Table of Contents
Advertisement
Error Type
Bad thread (weak,
uneven thickness, poorly
twisted, old)
Right-twisted thread
Excessive thread tension
Tension imbalance
between upper and lower
threads
Excessive tension &
stroke on take-up lever
spring
Cause
Change thread
Change to left-twisted thread
Adjust tension
Adjust tension and stroke
Inspection & Repair
Reference
Selecting thread
• soft, even thickness
tight, left-twisted
• Z-twisted: left
• S-twisted: right
left- twist (prevents thread
unravelling as the rotary
hook rotates
counterclockwise)
See 5.5.2
See 5.6.2
See 5.5.3
Hide quick links:
Advertisement
Table of Contents
