Lervia KH 4001 Instrucciones De Uso página 46

Upper thread tension is too low:
Loops are visible on the bottom of the fabric.
Increase the tension of the upper thread by turning the upper
thread tension selector 2 to a higher value.
Notice
The lower thread tension has been preset in the factory,
ensuring that it is appropriate for general use. Hence, no changes
in the setting are required for the majority of sewing tasks.
However, if you are sewing fine fabrics with thin thread, it could happen that
the correct adjustment of the thread tension will not adjust automatically by
means of the setting of the upper thread tension. Hence the user can readjust
the lower thread tension in accordance with the procedure described below.
Lower thread tension is too low
Small loops are visible on the surface of the fabric.
First reduce the (upper-) thread tension, setting a lower value by
turning the upper thread tension selector
satisfac-tory sewing results, even when the upper thread tension is set
at the lowest possible value, change the upper thread tension on the
spool as described below.
Spool
Increase the tension of the lower thread at the bobbin, using a small
screwdriver Y to turn the screw on the pressure tab of the bobbin
case in a clockwise direction. The screw should not be turned by
more than one complete rotation.
Do not forget to turn the screw back into its original position before
you recommence sewing!
2 . If this does not lead to
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Correct thread tension
The correct thread tension is important, as a tension that is too high or
too low will lead to a weakening in the strength of the seam and often
also results in a rippling of the fabric surface in the vicinity of the seam.
To fabrics being sewn
• fine tricot fabrics
• Lace
Very fine • Fine linen
fabrics • Silk
• Organza
• Chiffon
• Voile
Light- • Taffeta
weight • Synthetic fabrics
fabrics • Silk
• Batiste
• Cotton
• Gingham
• Poplin
• Percale
• Pique
Medium
• Satin
heavy
• Velvet
fabrics
• light woolen fabrics
• Fine corduroy
• Suiting materials
• Linen
• Muslin
• Denim
• Gabardine
• Tweed
Heavy
• Corduroy
• Canvas
• Sailcloth
• Simple weave
Knitted • Double weave
fabrics • Jersey
• Tricot fabric
Notice
1. Select the right needle size and thread strength according
to the table above!
2. As a rule use the same thread strength for the upper thread
(spool of thread) and the lower thread (bobbin)!
Needle
Strength of thread
sizes
• Cotton thread: 80
9 • Man-made thread
• fine, mercerised cotton
• Cotton: 60–80
• Sewing silk: „A"
11
• Man-made thread
mercerised: 50
14
(as is
• Cotton: 50–60
sup-
• Sewing silk: „A"
plied
• Man-made thread
with the
mercerised: 50–60
machi-
ne)
• Cotton thread: 40–50
16 • Mercerised:
„high-strength"
14
(with • Cotton polyester
tricot thread
border)