrective measure
Continued from the previous page
Needle hole in the feed dog
is too large.
Replace the feed dog with one that
has a smaller needle hole.
(Caution)
The feed dog comes in three different types with respect to the size of the needle hole. Use the
feed dog with the smallest needle hole as long as the needle does not break.
For heavy-
weight
materials
For medium-
weight
materials
For light-
weight
materials
Bobbin thread tension is
too high.
Decrease the bobbin thread tension.
(Caution)
When using a thin thread (with a higher count), stitch skipping or slip-off of the needle thread is
likely to occur when the remaining amount of bobbin thread is not enough.
Bobbin thread tension is too
low.
Extent of idling of the
bobbin
Increase the bobbin thread tension.
The presser foot rises at the
start of sewing.
Use the soft-start function.
- 62 -
jintex.in
Page 67
Phenomenon
Cause
Item to be inspected
Corrective measure
Thread is not smoothly fed
from the thread stand.
How the thread is wound
round the thread stand and
fed from it.
Adjust so that the needle is smoothly
fed from the thread stand.
(Caution) 1
Thread tension of the
tension controller No. 1 is
too high.
Reduce the thread tension of the
tension controller No. 1.
Operating range of the
thread take-up spring is too
large.
Operating range of the
thread take-up spring.
Decrease the operating range of the
thread take-up spring.
Hook of the moving knife
is not properly ground.
Replace the moving knife with a
new one.
Length of thread
remaining at the
needle eyelet after
thread trimming is
insufficient, or the
thread slips off the
needle eyelet after
thread trimming.
Tension disk fails to work
at the time of thread
trimming.
Action of the tension
releaser.
Properly adjust the tension releaser.
Thread trimming timing is
not properly adjusted.
Timing of the thread
trimming action.
Properly adjust the thread trimming
timing.
Longitudinal position of
the moving knife is not
properly adjusted.
Adjust the longitudinal position of
the moving
knife properly.
Needle-to-hook relation is
not properly adjusted.
The clearance provided
between the hook and the
bobbin case opener is too
large.
Adjust the clearance provided
between the hook and the bobbin
case opener to 0.2 mm.
The needle and the bobbin
case stopper have
scratches.
The clearance provided
between the bobbin case
and the throat plate is too
small.
Adjust the clearance provided
between the bobbin case and the
throat plate to 0.9 mm.
Correct the needle and the bobbin
case stopper or replace them with
new ones.
The moving knife fails to
cut the thread sharp.
Replace the moving knife with a
new one.
Thread is cut outside the
material.
Use the thread guide equipped with a
felt pad.
The felt pad of the thread
guide equipped with a felt
pad has a thread passing
mark and is flattened.
Actuate the thread trimmer with the
sewing speed reduced if the thread is
cut outside the material.
Replace the felt (22603708) with a
new one.
(Caution) 1.
When using a synthetic thread, the thread is likely to be wound round
the thread stand.
In this case, use the thread stand guide arm (asm.) supplied with the
sewing machine.
- 63 -
jintex.in
Page 68
Phenomenon
The wiper fails to spread the thread.
The V belt is not properly tensed.
The wiper is improperly positioned.
Cause
The wiper is improperly positioned.
The needle-up stop position of the machine is improper.
The V belt is not properly tensed.
The wiper is improperly positioned.
Item to be inspected
Position of the red marker dot engraved on the handwheel and the marker dot engraved on the machine arm when the sewing machine stops with its needle up.
Tension of the tension controller No. 1
Length of the needle thread remaining after thread trimming is excessive.
Timing of the thread trimming action.
The bobbin thread clamping pressure is too high.
The moving knife fails to cut the thread sharp.
Thread presser spring
Position of the moving knife.
Corrective measure
Adjust so that the wiper spreads the thread properly.
Properly adjust the needle-up stop position of the sewing machine.
Properly tense the V belt.
Adjust so that the wiper spreads the thread properly.
Adjust the tension controller No. 1 so that the needle thread of 35 to 45 mm remains after thread trimming.
Properly adjust the thread trimming timing.
Properly adjust the position of the thread presser.
Replace the moving knife with a new one.
- 64 -
jintex.in