JUKI MB-372 User manual

I.L^.
MODEL
MB-372
HIGH SPEED
SINGLE THREAD CHAINSTITCH
BUTTON-SEWING MACHINE
Instruction Book
TOKYO JUKI INDUSTRIAL CO..LTD.
From the library of: Superior Sewing Machine & Supply LLC

CONTENTS
Page
1. GENERAL DESCRIPTION 1
2. SPECIFICATIONS 2
3. NAMES OF PARTS 3
4. CAUTIONS BEFORE OPERATION 4
5.
LUBRICATION 4
6.
MOTOR PULLEY AND BELT 5
7.
NEEDLES 6
8. INSERTING THE NEEDLE 6
9. THREADING THE MACHINE 7
10. THE THREAD TENSION 8
11. FUNCTIONS OF THE THREAD PULL-OFF LEVER 8
12. THE THREAD NIPPER 9
13. ADJUSTING THE NEEDLE BAR 10
14. TO PRODUCE OPTIMAL STITCHING CONDITION 12
15. POSITION OF THE NEEDLE GUARD 14
16. TIMING THE NIPPER RELEASING PLUNGER OF
TENSION DISC NO. 2 14
17. CHANGING THE POSITION OF THE BUTTON TRAY ••• 15
18. STITCH SELECTING -15
19. HEIGHT OF BUTTON CLAMP 17
20. ADJUSTING THE BUTTON CLAMP PRESSURE 17
21. ADJUSTING THE BUTTON CLAMP STOP LEVER 18
22. ADJUSTING FOR 2-HOLES AND 4-HOLES 18
23. CHANGING THE BUTTON HOLDING CLAMP AND
ADJUSTING ITS HEIGHT 19
24. CAUSES OF MALFUNCTIONS AND REPAIRING 21
25. ATTACHMENTS TO MB-372 BUTTON ATTACHING
MACHINE 21
( i ) How to install the snap fastener attachment 22
(ii) How to install the wrapped-around button clamp attachment 23
(iii) How to insall the shank button clamp attachment 25
{iv) How to install the metal shank button clamp attachment ••• 27
From the library of: Superior Sewing Machine & Supply LLC

1. GENERAL DESCRIPTION
JUKI Model MB-372 is a single thread, chain stitch, button sewing
machine. It is widely used to attach flat two hole or four hole buttons
as well as snap fasteners, shank buttons and metal shank buttons. This
is an ideal machine to attach these buttons on all knit goods, men's
shirts, work uniforms, ladies' suits and men's suits.
This machine is equipped with 8 stitches, 16 stitches and 32 stitches
and these stitches are interchangeable without changing the stop motion
From the library of: Superior Sewing Machine & Supply LLC

