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9. TABLE OF TROUBLES IN SEWING AND CORRECTIVE MEASURES
Troubles Causes Checking Corrective measures
1. Thread breakage
Thread is worn out.
Needle thread trails 2 to
3 cm from the wrong
side of the fabric.
Thread path, needle point,
hook blade point or inner
hook resting groove on the
throat plate has sharp
edges or burrs.
Needle thread tension is too
high.
Needle comes in contact
with the blade point of hook.
Clearance of inner hook
guide is too large.
Needle thread tension is too
low.
Thread take-up spring
works excessively or the
stroke of the spring is too
small.
Feed timing is not proper.
Timing between the needle
and the hook is excessively
advanced or retarded.
Thread melts due to needle
heat.
Check the sharp edge or
burr on the respective parts.
Check the clearance.
Check the clearance.
Check the specified
dimension.
Remove the sharp edges or
burrs on the blade point of hook
using a fine emery paper. Buff
up the groove section on the
throat plate.
Adjust the needle thread
tension.
Refer to “Needle-to-hook
timing” on page 9.
Decrease the clearance.
Refer to “Adjusting the inner
hook guide” on page 7.
Adjust the needle thread
tension.
(This trouble occurs a lot when
using synthetic threads.)
Decrease the tension of the
spring and increase the stroke
of the spring.
Refer to “Main shaft-to-hook
driving shaft timing” on page 11.
Refer to “Needle-to-hook
timing” on page 9.
Decrease the sewing speed.
Use silicone oil.
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