JUKI MB-373 Manual
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JUKI MB-373 Manual

JUKI MB-373 Manual

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1. SPECIFICATIONS

MB-373
1
Sewing speed
2
Number of stitches
3
Amount of feed
4
Stitching pattern
5
Button size
6
Needle bar stroke
7
Needle
8
Automatic thread trimmer
9
Presser lifter
10
Stop-motion unit
11
Power supply
MB-377
1
Stitching pattern
2
Needle
Other specifications are same as those of MB-373.
Max. 1,500 rpm
8, 16, and 32 stitches
(6, 12 and 24 stitches are also possible by changing the cam.)
Crosswise feed
2.5 to 6.5 mm
Lengthwise feed 0, 2.5 to 6.5 mm
コ -shape, Z-shape, Π -shape, and X-shape
10 to 28 ø mm
48.6 mm
TQ x 7 #16 (#14 to #20)
Interlocked with the presser lifter.
Consists of a fixed knife and a moving knife.
Automatically operated (Pedal-system is also available.)
Automatically operated (equipped with speed slowing device)
200 W (1/4 HP) single- or three-phase
コ -shape, Z-shape, and X-shape
TQ x 1 #16 (In case of attachments for medium button (Z202) and
large button (Z201) TQ x 7 #16, #14 to #20)
1
1
− 
− 
−
−
Normal speed 1,300 rpm

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Summary of Contents for JUKI MB-373

  • Page 1: Specifications

    コ -shape, Z-shape, and X-shape Stitching pattern TQ x 1 #16 (In case of attachments for medium button (Z202) and Needle large button (Z201) TQ x 7 #16, #14 to #20) Other specifications are same as those of MB-373. −  −  − −...

  • Page 2: Standard Adjustment

    The upper engraved line should be aligned with the bottom of lower bushing 3 when the needle bar is at its lowest position. Standard needle for MB-373 : TQ x 7 Standard needle for MB-377 : TQ x 1 For TQ x 1...
  • Page 3 Following needles are equipped at the time of delivery. MB-373 : Standard needle TQ x 7 #16 MB-377 : Standard needle TQ x 1 #16 MB-377 / Z201 : TQ x 7 #20 MB-377 / Z202 : TQ x 7 #18 1) Adjusting the looper timing ™...

  • Page 4: Timing The Travel Of The Yoke Slide

    Needle bar Thread Needle Needle bar height Model Cotton TQ x 7 14 to 17 mm MB-373 Tetoron TQ x 7 14 to 18 mm TQ x 1 4 to 8 mm MB-377 TQ x 7 14 to 18 mm...
  • Page 5 Adjustment Procedures Results of Improper Adjustment ™ For adjusting the timing of the travel of the yoke slide, align ™ If the triangle loop positioning finger the engraved marks of the loop positioning finger cam and cam begins to travel too late, thread the triangle loop positioning finger cam with the engraved breakage, thread remaining, baloon mark of the cam and looper sleeve after the adjustment of...

  • Page 6: Positioning The Cloth Feed Cam

    Thread Needle Needle bar height Model Cotton TQ x 7 53 to 56 mm Needle bar MB-373 Tetoron TQ x 7 54 to 57 mm TQ x 1 44 to 47 mm MB-377 TQ x 7 54 to 57 mm − ...
  • Page 7 Adjustment Procedures Results of Improper Adjustment ™ Align the engraved point on the cam with the pivot on the ™ If the lengthwise feed cam and bed at the position of stop motion. Then, tighten the setscrew crosswise feed cam do not engage of cam.

  • Page 8: Lift And Pressure Of The Button Clamp

    Standard Adjustment (6) Lift and pressure of the button clamp 1) Lift of the button clamp A MB-372 : 12 mm MB-373 : 9 mm MB-377 : 8 mm for コ -shape 8 mm for Z -shape 10 mm for X -shape...
  • Page 9 (In case of MB-373/ Especially in case of MB-372, 377) thread tightness becomes strong at...

  • Page 10: Positioning The Thread Nipper

    Standard Adjustment (8) Positioning the thread nipper The clearance between thread nipper 1 and nipper block 2 should be 0.8 to 1.2 mm while the machine is in operation. (In case of MB-377 : 0.4 to 0.8 mm) 0.8 to 1.2 mm (9) Positioning the stitch adjusting cam The clearance between the roller and the recess of the cam should be 0.8 mm at the stop-motion position.
  • Page 11 Adjustment Procedures Results of Improper Adjustment ™ Remove the machine arm side cover (left), loosen the screw ™ If the clearance is too large, the of nipper bar block 3 and move nipper bar block 4 to the thread from the needle will become right or left to perform adjustment.