cams. A speed slowing device, an exclusive JUKI attachment, is
incorporated into this machine and consequently loosening of screws or
malalignment of stitches which sometimes characterize amachine with
a stop motion mechanism is completely eliminated and assures a safe
and stable stitching condition.
2. SPECIFICATIONS
Model
Sewing type
Sewing fabric
Sewing speed
Button-sewiniar
Needle bar stroke
Needle
Stitch number
Feed length
Button size
Presser bar life
Button clamp lift
Thread nipper
Stop motion
Lubrication
Power required
Lubricating oil
2.hole button
4-hola button
MB-372
Single thread chainstitch button-sewing
Knit goods, shirts & working wear etc.
Max. 1500s.p.m.
1 Lengthwise feed 0 2-hole button
2Lengthwise/crosswise feed ••• 4-hole button
3 By attachment Snap, Shank, Metal
shank or Wrapped round
48.6 m/m (1-7/8")
TQx7 (175x7) or TQxl) (175x1) #14-#18
8, 16, 32, Gam: not to be changed
6, 12, 24, Cam: to be changed
Crosswise feed •••2.5~6.5 m/m (3/32~l/4")
Lengthwise feed ••-0^2.5^6.5m/m (0~3/32~l/4")
Dim: 10-27 m/m (3/8-1-1/32")
Std. 12 m/m (15/32")
Automatic or foot operated
2-way cam type
Automatic (with speed-slowing device) type
Hand oil type
200 W
New Defrix Oil No. 1 & New Defrix grease
Snap
Shank button
W
Metal sbankbutton
Wrapped round button
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3. NAMES OF PARTS
m
® Needle bar (§) Nipper block (|i) Needle bar lever ® Thread pull-oft^
lever (D L shaped thread guide ® Tension disc No. 2 0 Tension
disc No. 1 (D Nipper bar 0 Thread guide No. 1 @ Nipper bar
actuating lever @ Machine arm @ Button clamp lifting link
Needle bar lever connecting rod (Q) Lengthwise feed graduated plate
(!|) Stop motion disc spring (g) Rubber washer ® Stop motion disc
applying pressure lever @ Needle driving pulley @ Stop motion disc
@> Ball joint eccentric @ Loopershaft tube (§) Crosswise feed graduated
plate @ Loop positioning finger cam, rear @ Loop positioning finger
cam, front @ Looper @ Button clamp leverjaw @ Feed plate
@ Needle plate @) Needle @) Button clamp lifting rod (0) L shaped
button clamp lifting rod @ Tension disc No. 3 @ Thread guide No. 3
@ Needle bar bearing block & thread guide @ Nipper releasing plunger
knurled thumb nut (g) Button clamp pressure adjusting spring nut
— 3 —
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4. CAUTIONS BEFORE OPERATION
* After unpacking the crating, clean out all the dirt of packing and
oil all the oiling holes.
* Before operating, be sure to read the Instruction Book thoroughly
and digest its contents.
* The machine is thoroughly adjusted at the time of shipping but
to be absolutely sure, release the stop motion mechanism and rotate the
machine with your hand before turning the switch on.
* The maximum sewing speed of this machine is 1,500s.p.m. but for
the first month operate the machine at the speed of 1,200-1,300 s.p.m.
For the number of revolutions, please refer to the Chapter on
"Motor pulley and Belt".
* The rotational direction of the machine is shown by the arrow in
It
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'ireotiM
5. LUBRICATION (Refer to Fig. 1, 2, 3, and 4)
In order to ensure a long life of the machine and to run it in a
smooth-running condition, the machine should be oiled twice daily,
before the morning and afternoon starts. Oil*all holes shown by the
arrows with JUKI New Defrix Oil No. I or JIS Special No. 1 White
— 4 —
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Spindle Oil. Remove the right side arm cover, remove the screw d),
Fig. 2, of the needle driving pulley, check the grease level and replenish
it, if required.
Also, loosen the machine arm and bed set screw ®, Fig. 1, and il"
the machine is tilted as shown in Fig. 4, you can sec the driving gear
(T) and the looper shaft driven gear (2). Grease these gears too. Some
times check
and see if the oil comes up to the surface of the felt inside
the machine sub-base and if not, fill up with oil.
=
6. MOTOR PULLEY AND BELT
For connecting directly to the power source, use an electric
motor of 3-phase 1/4 HP. The relation between the number of rotation
of the machine with the effective diameter of the motor pulley is shown
in the table below. (Effective diameter of the motor pulley means the
diameter measured from the center of the belt when it is wound around).
— 5 —
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Cycles Rotation
Part No. of
motor pulley
Effective diamater of
motor pulley
50
1,500 r.p.m.
1,200r.p.m.
B710137200H
B710237200H
70 m/m (2 3/4")
58.2 m/m (2 1/4")
60
1,500r.p.m.
1,300 r.p.m.
B710237200H
B710337200H
58.2 m/m (21/4")
50.3 m/m (1 15/is")
7. NEEDLES
At the time of shipping, the needle No. TQx7 (175x7) is attached
to the machine but needle No. TQx 1(175x1) can also be used. TQx 1
needle is shorther
than TQx7, so when attaching buttons, take in the
height of the button, thickness of the sewing material into consideration
and when the needle comes down to the lowest point, be careful to see
that the shank of the needle does not hit the button itself.
8. INSERTING THE NEEDLE (Fig. 5)
To insert the needle, loosen the needle clamping screw and insert
the needle into the needle bar as far as it will go, with the long gloove
to the front and tighten the set screw securely.
Long groove
V
Fig. 5
— 6 —
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To thread the machine, put it in stop
motion position, and thread in accordance with
the diagram as shown in Fig. 6, 7. Start from
thread spool stand—» needle thread guide pin
No. I ♦ tension disc No. I d)—» tension disc
No. 2 (g)—» thread puIl-ofTlever » nipper (§)—•
thread guide No. 2 (6)—♦ upper eyelet of (ace
plate—»thread guide No. 3 (2)—* needle bar bear
ing block
and thread guide (§)—* thread tension
disc No. 3
thread guide (9)-^ tension disc No. 3
» to the needle eye from front toward rear
and draw the thread out about 6-^7 m/m (about
1/4").
To draw out the thread, push the nipper
releasing plunger knurled nut, @ the nipper will
be released and the thread can be drawn out.
ThreadX
int
u IJ
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10. THE THREAD TENSION (Fig. 8)
The thread tension disc No. Ci) controls the tightness of the button
but only a light tension is required.
The thread tension disc No. 2 (D regulates the tension of the under
sideofthe button but a stronger tension than the disc No. 1 is required.
To adjust the tensions of these discs, turn the adjusting screw of the
disc toward the arrow direction to make the tension stronger but the
tension required will vary in relation to the types of thread, materials,
and thickness of buttons used.
11. FUNCTIONS OF THE THREAD PULL-OFF LEVER (Fig. 9)
@0)
The thread pull-off lever (Fig. 6 ®) controls the amount of thread
which is pulled through the tensions at the end of a stitching cycle to
From the library of: Superior Sewing Machine & Supply LLC