Reliable MSK-8420B User manual

MSK-8400B
MSK-8420B
Industrial Sewing Machine
Instruction Manual

CONTENTS
1. Brief introduction
2. Main specifications
3. Installation and preparation
3.1 Installation
3.1.1 Location of the machine
3.1.2 Installing oilreservoir
3.1.3 Mounting machinehead
3.1.4 Mounting kneelifter
3.1.5 Installing the motor
3.1.6 Connecting theclutch lever tothe pedal
3.1.7 Installing thethread winder
3.1.8 Installing the thread spool stand
3.2 Preparation
3.2.1 Cleaning the machine
3.2.2 Examination
3.2.3 Precaution before start
4. Operation
4.1 Coordination between needle thread and sewing material
4.2 Installing theneedle
4.3Winding the bobbin thread
4.3.1 Winding method
4.3.2 Winding adjustment
4.3.3 Threading
4.3.4 Stich length and reverse sewing control
4.3.5 Setting thebobbin
4.3.6 Drawing threadfrom the bobbin
5. Machine adjustment
5.1 Thread tension adjustment
5.2 Adjusting the pressure of presser foot
5.3 Use andadjustment of thesafety clutch device
5.3.1The function ofthe safety clutchdevice
5.3.2 Resetting thesafety clutch device
5.3.3 Regulating thestrength on thesafety clutch device
5.4 Upper feed adjustment
5.5 Presser foot lift volume adjustment
5.6 Hook oil amount adjustment
Operation instruction
1
1
1
1
1
1
1
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1. MSK-8420B Arm parts
2. MSK-8400B Arm parts
3. Upper shaft and presser foot parts
4. MSK-8420B Needle bar motion and Lower feed parts
5. MSK-8400B1 Needle bar motion and Lower feed parts
6. Rock shaft and thread looping parts
7. Rock shaft and thread looping parts
8. Stitch length adjusting parts
9. Knee lifter parts
10. Lubrication parts
11. Lubrication parts
12.Accessories
MSK-8420B
MSK-8400B
MSK-8420B
MSK-8400B
Parts manual
11 14
15 18
19 22
23 26
27 30
31 34
35 38
39 40
41 44
45 48
49 52
53 54

1
2
small
big
B
A
B
A
oil felt
-1-
Both the models adopt straight twin-needle and two horizontal hooks with auto lubrication for thread
looping, sliding lever for thread take up to form two lines of lockstitch seam. The upper shaft and lower
shaft is connected by ball bearing and driven by teeth-type synchronic belt; plunge oil pump lubrication
system. They adopt the compound feed mechanics of feed dog, needle bar and presser foot, even if for long
stitch length and long material, They can deal with them freely.
They are widely used in factories of suitcase, tent, cushion, leather goods, apparel, mat, etc..
The difference between the two models:
MSK-8420B adopts twin-needle, two large horizontal hooks with auto lubrication. With the parts it can
form ten different needle gauges.
MSK-8400B adopts single needle and form single line double lockstitch form.
1. Brief introduct oni
1 Application: medium and heavy duty materials
2 Max. sewing speed: 2000 spm
3 Max. Stitch length : 9 mm
4 Needle barstroke: 36 mm
5 Presser footlift height: 8mm(by hand); 16mm(byknee)
6 Hook: large horizontal hook with auto lubrication
7 Needle: DP 17 Nm125~180
8 Lubrication: pump auto lubrication (partial of manually oiling)
9 Needle gauge: (Twin-needle) 6.4, 3.2, 4, 4.8, 8, 9.5, 12.7, 16, 19, 25.4
10 Motor power: 0.37 kw (clutch motor)
2. Main Technical Specification
3.1 Installation
3.1.1 Location of the machine
To ensure a smooth running, the machine should
be located on rigid and flat floor. The insert of
rubber mat between machine stand and floor is
recommended for further reducing the running noise
and vibration.
3.1.2 Oil Reservoir Installation(Fig.1)
Put the oil reservoir into the table cutout, and
place the four cushions on the four corners of the
cutout, and place oil felt into the oil reservoir.
3.1.3 Mounting machine head(Fig.2)
Make the hinge A of machine headengaged with
hinge socket B on the table, then turn the machine
head freely till it is seated on the frame of table
cutout.
()
3. Installation and preparation
B
A

