Brother LK3-B434E MKII Instruction Manual page 35

7. CORRECT USE
7-6-1. Guide to maximum sewing speed
<Standard hook>
Use
8 layers of denim
12 layers of denim
Ordinary materials
<Large hook>
Use
8 layers of denim
Ordinary materials
7-6-2. Lower thread tension
weaker stronger
q
7-6-3. Upper thread tension
29
Max. sewing speed (rpm)
2,500
2,300
2,500
Max. sewing speed (rpm)
2,500
2,500
w
Stronger
Weaker
Stronger
Weaker
q
LK3-B434E Mark II
NOTE:
The thread may break due to heat under some sewing
conditions. If this happens, reduce the sewing speed, or
use the liquid cooling tank (option).
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.
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
adjust the remaining length of upper thread to 35 - 40
mm, when the thread take-up lever is not used.