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Trouble examples and Corrective actions
Chapter 9
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2. Trouble examples and Corrective actions
2-1. Thread breakage is highly visible.
If the followings seem to cause the trouble, please ask the distributor for information.
(a) The gap between rotary hook and rotary hook support is narrow. Timing between needle
and rotary hook is too early or too late. Scratch, abrasion of rotary hook.
(b) The gap between needle and hook point is not suitable. Bad adjustment of lower dead
point and/or upper dead point of needle bar.
(c) A play of rotary hook shaft is big in back and forth direction. There is a play on the fringe
of the frame.
(d) Rotation of the main shaft is not smooth. Abrasion/breakage of neighboring parts
of take-up lever drive and/or needle bar drive.
(e) A play of needle bar case (in right and left direction) is big.
Cause Troubleshooting
Bad thread tension
Adjust tension.
Upper thread 120 to 140 g, Under thread 20 to 30 g
Quality of thread is bad. Poor thread flow Use good quality thread. Spray silicone.
Direction of needle is bad or needle bents. Adjust to face to the front or to the right a bit. Replace.
Applique glue is stuck on needle. Remove adhered glue.
Contamination, run-out of oil of rotary hook Clean and lubricate the machine.
There are many fine stitches of 0.5 mm or less in
design data.
Remove fine stitch(es).
The fabric is lifted too much against the needle
plate. The fabric touches the needle plate too
much.
Stretch the fabric again so that it touches needle plate
lightly.
Run-out of oil of needle bar Lubricate.
There is a scratch on the thread course. Grind it with sandpaper etc. Replace.
Bad height of presser foot
Perform adjustment so that height fits to fabric/
material.
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