  • Page 12: Positioning The Stop Motion Disc And The Stop Motion Plunger

    Standard Adjustment (10) Positioning the stop motion disc and the stop motion plunger 1) The clearance between the stop motion disc and the stop motion plunger should be 2.4 mm while the machine is in operation or at the position of 3 to 4 stitches from the position of stop-motion. 2) The clearance between the stop motion plunger lever and the stop motion plunger should be 8.5 mm.
  • Page 13 Adjustment Procedures Results of Improper Adjustment ™ If the clearance is larger than 2.4 1) Perform adjustment to provide the 2.4 mm clearance after loosening screw 1 of the stop motion tripping lever. Remove mm, unstable entrance into the stop-motion state will result. On the the stop motion disc pressure lever and the needle driving contrary, if the clearance is smaller pulley, insert a 2.4 mm gauge or a 3 mm wrench between...

  • Page 14: Positioning The Needle Driving Pulley Pressure Applying Lever

    0.3 mm. Needle driving pulley clutch MB-372 (0.8 to 0.9 mm) Needle driving pulley MB-373 (0.2 to 0.3 mm) MB-377 (0.2 to 0.3 mm) 0.2 to 0.3 mm (14) Positioning the thread pull-off lever Adjust the position of thread pull-off lever 1 so that the dimension between thread guide pole 4 and thread pull-off lever 1 is 5 to 9 mm at the stop-motion position.
  • Page 15 Adjustment Procedures Results of Improper Adjustment ™ Loosen nut 1 of the screw of the needle driving pulley ™ If the clearance is too large, the pressure applying lever and adjust by screwing in and out clutch will slip causing starting screw 2.

  • Page 16: Adjustment Of Automatic Thread Trimmer

    3. ADJUSTMENT OF AUTOMATIC THREAD TRIMMER Standard Adjustment (1) The mechanism and the name of each component of the thread trimmer As shown in the figure below, when the button clamp lifting lever is actuated at the final stitch, the thread trimming connecting link (rear) moves forward, causing the thread separating claw of the moving knife to separate thread before it is trimmed by the knife.
  • Page 17 Adjustment Procedures Results of Improper Adjustment ™ Perform adjustment so that the clearance between the end surface of button clamp lifting lever 1 and the adjusting screw 2 becomes 0.5 mm. Then tighten nut 3. −  −...

  • Page 18: Adjusting The Position Of The Moving Knife

    2 should be 12 to 13 mm when the button clamp is at its highest position after the stop motion has been set. (For MB-377 : 10.5 to 12.5 mm) (For MB-373-11 only, adjust the distance to 15 to 16 mm.)
  • Page 19 Adjustment Procedures Results of Improper Adjustment ™ Make adjustment after tilting the machine head by loosening ™ If the adjustment value is small (10 two nuts 3 and moving connecting screw 4 back and forth. mm or less), the thread separating Loosen nuts 3 so that thread trimming connecting joint 5 claw will come in contact with the becomes almost horizontal.

  • Page 20: Adjustment Of Knot-Tying Mechanism (Exclusive For Mb-377)

    4. ADJUSTMENT OF KNOT-TYING MECHANISM (EXCLUSIVE FOR MB-377) Standard Adjustment (1) The mechanism and the name of each component of the knot-tying As shown in the figure below, when the machine is running, the stitch adjusting cam rotates and the thread bind arm roller rides over the thread bind notch attached to the stitch adjusting cam making the thread bind plate actuate by means of the respective links to hook thread.
  • Page 21 Adjustment Procedures Results of Improper Adjustment ™ Loosen screw 1 and adjust so that the clearance between ™ If the clearance is too large, the the outside periphery of the roller of the knot-tying arm and stroke of the thread bind plate will that of the stitch adjusting cam should be 1 to 1.5 mm at the become short.