A
A
C
C
B
B
3
4
5
A
C
B
-2-
3.1.4 Knee control presser foot lifter installation(Fig.3)
a. Installing
Install Connector A , Bell Crank B , Bell C
in the order shown in Fig.3.
b. Adjustment (Fig.4)
In the order of the following:
1.When the presser foot is at its lowest posi-
tion, keep the crank in the position shown by b
in the figure, turn Knee Control Stop Adjusting
Screw C to touch with the oil reservoir, and
tighten the nut of Screw C .
2. When operate by knee, the presser foot lift
volume is controlled by Screw B . Turn the
presser foot lever down, make the bell in the po-
sition shown by a in the figure, lift the presser
foot to 13 mm, adjust Screw B to touch the oil
reservoir. Then tighten the nut of Screw B .
3.1.5 Installing the motor (Fig.5)
Align machine balance wheelbelt groove A with
motor pulley belt groove B by moving the motor C
leftward or rightward.Be sure the belt is not touch
with table.
() () ( )
()
()
()
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A
B
C
D
G
F
E
10 - 12 mm
D
C
B
A
20¡«30
6
7
8
C
AB
-3-
D
E
ABA
3.1.6 Connecting the clutch lever to the pedal (Fig.6)
1)The optimum tilt angle of pedal A with floor
is approx.30 degree.
2)Adjust the clutch of the motor so that clutch
lever C and draw bar B run in line.
3)The machine balance wheel should rotate coun-
terclockwise for normalsewing when viewfrom opposite
side of balance wheel G . The motor is rotated in the
same direction. The rotation can be reversed by rever-
sing (turn over 180 deg.)the plug of motor.
4)Adjust the tension of V-belt F by moving the
motor vertically. The proper tension of V-belt is a slack
of 10-12mm when the belt is depressed at the belt span
by finger.
3.1.7 Installing the bobbin winder (Fig.7)
Align pulley B of bobbin winder with outside of
belt C and should be kept a properclearance between
them , so that pulley B could be contacted with belt
after the stop latch thumb lever A depressed, thereby
belt drives thepulley B while machine running. After
check bobbin winder is in parallel with belt slit E
of table, fastened by two wood screws D .
3.1.8 Installing the thread spool stand (Fig.8)
Locate thread spool stand at the right front of
the table, note that spool rest may not obstruct when
machine head is turned backward, then tighten wood
screw.
3.2 Preparation
3.2.1 Cleaning the machine
Before delivery, the machine parts are coated with
rust preventive grease, whice may be hardened and con-
taminated by dust during storage and shipment. The
grease must by removed by clean cloth with gasoline.
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9
10
11
12
oil mark
oil screen
-4-
3.2.2 Examination
Though every machine is confirmedby strict inspec-
tion and test before delivery, the machine parts may be
loosed or deformed after long. distance transportation
with jolt. A thorough examination must be performed
after cleaning the machine . Turn the balance wheel to
see if there is running obstruction, parts collision,
uneven resistance or abnormal nosie. If these exist,
adjustment must be made accordingly before run.
3.2.3 Precaution before Start
a. Oiling (Fig.9)
Oil amount should be filled according to the marks
in the oil reservoir. Mark (H) refers to the highest
of oil amount;(L) refers to the lowest, be careful that
the oil amount should not be lower than Mark (L),
otherwise the machine parts can not be fed with oil
and cause overheat and collision.
Be sure to use machine oil HA-8 or HJ-7
b. When the machine starts for the initial time or
reuse after a long period of time, the proper oil
amount should be filled in sections of machine shown
by arrows in Fig10,11.When it is in operation, observe
the oil sparking in oil screen to check the oil
condition.
Note: when the machine needs drop oiling , do not
start before drop oiling.
c. When a new machine starts running, for extending
its life, please run at a medium and low speed (1000
spm) for about a month and then raise the speed
gradually.
d. Please turn off the power when it is not in use
or the operator leaves away from it .
e. Replace the oil every month. When replacing,
fully drain off the old oil in the reservoir and add
the new one.
f. The needle gauge options are: 6.4, 3.2, 4, 4.8, 8,
9.5, 12.7, 16,19, 25.4 For getting it , the throat plate,
presser foot or alternating foot , needle holder, feed
dog, left and right sliding plates, thread guide should
be changed. It is provided with 6.4mm when it leaves
off the factory, For the other size, the relevant parts
can be ordered from the factory.

