Uneven Seams 5) - Brother LH4-B800E Service Manual

5-7. Uneven seams 5)......All stitches
Cause
Threading Needle thread
threading
Bobbin thread
threading
Needle Needle attachment
Needle number count
Thread chips Rotary hook rim
or dust Rotary hook edge
Around needle plate
hole
Needle Needle thread tension
thread
Thread and needle
Rotary hook Flaws on rotary hook
holder holder
Rotary hook stopper
and inner rotary hook
overlap amount
Rotary hook Lubrication
Bobbin Bobbin thread tension
winder thread
guide
Uneven bobbin
winding
Bobbin Bobbin thread tension
thread
Bobbin case Refer to "5-1. Needle thread breakage"
Stitch Purl stitch, Whip stitch
patterns
Check
Refer to "5-1. Needle thread breakage"
Reattach needle
properly
Replace needle with
thicker one
Remove thread chips
or dust
Increase needle thread
tension
Replace needle with
one that fits for the
thread
Refer to "5-1. Needle thread breakage"
Adjust the rotary hook
stopper and inner
rotary hook overlap
amount
Decrease the quantity
of lubrication oil
Adjust the tension on
the bobbin winder
guide
Move bobbin winder
guide up and down to
adjust its position
Adjust the bobbin
thread tension
Parameter No. 11
setting
Solution
Insert needle fully into needle bar
Adjust tension while checking
stitches
Adjust it with oil adjusting shaft
Check the quantity of lubrication as
follows; When the number of
stitches is about 114, sew 20 - 30
stitches and using the craft paper
check that the number of splashed
oil spots is about 10
Too small quantity of lubrication oil
will cause thread breakage
Decrease the tension to such a
degree that it does not cause
bobbin thread winding turbulence
Move it up in case (A)
Move it down in case (B)
LH4-B800E
5. Troubleshooting guide
Stopper should not
protrude from inner
rotary hook.
(A) (B)
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4-8
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