LH4-B800E
4 - 19
4. Adjustment
(A)
(B)
r
e
w
q
1 mm
e
y
t
y
(A)
(B)
e
q
w
(A)
(B)
e
w
1 - 2 mm
4-14. Adjusting the lower thread trimming
4-14-1. Adjusting the lower thread trimmer fixed knife engagement amount
Lower thread trimming complete
1. With the power turned off, move the lower thread trimmer cam lever
q
in the direction of the arrow so that the knife
driving lever
w
is in the position shown in the illustration. Check that the cam (A) of the movable knife
e
is sitting
securely on top of the cam (B) of the base plate
r
.
2. Loosen the screw
t
, and then adjust so that the fixed knife
y
and the movable knife
e
are engaged by approxi-
mately 1 mm.
*
If the engagement amount is too small, the lower thread may not be fully cut, and the material may get caught
when it is removed after sewing.
4-14-2. Adjusting the lower thread retaining amount
Smaller
Larger
1. Turn on the power and set the sewing machine to the home position.
2. Loosen the screw
q
, and then adjust the lower thread retainer
w
to a distance of 1—2 mm as shown in the
illustration.
*
If the lower thread retaining amount has been reduced, check that the roller (B) of the lower thread clamp plate
e
is sitting securely on top of the lower thread retainer cam (A).
*
If the lower thread is pulling up at the first stitch at the sewing start, check if the lower thread is being pulled out of
the lower thread clamp plate
e
, and that it is not too loose when it is coming out from the bobbin case.
<If the lower thread retaining amount is too small>
The lower thread will pull out of the lower thread clamp plate
e
at the first stitch at the sewing start, which can
cause problems such as lower thread cast-off, lower thread loops or poor lower thread winding.
<If the lower thread retaining amount is too great>
This can cause problems such as poor sealing at the sewing start, or wound lower thread sticking out of the rear
tack.
Summary of Contents for LH4-B800E
Page 55: ...LH4 B800E 2 30 2 DISASSEMBLY ...
Page 87: ...LH4 B800E 3 32 3 ASSEMBLY ...
