Brother T-8422C Instruction Manual page 79

Color in
Mark
Needle bar
lowest position
Mark
8. Loosen the screws (10), and then remove rotary hook
3041M
base cover FL (11) and FR (12).
(The screws (10) is designed so that they cannot be
removed from the rotary hook base cover FL (11) and FR
(12) to prevent them from being lost.)
9. Loosen the set screws (13) (three each at left and right).
(However, be careful not to loosen them too much,
otherwise the set screws (13) will touch the inside surface
of the rotary hook base and the pinion gear (14) will not be
able to turn. Loosen the set screws by the minimum
amount which will still allow the rotary hook to move
freely.)
10. Turn the rotary hook by hand to align the rotary hook tip
(15) with the middle of the needle. (Do not turn the
machine pulley at this time.)
11. Tighten the set screws (13).
(Tighten the three set screws (13) a little bit at a time in
order so that the pinion gear (14) does not become
tilted.)
12. Remove the tape that is securing the machine pulley.
3042M
<For T-8421C, T-8422C and T-8722C>
13. Use an oil-based marker pen to color in the hollow of the
needle.
14. With the needle raised, turn the machine pulley forward
while pushing the needle against the rotary hook tip (15)
with your finger to make a mark from the rotary hook tip
(15) in the hollow of the needle.
15. Check that the distance (C) from the intersection
between the mark from the rotary hook tip (15) and the
center line of the needle to the top edge of the needle
hole is 1–1.5 mm.
* If the distance is not 1–1.5 mm, loosen the screw (5)
* If dimension (C) has been adjusted, the highest
3043M
If using a thread such as polyester thread which does
not easily form stable loops
* If problems such as skipped stitches or upper thread
breakages occur, set the above distance (C) to 0.7–1.2
mm to make it easier for the rotary hook tip (15) to catch
the upper thread loop.
NOTE:
• When the stitch length is changed, distance (C) will also
change, so re-check distance (C) at such times.
• During quick reverse operation, distance (C) for the left
needle will become shorter, so do not set it to less than
0.7 mm, otherwise the rotary hook tip (15) may touch the
projection (D) and this could damage the rotary hook tip
(15).
2262B
T-8421C, 8422C, 8452C, 8722C, 8752C
13. STANDARD ADJUSTMENT
again and adjust the height of the needle bar.
reference line (3) on the needle bar (2) may be hidden
by the bottom edge of the needle bar base (4) when
the needle bar is at its lowest position, but this is not a
problem.
70