13
14
A
B
C
D
E
G
H
2
1
F
-5-
long groove
long groove leftward
clearance
(a)
(d)
(b)
(c)
A
4.1 Coordination betweenneedle, thread and sewing
material
Please use needleDP 17,Nm125-180.The coarseness
of needle should be in accordance with the nature of
material. If stitch on heavy duty material with a slim
needle, the needle will be easily bent, skip or thread
breakage occurs, on the contrary, stitch on tightly woven
material with a very coarse needle, the material will
be destroyed with over-big needle. So the needle and
thread should be properly selected.
4.2 Needle installation(Fig.13)
Turn the balance wheel to lift needle bar to the
highest position, loosen Needle Set Screw A , fully
insert the needle shank upto the bottom of needle
socket, keeping the long grooves of the two needles
opposite with each other,then tighten Screw A , For
single needle, keep the long groove of needle facing
the left of the operator. See Fig (b).
Note: Fig.(c) : insufficient insertion.
Fig.(d) : wrong direction of needle long groove
in insertion.
4.3 Winding the Bobbin thread
4.3.1 Winding method(Fig.14)
1) Install bobbin A to bobbin winder spindle B .
2) Pass thread C from spool through the eye 1 on
tension bracket E . Pass ti between tension discs 2 ,
and then wind the end of the thread a few turns on
the bobbin.
3) Push stop latch thumb lever D down to lock the
bobbin, the winder pulley F is thereby pressed on
belt G .
4) Start the machine to wind thread.
Note when thread is wound without sewing opera-
tion, be sure to keep the presser foot lifted.
5) When the thread isfully wound, the bobbin winder
stop latch automatically release the bobbin winder,
thus stopping the winding motion.
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4. Operation
single needle

