Brother LH4-B800E Service Manual page 104

4-13-7. Adjusting the upper thread scissors gradual opening timing
Starts touching at 1.5—2.5 mm
w
(A)
q
r
q
w
Turn on the power and set the sewing machine to the home position. Then press the RESET key to lower the presser
foot.
1. Loosen the screws q, and then adjust so that the distance (a) between ridge line (A) on the opening cam w and
the upper thread scissors e is 0.5 mm, and so that ridge line (A) on the opening cam w is parallel to the feed
direction.
2. Loosen the screw r, and then adjust so that the distance (b) between the rising section (B) of the upper thread
scissors e and the tip of the opening cam w is approximately 0.5 mm when the upper thread scissors e are
closed. If you would like the scissors to start opening earlier, make the distance smaller. However, if the distance
is too small, check that the work clamp does not touch the rising section (B) of the upper thread scissors e or the
opening cam w when it is lowered and prevent the upper thread scissors e from opening.
Check that the upper thread scissors e gradually start opening after the material has been fed by 1.5—2.5 mm.
*
* Apply grease to edge surface (C).
(B)
(C)
e
0.5 mm
(b)
0.5 mm
(B)
(b)
(a)
0.5 mm
0.5 mm 0.5 mm
(a)
r
(A)
LH4-B800E
4. Adjustment
4 - 17