Adjusting The Needle Bar And Looper Base Turning Center - Brother RH-9820 Service Manual

7-30. Adjusting the needle bar and looper base turning center

The turning center for the needle bar and the looper base is accurately adjusted at the time of shipment from the factory.
If the sewing machine has been disassembled (such as when replacing the needle bar gear block unit, needle bar or looper base),
adjust the position of needle bar bush U (2) so that the clearance <a> between the needle and the tip of eye looper (1) remains
uniform while the looper rotates through 360°.
NOTE:
Before adjusting the position of the needle bar bush U (2), check that there is no play in the needle bar gear block and the
looper base. If there is any play, adjust while referring to "6-2. Needle bar mechanism (1): Adjusting the pressure of the needle
bar gear block" and "6-8. Looper base mechanism: Looper base pressure adjustment".
Index mark
0752B
<Adjustment>
1. Loosen the two bolts (3), and then remove the needle bar guard (4).
2. Turn the upper shaft pulley until the tip of the eye looper (1) is aligned with the center of the needle.
3. Turn the looper base (5) by hand and check that the distance A between the tip of eye looper (1) and the needle when the looper
base (5) is turned to 0° is the same as the distance B when the looper base is turned to 180°.
4. If there is a large difference between distance A and distance B, loosen the three bolts (6) and move the needle bar (7) gently
forward or back to adjust the position of needle bar bush U (2). Tighten the bolts (6), and then repeat the check in step (3).
5. Turn the looper base (5) by hand and check that the distance C between the tip of eye looper (1) and the needle when the
looper base (5) is turned to 90° is the same as the distance D when the looper base is turned to 270°.
6. If there is a large difference between distance C and distance D, loosen the three bolts (6) and move the needle bar (7) gently to
the left or right to adjust the position of needle bar bush U (2). Tighten the bolts (6), and then repeat the check in step (5).
7. Carry out the check in step 3 once more.
NOTE:
• Once adjustment is finished, turn the upper shaft pulley and check that the needle bar moves gently up and down.
• If a sheet of paper is placed under the needle and the needle drop position is adjusted so that the needle makes a single hole in the
paper, the distance <a> between the needle and the tip of eye looper (1) will still not be uniform.
Needle
Eye looper(1)
When looper base is at 0°
When looper base is at 90°
RH-9820
7. ADJUSTMENTS
When looper base is at 180°
When looper base is at 270°
0753B
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