Brother SB4138 - Manual (Page 156)

APPENDIX
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154
Incorrect thread tension
■ Symptoms
• Symptom 1: The lower thread is visible from the upper side of the fabric.
• Symptom 2: The upper thread appears as a straight line on the upper side of the fabric.
• Symptom 3: The upper thread is visible from the lower side of the fabric.
• Symptom 4: The lower thread appears as a straight line on the lower side of the fabric.
• Symptom 5: The stitching on the lower side of the fabric is loose or has slack.
■ Cause/remedy/check details
❏ Cause 1
The machine is not correctly threaded.
The bobbin threading is incorrect.
Return the upper thread tension to the standard
setting, and then refer to “Upper thread tightened
up” (page 151) to correct the threading.
The upper threading is incorrect.
Return the upper thread tension to the standard
setting, and then refer to “Tangled thread on
wrong side of fabric” (page 152) to correct the
upper threading.
❏ Cause 2
A needle and thread appropriate for the fabric
are not being used.
The sewing machine needle that should be
used depends on the type of fabric sewn and
the thread thickness.
If a needle and thread appropriate for the fabric
are not being used, the thread tension will not
be adjusted correctly, causing wrinkles in the
fabric or skipped stitches.
• Refer to “Needle types and their uses” (page
38) to check that a needle and thread
appropriate for the fabric are being used.
❏ Cause 3
An appropriate setting on the thread tension
dial is not selected.
The setting selected for the upper thread tension
is not appropriate. Refer to “Changing the
tension of the upper thread” (page 58) to select
an appropriate thread tension. The appropriate
thread tension differs depending on the type of
fabric and thread being used.
* Adjust the thread tension while test sewing
on a piece of scrap fabric that is the same as
that used in your project.
Note
z If the upper threading and bobbin threading
are incorrect, the thread tension cannot be
adjusted correctly. Check the upper
threading and bobbin threading first, and
then adjust the thread tension.
❏ If the bobbin thread is visible from the right
side of the fabric
Press
(Thread tension key) in the
operation panel to decrease the tension of the
upper thread.
❏ If the upper thread is visible from the wrong
side of the fabric
Press
(Thread tension key) in the
operation panel to increase the tension of the
upper thread.
❏ Symptom 1 ❏ Symptom 3
a Lower side of fabric
b Lower thread visible from
upper side of fabric
c Upper thread
d Upper side of fabric
e Lower thread
f Upper thread visible from
lower side of fabric