Replacing The Bobbin Case And Threading The Thread; Thread Tension Reference Guide - Brother LK3-B438E MKII Instruction Manual

7. CORRECT USE

7-5. Replacing the bobbin case and threading the thread

Turn off the power switch before removing and replacing the bobbin case, otherwise the machine
may operate if the foot switch is depressed by mistake and serious injury could result.
Pull the shuttle race cover q toward
you to open it.

7-6 . Thread tension reference guide

Thread
Upper thread tension (N)
Lower thread tension (N)
Thread take-up spring height
(mm)
7-6-1 . Lower thread tension
weaker stronger
q
Adjust the thread tension to the weakest possible ten-
sion by turning the thread tension nut q until the bob-
bin case will not drop by its own weight while the
thread end coming out of the bobbin case is held.
23
CAUTION
e
q
Insert a new bobbin into the bobbin
case, and then pass the thread
through the slot w and pull it out
from the thread hole e. Check that
the bobbin turns in the direction of
the arrow when the thread is pulled
at this time.
#60 or equivalent
0.7 - 1.3
0.3 - 0.4
6 - 8
LK3-B438E Mark II
w
Pass the thread through the lever
thread hole r, and then pull out ap-
proximately 30 mm of thread.
Thread take-up spring tension
(mm)
Pre-tension (N)
Needle
7-6-2 . Upper thread tension
Turn the tension nut q(main tension) to adjust the
tension as appropriate for the material being sewn.
Furthermore, turn the thread nut w(sub-tension) to ad-
just the remaining length of upper thread to 35 - 40
mm when the thread take-up lever is not used.
r
30mm
0.4 - 0.6
0.1 - 0.3
TQ 1#12
w
Stronger
Weaker
Stronger
Weaker
q