21 BA_560_A4_180619_en
Unsufficient knotting of the threads may happen when:
Possible Reasons:
- the needle has reached its lower cusp point but the loop is still on the
looper back
Solutions:
- repolish the looper back by means of a diamond file and an abrasive
cloth
Unsufficient needle penetration may happen when:
Possible Reasons:
- the needle point is damaged
- the plunger is not set high enough
- the needle plate is too small and therefore the material cannot be
pressed far enough into the needle plate
- the pressure of the clamping plate is not correct
Solutions:
- change the needle
- reset the plunger
- choose a suitable needle plate
- if very thick material is sewn loosen the screws in setting ring, no
pressure is effected on the clamping plate any more.
The loop may come undone when:
Possible Reasons:
- the sewing starts with the needle penetration on the right hand side
Attention: start sewing process with the needle penetration on the
left hand side
(Machine on the handwheel one
- the cut thread end is not hold slightly by the thread
(on the needle plate)
turn continue turning)
- loops are not knotted tight enough
- the material is hard and the thread is smooth
Solutions:
- rebend spring slightly to reduce the distance between spring and
thread holder
- set upper thread tension tighter
- use a rougher covering yarn
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