Table of Contents
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Super-High-Speed Overlock Machine
High-Speed Overlock Machine / Safety Stitch Machine
MO-6000S series
MO-6900G series
(for Extra-heavy-weight Materials)
High-Speed Variable Top Feed Overlock Machine
MO-6900R series
MO-6900J series
(for Extra-heavy-weight Materials)
ENGINEER'S MANUAL
29355807
No.E350-01
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Table of Contents
Related Manuals for JUKI MO-6900R series MO-6900J series
Summarization of Contents
SPECIFICATIONS
(1) MO-6700S SERIES
Specifications for the 1-needle, 2-needle overlock, and 2-needle safety stitch machines.
MODEL NUMBERING SYSTEM
MO-6000 SERIES MODEL NUMBERING SYSTEM
Breakdown of the model designation for the MO-6000 series sewing machines.
STANDARD ADJUSTMENT
(1) Adjusting the needle height
Procedure to set the needle height from the throat plate surface.
(2) Positioning the throat plate
Adjusting the needle entry point relative to the throat plate edge.
(3) Installing position of the needle clamp
Setting the needle clamp connecting stud relative to the needle bar.
(4) Adjusting the length of the lower looper holder
Adjusting the center-to-center distance of the lower looper holder.
(5) Adjusting the lower looper
Adjusting the returning amount and clearance of the lower looper.
(6) Position of the upper looper guide
Setting the vertical and lateral positions of the upper looper guide.
(7) Positioning the upper looper holder
Adjusting the upper looper holder position relative to the frame.
(8) Positioning the upper looper
Adjusting the height and longitudinal position of the upper looper.
(9) Adjusting the double chain looper
Adjusting returning amount, longitudinal motion, and clearance of the double chain looper.
(10) Adjusting the height and clearance of the needle guard
Setting the needle guard height and clearance for different machine types.
(11) Adjusting the height of the feed dog
Setting the height of the main and auxiliary feed dogs.
(12) Adjusting the tilt of the feed dog
Adjusting the tilt of the feed dogs for proper material feeding.
(13) Adjusting the differential feed ratio
Adjusting the differential feed ratio for gathering and stretching.
(14) Longitudinal position of the feed dog
Setting the longitudinal position of the feed dog relative to the throat plate.
(15) Adjusting the presser foot
Adjusting the tilt and micro-lifting mechanism of the presser foot.
(16) Positioning the upper knife arm shaft
Setting the height of the upper knife arm shaft.
(17) Positioning the upper and lower knives, and available overedge widths
Adjusting knife positions and overedge widths.
(18) Resharpening of the knife
Instructions for resharpening the lower knife.
(19) Position of the thread cam
Adjusting the thread cam and looper thread cam guides.
(20) Adjusting the throat plate support
Ensuring uniform contact of the throat plate support.
(21) Adjusting the feed mechanism cover presser
Adjusting the feed mechanism cover presser to prevent rise.
(22) Adjusting the looper cover
Ensuring smooth closing of the looper cover without contact.
(23) Adjusting the cloth chip cover
Adjusting the cloth chip cover to prevent rattling or contact.
(24) Adjusting the needle mechanism
Disassembling and adjusting the needle mechanism components.
(25) Position of the upper looper lubricating pin
Setting the orientation and clearance of the upper looper lubricating pin.
(26) Longitudinal momentum of the top feed dog (Top feed amount)
Adjusting the maximum and minimum momentum of the top feed dog.
(27) Vertical momentum of the top feed dog
Adjusting the vertical momentum of the top feed dog based on material type.
(28) Adjusting the height of the top feed dog
Setting the lowest point height of the top feed dog.
(29) Locus cut of the top feed dog
Adjusting the locus cut mechanism for stitch prevention.
(30) Adjusting the longitudinal position of the top feed dog
Setting clearance between top feed dog and presser.
(31) Adjusting the lateral position of the top feed dog
Adjusting lateral position to prevent contact and noise.