  • Page 22: Positioning The Knot-Tying Notch

    Standard Adjustment (3) Positioning the knot-tying notch (When the needle TQ x 7 is used : 40 to 45 mm) (4) Adjusting the thread bind plate (Exclusive for MB-377) A clearance of 1 to 1.5 mm should be provided between the needle and the thread bind plate when the roller of the thread bind arm rides on the outmost periphery of the thread bind notch.
  • Page 23 Adjustment Procedures Results of Improper Adjustment ™ Loosen two screws 1 and adjust so that the roller of the ™ If the position is higher than that of knot-tying arm comes in contact with the knot-tying notch the specified adjustment value, when the needle bar goes up at the fourteenth stitch as high tightness of stitch at the final stitch as 30 to 35 mm above the needle bar upper bushing.

  • Page 24: Adjusting The Tension Lever (Exclusive For Mb-377)

    Standard Adjustment (5) Adjusting the tension lever (Exclusive for MB-377) When the machine is in the stop-motion state, the distance between the end surface of the tension guide and the tip of the tension lever should be 8 to 10 mm. Be sure at the time of starting (push the pedal once when the power is OFF) that the hole of the tension guide is located within the range of the slot of the tension lever.
  • Page 25 Adjustment Procedures Results of Improper Adjustment ™ Make adjustment by loosening screw 1 of the tension lever. ™ If the clearance is too large, thread- At the time of starting, make adjustment by loosening screw breakage will occur. 2 of the tension guide. ™...

  • Page 26: Corrective Measures For Stitching Troubles

    5. CORRECTIVE MEASURES FOR STITCHING TROUBLES (1) Thread breakage 1) The looper hooks thread twice due to improper lengthwise positioning of the yoke slide. ™ Move the loop positioning finger cam back and forth to make readjustment so that the blade point of the looper passes through the center of the thread triangle at the 9th or 10th stitch.

  • Page 27: Skip Of Stitches

    (3) Skip of stitches 1) Readjust and coordinate the needle and looper timing. 2) For stitching heavy-weight or hard materials, the needle guide should touch the needle by 0.1 to 0.2 mm as shown in the figure. 0.1 to 0.2 mm (4) Thread slippage from the needle (Thread slips from the needle, and stitches are not formed from the beginning.) 1) Increase the travel of the thread pull-off lever.

  • Page 28: Corrective Measures For Mechanical Failures

    6. CORRECTIVE MEASURES FOR MECHANICAL FAILURES (1) Defective stop motion 1) The sound of the stop motion is low, and the machine stops 0.8 mm before reaching the required position. ™ Decrease the clearance between the stitch adjusting cam and the roller. ™...

  • Page 29: Thread Trimming Troubles And The Corrective Measures

    Model Moving knife position (adjustment) dimension MB-373 12 to 13 mm MB-373-11 15 to 16 mm MB-377 10.5 to 12.5 mm...

  • Page 30: Causes Of Troubles And The Corrective Measures For Mb-377

    8. CAUSES OF TROUBLES AND THE CORRECTIVE MEASURES FOR MB-377 Troubles Causes Corrective measures 1. Needle thread breaks The tension lever has been improperly Properly adjust the tension lever. after the machine adjusted. stops. Lifting amount of the button clamp jaw Adjust the lifting amount of the button clamp jaw unit is excessive.
  • Page 31 PREFACE This Engineer’s Manual is written for the technical personnel who are responsible for the service and maintenance of the machine. The Instruction Manual for these machines intended for the maintenance personnel and operators at an apparel factory contains operating instructions in detail. And, this manual describes “Standard Adjustment”, “Adjustment Procedures”, “Results of Improper Adjustment”, and other important information which are not covered by the Instruction Manual.

  • Page 32: Table Of Contents

    CONTENTS 1. SPECIFICATIONS ......................1 2. STANDARD ADJUSTMENT ................... 2 (1) Height of the needle bar ........................2 (2) Positioning the needle and the looper ....................2 (3) Timing the travel of the yoke slide ....................4 (4) Positioning the cloth feed cam ......................6 (5) The floating timing of the tension disc No.
  • Page 33 SINGLE THREAD, CHAINSTITCH BUTTON ATTACHING MACHINE WITH AUTOMATIC THREAD TRIMMER MB-373 MB-377 (WITH KNOT-TYING MECHANISM) ENGINEER’S MANUAL 29231701 No.01...
  • Page 34 ＊ The description covered in this engineer’s manual is subject to change for improvement of the TELEX : J22967 commodity without notice. Copyright C 2000 JUKI CORPORATION. All rights reserved throughout the world. 00 · 11 Printed in Japan (E)

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