Adjusting The Needle And Looper Timing - Brother RH-9820 Instruction Manual

9-4. Adjusting the needle and looper timing

NOTE:
The needle bar moves through two needle drop cycles for each single turn of the upper shaft pulley. The needle drop
movement toward the left side (knife cutting side) is called the "inside sewing position", and the needle drop movement
toward the right is called the "outside sewing position". In addition, the amount of movement involved when the needle bar
rises from its lowest position until the tip of the looper at either the left or right is aligned with the center of the needle is called
the "loop stroke".
The left and right loop strokes must be the same as each other. This section describes the adjustments to be carried out so that
the left and right loop strokes are the same.
* Before carrying out these adjustments, set the zigzag width (stitch width). (Refer to "9-2. Adjusting the zigzag width (stitch
width)".)
0484B
1. Remove the two screws (1), an then remove the needle bar guard (2).
2. Turn the upper shaft pulley (3) to set the needle bar to its lowest position at the inside sewing position.
3. Use calipers to measure the length from the edge of the needle bar (4) to the top of the needle bar bush holder base (5).
4. Next, turn the upper shaft pulley (3) until the tip of the eye looper (6) is aligned with the needle center (7).
5. In the same was as in step 3, use calipers to measure the length from the edge of the needle bar (4) to the top of the needle
bar bush holder base (5).
6. Calculate the difference <a> between the value obtained in step 5 and the value obtained in step 3.
7. Repeat steps 2 - 6 and calculate the difference <a'> for the outside sewing position in the same way as for the inside sewing
position.
* For the inside sewing position, align the tip of the eye looper (6) with the needle center (7), and for the outside sewing
position, align the tip of looper R (8) with the needle center (7).
0487B
Lowest position
of needle bar
(Seen from the front)
0488B
RH-9820
When center of needle is
aligned with tip of looper
(Inside sewing
position)
8. Loosen the screw (9).
9. Move the LS holder base (10) to the left or right to adjust
so that length <a> and length <a'> are the same.
10. Once adjustment is complete, securely tighten the screw
(9).
9. STANDARD ADJUSTMENTS
<a> = <a'>
(Outside sewing
position)
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