(32) Position of the motion of the top feed dog
Adjusting motion position (constant, rear, front) of the top feed dog.
(33) Adjusting the feed bar guides A and B
Adjusting feed bar guides to remove lateral play of top feed dog.
(34) Adjusting the top feed dog pressure
Setting the top feed dog pressure for quiet operation.
(35) Lifting amount of the top feed dog (when operating the pedal)
Setting the top feed dog lifting amount when pedal is depressed.
(36) Height of the presser (pedal operation)
Setting the presser height when operating the pedal.
(37) Lifting amount of the top feed dog (when the presser lifting lever is operated)
Adjusting top feed dog lifting amount when presser lifting lever is operated.
(38) Position of the thread guides and the looper thread take-ups
Positioning thread guides and looper thread take-ups for various threads.
(39) Adjusting soft chain making mechanism
Replacing parts and adjusting for soft chain making.
(40) Position of the thread guides and the looper thread take-ups of MO-6900G(J)
Positioning thread guides and looper thread take-ups for specific models.
ADDITIONAL INFORMATION AND PRECAUTIONS
(1) Thread tension
Details on tension springs and their usage for different models.
(2) Upper looper
Information on upper looper part numbers and needle compatibility.
(3) Center-to-center distance of the upper looper holder
Table of center-to-center distances for upper looper holders.
(4) Caution in assembly
Guidelines for applying sealants during assembly.
(5) Kinds of motor pulleys, belts and frame support plate bolts
Information on motor pulleys, belts, and support plate bolt part numbers.
(6) Inspection and replacement of the cartridge filter
Procedure for inspecting and replacing the cartridge filter.
ADJUSTMENT OF THE NEEDLE HEIGHT AND LOOPER TIMMING
(1) MO-6000 SERIES
Detailed table for needle height and looper timing adjustments.
TROUBLES AND CORRECTIVE MEASURES
1. Needle thread breakage
Common causes and solutions for needle thread breakage.
2. Looper thread breakage
Causes and corrective actions for looper thread breakage.
3. Needle breakage
Reasons and solutions for needle breakage issues.
4. The needle point is crushed. (Double chain stitch needle)
Troubleshooting for crushed needle points in double chain stitches.
5. Overlocking needle thread stitches are skipped.
Solutions for skipped stitches related to overlocking needle thread.
6. Lower looper stitches are skipped.
Causes and fixes for skipped lower looper stitches.
7. Upper looer thread stitches are skipped.
Troubleshooting for skipped upper looper thread stitches.
8. Double chain stitches are skipped.
Solutions for skipped double chain stitches.
9. Triangle double chain looper thread stitches are skipped.
Troubleshooting for skipped triangle double chain looper stitches.
10. Triangle double chain needle thread stitches are skipped.
Causes and solutions for skipped triangle double chain needle thread stitches.
11. Overlocking chain-off thread is bad.
Corrective measures for poor overlocking chain-off thread.
12. Problems with double chain stitch chain-off thread.
Solutions for issues with double chain stitch chain-off thread.
13. Overlocking needle thread is loose.
Troubleshooting for loose overlocking needle thread.
14. Double chain stitch needle thread is loose.
Solutions for loose double chain stitch needle thread.
15. Uneven overlocking stitches
Causes and fixes for uneven overlocking stitches.
16. Uneven double chain stitches
Troubleshooting for uneven double chain stitches.
17. The looper thread bulges out
Solutions for looper thread bulging out.
18. Looper thread bite
Causes and fixes for improper looper thread bite.
19. Knotting position is not correct.
Correcting knotting position issues.
20. Uneven material feed
Troubleshooting for uneven material feed.
21. Puckering
Solutions for puckering, especially with double chain stitch.
DIMENSIONS OF TABLE
(1) Semi-sunken type
Detailed dimensions for the semi-sunken table installation.
(2) Fully-sunken type
Detailed dimensions for the fully-sunken table installation.
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