L7 L5 L4 L3' L3 L2' L2 L
R7 R1
15
16
17
-6-
A
A
B
C
C
D
E
A A AB B
L11 R11
L8
L9
L10
L11
L12
L13
R8
R9
R10
from right to left from left to right
detail chart
thread
L6
R6
R11
R12
R13
R5
R2
R3
R4
4.3.2 Winding adjustment (Fig.15)
1) Wound bobbin thread should be neat and tight,
if not , adjust the thread tension by turning tension
stud thumb nut A of bobbin winder tension bracket.
Note: nylon or polyester thread should be wound
with light tension , otherwise bobbin D might be
broken or deformed.
2) When the wound thread layer does not present a
cylindrical shape as in Fig.15a, loosen tension bracket
screw B and move tension bracket C leftward or
rightward. If thread is wound as shown in Fig, 15b,
move the tension bracket rightward, while if thread
is wound as shown in Fig.15c,move the tension bracket
leftward, After adequately positioning the tension
bracket, tighten screw B .
3) Do notover fill thebobbin , theoptimum capacity
of thread will fill about 80% of bobbin ouside diameter,
this can be adjusted by stop latch screw E .
4.3.3 Threading (Fig.16)
Every thread should be drawn through Thread Hole
A , when use light and smooth thread (polyester or long
silk thread), it should be drawn through Hole B , Keep
the thread take-up lever in its highest position ,draw
every thread in the following numerical order.
4.3.4 The stitch length and forward and reverse sewing
control (Fig.17)
The stitch length can be regulated by Stitch
Length Dial A . Turn it counter-clockwise to expand
its length and clockwise to shorten its length . The
numbers on Dial A show the sizesof the stitchlength
in mm.
For reverse feed, press down Release Feed Lever
C to perform reverse sewing , Release the lever, the
reverse feed lever can reset automatically and the
forward sewing is resumed.
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21
20
19
18
Normal
A
B
C
-7-
hook
thread
sliding plate
hook
sliding plate
tension adjusting screw
loosen
tighten
inner stop piece
1
1
2
thread
4.3.5 Placing bobbin (Fig.18)
Note: when bobbin is placed into the bobbin case,
the thread should be wound properly in the correct
direction shown inthe figure.
4.3.6 Drawing thread from the bobbin (Fig.19)
a. Draw thethread end to Bobbin Slot (1) shown in
the figure, and pull it out down through theinner
bobbin stop piece.
b. Hold the thread with left hand , turn the balance
wheel slowly andget the bobbinthread, then draw
them a little apart from the presser foot.
5.1 Thread tension adjustment
All forms of stitches are shown in Fig.20.
The normal stitch of sewing machine is shown as
Fig.(A) If stitchis abnormal , the puckering and thread
breakage will occur, and the needle thread tension and
bobbin thread tension should be adjusted so that the
normal stitch can be obtained.
a. If the stitch seam shows as Fig. 20B, indicates
that the needle thread or bobbin thread tension
is too loose, then turn the thread tension screw
counter-clockwise to release the needle thread
pressure; or turn the adjusting screw with a
screwdriver to increase the bobbin thread ten-
sion.( see Fig.20,22 )
5. Machine Adjustment
thread

25
24
23
22
button
balance wheel
pressure adjusting screw
reduce
increase
teeth - belt pulley
shaft
safety clutch device
-8-
needle thread tension
increase
reduce
b. If the needle thread is too loose and the bobbin
thread is too tight, then shows as Fig. 20C, And
turn the threadtension screw clockwiseto increase
the needle thread tension; or turn loose the
bobbin lace screw to reduce the bobbin thread
tension. (See Fig. 21, 22)
For special sewing with special thread, the ten-
sion needed can be obtained by adjusting the power and
stroke of the thread take-up spring.
5.2 Adjusting the pressure of presser foot (Fig.23)
The pressure of the presser foot should be adjust-
ed according to the thickness of the sewing materials.
If stitch on heavy duty material, the pressure should
be increased and turn the pressure adjusting screw on
the back of the arm clockwise if reduce the pressure,
turn it counter-clockwise.
5.3 Use and adjustment of the safety clutch device
The function of the safety clutch device is to
prevent the hook and teeth-belt from destroy when the
needle thread is drawn into the hook for adnormal load
during the operation.
5.3.1 The function of the safety clutch device(Fig.24)
a. When the safety clutch device is functioning,
the teeth-belt will remove the load and the rock
shaft will stop rotating, only the upper shaft
rotates, and the machine stops work.
b. Clean off the needle thread which is drawn in
the hook.
c. Turn the shaft of the teeth-belt with hand to
check if the rock shaft can turn smoothly, then
reset the safety clutch device.
5.3.2 Resetting thesafety clutch device.
a. While press down the button in the bed surface
with left hand, turn the balance wheel slowly
with right hand in the direction shown in Fig.
25.

26
27
28
stop plate
white mark
eccentric
lower shaft
loosen
tighten set screw
belt
eccentric
reference line
button
special screw
horizontal shaft crank
upper layer feed reduce
upper layer feed increase
link
b. When the stop plate stops the balance wheel,
more strength is needed to turn the balance
wheel to reset the safety clutch device.
C. Release the button in the bed. So the resetting
of it is OK. (See Fig.26)
5.3.3 Regulating the strength on the safety clutch
device(Fig.27)
a. When the white mark of the eccentric pin aims
at the center of the rock shaft, indicates that
the strength on the safety clutch device is the
minimun.When the white mark points outward, the
strength is properly increased.
b. For regulating the strength of it, move theteeth
- belt and loosen the set screw of the eccentric
pin, and turn the eccentric pin.
c. After regulation, please tighten the set screw.
5.4 Upper feed adjustment (Fig.28)
If the upper and lower feed are not in timing
during sewing, the long hole of the horizontal feed
crank should be adjusted to get the length of upper
feed.
Adjust as the following:
a. Loosen thespecial screw.
b. Move the special screw upward to reduce the feed
amountor upper layer of material.
c. Move the special screw downward to increase the
feed amount. Theoretically when it is on the
reference line of the horizontal feed crank, the
upper feed amount equals to the lower feed
amount.
d. After adjustment, tighten the special screw.
-9-

30
29
oil amount
adjusting screw
increase reduce
nut
special screw
crank
increase
reduce
crank link
-10-
5.5 Presser foot lift volume adjustment (Fig.29)
when stitch on the very elastic material or the
thickness of the sewing material is changed. The ad-
justment should be done in the following order:
1. Loosen the special screw.
2. When the centerline distancebetween the special
screw and the presser foot lift rear crank becomes
shorter, thepresser foot liftvolume will become longer.
On the country the distance becomes longer, the lift
volume will become shorter.
3. After adjustment, tighten the special screw. The
common presser foot lift volume can be adjusted in
the range of2-6 mm.
5.6 Hook oil amount adjustment (Fig.30)
It adopts plunger full auto lubrication system,
even at very low speed, it can supply and suck oil very
well. Generally only the hook oil amount can be ad-
justed, the other can not be adjusted. The hook oil
amount can be obtained by the oil amount adjusting
screw. First loosen the nut of the adjusting screw,
turn the scre clockwise to increase the oil amount,
on the contrary reduce the oil amount. After adjust-
ment, tighten the nut.
w

Parts Manual

1
-11-
2828
3434
3333
1313
1212
3232
3131
3030
2929
2727
2626
3535
3636
3939 2525 2424
3737
13
12
13
12
6666
6565
4040
2323
2020
1919
2222
2121
1313 1313
1212 1212 4343 4242 4141 1313
1212 1111 1010 99
77
88
22
66
33
44
55
1414
1616 1515
5555
6464
6363
6262
4949
5050
5151
5252
5353
5454
5656
5858
5757
6161 6060
5959
4444 4545
4646
4747
4848
11
1818 1717
3838
1. MSK-8420B Arm Parts

Item Part number
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19..
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
1. MSK-8420B Arm Parts
-12-
1WF1-001
1WF1-002
1WF1-041
1WF1-042
1WF1-015
1WF1-016
1WF1-017
1WF1-011
1WF1-032
1WF1-038
1WF1-039
1WF1-019
1WF1-030
1WF1-027
1WF1-028
1WF1-003
1WF1-004
1WF1-005
1WF1-034
1WF1-036
1WF1-007
1WF1-006
1WF1-018
1WF1-013
1WF1-009
1WF1-008
Bed
Arm
Pin
Screw
Screw
Trade mark plate
Model plate
Nail
Upper thread guide
Screw
Back cover
Screw
Washer
Cover
Front slide plate
Screw
Tread take-up lever guard
Back front cover
Screw
Spring
Thread retainer
Low thread figer
Screw
Screw
Screw
Screw
Middle thread finger
Rubber plug
Face plate
Screw
Upper thread finger
1
1
2
1
3
1
1
4
1
2
1
15
15
2
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
2
1
Description Pcs

1
-13-
2828
3434
3333
1313
1212
3232
3131
3030
2929
2727
2626
3535
3636
3939 2525 2424
3737
13
12
13
12
6666
6565
4040
2323
2020
1919
2222
2121
1313 1313
1212 1212 4343 4242 4141 1313
1212 1111 1010 99
77
88
22
66
33
44
55
1414
1616 1515
5555
6464
6363
6262
4949
5050
5151
5252
5353
5454
5656
5858
5757
6161 6060
5959
4444 4545
4646
4747
4848
11
1818 1717
3838
1. MSK-8420B Arm Parts

-14-
Item Part number
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
59.
60.
61.
62.
63.
64.
65.
66.
Guid set plate
Set plate
Oil retainer
Tread releasing lever
Pin shaft
Thread releasing lever
Right sliding plate
Left sliding plate
Plug
Plug
Back fitting cover
Plug
Tread tension set plate assembly
Thread guide bracket
Thread guide plate
Spring
Thread guide bracket screw assembly
Tread releasing pin
Tread tension nut
Thread tension spring
Thread tensing plate
Thread tension plate
Screw
Screw
Thread control plate assembly
Screw
Stop plate
Thread take-up spring
haft for thread take-up spring
Set screw
Thread releasing pin
Thread tension retaining plate
Thread releasing spring
Spring retaining plate
Screw
S
Description Pcs
1WF1-012
1WF1-021
1WF1-020
1WF1-035
1WF1-037
1WF1-023
1WF1-033
1WF1-040
1WF1-029
1WF1-022
1WF1-031
1WF1-014
1WF1-010A
1WF1-010B
1WF1-010C
1WF1-010D
1WF1-010E
1WF1-010M
1WF1-010H
1WF1-010G
1WF1-010S
1WF1-010F
1WF1-010R
1WF1-010Q
1WF1-010J
1WF1-026
1WF1-025
1WF1-010K
1WF1-010I
1WF1-024
1WF1-010L
1WF1-010W
1WF1-010P
1WF1-043
22T2-004
1
1
1
1
1
1
1
1
1
1
1
1
1
2
2
2
2
1
3
2
2
4
1
2
2
1
1
1
1
1
1
1
1
1
1
1. MSK-8420B Arm Parts

2
-15-
26
32
31
13
12
30
29
28
27
25
24
33
37 23 22
35
13
12
63
64
38
19
20 21
13 13
12 12 41 40 39 13
12 11 10 9
7
8
2
6
3
4
5
14
16 15
62
53
42 4344
45
46
62
61
59
58
57
56 55 54
52
51 50
49
48
47
1
18 17
2. MSK-8400B Arm Parts

2. MSK-8400B Arm Parts
-16-
Item Part number
Bed
Arm
Pin
Screw
Screw
Trade mark plate
Modle plate
Nail
Upper thread guide
Screw
Back cover
Screw
Washer
Ccover
Front slide plate
Screw
Thread take-up lever guard
Back front cover
Screw
Low thread finger
Oil felt
Screw
Screw
Screw
Middle thread finger
Rubber plug
Face plate
Screw
Upper thread finger
Guide set plate
Set plate
Description Pcs
9WF1-007
1WF1-002
9WF1-005
9WF1-006
1WF1-015
1WF1-016
1WF1-017
1WF1-011
1WF1-032
1WF1-038
1WF1-039
1WF1-019
1WF1-030
1WF1-005
9WF1-001
9WF1-002
1WF1-034
1WF1-036
1WF1-007
1WF1-006
1WF1-018
1WF1-013
1WF1-009
1WF1-008
1WF1-012
1WF1-021
1
1
2
1
3
1
1
4
1
2
1
15
15
2
1
1
1
1
1
1
1
1
1
1
1
2
1
2
1
1
1
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19..
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.